Section 11: M cars (M1, M3, M5, M6)

11.1: Overview

         11.1.1:   M1 history
         11.1.2:   E30 M3 Evolutions
         11.1.3:   96 M3 scoop
    11.2: Engine
         11.2.1:   E30 M3 Valve Adjustment
         11.2.2:   E30 M3 oil leak
         11.2.3:   E36 M3 Valve tappet noise
         11.2.4:   E34 M5 Accessory Belts

11.3: Brakes
11.4: Misc

         11.4.1:   E30 M3 Wheel Offset
         11.4.2:   E30 M3 wheel fitment
         11.4.3:   E30 M3 Front subframe cracking
         11.4.4:   E36 M3 Shifter fix
    11.5: Performance
         11.5.1:   E36 M3 LiteWeight parts
         11.5.2:   M5 suspension tidbits
         11.5.3:   E36 Exhaust
         11.5.4:   E30 M3 Sway Bar mount points

(NOTE for additional information see the chapter for the body style - e.g. for an E30 M3 see the E30 chapter, FAQ.15)

A short history and overview of the BMW M1. (C)1994 Andrew E. Kalman.

Basic Facts (and some rumors): The M1 went through several preliminary designs (e.g. the BMW turbo (2 units made), not to be confused with the 2002 turbo) before the design was finalized. Project E26 (1976) was really the first look at what would become the production M1. Lamborghini was originally supposed to do much of the production, but their financial woes ultimately prevented this, so BMW got a bunch of companies together (T.I.R., ItalDesign, Ital Engineering, Baur) to do design, fabrication and assembly. Final test and quality control happened at BMW, with a test drive. Cars were sold at approx. 100,000DM. It was widely rumored that BMW lost considerable money on each car. About 50 cars were sold as race cars from the factory, the rest as street cars of which many were converted to racers. 448 numbered cars left the factory. Several years ago a German bought a lot of the remaining parts with the intention to build a couple more, but I believe that never materialized. Every M1 engine (an in-house, 4-valve design, straight-6, 3.5l, iron block, dry sump, two-part aluminum head, mechanical injection, Marelli ignition/electronics), type M88, was broken in for seven hours on the dyno and guaranteed to deliver a minimum of 277hp (DIN). The Group 4 race car had 470hp (DIN), normally aspirated. These were the ProCar-series cars. The Group 5 car had turbos with over 800hp (DIN). M1s were made from November 1977 to December 1980.

Loose facts: The M1 has a lot of over-engineered parts. The brakes are huge (for 16" wheels w/205/55 and 225/50 P7's), the hub carriers are massive. Suspension can be set to one of three ride heights. The transaxle is quite strong (for the 277hp application, at least). It's a frame car made up from rectangular tubing and pressed sheet sections in and around the passenger compartment. Fiberglass body. The suspension geometry is designed to minimize squat under acceleration. 5 speeds, limited-slip, power assisted brakes, unpowered rack and pinion steering, radiator up front, the usual amenities (PW, A/C, stereo, etc.). Steering racks were made by two different suppliers (? and TRW), transaxle is ZF, brakes are ATE, wheels by Campagnolo, seats by Recaro (custom for the M1, not as fancy as the aftermarket ones). It has a near-smooth underbody (like the new Ferrari F355). Some parts can be recognized as coming from other BMWs of the era (steering column, handbrake lever, dash knobs, etc.). The later evolution of this motor was into the M635CSi, to (first-generation M5 and M6) electronic fuel injection, to variable intake plenum for low-end torque (second-generation M5) and now to 3.6l and other changes (third-(second-generation M5) and now to 3.6l and other changes (third-generation M5). A recent comparison of the M-cars in european car ("a visit to Motorsport" or something like that) shows that despite its age, the M1 is still the quickest, fastest and most valuable of the M cars. It is a bit antiquated in terms of technology (and emissions), though...

Legalities: BMWNA had absolutely nothing to do with the M1. M1s brought into the U.S. had to be federalized, and if you look at M1s in the U.S. you'll see many detail differences in how the met the specs. For example, some cars still have their filler caps outside on the body (twin tanks), but others had them moved to behind the little rear windows. The quality of the conversions varied a lot.

Subjectives: The M1's ride is FIRM. It handles like it's "on rails", and will smack you around a lot on turns because there's imperceptible roll and the seats do a poor job of keeping you in one place. It isn't too forgiving if the tail lets loose (this requires serious provocation or ineptitude). It's pretty loud inside, but european-spec cars often sound different, more turbine-like, than American-spec cars. Most parts are expensive, and sometimes not available. The fact that this motor showed up in the M5 and M6 means that there are some people in North America who know how to service it. The performance is pretty gutless below 3500 rpm, but takes off after that and really hits its stride around 5500 all the way to redline. The shifter, because of its long linkage, is a bit vague. If you come off the power and into neutral the car coasts forever - nicely built for high-speed driving. I've been on the Autobahn at an indicated 150mph (a motorcycle was in the process of passing) in an M1 and it was like driving 90mph in a 5-series. There is a good German book on the M1 ("Autos die Geschichte machten - BMW M1", Lothar Boschen, Motorbuch Verlag, ISBN 3-613-01265-0) but I don't know if it's in print any longer. M1s will fetch well over $100,000 today, and they do crop up for sale every once in a while. Some BMW parts importers can supply owners with parts your local BMW dealer swears don't exist. I would attribute is lack of dominance as a race car to its weight - the 911s of the era had quite an advantage over it.

> I heard that the M3 went through 3 evolutions but that only the first > evolution made it to the US. Is this true and if it is, what was involved in > the evolutionary process?

I can't comment on what evolutions went to the US, but I can tell you that there were actually 2 evolutions of the car over its production duration.

The first car was known as just the M3. It was not an evolution model, and produced 200bhp (2.3 litre). It proved highly successful in touring car racing. It first arrived on the scene in 1986-87. About 10,500 were produced.

In 1989 BMW made the evolution 1 which produced 220 bhp from 2.3 litres. This car again was very succesful in touring car racing. 500 of the evolution 1 were produced.

Finally in 1990 the evolution 2 was made. It was actually known as the "Sport Evolution", and had been bored and stroked to 2.5 litres. The car produced 238 bhp in road trim , and 365 in race. The reason for the increase in displacement was that the German Touring Car Championship allowed a maximum of 2500 cc, hence all manufacturers took advantage of this rule. 500 Sport Evolutions were made.

There was another evolution (I'll look it up tonight) M3 that had a 10k red line, did 0-60 in ~4.5 sec, active spoilers, (don't remember the 1/4 mile time), and a few other nifty things that went for 100k.

<from perelet_at_wri.com (Oleg Perelet)>
As i know 17184 87-92 M3 was produced.
This number includes:
786 convertibles.
330 racing.
600 evolution II models.

I believe 87 models were handmade by 2-3 craftsmen - one car in 3 weeks.
88 and later only engine was produced by hand, rest was produced on line.

Everything in new M3 will be produced on production line.

There was some discussion between M factory and main BMW about the model for this car: 330CSi or M3; design & production was voting for 330CSi marketing for M3.

Here is some info:
M3 built Sep 86 - Jul 1989, 195HP CAT, 200HP no CAT. Imported in US from 1987 as 1988 model year.

M3 Evolution 505 units built from Feb to May 1987, non CAT 200HP. I think valve cover/air box were red????.
No US models.

M3 Evolution II 501 built from Mar to May 1988, 23 4S 1 engine, 11:0 compression, larger throttle bodies, valve cover/air box white & M strips, lower front spoiler, lighter body panels, thinner glass.
No US models.

M3 Sport Evolution III 600 buit from Jan to Mar 1990, 2.5 cat engine 25 4S 1, 238HP. Exteriour Black or Red only (what red it was?), tinted
windscreen, adj front/rear spoiler, M seats, drivers footrest, red seatbelts, M steering whell, illuminated gear knob. Leather interiour as option, plaque on console with build number. No US models.

M3 Europa Meister 88 Celebration, Oct-Nov 88, 195HP CAT engine. All signed by Roberto Revaglia.
No US models.

M3 CECOTTO/RAVAGLIA Apr-Jul 89, 215HP CAT engine 23 4S 2. All cars were Misano red with matching cam cover or Nogaro silver with matching cam cover, driver foot rest & console plaque.
No US models.

M3 Convertible Mar 88 - Jun 89 non CAT, Mar 90 Jun 91 CAT. No US models.

PS. I have not seen much of Evo cars for sale in US. All are gray market.

Oleg.

This was the ultimate development of the E30 based M3. The car was give many modifications and a hefty price increase over the standard M3 (10,000 pounds sterling!).

The car was developed to allow BMW Motorsport to take full advantage of the German and Italian touring car race regulations (and give a lucky few vast amounts of driving pleasure!).

The modification/changes (taken from a sales bulletin) to the standard M3 are;

• Larger engine capacity (2.467 litre).
• Sodium filled exhaust valves.
• Larger inlet valves.
• Pistons cooled by new oil jets.
• Camshaft with modified timing.
• New air splitter on front spoiler adjustable to 4 positions. (185lb of

  extra downforce on front axle in max position - ~zero lift!).

• Rear wing now adjustable to 4 positions. (88lb of extra downforce on

  rear axle- slight lift)

• Lowered front suspension (10mm )
• Reduced weight:

  Lighter boot lid Roof grab handles deleted Map reading light deleted Lighter front and rear bumper mountings and foam filling front and rear. Lighter rear screen. Lighter rear side windows.

• Front wheel arch cutout enlarged. (to accept 18" wheels in competition

  cars).

• Brake cooling ducts replace front fog lights.
• Front brakes matched to increase performance with new brake disc

  material.

• 62 litre fuel tank.
• 7.5J x 16 cross spoke alloy wheels with the cross spokes painted

  in Nogaro Silver. 225/45 ZR 16 Michelin MXX tyres. (I now have the Pirelli P-Zero system fitted to my car)

• Red spark plug caps
• Motorsport sports seats with more marked contours and similar appearance

  to racing seats. Fixed head restraint extension with cutout for full harness seat belt. Seats adjustable for height, reach and angle.

• The cloth interior upholstery features centre panels of seats in

  Motorsport design and single colour side panels. The door trim inserts are in Motorsport design. <- Best I've seen in any E30 3 series!

• The seat belts are Motorsport Red only.
• M Technic steering wheel (different to other M3s).
• The steering wheel rim, gear knob and handbrake handle are all covered

  with a racing type rough leather finish.

• Colours : Jet black with contrasting red stripes on bumpers.

  Brilliant red with contrasting black stripes on bumpers.

• Graduated tinted windscreen. (on all evolution models I think?)
• M3 logo on door instep.
• Illuminated gear knob
• M Techinic drivers footrest

Only 600 cars were produced (Jan-Mar 1991) and only 51 of those were imported to the UK (i.e. English labeling). The car I have is Jet Black and has the following equipment spec;

        Electric windows
        Interior adjustable headlamp (throw)
        Headlamp deflector adjust (LH or RH driving)
        Headlamp wash/wipe  (option)
        Clock & temperature gauge
        Electric sunroof (option)
        Central locking + deadlocks
        Active check control
        Dealer installed alarm/imobiliser
        Heated door locks/washer nozzles
        Electric & heated side mirrors
        Cloth trim
        ABS
        LSD
        Full exhaust catalysor
        Speed sensitive power steering
        Schnitzer front and rear strut braces

M3 Evolution Spec;

Engine Type     :       4 cylinders (in-line) dohc with CAT. (code:254S1)
Displacement    :       2467cc
Bore            :       87mm
Stroke          :       95mm
Compression     :       10.2:1
Max Power       :       238BHP _at_ 7000rpm
Max Torque      :       177lb ft _at_ 4750rpm
BHP per Litre   :       96.5
Power/weight    :       201.5 bhp/ton
Gearbox         :       Getrag 5 speed manual (dog leg first)
Gearbox Ratios  :       3.72/2.40/1.77/1.26/1.00  R=4.23
Final drive     :       3.15
Fuel Tank       :       62 litres
Wheels          :       7.5Jx16in, Michelin MXX 225/45

Cost when new   :       34,500 Pounds sterling (inc tax)
                        + options (A/C, roof, stereo, etc)

Performance;

0-60mph         :       6.1 sec
0-100mph        :       16.0 sec
standing 1/4    :       14.7 sec
Max speed       :       154 mph

Did you know that there are actually 12 versions of the E30 M3? Well actually there are 13! There is one M3 that is 4WD and was specially built by BMW Motorsport - that's what I've read!

Some interesting info (direct from BMW).......

                        MODEL ENGINE      NUMBER  NUMBER  DATES      CHASSIS
MODEL               CAT CODE   CODE  BHP PRODUCED IN  UK PRODUCED    NUMBERS
- ------------------- --- ----  -----  --- -------- ------ -----------
M3 USA               Y  1003  234EA  195    ?       0    12/86-12/90 2195001-2198685 AE33000-AE34628
M3                   N  1001  234EA  200    ?       ?    09/86-07/89 0842001-0845000 2190001-2192224 AE31000-AE31242
M3                   Y  1005  234EA  195    ?       ?    09/86-05/89 1891001-1894694 AE40000-AE40899
M3 Evo I             N  1001  234EA  200   505      7    02/87-05/87 2190005-2190787 Letter E stamped on Cyl Head block
M3 Evo II            N  1001  234S1  220   501     51    03/88-05/88 Don't have that page - sorry!
M3 Europa Meister    Y  1005  234EA  195   150      0    10/88-11/88 NOT KNOWN
M3 Cecotto/Ravaglia  Y  1005  234S2  215   505     25    04/89-07/89 Don't have that page - sorry!
M3                   Y  1005  234S2  215    ?       ?    09/89-12/90 AE40900-AE42418
M3 Sport Evo         Y  1007  245S1  238   600     51    01/90-03/90 AC79000-AC79599
M3 convertible       N  BB01  234EA  200    ?      41    03/86-06/89 2001552 2385001-2385042 EB85000-EB85093 (see note)
M3 convertible       Y  BB05  234EA  195    ?       0    10/86-06/89 2001613? 3559001-3559088 EB86000-EB86085
M3 convertible       Y  BB05  234S2  215    ?       1    03/90-06/91 EB86086-EB86561

Note: EB85020 was fitted with EVO II engine by BMW Motorsport.

• --

  ---

  Paul Marshall Phone : +39 (0)863 420218

While I also can not comment on what did or did not come to the US the table above suggests that NO Evo models were imported by BMWNA. As you can see there are actually THREE evolutions of the M3 with a few other special models. The Sports Evolution is Evo III not II and 600 were produced! The Evo models were used (as was previously mentioned) to homologate new & improved parts for use by the race cars. The parts fitted to these Evo models were usually the actual Gp.A parts and generally consisted of lighter body panels & glass, and aerodynamic aids/modifications.

OK, this is the scoop, as relayed to me by an NA rep at O'fest '95

There will be 1995 M3's until December ...

There will be NO 1996 M3's since the S50US/B30 engine would have to be emasculated to meet the 1996 Emissions regs ..

(Flame on: DAMN ECO-NAZIS! ... Flame off)

At that time it was presumed that there would be a 3.2l version of the new 328i 2.8l alloy L6 for the 1997 M3 ...

The 1997 M3 was supposed to hit the shores in the summer of 1996 ...

HOWEVER a slight GLITCH has hit ...

The 2.8l was to be made of Nikasil alloy, the same as used in the M60 V-8 blocks .. this material was found incomatible with a lot of US fuels due to sulfur content ... so for the M60, they are going to sleeve the blocks in the 3.x and 4.x liter V-8's ...

There is not enough "meat" in the 2.8 block to sleeve, so they are changing the alloy to Alusil (same as the M70 V12) which is immune to sulfur but more expensive ...

This is requiring reengineering of the 2.8l and presumably 3.2l M3 blocks

Only time will tell ...

Jim

The valves are easy to adjust:

• obtain valve adjusting tool
• obtain new OEM valve cover gasket, if required
• obtain valve shim kit *or* wait until you measure lash and purchase needed shims
• obtain feeler guage
• obtain shim pliers, or use compressed air/magnet
• obtain micrometer or measuring calipers
• let car sit overnight, you want the engine COLD
• remove fan so you can put a wrench on crank bolt for engine rotation
• pull spark plug wires off plugs and carefully pull out of way, I usually undo distributor cover to provide more freedom,*careful*
• remove spark plugs *if* you want to ease engine rotation
• diconnect hoses from valve cover
• remove acorn nuts that secure valve cover, put them somewhere safe
• remove valve cover
• since engine is canted to the right, oil pools at exhaust valves, use turkey baster or other vacuum device, or rags, to remove this oil
• starting from leftmost intake valve (cyl 1), rotate engine with wrench (36mm) to get cam lobe ramp off shim (make it so "pointy" part of camshaft points at you)
• measure valve clearance (should be .28 - .33 (?)) spec is located on sticker on or near left shock tower
• record this number, or change shim if out of spec. At this point decide if you want to measure all clearances first or do the measure-replace-move on thing
• progress left to right, doing intakes first, and rotating engine to obtain proper cam position reative to shim
• the valve spring compressor tool only depresses one bucket at a time. It has two sides, one is narrower, one is wider. Use tool by placing between cam lobes and levering toward center of engine, you will see which side of tool is for which valves, intake or exhaust
• R&R shim if out of spec. Compressed air works *sweet*, then a magnet to extract.
• read number on shim, or measure if illegible. If lash was out of spec (usually on the high side, and more prominent on exhaust valves), subtract spec from measured clearance and add this number to the thickness of shim just removed to get thickness of replacement shim
• perform procedure on all 16 valves
• clean gasket surfaces thoroughly, replace gasket, valve cover, hoses, plug wires, engine cooling fan
• I record EVERYTHING so I know what size shims I put in for future adjustments. Record date and mileage. I make a chart depicting intake/exhaust valves, then add numbers. I find this helpful.

Owners of 325i & M-3 cars with oil coolers (It's tucked behind the front air dam) BEWARE ! there is an inherent problem with leakage from the oil filter head. Previously the only fix was to buy a new filter head for $135. Now a repair kit is available under part # 11-42-9-059-338 for only $4.83. This repair is also covered under SECRET BMW Warranty. Have your dealer refer to service bulletin # 11-09-90 dated January 1991.There is a fair amount of labor involved & is a MESSY job. try to get done under warranty.

> 2) Highest safe rev limit for the M50TU engine is 6800rpm .. >
> For the S50US, it is 7000 (per a back door to BMW Motorsport) >
> Most of the "chips" set the rev limit for the M50TU at 7000 which > is too high for an engine with single valve springs ... >
> There have already been cases of engine damage by these chips!

For what it's worth, the hydraulic tappets on the S50 don't seem to enjoy prolonged 7000 rpm's. I've seen a '95 M3 autocrossing (lots of redlining in 1st) and often, the car would pull off the course with a loud tapping seemingly coming from a tappet that collapsed momentarily. A short drive at normal revs seemed to correct it.

Ben

>> Al, Carl, complained about lifter tick in their E36 M3 after racing <<

Guys, I can comfirm that there is a problem with the E36 M3 lifters. I first complained about this problem a year ago after autocrossing my M3 and noticed the lifters ticking. Like you, the tick only lasted a minute or two until the lifters pumped themselves back up. I've checked around quite a bit on this topic and found this problem is common to all US E36 M3s (S50US motor), as well as the E36 325is (M50). Russ Wyles, and all M3 autocrossers I know, are aware of this problem.

I wrote to the Roundel ~6 mo ago and recieved no feedback on this (Elle, why is this?). The dealer and regional reps were also ignorant on this subject.

Now, how serious a problem is this, really? Probabley not real serious. Consensus is that it is *not* an oil starvation problem. Rather, it is an oil *foaming* problem, causing air entrapment in the oil that collapses the lifters temporarily. I would like to note that the standard M3 oil pan *is* baffled and has a windage tray (though it is different from the M3 Light oil pan). I would also like to note that other cars with hydraulic lifters also have this "characteristic" during autocrossing/racing (my Miata, for instance).

So....I think there is a problem, but I don't think it's as serious as you make it out to be. The M3 motors ruined at the IMSA Alanta race, to my knowledge, including 1 from our own IMSA team, resulted from missed-shift *overrevs*... *not* oil starvation. M3 Lights, incidentally, do *not* appear to have this lifter tick problem.

So what is the solution? I don't know...perhaps a redesigned oil pan or windage tray (like the M3 Light) or perhaps redesigned lifters. Easiest, though, would be to locate a good anti-foaming oil, if one could be found. I know from experience that Valvoline conventional and synthetic are *not* anti-foaming enough. Perhaps Redline or Amsoil would be better....any experiences out their from the SSA or autocrossing crowd?

Roger W. Graves
'95 M3

     As Al exited the skid pad on Oct 9th, I was the one who indicated
     to him that his engine was really noisy.  I am not proud to be
     the first, but I am primarily concerned with the long term
     effects  of what the skid pad does to BMW "cars" in general, not
     only the engines..

     In search of the bottom line answer, I called Prototype
     Technology Group (PTG) owned by Tom Milner in Winchester, Va.
     (PTG is only 1 hour away, so I frequently hang out there and see
     what secret projects they are working on.)  As you guys might
     recall, PTG has an agreement with BMW NA to supply and service
     all BMW NA racing efforts.  PTG campaigns the two IMSA GT2 M3 and
     also built and serviced 4 IMSA Street Stock M3 LW (lightweights)
     which are campaigned by other private teams.

     The IMSA GT2 racers have the European engines with the associated
     solid lifters. But the four LW's have basically the same motors
     found in the M3 available to the US.  The factory oil pan was not
     sufficient even for the GT2 with their racing slicks.  PTG had to
     fabricate their own dry sump system.  You might recall that oil
     problems caused the cars to fail in the 95 24 Daytona race.  the
     team was also plagued with oil problems at Sebring and Road
     Atlanta.

     I spoke to Gregg Forde who is the chief mechanic at PTG.  Now
     this guys eats and breaths racing stuff.  I asked Gregg about the
      M3 oil starvation problems and these are his comments:

     o  The US M3 engine indeed will have oil starvation problems on
     left handed, high G corners at "limited duration". (I think about
     10 seconds)
     o  It is a combination of oil starvation and oil foaming (This
     was mentioned many times before in previous threads).
     o  A temporary remedy is to put 1 to 1-1/2 quarts of extra oil in
     the crankcase during track events.
     o  The E36 M3 engine does not experience the same problems as the
     E30 M3 engine when the oil is over filled.  The E30 M3 engine
     will blow or leak oil out of the rear engine seal if too much oil
     is used.
     o  A low cost fix to the problem is to install the M3 LW oil
     pan/pump kit.  The LW kit has two pickup points in the oil pan
     and is indeed tricked.  PTG has the kit for approx.. $1600 w/o
     the gasket.  The gasket should be under $100.  The 150 club
     members who came on the Tom Milner Tour on April 9th saw the LW
     oil system.
     o  The US M3 engine produces approx.. 4 bars of oil pressure in
     the block and 1 bar to the head.

     Now, please don't run out and buy the LW kit yet!  I am trying to
     let PTG loan us one of their LW cars to take to Summit Point ( 20
     minutes away from Winchester) to test on the skid pad.  The NCC
     (National Capital Chapter) will have a driving school on November
     11-12 at Summit Point on the new 1.1 mile Jefferson Circuit.
     This sounds like a good time to do all the testing and report
     back to the list.  I learned from experience you can't believe
     what you hear when something costs more than $100.  So hold tight
     and wait for the results on the LW oil pan/pump system.  In the
     mean time, fill your crankcases and stay off British racing
     circuits (they go counter clockwise). :)

     P.S.  The two PTG M3 GT2 race cars are guaranteed to win the 96
     24 hours at Daytona.  I also talked to Oliver Kuttner who drives
     the Pegasus WSC (World Sports Car) with the BMW v12.  He also
     assured me that he will be the overall winner in 96.  Both teams
     have learned from the 95 season and are ready for 96.  I can't
     wait.

     Some of my crazy friends and I will have a "fun" Cannonball type
     run from Washington DC to Daytona for the 24 hours race.  I
     convinced them to lower the expected average speed from 85 to 70.
     Therefore if you leave Washington (the location TBD) and average
     exactly 75 including fuel, food, and leak stops and reach the
     front gate of Daytona International Raceway, you will be the
     winner.  Too fast or too slow, you loose.  So far, we have 16
     cars.  Stay tune for more details.

     --ed

     '88 325i (begging to be a race car)

>From personal experience all M50 motors (325 and M3) need to be over filled with oil by 3/4-1 qt! As in the E30 M3 this motor has a oil starvation problem when driven hard, it may not relate to the tick of lifters but it should be addressed---cant hurt---

Will Turner

From: "fastestM5 " <fastestM5_at_msn.com>
Date: Fri, 17 May 96 12:50:47 UT

Phil Marx is correct to report about the need to inspect the accessory drive belts on the S38 engine. If my memory serves me correctly, I believe there may even have been a BMWNA technical service bulletin to the effect that the belts on this engine (the ultimate BMW engine) must be replaced at Inspection II's in order to maintain the factory warranty (or extended warranties). The alternator belt is particulary susceptible to wear.

The belt replacement part nos. are as follows:

        Alternator Belt         11 23 1 315 357
        Power Steering Belt     32 42 1 706 825
        A/C Belt                        11 72 1 315 356

The belt are among the most inexpensive maintenance parts on the S38 engine, yet are critical for its operation. All E34 M5 owners should do themselves a favor and inspect and replace the belts as needed. Also, if one needs replacement, do them all and save yourself the effort or labor cost of doing them on a piecemeal basis. Keeping the belts fresh is very cheap insurance.

          Many people use TSW Evolutions (16 x 7.5)
          on M3's with a +15mm offset and they seem to work fine
          (225/45-16 tires).  As a reference point, BBS recommends a
          20mm offset for their 16 x 7.5 wheels on an M3.  The
          Hockenheim that was originally recommended and sent had a
          +10mm offset.  We mounted these, without tires, on both cars
          and found 30mm clearance between the shock and wheel but the
          wheel stuck outside the fender well 10mm.  TSW is currently
          fabricating wheels (i.e. drilling the correct bolt pattern
          and using pressed-in steel inserts in the lug nut holes if
          necessary) for us on a +20 mm offset wheel.  They seem to
          think that this will work.  This will make the wheel flush
          with the fender (while on stands) and give about 5 mm more
          clearance with the shock than I currently have with a stock
          wheel.  I'm leary of the possibility of pressed lug bolt
          hole inserts, but I called TSW direct and they said people
          race on their wheels that way and have no problems.  

...

5, 6 and 7 series wheels will bolt onto an E30 M3 (same bolt pattern and center hole). Some look better than others and the offset may be slightly different between wheels. I know that 390mm OEM wheels will bolt on but the TRX tires are to tall. The 15" 'bottle opener' wheels from the '90 or so 7 series also bolt on. Again, the tires are to tall and a lower profile is nneded. Having just put 16" wheels on my M3 I'll tell you what I learned.

5, 6 and 7 series wheels will work but the tire needs to be lower profile to look right and to gaurantee no rubbing. Try to stick with tires as close to stock diameter as possible.

M3 wheels have the following requirements:

5 x 120mm bolt pattern - 5, 6 and 7 series meet this 72.5 mm center hub - 5, 6 and 7 series meet this. It is important that

        the wheel is hub-centric (like 72.55mm center bore) so the wheel
        isn't supported by the lug nuts.

Offset is critical. For a 16" x 7.5" wheel the offset should be between 15 and 30 mm. 30mm makes a 225/45-16 tire sit within 4mm of the shock. 15 mm puts the outside of the tire even with the fender lip. A friend as Borbet 16 x 7.5 type C's with a 15mm offset and a lot more junk is thrown on the car. I have TSW Hockenheim's w/ a 30mm and the car stays clean, but doesn't have as wide a stance. 20mm is probably about perfect. As a point of reference, the Evolution M3 had a 16" BBS wheel option and it had a 28mm offset. That's why I went with 30mm. We are both running Yoko AVS Intermediates 225/45-16. I have no rub, he has a little at full lock. If you went with an 8" wide wheel you probably couldn't go over a 24mm offset.

To make 16" or 17" wheels work you are supposed to have offset control arm bushings. Later M3's came with them and aluminum control arms. Earlier cars had steel control arms and a centered control arm bushing. Mine is a 12/87 DOM and had offset bushings and steel control arms, a transition car! To tell if you have offset bushings, jack up either side of the car, put a jack stand in place, and look at the rear most piece of the control arm where it bolts to the frame. If the piece of rubber it passes through has the hole in the middle, you have the old bushings. If the hole is obviously not centered than you have the correct bushings. These change the caster of the front suspension enough to allow fatter tires.

I have no experience with 17" wheels on M3's but have seen them at O'fest and in various car rags. I have heard that 15" is the ideal wheel for the track for this car (with stock suspension / engine). I have my Comp T/A R1's on the factory wheels and keep the 16" set on the street.

Hope this helped.

matt

-------------------------28-Sep-94 5:53:00-GMT,3949;000000000001 From: "RON CHECCA" <rchecca_at_VNET.IBM.COM> Date: Tue, 27 Sep 94 12:12:59 EDT

I've uncovered a not too well publicized problem which affects some or possibly all '88 E30 M3's. It concerns cracking front subframes where the motor mount bolts come through the sub-frame.

Background: For those who don't know what the front sub-frame is, it's the large black steel cross member which goes from left to right across the lower engine compartment. It supports the engine, steering rack and lower steering control arms.

History: This past weekend at Watkins Glen, my '88 M3 track car developed a new "squeaking" sound from the engine compartment upon mild accel/decel. Rick K. popped the hood and shook the motor while I was fueling it up, and VIOLA, the squeak came to life. At the track, we jacked it up, removed the motor mount and observed a crack between the bolt hole and the locating dowl slot. It was about 1/4 inch long, and it appeared to go through the metal. We took out my super stiff Gr-N mount and put in a stock one along with a larger washer, shook the motor and the squeak was gone. After two run groups however, the squeak returned, suggesting that the crack progressed, although I have not had time as yet to verify this.

Who should care?: I'd say anyone with an '88 M3 WHO TRACKS THE CAR. It seems the G-forces generated in cornering can cause this problem. If you only drive your '88 M3 on the street, you probably don't have anything to worry about.

Monday AM, I called my buddy Nathan at Hendrick BMW and had him investigate front subframe part numbers for me. He confirmed what I had been warned of - THE FRONT SUB-FRAME ON '88 M3's HAS BEEN SUPERCEDED !!! The '88 M3 had a unique subframe!! BMW superceded it with the subframe used in the "brother" E30 cars. IE: the bigger beefier one from 325e/es/i/is etc. He did not have a manufacture date of when they started building M3's at the factory with the beefier front subframe, but did say that '88's "only" had the unique (now obsolete) part number. So we don't know if it was a "running change" during the '88 model year or weather it was introduced at the beginning of production of the '89 model year.

Cost: $349.50 from Hendrick with 'CCA discount. My local dealer estimated $240 to install it. (Rick K. and I will change it this weekend...) I'd imagine that it could be welded and extra bracing could be added, but I'm not going that route since the rest of the peice might be "underspeced" as well. I don't think this has anything to do with the fact that I have a higher power 2.5l engine in the car. Several people have since told me that they cracked theirs with 2.3l stock engines...I believe it to be cornering forces which can be greater than 1G which cause this.

This may be something that should be added to the pre/final tech procedure at drivers schools. I can't see the throttle sticking as a result of a major crack/mount failure due to the ball joints on the linkage, but you never know!

What to look for: Open the hood, grab the engine and gently shake it side-toside. If you hear a squeak from down low in the engine bay, you probably have a crack.Good luck!

Ron Checca
'90 M3 Street
'88 M3 Track:(
'87 325es Road

(NOTE: the following refers to a fix for the problem of shifting an E36 M3 from 5th to 2nd or the like, thus causing engine overrev damage.)

part # is 23-31-1-222-992

SUBJECT: Special Considerations for Installing Competition Parts MODELS: 1995 M3 Lightweight (BMW NA model code 9520) of 8/95 thru 10/95 Production.

Situation: A small quantity (approx. 100 units) of M3 vehicles will be produced which are aimed at the performance purist and/or active competitor. This street-legal model (as delivered to the dealership) eliminates several comfort and convenience items for weight reduction purposes which are normally found on standard M3 models. The M3 lightweight comes with several performance upgrades which are based on the European M3 GT homologation series for worldwide GT racing.

<differences between M3 lightweight and M3 deleted>

Parts: The parts listed below are provided for racing purposes only and are not certified for street use. Installation instructions will be provided in S.I. 00 18 95 (4317)

(in BOLD) If your dealership personnel installs any of these competition parts, you will be in violation of the Federal Motor Vehicle Saftey Act of 1968. As such, the vehicle must not be allowed to be driven off your premises onto public roads. Rather, it must be trailered. Furthermore, use of these parts voids the Limited New Vehicle Warranty.

Oil Pan
Dual Pick-up Oil Pump
Comment: Suited and needed for track use only and for extended high lateral acceleration. Only use these parts for racing and check every 2500 miles. If installed, check the hydraulic valve adjusters for wear on the tappet surface every 2500 miles. Installation of this oil pan or oil pump voids the warranty. Installation should be delayed until the completion of the vehicle's break-in process (approx. 1250 miles).

Front Strut Upper Crossbrace
Underbody Crossbrace
Comment: Stiffens the front body structure and chassis to improve handling and stability under severe driving conditions such as racetrack driving. As a result of the added stiffness to the structure the braces are not street-legal and should only be used for track activities.

Adjustable GT Race Rear Wing
Spacers for GT Wing
Comment: The GT rear wing is aerodynamically optimized for the M3 to reduce lift in the rear with minimal additional drag. This may result in greater fuel consumption and faster tire wear. The wing should only be installed if higher downforce at high speeds is needed while in track use. Installing the spacers further increases the downforce. Since the wing could cause permanent deflection of the trunk lid in the event of a rear impact, it is not street-legal. The GT rear wing can be installed in place of the standard-equipment spoiler.

<Parts applications for 1995 M3 light weight, descriptions and quantities deleted>

General: The M3 Lightweight is street legal without the installation of the parts provided for racing use only. The results and the nature of these parts alter the certification and performance of the vehicle. Any alteration of the M3 Lightweight with these parts voids the warranty.

These parts are sold "as is" without any warranty whatsoever. Implied warranties, including warranties of merchantability or fitness for a particular purpose, are excluded. The entire risk of quality, performance and installation of these parts is with the buyer. Should these parts prove defective following purchase, the buyer, and not the manufacturer, distributor or retailer, assumes the entire risk and costs of all unnecessary services and/or repair.

Direct any inquiries on these parts to:

Prototype Technologies Group, In.
<address deleted to protect the seemingly innocent>

Warranty: Using the M3 for any competitive events or racing with or without the parts installed automatically voids the limited warranty on the vehicle.

<signed by H.G. Duenzi, VP of Aftersales and Engineering and Ray Schroth, Manager of Quality and Service Engineering>

Carl Buckland asked about M3 suspension mods.

I wrote this recently about suspension modifications to my E28 M5. It was posted to the M-digest (M5/M6 list, jrallen_at_halcyon.com) in December.

While it's specifically about the M5, it may give some perspective on the Dinan approach to modifications.

Over the past several months, I've installed the equivalent of a Dinan Stage 3 suspension in my 1988 E28 M5. First stiffer springs and negative camber plates, next Bilstein Sport shocks all around which eliminates load leveling, and finally adjustable sway bars.

My upgrades are nothing original. Dinan Stage 3 suspensions are on many M5s as reported in Stan Simm's M-register newsletter. Considering all the good reports, I made the changes mostly on faith. I'd have felt more comfortable knowing why the changes work and some numbers to describe "firmer".

I'll try to provide an explanation and give some numbers. The spring and sway bar numbers are calculated by measuring the components and then plugging the values into formulas from the book "How to Make Your Car Handle" (Fred Puhn, HP Books). If I'd originally planned to report my calculations, the measurements would have been more careful. The numbers aren't perfect, but they should be pretty close.

To make this more "digestible", I'll give the basics in this "Part 1". Then later, I'll post more "Parts" for the calculations and further details.

M5 SUSPENSION -- PART 1, Overview

BMW engineers are more capable car designers than any of us and probably most aftermarket suppliers. It comes down to tradeoffs. Suspension performance improvements generally compromise ride comfort for a stable, controlled ride -- read firmer and lower. Firmer and lower always feels better the faster you drive on dry, smooth surfaces. Firmer isn't always better though. Bumpy, wet, surfaces feel better with softer suspension.

BMW transformed the 535i into the M5 with a more powerful engine (256 hp vs 182 hp), wider tires and wheels (225/50-16 vs 200/60-15.35), bigger brakes (11.8 vs 11.1 inch front), and stiffer suspension. I'm not sure how much stiffer the springs are, but sway bar size increases dramatically (25mm/18mm vs 19mm/15.5mm).

Larger sway bars make sense for performance street cars. They reduce roll without the harshness caused by increasing spring stiffness for the same purpose. It seems the M5 sway bars can't get much bigger without overstressing the mounting points. Dinan uses adjustable sway bars very close to the stock size (25mm/19mm). Roll stiffness and response to bumps increases both through sway bar adjustment and stiffer springs. Then stiffer sport shocks cope with the increased spring rate.

My major complaint with the M5 is understeer (pushing) and related front tire rollover. Although the M5 is much faster at the track, it doesn't seem to have quite the balance of the 535i. This is most noticeable on wet skid pads where it's difficult to get the tail out (oversteer). The 535i understeers slightly, but can be changed to oversteer with the throttle. At the track, I usually end up with six psi more front than rear pressure to balance out the M5's constant understeer.

The different balance is, once again, a deliberate choice. M5s have extra understeer designed-in to compensate for the increased power and speed. Cars generally oversteer more at higher speeds. The front has more downward force while the rear has some lift. More power also causes oversteer. Rear tires can handle both cornering and acceleration forces at the same time, but they can only do so much. With more power, the total acceleration and cornering forces overcome traction at that end, so the rear tires slip (oversteer). To compensate for the power and speed related oversteer, front sway bar stiffness is increased more than the rear. This brings the car back to a strong understeering tendency.

Understeer is safer than oversteer. Most driver's natural reaction in either case is to let-off the gas. This transfers weight from rear to front that reduces understeer, but increases oversteer if done too quickly. So the extra understeer keeps people out of trouble but, for my tastes, they went too far.

1st Change -- Camber Plates and Springs

Camber is the angle tires make with vertical. Negative camber means the tops of tires are closer than the bottoms. Like everything else, camber is a compromise. Zero camber works best for braking and tire wear in a straight line. However, during hard cornering, the outside wheel tucks under (camber becomes more positive) causing the tire to roll up onto its outer edge. Increased negative camber keeps the outer (heavily loaded) tire tread flat on the surface.

The Dinan plates produce a total of about 1.0 degree negative camber, 0.33 negative stock plus an additional 0.625 negative from the plates. The front strut upper mount comes off during plate installation so it's a good time to change springs (and shocks, in 20/20 hindsight).

Dinan springs are shorter and stiffer. Ride height lowers about 0.75 inch. Springs are 30% stiffer in front, (187 lb/in vs 144 lb/in) and a whopping 65% stiffer in the rear (267 lb/in to 162 lb/in). The front value seemed okay, but the rear increase didn't make sense until I thought about it.

First, the "effective" stock rear spring rate increases somewhat through the load leveling assist. Second is that rear springs are generally stiffer than front springs. This isn't intuitive because you'd think a car with approximately 50/50 weight distribution would have equal spring rates front and rear.

The reason front and rear springs aren't equally stiff is to absorb bumps without the car pitching. Front rates are less than the rear, so the rear can "catch up". The front hits a bump first and reacts slower so the rear can finish its cycle at the same time as the front.

This front to rear "natural frequency" difference is usually optimized for the speeds a car normally travels. It works out to about 50-60 mph with the Dinan springs.

After spring installation, front to rear rake is adjusted by changing load level height. Dinan recommends 0.5-0.75 inch front to rear rake measured at the rocker panel behind the front wheel and just in front of the rear wheel.

Adjust load level height by rotating the U-clamp at the center of the rear sway bar. As the rear suspension drops, the sway bar rotates and moves a load level sensor arm. The load level system pumps the rear ride height up until the sensor arm is back in it's original orientation. Reorienting the U-clamp and attached sensor arm changes ride height.

Well, the increased roll stiffness from the heavier springs and negative camber from the plates reduced front tire rollover and understeer, but the 100,000 mile original shocks were not up to the task. The ride was much too active or underdampended.

Dinan normally recommends at least front Bilstein Sport shocks with the spring set, but I tried to go cheap. Probably my stock shocks were worse than I realized, but it seems that the stock load leveling shocks, even in good shape, must be underdampened with the stiffer springs. However many people in the M-register report satisfaction using Bilstein Sport front shocks while retaining the stock load leveling rear shocks.

2nd Change -- Bilstein Shocks and Load Level Elimination

Load level rear springs are larger diameter (4.5 inch M5 vs 3.9 inch diameter 535i rear spring). So load level replacement required two 535i size short rear springs of the same rate (267 lb/in) and the following BMW parts.

Quan Part Number Description

Bilstein Sport shocks work with shorter, stiffer springs (most aftermarket springs). Softer Bilstein Heavy Duty shocks, designed for longer, softer, 535i springs are available and fit the M5. Any standard 535i size rear shock installation, Sport or Heavy Duty, requires a 535i size spring and the load level elimination parts above.

As with load leveling, adjust front to rear rake by changing the rear ride height. Bilstein Sport rear shocks have six adjustment grooves 0.37 inches apart. Change height by moving the circlip that holds the lower spring perch.

Setting the Bilsteins at the fourth groove down from the top with Dinan springs, gives 0.75 inch rake along the rocker panel. Front and rear rocker panel heights are 7.75 inches and 8.5 inches respectively. Ride height lowers about 0.75 at each end. Clearance to the catalytic converter is 4.2 inches and about 5.2 inches to the oil pan.

At first the Bilsteins didn't have much compliance. Then after a few hundred miles the seals seemed to break-in, making the ride much more comfortable. Be sure to follow Bilstein's instructions for lubricating the shock seals. Push the damper rod _all_ the way down before installing the shock. Otherwise they will feel rock hard at first.

The Bilstein shocks made a tremendous difference, less pitching and faster settling time. Of course the huge difference was partly because the car was so underdampened with the stiffer springs and worn original shocks.

3rd Change -- Sway Bars

Sway bars are just torsion springs. Stiffness increases to the fourth power of bar diameter. So the easy way to determine sway bar stiffness increase is:

(new diameter/old diameter) to fourth power

So changing the M5's rear bar from 18mm to 19mm increases sway bar stiffness 24%. (19/18)^4 = 1.24

Suspension Technique (ST) bars have three adjustment holes in front and two in the rear, at one inch increments. Calculate actual bar stiffness by measuring the bars and plugging the values into an equation. Adjustment holes just change the measurements used for calculating the stiffness. Adjusting to the inboard holes or full tight increases front stiffness 22% over stock (285 vs 233 lb/in) and rear stiffness 58% over stock (139 vs 88 lb/in).

An interesting number is the front to rear sway bar stiffness ratio. It's 2.6 for a stock M5 (233/88) and 1.6 for a 535i (78/48). ST bars come out somewhere between at full tight (about 2.0, 285/139). This difference in ratios certainly helps explain why an M5 understeers more than a 535i. However, as mentioned earlier, the M5's extra power and speed require more front to rear stiffness than the 535i.

Sway bars are much easier to install than shocks and only take a few minutes to adjust. Just jack up the car up so both wheels are off the ground (no twist in the bar), and move two bolts to different holes. Adjustments are harder than changing a tire, but easy enough to encourage some experimentation.

Adjustable sway bars provide the final piece to car balance. After some experimentation, the balance now is moderate understeer with throttle controllable oversteer available. A wet skidpad is now lots of balanced, tail-out, fun instead of frustration.

Summary

Bilstein Sport shocks are quite firm for the first few hundred miles until the seals break-in. My car is a daily commuter and I'm very happy with the overall ride, but the roads are fairly smooth. Sport shocks and springs may be too stiff for people driving rough roads all the time.

Here are the choices in order of increasing commitment

1. If the car feels good, keep it stock because it is quite

   good.

2. If handling seems a little sloppy but fine otherwise,

   maybe just replace the stock shocks with Bilstein HD or equivalent Boge shocks. Unless you drive hard, don't bother with the camber plates.

3. Aggressive drivers should go for it all, springs, sport

   shocks, camber plates and sway bars. Don't worry too much about getting rid of load leveling. With the stiffer springs, 300 lbs in the trunk only drops the car about 0.5 inch.

Prices

• - much more so than the average aftermarket supplier. I bought shocks and sway bars elsewhere because I mistakenly thought Dinan was much higher than other sources.

I was using the 1993-94 Dinan catalog which lists the Stage 3 kit at $2059, but they changed their pricing recently. The 1995 catalog lists the same kit for $1579. It's a competitive price and they offer a 10% BMW CCA discount. At the new price, I would have made my life easier by buying everything from Dinan.

If you're more comfortable with another vendor, the equivalent parts should work fine. Here's some price information. BMP prices are used for comparison because I happen to have their catalog. They are usually competitive.

Dinan Stage 3 Kit $1421 ($1579 - 10% club discount)

Equivalent Parts $1281 ($140 less or about 10% savings)

  Camber Plates                     $198 (Dinan $220 - 10%)
  Shorter/Stiffer Springs           $250 (BMP)
  Bilstein Sport shocks             $384 (BMP)
  Load level elimination kit        $ 63 (Stock BMW parts)
  Suspension Techniques sway bars   $386 (BMP)
                                   -----
                                   $1281

The Dinan catalog suggests eight hours installation labor for a Stage 3 kit with load level elimination.

Regards,

Pete Read
88 M5
read_at_engr05.comsys.rockwell.com

>>Several people have written about performance mods to the US E36 M3<<

You know, the holy grail of easy HP is a very seductive attraction...modifying a car to make it *better* is part of the fun....lord knows, the aftermarket thrives on this stuff. But talk about a few bolt-ons transforming the M3's acceleration to the *violent* level makes me want to respond. You know, if these claims were true, these people are wasting their time playing around with street cars....there are race teams that pay big $ for this.

Now my *contary* experiences with an M3 CSL IMSA Street Stock team based here in Florida. We've spent a fair amount of Dyno time checking exhaust system performance of Borla, Flowmasters, Straight pipes, etc., and we have never seen much of an actual improvement in net HP....the stock system is darn good. Also, with regard to airbox mods, let me say that we found that its easy to do more harm than good...hot air entering the intake drops HP faster than the small flow advantage of some of these "shade tree" modifications. Though wadvantage of some of these "shade tree" modifications. Though we did not test the Korman system, it's design of providing maximum cold air would appear to a more logical way to go. We've also played around with cams, cam timing, and chips.....but we won't get into that for now. So...what can a few intake/exhaust bolt-ons really do for you? If done right, you *may* get 10 horsepower, and more noise (music?) to go with it. Done wrong, and you'll get more noise and less horsepower. Big improvements just aren't in the cards....

Regards,
Roger W. Graves
'95 M3
'91 Miata
GT3 race car
rgraves_at_snake11.orl.mmc.com
RogRacer_at_aol.com

(When installing big sway bars...)
>I've heard that not stregthening the mounting points for the bars will >eventually cause them to rip away.

No question about it. The worst problem is with the inner mounts up front. Stock, the bars attach to a flimsy tab off the back of the subframe. But because that is a known problem, most front bars come with a stronger mount that uses one of the subframe bolts as well as the tab. That seems to completely solve the front problem.

Soon after installing big rear bars almost everyone breaks the little triangle on the trailing arm that the bar end-link bolts to. Many bars come with triangular metal parts that are intended to be bolted on either side of the tab like washers. They help a little, but not much. The best solution is to have a welder re-enforce that tab with buttresses back to the trailing arm itself, as well as thicken the tab with an extra layer of steel welded on. You have to be careful because the brake line passes right under the tab. Overall it's an easy job because access is so easy (no need to pull the arm off).
The heat of welding will destroy the undercoating around the tab both inside and outside the trailing arm, so if you care about that kind of thing, be sure to re-undercoat outside, and spray some body-cavity sealer into the arm (the access hole is on the outside end where the wheel mounts, covered by a small plastic cap).

A second problem in the rear is that the inner sway bar mounts (to the car body) will flex, fatigue and eventually fail. This is less common. It seems to happen faster with setups having softer springs and stiff bars (street/track setups, rather than track-only setups), but I've seen evidence of it starting on nearly every tweeked E30s I've looked at that is run on the track. I was hearing a loud popping when turning over road elevation changes for several months as the cracked mount would "oil-can" and the sound would echo through the car. Eventually it failed on a steep driveway and the bar ripped off completely. ("So THAT is what that noise was!!")
Unfortunatly it failed just a week before a track event!

To fix it you will need to pull out the sway bar and on the passenger side pull off gas tank filler pipe. (CAREFUL welding with that gas tank open under there!) You can comfortable work around the axles, diff, etc down there. It takes a little fabrication to build steel tabs to strengthen the mount. I found it best to just double up the existing mount with 1/8" steel on the "inside" (front) in such a way that left the bar bracket mounting area untouched. That let me use the old sway-bar brackets, and we didn't have to fabricate new ones. This will be tough to re-undercoat well because of all the corners and stuff, but if it's a street car be sure to do it, as it WILL rust (because of all the corners and stuff).

There is another alternative for the rear body mounts. Some tuners sell a re-enforced mounting bracket that bolts through the trunk floor as well as to the sway bar bracket. Costs over $200 from Korman. You have to add it BEFORE you fatigue the mounting point, it's not an after-the-fact fix. No experience with it.

rick
'88 M3