Suspension-all "I" can do

Peter Coomaraswamy

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Dear forum members,
A great big thanks for all your help! Today I officially announced my project "done" meaning that now she's a "driving restoration". We have discussed the fact that these cars are never really done, but I think I have done everything I can and now it will be little improvements or repairs along the way to hours of blissful driving . Since my last posts have been about suspension I thought I would attach multiple shots of the set-up and give you my results although my results are really "feelings". Still not up to race car standards, with the recent help of Ben/Carl @ LaJolla, sfdon and our "club car racer" I was able to figure out a couple of things that resulted in a very "fun" test drive vs. my previous runs which were not confidence inspiring, so here is what I came up with; First there was a backfire problem which in my case seemed to be caused by a lean mixture caused by fuel starvation; I put in an electric flow through pump that operates only when the starter is cranking, but that seems to have been enough to keep the system pressurized I think it also incorporates a check-valve preventing fuel from returning back to the tank. In any case good starts and no more back-fire. Next, return to center issue; you all guessed it! The washers were in backwards on one side-I had a friend do this for me, and no anger-it was free, but when I took them apart there was some scoring on the steel perch indicating that the bearing case was riding on the plate under load. DQ sent some pictures so I simply could not get it wrong, BTW if you are using CN springs there is hardly a need for a spring compressor to safely remove the bearings. The handling is vastly improved with the fix and new bearings were put in for good measure. The last issue I have been addressing is the excessive "bounce" in the rear when cornering. This was vastly improved with the replacement of the front bearings, although there is obviously no effect on the shock/spring travel in the rear, the handling was better in that I could get the car to slide around a corner rather than giving me the sensation of possibly rolling over. I may have more to address on that in the future but it's handling like a BMW now. So below are the pictures of the set up on multiple posts.
Cheers! ALL!!
 

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Peter Coomaraswamy

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More suspension

Real easy to remove, 9 bolrs, clip a wire and loosen the sway bar connector

little notes, I had to use a mini wire wrap to keep the brake line spacer in place and

I mounted the sway bar bolt upside down and put a length of fuel hose (screwed on) just in case the rubber brake lines came in contact.

The ST sway bar is pretty thick

how the front hangs with no load
 

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Peter Coomaraswamy

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Rear hanging lose, CN Springs, Bilsteins

ST adjustable rear sway bar using most forward position

Sorry- I did not paint the calipers gold :-(

IE's camber adjustmant plates.

How she sits after a test drive
 

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kasbatts

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Looking good, Peter, and nice work on the underside.

But.?

I may be wrong, but that last shot of the car, the rear end looks wrong, There seems to be way to much positive camber on the rear wheels, you mentioned the "bounce" in the rear when cornering, I would be 99% sure this will be caused by the rear camber, at a guess without seeing more pictures of the car I would think the rear wheels for want of a better description, would be trying to fold themselves under the car during cornering causing the bounce effect you mention.

When the e9 sits up high, the rear suspension design will cause the wheels to do what yours looks like its doing, What length are your rear springs? lower height or a standard length?

Other Guys will chime in with there comments
 
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shanon

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feedback

Have agree with Kasbatts, rear camber looks off...

Discovered this summer that eliminating (or just DC'ing) the rear sway bar all together improves handling, stability and cornering. This was suggested by seasoned race driver/coach who shared floggin' my coupe some 1000 miles on pristine, track smooth, NorCal back roads. They did this to my bros. old E9 racer on race weekend and shaved 3+ secs a lap....

"The tail is a little nervous (I had the rear sway at mid setting, center hole), it wants to come around a bit, let's loosen the rear sway tonite and see," he said as I was being taken for 'ride' in my coupe....whoa! I disconnected it that nite and it made a difference we both noticed, it was smoother thru the corners.

Coupes (Das Boots!) like a little roll in the tail.....keeps them firmly planted and 'hooked up'.

hth
-s
 

bdigel

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Looks great Peter !
too stiff a bar can cause some handling issues as other's have already said, (although , I haven't personally seen them causing a bouncing issue)
you can disconnect the bar from the endlink's and zip tie the links out of the way , drive it and see if that settles the bouncing down
 

Brian D

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Did you happen to torque the rear control arm mount bolts with the car in the air, i.e with the trailing arms hanging down? If you did, the rubber bushings in the control arms will be preloaded in the wrong position and it will keep the rear end from settling as it should.
 

Peter Coomaraswamy

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Thanks! Well, that rear end thing is really the final item to be addressed and by the suggestions below it should be very easy to try the remedies. I'll post some direct-from-behind shots and try running with the sway bar disconnected to see if that's the major culprit and I'll take some with /without shots. Finally, yes, the rear links were torqued while the car was "hanging" so that could be an issue too. I'll run through all the scenarios and report back.

Again, many thanks!
 

'69 2800cs

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Peter-From your posting on the alignment specs I have two observations.

In the front, your camber and caster are pretty different from side to side. This speaks to the value of adjustable front camber plates. When you match the caster from side to side you can really feel it in the steering.

In the rear, I think you need more negative camber. I recall you didn't get the specs you asked for at the alignment shop, what are the recommended specs from the experts you've spoken to?
 

tmason

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Great looking car Peter! But the Grateful Dead wheels caps will make your car ride high as well:)
 

Peter Coomaraswamy

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still seeking advice

From earlier posts and replies I have got a few more things dialed in regarding the suspension.

I'm running the ST sway bar up front and I did have the ST rear bar in but I removed it and now am running no bar at all. I do have the Bilstein HD's and CN springs and 3-dot perches in the rear and the handling W/O the rear sway bar is "better". My tire size is 225/45/16 all the way around- my question(s) are- do you think handling would improve if I changed the tire size up front to 205's and leave the rears alone. Also my friend who is an engineer but has no specific BMW experience said that if the rear differential were lowered that might help. I have not heard that mod on the forum so I thought I would ask.
 

DerSchwede

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Hi,

There are two things I see there that make it worse than it should be:

The rear end is too high vs. the front end - lower the rear and fit a standard sway bar there. DON'T try to lower the final drive since that will be prone to cause judder and put stress to the DS.

The tires: 225/50/16 would be more correct and will make a difference.

Good luck!
Cheers
A
 
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