>I just wanted to ask whether or not it's true that my '85 528e will be rather
>dangerous to drive in the snow. I just got her and have not experienced
>winter, which is normally quite extreme here in Providence RI. Should I get
>snow tires? Chains (?!)-rather not.
>I have already skidded on wet pavement and it was quite frightening.
>Fortunately, nothing was damaged and no one injured. Except my ego...
The E28 chassis is known for being a bit "tail happy" at times. This
is not so much a flaw, but a characteristic. This behavior can be very
useful or very dangerous, depending on the driver's knowledge of car
control. The car can get tail out under two circumstances:
Too much throttle in a turn -- typically encountered when
accelerating through an intersection. The rear tires loose traction
due to wheel spin, since the car is already rotating in the turn, the
rear end swings around.
Letting off the throttle or applying the brakes in a turn. Slowing
down transfers weight (and traction) from the rear to the front. With
a semi-trailing arm rear suspension, the loss of traction is
exacerbated by the fact that the camber goes from negative to
positive. This can lower the traction in the rear to the point that it
starts to slide. Again, since the car is rotating through the corner,
the rear end swings out.
If situation number one happens, and the driver's reaction puts the
car into situation number two, the car will spin really well.
Here's some advice:
Go to some kind of car control school, preferably one which has
wet skip pad work. Get very comfortable with the correct-pause-recovery
process of controlling a tail-out skid. (It's waaaaaay fun.) Find a
nice, big, wet, empty parking lot to practice after you have learned the
If you expect to encounter ice, throw a 100 pound bag of sand in the trunk.
I believe this advice can be found somewhere in the owners manual.
Snow tires are probably a good idea. Being from sunny California, I
can't help much here.
Rear drive cars give higher performance and better control, but if you
don't know what to do with the extra control, you may find yourself
pointed in the wrong direction.
Peter LaPine: plapine_at_star.enet.dec.com
Don Eilenberger: dje_at_bellcore.com
>I plan to attempt to do a valve adjustment on my car this weekend (my
>first time!). I have a feeling that the job is really easy, but that
>having someone experienced offering tips like pointing to the valves
>:-) would be handy. I have the Bentley book, which is reasonably
>clear, but I was wondering if one of you old pros could recall some of
>the "lightbulbs" that went on the first time you did it yourself.
>Before starting, looking through the guide, here are some questions
>1) Crankshaft rotation is done on the "vibration damper bolt". Where
>is that? Figure 4-25 of Bentley shows the vibration damper: is the
>bolt where the pictured wrench is securing it? Or is it somewhere
I don't know about the 325 engine.. but I find it MUCH easier to
rotate the engine using the nut on the alternator. I can fit a large
socket (I think 19mm) and a 1/2" ratchet on this nut.. no way I could
get it on the crank "vibration-damper-bolt" - which is the bolt at
the end of the crankshaft which holds the damper on. (Dead center
at the bottom of the engine, facing the radiator). You may have
to use one hand to put some additional tension on the alternator
belt when turning it.. but it sure beats trying to get a wrench
all the way down to the crankshaft. Always turn clockwise...(or the
nut will loosen up).
On the 535i, I remove the fan clutch assembly by loosening the large
nut immediately behind the fan clutch. NOTE: it is reverse threaded!!!
So turn it CLOCKWISE (instead of counterclockwise) to loosen it. I
use channel locks to remove it. Then I use a large screwdriver blade
against the heads of the bolts which fasten the fan pulley to the
water pump to turn the engine over to potition the cam lobes for
appropriate valve adjustment
Place the screwdriver blade against the top of bolt head in
clock position 1 and against the bottom of the bolt head in
clock position 7. With the handle sticking out past position
1, push down and the engine will turn over. Besure to keep pressure
toward the engine. Be careful not to slip and punch a hole
in your radiator...
>2) The stiff wire tool: can I use a coat hanger?
IF you can find one the right size.. I usually use a allen wrench
(don't remember what size..) it is very stiff, and has the
needed "L" shaped hook in it. Rummage through your tools.. you'll
find something that works. I sorta think a coat hanger wire might
not be strong enough.
>3) Do I really need to take my plugs out to do the valves? I'm
>planning on replacing them anywaythis weekend as part of the
>Inspection II; does this really help.
YES! Unless you're godzilla! IF you don't take out the plugs, you'll
be attempting to turn the engine over against cylinder compression.
Removing the plugs makes this a WHOLE LOT EASIER! (And if you're
replacing the plugs.. why NOT?)
>4) Figure 4-27 shows the feeler gauge being inserted. Where exactly
>is it going - between the rocker eccentric and the top of the valve
Exactly. And - to really adjust it correctly, I make certain that the cam
lobe is facing exactly away from the rocker mating surface when I make the
adjustment. This does require more turns of the crankshaft-- but makes for
a better job.
Just make all the valves have the same tension- that's important because
you don't want the relative clearances to change when the engine heats up.
loosen the nut
place the feeler gauge between the concentric disk
and the valve stem
press the concentric disk towards the valve stem and
at the same time tighten the nut
recheck the clearance (should be a SLIGHT drag -
you shouldn't have to force the gauge in, nor
should it slide in with no resistance - just some...
this 'feel' is what comes with experience...)
and repeat, if necessary, until it's right.
this is where you can spend some time. I usually
have 2 or 3 that require diddling back and forth
a few times until they're right. Remember, since
you're taking the time to do it, you may as well
get it right...
>5) What exactly is being accomplished by adjusting the valve
>clearances - if the valve is closed, and there's clearance between the
>rocker and the stem, why should it matter if the tolerances are off a
>bit? What would the performance implications be?
You're setting the valves so they open the correct amount, and at the
correct time in relation to the ignition/exhaust cycles. The tolerances
are surprisingly small - minor changes do lead to rough idle. As far
as performance.. if they're way to tight, you stand a good chance of
burning the valves (they aren't closed enough to cool), and ruining
a camshaft (constant contact lobe/lifter - can lead to oil starvation
and galling of the cam). If they're too loose, about all you'll have
it lots of noise and a loss of power (not open long enough to let all
the mixture in, or all the exhaust out). I guess it is possible that
the extra impact on the cam/rocker could also cause some damage if they're
too loose.. but I've never seen this personally.
>6) Any tips on different clearances I might want? '86 325
Set the plug gaps to at least the BMW specs... a bit over won't hurt
(0.002-4) and on 535's is known to improve the idle. (NOTE, this offers
no advantage on the M20 (2.5/2.7 liter) engines.)
>Any other useful tips
Several to be exact:
Do it with the engine stone cold! - Meaning do it after the engine
has sat not running overnight! I have found from experience that you
cannot adjust BMW valves on an engine that is even a little warm.. the
aluminum head changes dimensions so much with temperature that by the
time you've gone from one end of the valve train to the other, the
settings you set at the beginning are not anything like what you set
for the last one.
Do it at least twice.. don't ask me why, but BMW valves always seem
to require this. The first time through you get them close.. the second
time you'll get them dead on. I always use three feeler guages. The 1st
is 0.001" smaller than spec, the 2nd is the specified spec, the 3rd is
0.001 larger than spec. When you're done #1 should go through with NO
drag. #2 should go through with a bit of drag. #3 should be very hard
to push through.
Get angled feeler gauges (Sears used to have them) that are made
for adjusting valves. The layout of the BMW valve train is such that
the slight (30 deg. or so) angle on the end of the feelers makes the
job MUCH easier.
Don't do it when you're likely to be in a rush. If you know you have
to go somewhere in 3 hours, wait until the next day.. the first time
you do this it will take a while, and the job will go better if there
isn't an S.O. popping out every so often asking "are you almost done??
We have to leave soon..."
Don't drink and adjust valves (a lesson I learned when I owned a
Jag XKE - which required REMOVING the twin cams to adjust the valves).
Buy a new valve cover gasket. Old ones USUALLY work - but when they
don't it's a pain to have to remove everything to get at it again!
Change the oil afterwards.. just in case any crap fell in while the
engine is open.
While buying the valve cover gasket.. get a few extras of the lock
nut and little bolt that go though the eccentric adjuster. I've never
broken one.. but they are very small and look easy to bust (which would
ruin your day if you don't have a spare). I use the 10MM box wrench from
my trunk tool kit on these - it's about 6" long and seems to provide just
enough leverage to keep me from overtightening these. I don't know what
the torque spec is on them, but it would be difficult to get a wrench in
there anyway while attempting to keep the eccentric from moving.
Doing the actual adjustment.. I usually loosen the nut enough so the
eccentric moves easily, then insert the feeler and move the eccentric
until I can feel it contact the feeler/valve stem. I then tighten the nut
just a bit, and try moving the feeler. You'll find that tightening the nut
tends to close up the adjustment, so you will have to now move the
eccentric with the slightly tightened nut. When you think you have it
right - use feelers 1, 2 & 3 to check. If it feels OK - then tighten
the nut a bit more, and check with the feelers. After you do the
first few, this will become easier. Make sure you check after each
tightening of the nut with the feelers.. the clearance does tend to
change *just* a bit. Don't overtighten the nut/bolt - I use 3 fingers
on the end of the 6" wrench.. haven't had one break or come loose yet!
Replacing the plugs.. hopefully you're using the silver ones that
BMW specs.. others just don't seem to work as well. You should not
need anti-seeze (the plugs are nickel plated).. and you should TORQUE
them to the correct specs. Overtighten and you stand a chance of
stripping the threads in the head. Undertighten and they'll back out
while driving.. a good torque wrench (Sears ones are OK) is a cheap
long-term investment that any driveway mechanic SHOULD have.
14.3.2: Loose Big 6 Oil Spray Bar Bolts
The hollow bolts that hold and take oil to the bar which
provides oil to the cam lobes on the big 6 engines are
prone to loosen up, with potentially serious consequences!)
(by dje_at_mail.bellcore.com (Don Eilenberger))
Actually - there are two of them to look for (and it turns out
BMW-Alfred of the 528i/533i's has had them come loose also,
plus my mechanic friend ALSO said "they all do that...").
So.. whilst the valve cover is off for your periodic valve
adjustments - check the TWO bolts (13mm heads) that go
THROUGH the oil spray bar line that runs forwards/back on
top of the engine (over the camshaft). They'll be pretty
I tightened to something like 10-11 ft/lbs - more than this
I wouldn't go - these are hollow bolts - and possibly
aluminum - so there is a GOOD chance of shearing off
the heads if you overtighten them. At about where I
stopped, I could just see a bit of deformation of the
actual oil spray line..
2. HOLLOW BOLT - A new hollow bolt has been developed and
is now available to secure the camshaft lubrication pipe
on all BMW models equipped with M10, M30 and M70 engines.
The redesigned bolt features a Tuflok(tm) coating on its
threads, which eliminates the need to retorque the bolt(s)
after the initial installation.
There has been a thread here - on the number of times
people have found these bolts loose - they should be
checked whenever the valves are adjusted. The last time
I adjusted BOHICA's valves - I installed the new style
bolts. The article claims that once they are installed
and torqued properly, they should not be removed, loosened
To identify if you need the new bolts (1) if they loosen
up by themselves - you do (2) if your bolts do NOT have
a ring machined in the top of the bolt - you do. I would
also suggest replacing the crush washer that goes under
the bolt at the same time (something the article doesn't
The part number is 11-41-1-738-621, and suggested tightening
torque is 11-13Nm (8.1-9.6 Ft/lb).
Don Eilenberger (dje_at_mail.bellcore.com)
14.3.3: Transfer pump
For more info (checking the xfer pump,etc), see the E30 chapter (15)
(by Harvey Chao: Harvey_Chao_at_smtp.esl.com)
You will need:
1 screw type 1/2" hose clamp
1 screw type 3/4" hose clamp
(These are to replace the crimpons, which you just wheedle out
carefully with needle-nose pliers)
That's it! Of course, to be really safe, you should buy the gasket
that seals the transfer pump to the gas tank. The sending unit
is in the center of the transfer pump mechanism. The sending
unit is non-servicable. It is a silver canister, about a foot long,
with electrical connections on top and a small nut with ground
strap on the bottom. There are a couple of small (2 to 3mm)
holes down the side of the pump. You'll get gasoline all over
yourself if you aren't careful when you remove it. The new
sending unit should have the o-ring, but check to make sure
it does. I tried to take my sending unit apart, but all I did was
screw it up worse (silly me - I thought it was the transfer
pump at first!)
Steps to get the unit out:
get access to it first (remove trim piece in back of trunk)
lift up floor of trunk
Unscrew the cover - it's a disk about 8" in diameter
You need a 7mm socket wrench. Pretty small, so make
sure you have one. It's the same size that the distributor
cap uses on an '83 528e.
Take the hoses off FIRST - makes life a lot easier
There are two nuts for the sending unit - you have to
take the sending unit out to get the transfer pump out,
unless you like to spend about 5 minutes trying to angle
the whole assembly out
Unscrew the 8 or 9 bolts for the transfer pump slowly,
going round and round (I did that because I didn't have
a new gasket and didn't want to mess it up)
>The oxygen sensor light went on in my 1988 528e. I have replaced the
>sensor with the same exact model/part number as the one that was in it
>before (A Bosch; 4 wires attached to the sensor) at the cost of 150 bucks!
>The light still stays on.
save your $225!!
there's supposedly a 100mA fuse in the back of the instrument panel
behind the speedo that needs to be replaced in order to turn
off the light.
Above the accelerator pedal, there's a plastic gizmo box that
is a little odometer. It basically blows the fuse after
every 30Kmi or so. You need to reset that by pushing the
recessed button with a screwdriver or pencil, so it can blow
the new fuse you will put in 30Kmi later...brilliant huh?
Now, don't ask me why the O2 light is run off of a not-readily
accessable fuse that needs to be replaced every 30K mi. That's
outright stupid for those who can remember to replace the O2
sensors ourselves. (It's more reason to charge more labor and
therefore justify the charge to replace the O2 sensor at the
Anyways, I haven't bothered with replacing my fuse just yet. I'll
do it the next time I yank the instrument cluster out and take it
In the meantime, I've just removed the O2 light from the panel
above and moved it to one of the spare locations. My O2
'light' stays off :-)
14.3.5: Idle problems
From: dje_at_mail.bellcore.com (Don Eilenberger)
Date: Thu, 8 Dec 94 22:40:45 EST
Evan W Evans (de'juvu).. asks about 535 idles problems. Something I just
happen to know a bit about (a 2 year battle with BOHICA).
>Subject: 535is Driveability Problems
>I just installed a new Bosch idle control valve in my '88 535is (55K) hoping
>to cure an annoying idle/driveability problem (it didn't help so I cleaned the
>old one up and reinstalled it, car runs the same maybe slightly better).
>Symptoms: Idle tends to vascilate between 650-750rpm and the driver can
>perceive a slight shaking of the car due to the idle while at a stop. The car
>stumbles slightly when cold and I think I'm hearing a slight backfire before
>it's warmed up. I've also detected that it doesn't pull smoothly once I'm
>around approx. 2700rpm. It feels like the car pulls....hits 2700rpm and
>begins to lose power then pulls through 3000rpm.....and loses a little torque
>andthen begings pulling thru the rev range again. Granted this is such a
>slight loss in power it's probably imperceptable to most, but I want to fix it
>unless I find out that "they all do that." I've checked for vacumn leaks and
>found none. I've installed new Bosch Platinum plugs and increased the gap as
>advised. What else am I missing? Also, any remedies for the "hard to shift into
>second gear when it's cold problem"? Any thoughts on installing a K&N air
>filter or other mods i.e.,short shifter kit, chip, etc.?
Even, I won't go into the other item's you address, but THEY ALL DO THAT,
more or less. Things to do:
Throw out the Bosch Platinum plugs - they're basically not compatible
with this car. Spend about $4/each for the Silver ones that are ESPECIALLY
made for just this engine (check a BOSCH cross-reference book - guess what?
The only engine using these plugs is the big 6!).
Set them to 0.032" minimum gap. Even to 0.035-38" won't hurt, the
ignition system can easily handle it.
Install and TORQUE them in with no anti-seeze. 20 fl/lbs is about right.
Adjust valves to minimum of +0.002 over spec. +0.004 isn't even
noisy and will help even more.
Run mega-dose of techron full strength stuff (not the watered down
k-mart stuff) [mega-dose = 2 16oz can's in the last 1/4 tank. Run until
almost empty. Fill up. Change oil!!).
Run the piss out of it. It will like it.
Problems with the '86-88 big six engine idle is related to exceeding
(vastly) the EPA emmisions standards. The things run VERY lean at
idle (CO is almost unmeasureable at the tailpipe). None of them idle
great - but the above can make it tolerable - and not embarrassing
at a stop light (car rocking and rolling). The biggest change is made
by opening up the valve adjustment, followed by the correct plugs
and a wide gap. You'll notice as these open up with normal wear,
the car runs better and better - I'm often disappointed after I tune
BOHICA up, 'cause it runs WORSE - and end up resetting the new plugs
to the gap the ones that came out were at - and doing the valves again.
I'm currently running the valves at 0.014 +.001 - .000 - this seems to
work well, and with BOHICA gonna reach 100,000 miles TOMORROW - the
cam and lifters look JUST LIKE NEW - the car uses no oil, and the
compression is excellent, and very even. It won't hurt the engine
to run these wider - and will greatly improve the idle.
Don Eilenberger says:
What do I set the valve clearance (lash) to on my '87 535i?
The answer is 'usually 0.02" over specs' - which are
0.012" cold. So the answer is 0.014" clearance.
The reason - it helps the crappy idle these engines are
afflicted with due to BMW's attempts to meet emmission
regs from around 1985-88 (they actually FAR exceeded them..
there is NO measureable CO at my tailpipe - have to go back
to the exhaust manifold to see a reading).
If the car IS tuned to specs - it idles very poorly and
tends to intermittently stall. Not all of this may be due
to the valve clearance and plug gap - but using the wider
settings sure helps.
Don Eilenberger says:
What do I set the plug gap to on my '87 535i?
I also set the plug gaps oversize - same reason again - in
this case, spec is 0.028" - I typically use 0.032"
If the car IS tuned to specs - it idles very poorly and
tends to intermittently stall. Not all of this may be due
to the valve clearance and plug gap - but using the wider
settings sure helps.
The following is copied from the Sunbelt Chapter BMWCCA July Newsletter,
which quotes John Watts of the Buckeye Chapter as follows:
"Owners of the following BMWs take notice of a potential
problem: all E24 bodies (6 series), all E28 bodies (5 series), early
E32 bodies (new 7 series, 1988 & 1989 models), and early E34 bodies (new
5 series, 1989 model). There is evidence of a design flaw in a bolt
that holds the steering box in place. Out of three vehicles we checked
we discovered one catastrophic failure, one significant deformation, and
only one appearing normal. What I am saying is this: I believe a
questionable bolt may be holding most of your steering boxes in place.
The old bolt part number is 32 13 1 123 865. The new bolt part number
is 32 12 1 136 051 and retails for about $12.00."
I'm just passing this along for what its worth....I'm a lawyer, not a
mechanic...but it seemed of a least some possible passing (!)
(by Don Eilenberger:dje_at_mail.bellcore.com)
I think the one thing that becomes obvious from the mail on
E28 front ends is that vibrations (1) are fairly common
(2) may not be caused by one single item.. but may be
the result of marginal conditions of several components.
Here on the list over the past year - I have heard the following
to cure front end vibrations:
Tie-rods, center rod, etc..
Upper strut bearings
My feeling is, that as ALL these components age - they work
together to ALLOW the vibrations. Good tight bushings may help
to damp possible vibrations that would be caused by very
slightly warped rotors. Absolutely perfect rotors would
not try to induce vibrations that could be amplified by
worn bushings. etc.. etc..
It appears from following the postings for the past year -
that the same symptoms are often cured by different fixes.
As was mentioned, the E28 front end is very simple and
lightweight, and probably is prone to component induced
vibrations - and ALL the components must be in good condition
for it to work like BMW intended.
(NOTE: Also see the section on suspension and steering Vibration (14.4.2))
From: Steven J Bernstein <stevenb_at_mordor.com>
Date: Tue, 8 Aug 1995 00:41:14 -0400 (EDT)
After much delay, I have finally created the E28 Brakes FAQ. I believe it
to be the most accurate information, to date, on this issue. If you find
anything in this FAQ that is incorrect or misleading, I would appreciate
it if you would contact me so that I can update the FAQ. I'm creating a
WWW page for myself on Mordor, and I will include this with all my E28
info there (be patient).
My knowledge of the E28 stems from about 7 years of ownership of one 1983
E28 that, at the time of this FAQ, has almost 250k miles on the clock (and
half a year's ownership of an '87 E28). I am a do-it-yourselfer, and my
experience is from the following: working on these cars, getting advice
from a particularly outstanding CCA Tips Rep who has serviced hundreds of
E28s, and from helping friends that have purchased the same BMW model
(E28) and have experienced similar problems with their cars.
If you have corrections, updates, or any additional information that you
feel can improve this FAQ, please send mail to bernstein_at_mordor.com.
Why is the FAQ needed?
It seems that the E28, the 82-88 5-series, while a popular car amongst BMW
people, has a reputation for developing a shimmy upon braking. This
shimmy becomes more noticeable over time and mileage. There are many
proposed solutions, but no one except BMW AG has spent the research
dollars and time to figure out the best solution, and IMHO, they have
found it. There has been some conflicting information on this list and
amongst some Roundel aftermarket suppliers about the best solution. The
intent of this FAQ is to clear up some of these questions.
2. In a nutshell, why does the front end shimmy upon braking?
This is a two-part answer:
(1) This car's suspension was intentionally designed to be responsive and
nimble, unlike many big American sedans which allow heavy weight to rest
on the front wheels. As a light suspension, it is more prone to
transmitting vibrations through the steering wheel. In the E28 (and to
some extent the E30 and E36), these vibrations are caused by deteriorating
components in the suspension. As these various components wear, the
evidence of their wear becomes apparent through vibrations in the steering
wheel most noticeably upon braking, and particularly between 50-65 mph
(2) The other half of the problem rests with the material used in the
brake pads and how it interacts with the rotors, and the combination
thereof. In the mid-80's, asbestos was outlawed in the USA. After the
E28 had already been *designed* and produced, BMW had to search for a
semi-metallic pad for replacement parts (scheduled maintenance), because
they couldn't sell the asbestos pads once the asbestos law went into
effect. The asbestos pads were originally selected because they were able
to generate acceptable levels of heat, while it was much more difficult to
reach similar specifications with semi-metallic pads. In time, the
additional heat generated caused the rotors to warp. During this period,
BMW issued many "updates". They used a number of rotor and pad
manufacturers, including Textar and Jurid. They did this until they felt
they got the proper pad-rotor combination. It was fairly common for
dealerships to replace set after set of warped rotors and ruined pads in
some customers' cars (dealers can fish for an answer, too). The rotors
were often replaced free under the 12-month parts warranty.
3. What parts should be replaced?
If you experience the symptoms mentioned above, your rotors are most
probably warped. If you get the shakes at different highway speeds even
prior to braking, you definitely have one or more worn suspension
components. Whether or not your need to replace suspension parts is a
question based on the car's history, age, and mileage. You should not
blindly replace the brake components without examining the rest of the
suspension. It is common to need additional suspension work in addition
to the brakes, particularly on cars with over 100k miles.
Replace all four rotors and pads with stock pads. From a dealer. They're
inexpensive. So do all four. ALL FOUR. The labor is so bloody easy that
you won't be sorry. Besides, after you do it, and you've insured the rest
of the suspension is working, you'll be really happy. REALLY. The most
recent service bulletin on this problem (which I have read but do not
currently have a copy) recommends replacing front and rear rotors as well
Brake Replacement Parts list:
Front pads (1 set - usually Jurid 506EE)
Rear pads (set)
Factory balanced rotors x 4
Front left brake sensor
Rear right brake sensor
Hex key screws x 4 (provide month/year of your E28 mfg.)
1-2 quarts brake fluid (per mfg. spec.)
As I said, the brake job is quite easy, so I don't see a reason to go into
excruciating detail about the procedure for replacing brakes. Bentley, as
well as the BMW shop manual, are very clear.
4. Why can't I simply turn the rotors?
Warped rotors cannot be turned. The excessive heat that has caused the
rotors to warp changes the composition of the metal so that they will not
turn properly, and the problem returns virtually immediately. New rotors
from a BMW dealer, with a BMW CCA discount, are so inexpensive that it is
economically foolish to turn old ones.
5. I'm trying to get the old rotors off, and I'm afraid of stripping the
hex key that holds them on. What should I do?
Don't strip the hex key! Use a fine dentist-type tool to clean out the
vertices of the hex key, so that a hex socket can be completely inserted
into the screw. Give it a shot of Wurth Penetrating fluid if you've got
it. Then (I do this before I remove ANYTHING else), with someone pressing
the brakes (or handbrake, if rear), apply a firm torque to the screw.
These screws shouldn't be too tight, although dirt and corrosion can make
it more difficult. If you strip it, get the easy-outs. I have, twice,
successfully removed these screws with easy-outs. It requires patience.
Otherwise, drill out the head of the screw and remove the rotor. If all
else fails, a sledgehammer (seriously) can be used. One or two whacks to
the backside of the rotor (be careful not to hit anything else) will, in
fact, do it. Remember, it is only a set screw. The wheel bolts firmly
attach the rotor to the hub. Also, on the rear wheels, you must loosen
the emergency brake so that the shoes back away from the inside walls of
the rotor. The adjusting nuts are accessible through the lug holes in the
hub. Then you can remove the rear rotors.
6. Should I flush the brakes?
You should be flushing the brakes once per year ANYWAY. Just do it.
7. Any other nebula to consider, Mr. Enginerd?
Yes, I'm glad you asked. Make sure you torque the wheels to 85 ft-lbs.
No more, no less. Believe it or not, this torque spec. insures the proper
heat dissipation between the brakes and the wheels.
8. I replaced the rotors and pads with the OEM stuff you suggested. It's
only 5k later, and they're warped again. Why??
This is a sign that you didn't find the root cause of the problem.
Assuming that they warped in less than 1 year and you got them from a
dealer, the rotors are under warranty. You can replace them for free.
But you have to examine the other components in the suspension, one by
one. Clearly, one must examine each bushing, each tie-rod assembly, and
the shocks. Bushings should be checked for hairline cracks; specifically
look at the lower control arm bushings and thrust arm bushings. Tie-rod
assemblies, track rod, and idler arm should be checked for play, and can
be checked by hand. Ball joints (in lower control arm or thrust arm) can
be checked by the bar-under-the-wheel test, usually, and should also be
checked for visible signs of boot deterioration. Shock diagnosis is
difficult, since the "bounce-test" is useless. Often, the type of driving
and mileage must be considered, as well as how tires wear, how well the
car tracks at high speed, and how much the car leans on cornering. My
first E28 lasted with shocks until 150k, my newer one seems to need them
after only 80k. Finally, a four-wheel alignment should be performed so
that the rear wheel alignment can be measured (there are no adjustments
here) and the front wheel alignment can be measured and adjusted. In my
older E28, the front strut bearings were the culprit, in addition to the
shocks. This made sense, since worn-out strut bearings are not able to
properly hold the strut in place upon braking, and the result was a couple
of BADLY shaking strut assemblies.
One other thing - don't forget that your wheels and tires are also
suspension components, and MAJOR ones. Admittedly, I have only used the
stock 14" rims. Rims must not be dented or out-of-round. The same is
true for tires. I have seen worn tires make a car feel like it was on its
last leg. Save the worn tires for the driving schools. You may need to
purchase new tires, but that's the subject of another FAQ. 8^) Whatever
you do, don't be a cheapskate when considering tires. (as an aside, for a
performance touring tire, I just got the MXV4-Energy tires, and love them)
9. Why buy stock?
I consider this to be fact; others say it's subjective, so standard
disclaimers apply. First, with the CCA discount, the price can't be beat.
If anyone finds a comparable set of pads/rotors that beats the factory
prices, I'd like to hear about it (local ADAP parts need not apply).
Second, all parts (excepts bulbs and brake pads) come with a 12-month,
*unlimited* mileage warranty. As long as you have a valid receipt from a
dealer, they will allow you to replace warped rotors - for those
do-it-yourselfers, the only cost is your time to do the labor. I would
check with the dealer, at the time of purchase, what procedure they use to
replace rotors under warranty. I have dealt with Foreign Motors West (MA)
and Hendrick Imports (NC), and they both are completely reasonable. Some
dealers will replace them for you even if you didn't buy them there, but
this is rare, so don't count on it. One year I went through 4 sets of
rotors until I isolated the worn suspension part that was causing the
problem (see previous question). As far as I know, I have not been able
to locate the Jurid brand pads from anyone other than the dealer. Also,
see the next question for a discussion of stock vs. aftermarket rotors.
10. C'mon, what's the difference between the stock rotors and the
same rotors from an aftermarket?
Well, aside from the warranty, which is REALLY important to me, the stock
rotors are spin-balanced at BMW after the OEM manufacturer (Brembo, Ate,
Balo, etc.) ships them to BMW. Some manufacturers claim to spin balance
their rotors, but they may use less reliable clip-on or glue-on weights,
whereas BMW shaves metal off the rotor to achieve the proper balance. My
experience is that from a reputable BMW dealer with an aggressive parts
department, you can buy rotors CHEAPER from the factory. The aftermarket
dealers that advertise in Roundel have been, in EVERY case, MORE expensive
(to my surprise as well), and there is rarely a warranty with their
11. OK, now I'm replacing suspension parts. Do polyurethane bushings help?
Not really, unless you are planning to modify the springs, struts, and
sway bars. Some people have claimed to use the 750iL bushings
successfully, but my feeling is that the car, in its stock form, wasn't
designed to run with these, and these stiffer bushings will put more
stresses on the rest of the suspension, which were not designed to work
Needless to say, any new bushings WILL help, if your existing ones are
worn. The stock bushings are very cheap - the labor is difficult, unless
you can remove the ball joint without damaging it, and have a workbench to
carefully press out the old bushings and press in the new.
12. OK, I'm using the stock pads and I'm happy. But the stock pads
generate a lot of brake dust. Can I use dust shields?
General consensus has been that dust shields are the WORST thing you can
do for the health of your suspension. While they do appear to keep the
dust off of the wheels, some people have claimed that the heat from
braking isn't dissipated properly, and some have empirical data of
amazingly fast rotor warpage with their use. A good wheel cleaner is the
best solution. I happen to prefer P21S, due to its overall excellent
design and environmental-friendliness (it won't kill your cat, it won't
ruin your glasses, it won't destroy your brakes). Admittedly, it requires
a bit of elbow-grease. But, like Zymol Wax, the results speak for
themselves. There has been some speculation about the negative side
effects of Armor All's QuickSilver wheel cleaner, but I don't know much
about that, except to say that anything corrosive should not be sprayed
near any brake components. Period.
14. Speaking of driving habits, can my driving habits cause my brakes
This is a tough question, because I have some firm opinions here, which
all may not agree with. I don't believe in automatic transmissions,
because I believe they relinquish much car control to mechanisms that
don't have eyes. I feel that with automatics, one must use the brakes
much more often since they have less control over the drivetrain. Some
people claim that braking with the engine (ie. downshifting) is wrong
because brakes are cheaper to replace than a clutch. Well, I got 220k out
of my first clutch, and I downshift ALL the time. I'd much rather replace
a clutch than play detective with my front suspension. Determining worn
suspension parts can be an expensive, frustrating, iterative process.
I guess my real point is that you shouldn't ride the brakes. You should
be aware of your driving so that you don't use the brakes until you need
to. That may sound simplistic, but if you think about it, and practice it
while you drive, you can drive smoothly and preserve your brakes for when
you actually need them. Short, firm braking, combined with downshifting,
allows far more cooling than riding the brakes for a hundred meters before
a stoplight, tollbooth, etc. Your brakes need the time/air to cool. I
also don't sit with my foot firmly on the floor at a stoplight, pressing
the pads against hot rotors, but this probably isn't an option on an
15. Can I do driving schools with an E28, or will it warp my brakes?
The answer to this is completely subjective. 8^) My answer would be yes,
but to be fair, the stresses on your car during a school are quite high,
so you shouldn't complain when things break. As Richard W. says, schools
do wonders at "exposing weaknesses" in your car. You can surely commence
rotor warpage during a day of "spirited" driving at a school.
16. Are BMWs the only cars that warp rotors?
No. In fact, due to non-asbestos pads being mandated by the government,
all cars now use them. One reason that this wasn't as much of a problem
with American cars is that they would die long before the rotors warped.
On my first E28, they warped after 130k miles. Another reason is that
these other cars are designed to provide very soft rides, which usually
means very heavy front suspensions, which masked out many vibrations until
the vibrations were quite serious. Now, with CabForward designs and more
nimble suspensions, I commonly hear about those new Chryslers warping
rotors in only 25k miles of driving!
17. Steve, are you this anal retentive with all your automotive repairs?
Date: Tue, 8 Aug 1995 12:51:22 -0400
Just a couple of points to add to your E28 Brake FAQ:
In my E28 M5 the factory replaced the front bushings with 750 hydraulic
bushings. With the larger wheels and tires which are stock on the M5
(225/50/16ZR tires), this is the only thing which prevented the shimmy from
recurring every 8k miles (on a new car, with nothing worn).
There is available a spun stainless steel hub cover, which redirects air
flow, and GREATLY reduces the incidence of rotor warpage. These can be
obtained from Carl Nelson at CNPR 1-800-466-8184.
For track use, if you wish to engage in spirited driving, and do not want
warped rotors, Cool Carbon Pads are a MUST, IMNSHO. They are the only way I
have avoided the problem. At a BMWACA drivers school at Laguna Seca, the
Instructor asked me why my rotors weren't warped, as all the other E28 M5's
he had been that day were. For the answer, see above.
>One further question on the "bomb", does anyone know just how it works? It
>appears to be just about the last thing in the car ("84 633) to go bad: heavy
>solid piece of metal with no moving parts. I now own a replacement unit at
>he suggestion of a local mechanic and am wondering what are the tricks to
>installation (and just possibly why I spent the $75).
...is a pressure accumulator, the hydraulic equivalent of the water storage
tank used in homes that draw well water. It stores pressurized hydraulic
fluid for power brake assist with no engine power, as well as instantaneous
response. This latter point provides a clue for failure diagnosis.
It is constructed to withstand > 25x atmospheric pressure, but internally
it contains a rubber bladder which can rupture. The sealed side of the
bladder is precharged to a high pressure (not sure how high), typically
with dry N2.
Recall Physics 101: fluids are nearly incompressible, but gasses are
readily compressed. As hydraulic pump output pressure increases above the
precharge pressure, the bladder deflects, further compressing the precharge
and accumulating hydraulic fluid. This fluid volume will remain at nearly
a constant pressure as it is withdrawn for braking even if the pump is not
If the bladder fails, the system becomes totally reliant on the pump for
pressure, as there is no longer any compressible volume in the hydraulic
system. This can result in hard initial brake pedal feel, an instantaneous
illumination of the red dash "brake" light (triggered by a sudden loss of
hydraulic pressure), then a softening of the brake pedal as pressure from
the hydraulic pump builds again.
Replacement is not particularly tricky, as the unit is sealed. However,
make sure to keep all ports/hose connections scrupulously clean, tight and
The above info comes from some use/design of industrial hydraulic systems,
but, particularly, from personal experience after nearly rear-ending
someone in city traffic in our '79 733 with defective accumulator!
Don't ignore the telltale signs, this is a safety issue. Power assist
for emergency manuevers will be delayed, reducing stopping margin! ***
Hope this helps!
BMW CCA #1167
325 iX, among others...
I have seen someone ask recently whether there is a bolt-on rotor upgrade for
the E28 M5. I will pass along information learned from Michael _at_ Bavarian
Professionals (Berkeley, CA ) at last weekends ///M car festival.
Rather than using 850 rotors, 750 rotors are a direct swap. According to a
reliable source, this is the rotor Dinan uses in their upgrade kit. Could
save you a lot of cash to buy some 750il rotors _at_ dealer w/your club discount
(not to flame Dinan).
As for whether M5 rotors will swap with the E28 535i, the answer is no.
14.6.1: Heater Control Valve Problems
The control valve in the engine compartment fails open resulting in
continuous heat. The core can be changed out for ~$35.00. You can check the
working of the rheostat by putting a VOM across the leads that feed the
valve. As you go from full cold to full hot on the rheostat, the voltage
should go from steady 12 volts (valve closed) to oscillating every few
seconds when the actual temperature matches the rheostat temperature, to 0
volts in the full heat position (valve open).
If the voltage does not vary as described, the rheostat is at fault. Good
luck tearing into the console!. Odds are that it will function as
described, in which case the valve is at fault. 4 screws and one connector
(plus $35.000) and you should be fixed. The whole valve assembly is $125.00
so be careful that you get the core only.
From: prreitz_at_amp.com (Paul R. Reitz)
Date: Mon, 20 Mar 1995 10:21:56 -0500
RE: Victor Fischer <vfischer_at_isbe.state.il.us>
>Date: Sun, 19 Mar 1995 09:12:18 -0600 (CST)
>Subject: 528e cool heater
>Last September I purchased a 1982 528e. In cold weather, when driving
>below 40 mph, the heater works fine. Above 40 mph almost no heat comes
>into the passenger compartment. In fact, it seems to get colder as the
Sure Victor. The problem is in the heater solenoid control valve. When the
internal rubber gasket rips, the valve doesn't leak, but the circulating
coolant can be sufficient to keep the valve closed when the modulating
electrical control shuts it off, and will even pop it closed without
electrical actuation at higher revs. You can get heat back for a while by
momentarily putting the car in neutral and allowing the engine to return to
idle. If the heat control selector is all the way up, the heat may stay on
for some time.
The fix is to replace the guts of the control valve. I've found some shops
that propose replacing the entire valve (at around $ 90 + labor), but some
of the aftermarket parts houses sell the valve guts for about $ 25. It's a
simple 10 minute job involving removing 4 screws, pulling the old valve and
inserting the new one. You'll lose coolant unless you drain some first.
Hope this helps!
Paul Reitz (prreitz_at_amp.com)
14.6.2: Fan Blower
From: Laurence R Swain <lswain_at_world.std.com>
Date: Wed, 4 Jan 1995 15:48:25 +0001 (EST)
The first dashboard heater fan on my '85 528e failed around 50K miles.
Fix it, I said. Ouch!, I said when I picked up the car -- $325 to replace it!
The second lock-up ocurred around 100K miles. Can't it be lubed, I asked?
Nope -- another $325! But this time I asked for the failed part.
The fan assembly has a 1920's look to it, but is really rather flimsy. I lubed the failed fan w/ 3-in1 oil from an oil can with a flex spout.
Hooked it up to benchtop 12V supply and ran it.
It was fine! Relubed and ran on the bench a few more times to assure that bearings
were liberally doused with oil, and put fan assembly back into the box.
At 150K miles, when the second replacement fan failed, I replaced it with the
one I had oiled.
A short while back, that fan started squeaking. Oiled it in place;
still running fine.
What I have learned: The bearings are lousy. Oil them from time to time
(especially if a squeak develops), and the fan's life should be determined
by wear on the commutator, rather than by failure of the bearings.
14.6.3: Heater Core Service
From: Larry Schuette <schuette_at_ait.nrl.navy.mil>
> My heater core needs replacing. My shop manual says
>I need to remove and discharge my AC unit. Is this true?
Short answer: Maybe not.
I replaced the heater core in my 83 528e over the weekend.
Fascinating project. Tear out interior, tear out firewall in the
engine compartment. remove 20-30 metal clips holding plastic together...
The good news was I didn't have to remove the AC unit. Instead of
removing the heater box as indicated in the manuals, I split the
heater box in situ, and removed the heater core. The old heater core
failed, because the foam to protect it from chaffing had worn out and
the plastic wore through. I wrapped the new one in foam and put it in the
heater box, reassembly was interesting, but doable.
I don't know what the dealer charges for this job, but
it's probably a bargain. I spent 12 hours doing this job, although
I work slowly and took numerous "cursing" breaks.
14.7.1: Wiring fog lights to work with low beams
Instructions for E28 535i (should apply to any E28)
There are two philip screws which attach the top of the fuse box (or power
distribution panel as the book calls it) to the bottom of the box. Remove
these two screws. You may have to remove the relays above the screws to get
at them. Find and remove the fog relay (marked in the owner's manual and
the Bentley). Remove the connector in the top part of the fuse panel (it's
in the slots that you push the relay in) for the 85 lead on the relay (if
you look at the bottom of the relay, the leads are labeled with the numbers
30, 86, 87, 85...so on). The easiest way to remove the connector is to use
a very thin flat screwdriver and push on the back of the spade to push the
little tab back into the spade so it slides out the bottom of the fuse
panel. Drawing below:
| <-- thin screwdriver
______ |__________ top of fuse panel
|\ <-- push this tab in from above
| to slide connector out the bottom
Now pull the connector out the bottom of the panel by separating the top
and bottom halves of the fuse panel. The halves do not separate much maybe
3 inches. Tape this connector up or use shrink tubing. You won't be using
this connector again. The next step is to remove the connector of the 85
lead of the high beam relay (this is ground, you might want to test for
such) in the same way but you will use this again.
Make a y connector with two leads to fit in the two slots you just removed
the connectors from and the third lead to fit in the connector that was
connected to the 85 on the high beam relay. Plug the y connector in (slots
and the extra lead). Tape or shrink wrap the y connector to previous 85
high beam conector. All that is left is to plug in the relays and test the
new feature (fogs on even with high beams on) and put the two halves of the
fuse panels back together. TEST!! before putting the halves together.
Instructions for E30 318i (should apply to any E30)
Same as above except disconnect 85 on the fog relay and put the y-connector
to the connector on the 86 of the high beam relay (this is +12v when the
ignition in the run position) and the 85 lead of the fog relay.
The nice part of this rewiring is that it is entirely reverseable since no
cutting is involved. I have seen as a Porsche mechanic too many car wiring
systems destoryed by poor rewiring for extras and especially sound systems.
I have also wired my fogs to function as longs as the light switch is in
the park or on position but that extra bit is more complicated than I can
explain in this media.
14.8.1: Replacing a clutch
From: Larry Schuette <schuette_at_ait.nrl.navy.mil>
Date: Mon, 13 Nov 1995 09:54:49 -0500 (EST)
How to replace the clutch in a BMW 1983 528e.
Or, how Larry spent his Christmas '94 vacation & $350.00 in parts.
My 83 528e is still going strong, with 151K miles on it. The
throw out bearing started to grind and make a lot of noise. I
could almost live with that, but I could also hear the pilot bearing
above the engine noise. That started to concern me. Not being
able to stand the thought of getting someone else to do it, I
pulled the transmission and replaced the clutch myself. I thought
this might make good FAQ bait.
The shop says that this is a 7 hour job. I can believe that
if you've done it 3 or 4 times. I spent two full days doing
this job. I have a very comfortable garage, complete with machine
shop (mill/lathe/welders), and air tools. (and a refigerator with
Xmas cookies and beer :)
First, if you're going to replace the clutch, buy the parts mail order.
Pressure plate, release bearing, pilot bearing and clutch plate
are standard. I would also plan on the Guibo, and the plastic
fulcrum point that the slave cylinder leverages off of. Mine was broken,
and was the reason that the release bearing fell apart.
In any event it's a $2.00 part that can only be replaced by
pulling the clutch. I replaced mine with a custom made brass piece
(convienent having a lathe). BMW also recommends that most of the
bolts & nuts you remove be replaced.
To wit; the 6 Nuts that connect the drive shaft and Transmission
the 6 bolts that hold the pressure plate on
the 6 copper nuts that hold the exhaust to the header
the 4 nuts that connect the rear drive shaft to final drive
I have had VERY good response from Maxmillians (see the FAQ) for
parts direct from Germany at good prices.
Besides the usual, you'll need to make or buy a Pilot Bearing Puller.
I've seen these advertised by Bavarian Auto Sports 1(800)535-2002 for
$30.00. I made mine by machine down an 8" long 3/8" bolt. By putting
a lip on the end, and then putting a 3lb brass "slammer" on it, I
was able to work it out (hold the slammer at an angle, and work your
way around the bearing).
A clutch plate alignment tool is a good idea. I machined one
from Delrin. 23mm body with a 12mm stub for the pilot bearing
(less a few thousands).
You'll also need a Torx socket. This is a female socket, I think
it's the E14 size. This is for the bolts from hell that connect
the transmission to the engine.
Safety glasses are nice to keep the crude from falling in
your eyes... (My car had lots of crude)
First, using 4 jackstands, get the car in the air far enough to
work under(make sure it's solid). Remove the wheels.
Put a hydraulic jack under the engine, use a block of wood
to prevent it from crushing the oil pan.
Remove the exhaust system completely. I took the oppurtunity to
recoat the O2 sensor threads. (13mm socket, and 15mm socket)
Remove the shield that covers the drive shaft (10mm socket)
With the transmission in gear, and a partners foot on the brake,
loosen the 17mm nuts holding the rear drive shaft to the final drive.
These are tightened teutonically tight. A long spanner & hammer worked.
Remove the 19mm nuts holding the Guibo and tranny together. Air drive
really helps here, other wise, put it in gear and loosen all before
Remove rear drive nuts and the center bearing bolts.
To pull the drive shaft out of the tranny was teutonic task. What
worked for me was wrapping nylon webbing around the drive shaft and
then using my foot to push the driveshaft off. This was an inovation
I was really proud of.
Remove the slave cylinder and tie it back up in the wheel well with
a coat hanger, or a $.10 welding rod :).
Remove the sensors from the bottom of the tranny - mark/remember
which one goes in which hole.
Remove the 17mm nuts and 8mm allen head bolts that hold the starter
motor. Yes, it is possible to jam your hands in there. I loosened
a couple of heater hoses and the air intake to get more room. A 5"
extension on a 17mm socket worked well.
Remove the 10mm bolts that hold the lower sheet metal on the bell housing.
While the crude and radiator fluid are idiopathically dropping on
your face, use the portable phone to request "Sink the Bismark" from
the local country station.
Put a second hydraulic jack under the transmission and remove the
rear mounts (13mm socket).
>From the inside of the car, remove the shift boot and pull all the
insulation up. Disconnect the backuplight switch, and using a
pair of needle nose plyers, remove the circlip holding the shifter.
Get a good look at how it goes together. Set aside for cleaning
Remove the shift mount assembly (13mm socket). WD-40 on the threads
seemed to ease the abuse that the rubber bushing was taking.
Now comes the fun part:
I'm told that you can remove the engine mounts and lower the
engine down 2-3 inches, so that there is more room above the transmission.
In any event, I didn't do that. There are 4 torx bolts that connect
the tranmsission to the engine. 2 are trival to get, 1 is sort of
challenging. 1 is an unmitigated pain. In order to get extra clearance,
I did the following. Remove insulation (carefully is optional),
place a piece of wood on top of the tranmission and jack it up to
crush the firewall/tunnel to get an extra 1" of clearance.
If you lower the transmission, and then lower the engine jack so that
the whole assembly tilts backwards, you get a fair amount of clearance.
Mine tilted back so that the head almost touched the firewall.
Then, using a universal joint (electrical tape wrapped around the joint
helps restrict the movement and stiffens it up - works great, another
innovation that I liked). Oh, Torx socket, universal joint, 3 5"
3/8" extensions and a 8" 1/2" extension and a breaker bar were needed.
I loosened all, then removed starting with the top. (Truth time,
I could'nt believe there was one up there, until the tranmsission
refused to seperate. I never actually saw the bolt, I could only
feel it. - Swear off German beer).
With a jack under the tranny, ease (with a pry bar) off the tranny.
It only weighs about 40 lbs, don't drag it across the floor.
Remove the abestos dust, and look at the flywheel. Any blisters?
Gouges? No, great, remove the pilot bearing. Otherwise, machine it
or buy a new one.
This is an excellent time to replace the tranny oil and take a break
(besides it 8pm, and it's dinner time)
Clean and replace/grease the release bearing.
Using the alignment tool, put the clutch plate and pressureplate
With a willing partner ease the tranny up to the engine. Be sure
to have it in gear (reverse was what it was supposed to be in), and
rotate the drive point. This will align the spline so that the
tranny can go in.
Start the Torx bolts, and on the three easy ones, tighten all the way
down, and then remove 1/2". This gets everything set.
Put in the top Torx. When done, re-call Country station and
request "Sink the Bismark".
Torque Torx to 65lbs, they were probably 100lbs from the factory. I
was told that this excessive torque is what warps the blocks and
causes asymetrical wear on cylinder #6.
In order to get the cluster out of the car you have to lower the steering
column on the 6 series. There are 2 10mm bolts accessable from below.
You don't need to worry about the steering box, since there is a rubber
guibo (sp?) in the column which provides enough flexibility. As for
the light switches. The main (left) switch has to come out with the cluster.
The fog light switch can be dismounted from the cluster by first unscrewing
the know, block the spindel from turning with a pin (hole is provided in
spindel) and then undo the nut with a fork wrench.
Just a word on TRXs. I've seen much on the list recently, good and bad (very
bad). Below is an example of the last kind that I'll try to explain after
addressing the main subject: why buy or not buy TRXs?
First, TRX was patented by Michelin in the 70s (if I remember correctly) as
a way to improve tire responsiveness/quickness/control, so mainly handling
performance, by increasing and controlling the tension of the radial carcass
all the way down to the rim (whereas other tires experience a strong
variation in tension of the carcass between the rim and the equator of the
tire, at the middle of the sidewall). It worked really well, so well that
those tires are still kept as references for responsiveness in handling by
car makers such as BMW, Peugeot and Mercedes in internal tests. However,
they require a specific rim hook profile, and this is where things got
tricky. In order to prevent mismatchs (people putting TRX on standard rims
and reverse), which would have been potentially very dangerous, NHTSA and
similar European bodies pushed for a metric rim to be used with TRX; this
way, no mix could be done. However, when TRX (despite its technical
advantages for the era) did not expand because of marketing and patenting
reasons, Michelin stopped developing new tires using this concept (I believe
around 1985). Hence the profil, tire pattern, and structure of the tire are
extremely outdated now, by 15 years or maybe more. Namely, the wear,
adherence, noise, bad weather performance (I'm talking normal TRX, not
all-season nor snow) all are pretty inacceptable now compared to a newly
engineered tire, while the handling is still great on cars that can
accomodate its power. The cars on which the TRX was originally fitted are of
the E24, E28 generation.
I certainly see no reason for anybody to switch to TRX on a modern car. For
those who are stuck with TRX wheels and do not care for the tires as long as
they provide performance for money, by all means switch to more modern
tires, despite the cost of the wheels. And for the happy few who own a
beauty originally issued with those tires and want their car to retain all
of its original, specific taste, those have much to gain in keeping their
14.9.1: One epxerience with a E28 Dinan chip
(by Don Eilenberger: dje_at_bellcore.com)
Low end torque.. as much or more than before.. is LOTS smoother
coming up the revs, so...
Idle is if anything improved (see next..)
Fuel economy... very hard to tell since on 10/1 they put the crap
oxy-gas in effect in NJ for the winter. Last year as soon as this
garbage started, my avg MPG (by the computer) went from around 21
to 18.. same this year. The reason I can't say exactly is that I
only had 2 tanks of gas go though it before I put the chip in (crap
gas that is..), and it seemed about the same effect as last year.
Since I put the chip in, I'm on my second tank.. the first gave
me about 19.5mpg.. the tank now is indicating about the same, maybe
a bit higher.. but was lots of high-speed driving so far (some
around 70-80mph for an hour or so - 6AM on the Garden State
The crap gas also effects the idle.. and so far since the chip has
been in, the idle is damn near good.. which last year I couldn't
say. I have been using Shell gas, which is supposed to contain techron,
which improves idle anyway.. so, your call on this.. it sure ain't
4. Hot/cold starting - seems about the same. Starts fairly easily
hot or cold, with a bit of a stumble the first 10 seconds after
a cold start...
General running is MUCH improved.. I do tend to give it full
throttle fairly often, since it seems to REALLY LIKE this
now.. very smooth right to where the automatic shifts it
at full throttle (about 6,200 rpm or so.. exact is hard to
tell since it happens pretty quickly). Had some passengers in
the car this AM - 13 year olds - whose comment was "wow.. this
car rules!".. so, take it from there!
I like the chip - and what is interesting is I found my copy of
the original sales brouchure for the car, which includes the
528 and M5 - and was looking at the fuel requirements for all of
them.. the 528 and M5 "REQUIRE" premium.. the 535 was supposed to
run on 87 octane.. so it looks to me like they had retarded the
piss out of the timing for the 3.5l engine. Dinan requires that
you use 91 octane with the chip "or pinging or knock may occur"..
no problem for me, since I always use premium for the extra