From digest.v6.n594 Mon Apr 28 18:49:23 1997
From: "Carl Buckland" <buckland_at_xmission.com>
Date: Mon, 28 Apr 1997 12:14:34 +0000
Subject: Coilovers for E36 M3
Bob Stommel, an instructor for the BMWCCA Drivers Programs, asks...
> I've been bitten by the coilover bug. One of my students at Putnam
> Park in April had a coilover suspension on his 95 M3 and the car's
> handling was phenomenal (at least from what I could tell from the
> dummy seat). Could you give me some advice on a good coilover
> system that will still allow me to drive the car on the street
> without inducing vertebral fractures? One Digester warned against
> the Group N system because the rear system replaces the separate
> spring spring with a true coilover design over the shock, which led
> to shock tower cracks. Does the rear coilover suspension on your
> car retain the separate spring design?
> Any general advice on parts and spring rates would be greatly
> Bob Stommel
> Indianapolis, IN
"Coilovers" is tossed around as a general term more than it should
be. Technically, it just means "the strut sits inside the coil
spring." The McPherson struts that are stock on most BMW's are
"coilovers," though not adjustable. The stock setup for the rear of our E36
cars is a seperate shock and an inboard spring.
The H&R coilover system retains the stock approach, whereby the
fronts utilize a strut with a spring around it, and the rear is still
a seperate shock and inboard spring. The H&R system, by retaining
the stock setup, is legal in SCCA Street Prepared competition,
whereas a system that converts the rears to "coilovers" is not. I
have also heard that the rear shock towers will NOT withstand the
pounding that they will get if the spring is brought in to the shock.
I would recommend staying with the stock type arrangement.
The Bilstein Group N system, as I understand it, converts the rears
to coilovers. I also know that the shock/strut valving is VERY
heavy, and the only springs that are offered are VERY heavy. There
are also patched together coilover sytems offered by Koni and maybe
others, but I think that the H&R is the only one that was designed
ground up for the E36 .
The H&R coilover system can be purchased from BMP at 1-800-
648-7278. I believe that the cost is in the $2500 range, although
that is not a current quote.
The front ride height is adjustable, because the spring sits on top
of an adjustable perch. Be sure to also order the tools that are
needed to make this adjustment easy. There are many factors to
consider when determining ride height, one of them being "corner
balancing." Even with only the fronts adjustable, lowering or
raising the fronts affects the weight on the backs. The best way to
adjust them is to put the car on 4 corner scales. Generally, the
lower the fronts, the more weight is transfered to the front corners.
The system comes with valving and spring weights that make the car
very streetable, yet give a much improved, firmer ride for the
track or autocrossing. The BIGGEST advantage of getting the H&R
system is that Roland Graef, director of H&R USA, can offer you a
vast assortment of spring heights and weights. The system starts out
with 340 lb front springs and 380 rears (the stock springs are about
115 front and 335 rear). The car drops .75 at the rear, and the
front, which is adjustable, drops .75 to 2 inches (that is very low).
I have gone from the 340's at the front to several levels stiffer,
which also entailes using tender springs. Roland can advice you on
this. I have also gotten several sets of rear springs, and have
found that you almost can't get too stiff for the track, but you will
turn the car into a monster for street and autocross. Even with the
"stock" coilover springs, the understeer has nearly gone away, as
stiffening the rear springs and going to a stiffer sway bar
The springs, especially the front springs, are very small in
diameter, and will give you plenty of room for all the negative
camber that you could want. The stock size springs will interfere
with the wheel and tire when you go to the more radicall camber
settings. I would assume that the H&R coilover springs give a weight
savings in the unsprung weight department as well.
I have now had the H&R coilover system for over a year, and have had
no problems. It seems to work with respect to the clock, as well,
because with the system, my M3 has now become quite competitive in
CSP, where the Hondas once dominated. I won the Solo Trials
Nationals last summer, and Bob and Patty Tunnell, co-driving our car
with us at the San Bernardino National Tour, and then the Pro Solo,
each came away with a win. Bob has since begun setting up his car
for CSP, but he is using revalved adjustable Konis with the
traditional H&R springs. It will be hard to compare the two systems,
not only because I have also done a lot of other development that Bob
will not have done for a while, but Bob could beat me (and most other
Solo 2 drivers) in a STOCK M3!
For negative camber, I have tried both the Ground Control Adjustable
camber plates, and the Dinan fixed plates, which come in two
variations: stock plus .5 degrees, and stock plus 2 degrees. Each
of the approaches to negative camber has its advantages. The GC
adjustables requires removal of the stock, rubber strut mounts, while
the Dinans do not. Metal-to-metal suspension mounting gives quite a
bit more feel, but will further remove the car from that stock BMW
feel. On the other hand, the Dinan stage 4 plates (plus 2 ) will
give AT LEAST 3 degrees of ALL TIME neg camber, which is great as
long as the car is always being driven hard thru corners, but will
lead to rapid tire wear (inside edge) on extended long distance
I have gone so far as to have springs in the front that are SEVERAL
times stiffer than stock, and rears that are off-the-map. It is
probably way too stiff for autocross, but for the track it is like a
panther on the carpet. For the street, as long as I retain the stock
rubber strut mounts, the ride is decidedly "firm," but STILL not
harsh. That is not just my opinion--others who have ridden in the
car are surprised at how mellow the ride still is, considering how
much stiffer EVERYTHING is over stock. If stock sponge is your cup
of tea, the "stock" coilover system will be firm, but still fine, but
I would not go any stiffer or you might be dissappointed. I would
describe the ride, with ANY stiffness of H&R springs, to be "firm,"
but not harsh. Harsh , to me, is where your wheels are bouncing off
the ground every time you hit a bump. The dampening and rebound of
the struts/shocks are so good that it seems that the wheels and tires
just follow every nuiance of the road surface.
I won't have time for any more details. Please call BMP or Roland
for more information. I will publish Roland's new number when I have
it (I think that he has recently moved).
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Salt Lake City, Utah
E36 M3, #27, CSP