<E36> M3 Suspension Upgrade

["Mudry, Robert (CAP, AMR)" <rob.mudry@xxxxxxxxxxxxx>]

>Thanks for the feedback. I'll answer what I can. Hopefully we can tie-up
the lose ends in swapping an E36 M3 suspension in an E36 325/328. Please
read on >below. 

See my comments below...  Again, the information is re '96 328is sport
package.  YMMV.

>>I agree, 328is with M3 suspension handles wonderfully, but your post
didn't
>>make it clear whether you swapped the strut bearing plates. This is a key
>>item since it sets up the camber and caster angle of the front suspension.
>>Yes, it is possible to reuse the 328 bearing plates but if you're gonna go
>>for the correct M3 suspension alignment, make sure to buy the new M3 strut
>>bearings. You can even swap them L-R to get an additional degree of 
>>negative camber. 

>You've got a great point that future upgraders should take note of. As for
my car, if by strut bearing plates you're referring to what the factory
calls the spring plate >(which goes at the top of the strut and holds the
spring in place), then I do have the M3 piece (I'm getting this from a BMW
technical diagram). I didn't swap the left >and right sides, though (I had
forgotten about that trick). If the strut bearing plate is some thing
different from what I've described, then I don't have the M3 piece on >my
car. 

Jay,  the strut bearing plate (aka strut mount) is the piece that has the
three bolts that you fasten to the strut tower.  It contains a bearing
inside that allows the strut to rotate as you turn your steering wheel. You
can see it under the hood if you pop off the strut mount cap.  The spring
plate is just a plate.  Yes, you do have to use an M3 plate as the 328 plate
is bigger and will rub inside the strut tower while turning if you have the
M3 strut mount.  This was the surprise that I didn't anticipate.  
 
>>Also, did you buy new spring pads? I found that the '96 328 pads were a
bit
>>bigger (the '96 M3 springs have smaller diameter than 328 sport springs.
>>'95 M3 springs are even slightly smaller in diameter).

>Yes, the spring pads in the 328 and the 95 M3 are different sizes. I didn't
have new spring pads at the time of the installation (this was unforseen)
and so right now >the cars doesn't have spring pads. To ask an innocent
question, what function do the spring pads play and how critical is it for
me to put them in? Can someone >shed light on the matter? 

You should get the pads.  I understand they provide additional cushioning
between the spring and the strut (body) of the car.  Yes, they will increase
your height by approx.  .25" each -> total of .5".  The pads may also
prevent metal to metal contact friction which may contribute to rust and
possibly strut plate failure.  I'm purely guessing here.

>>Also, what do you mean you can re-use 328 sway bar linkages? My 328 front
>>sways were attached to lover control arms by a short linkage. The M3 strut
>>linkage is about 2x longer. Did they change that for '98?

>No, the 98 328 still has the short linkages that attach the anti-roll bar
to the control arm. You can reuse them if you don't mind attaching the new
bar to the control >arm as well. But, if you want to follow M3-spec, you
have to buy longer linkages that will attach the front anti-roll bar to the
strut housing instead of the control arm. >This is the route that I took.
The longer M3 linkages cost about $35 each ($70/pair). 

Yes, if you're converting to the M3 suspension you should do that.  Why cut
corners when you're already in there.

>>Is there any reason why you didn't swap out the rear sway bar? 

>As far as anti-roll bar size, my installer (a motorsports shop in Mountain
View that is NOT Dinan) claimed that the M3 has the same anti-roll bars
front and back as >my 328 (the diameter and weight are the same, the only
difference is the linkage in the front). I didn't verify this myself. By the
way, from past postings in the digest >pointed out that the 325/328sport
package has *bigger* anti-roll bars than the M3. So, Mark, your stock bars
are bigger than the M3 bars you put on. Do let me >know your feedback. I'd
be glad to compile all responses and post the summary to the digest to guide
other people in the future on this upgrade. Thanks.

Wrong!  The rear sway bar on the M3 (at least '96+) is thicker than the '96
328is sport.  I don't have the numbers in front of me, but I did point his
out to my helper when we looked at them side by side. 
The front sway bar is actually thinner on the M3, but since it attaches to
the strut instead of the control arm, it generates a greater moment or
leverage and hence is more effective.

So to paraphrase, you need the following parts when upgrading to the M3
suspension:

       FRONT
- -take-off springs, struts
- -take-off sway bar
- -take-off sway bar bushings (2)
- -new spring pads (2 per side)
- -new sway link (with nuts)
- -new spring plate
- -new strut mount
- -new paper gasket between strut mount an the tower
- -new strut tower nuts (3 per side)
- -new strut to knuckle bolts (2 per side)
- -new strut piston nut
- -new strut tower Motorsport cap (optional -  looks good though!)

        REAR
- -take-off springs, shocks
- -take-off sway bar
- -take-off sway bar bushings (2)
- -new shock mounts
- -new shock mount nuts (2 per side)
  
All those new bolts and nuts are required as they contain 'lock-tite'
coating. Better safe than saving a couple of bucks.  

Rob Mudry
'96 328is 
BMW CCA #135536

>Jay Sala
>BMW CCA, Golden Gate Chapter 
>Cross-bred 328i 

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