Rear Suspension... or Lack Thereof!

[Neunelfer]

Is it too Low? Maybe they set the shocks to full stiff??

I told you I'd be bugging you now...

Details:

71 Tub
75 AL control arms
New Konis
Old Konis

I'm having a bear of a time getting any sort of suspension out of the rear of the car.

I had a set of old Koni's on there and they just didn't fit. A new set seemed to go on fine but, I'm having my doubts (I didn't install this set). The car is low but I would think there should be some travel. It seems as though I'm bouncing along on the rubber of the tire (I feel like Oliver on the tractor at the beginning of Green Acres... Porsche Tractor of course!) I took a look last night and the shock comes aweful close to both the heat exchanger and the crossover oil line on the passengers side (is rubbing close enough?)

I raised the car up and the suspension comes down fine. I drop it down and the car settles but, when I do the corner bounce test, it's stiffer than Bill Clinton at the Cheetah Club. No bounce.

I asked Sherman and others here a while back when I was trying to get the old shocks on. There was no definative answer. Some said only Bilsteins would work. Others said Konis w/o the dust cover and still others said Koni's fit fine. Others said the upper mount assembly needed to be modified (which it hasn't). And... others said there was a mount adapter for the bottom that repositioned the shock forward to the original 71 position.

Has anyone put Aluminium control arms on an early tub (of course you have)? What did you go through to make it work? Anyone with Konis? I know this is generally a Bilstein crowd but...

Maybe it's too low but even if I raise it 1/2 inch I get a whopping 1/2 travel??

Anyone BTDT?

[pu911rsr]

Eric,
Koni's can be built with shorten travel to deal with a lowered car. Do these have the adjustable damping, what size torsions are you running. Most 911's with big torsions and any kind of new shock don't bounce very easy.
Phil

[Eric911S]

Hello: How low is the car? If it is lowered too much you will bottom out any standard shock. The main difference between the older car Koni and the newer car Koni is the bottom mounting bolt is larger on the aluminum trailing arm. If you want newer style Koni or Bilsteins you need a sleeve for the old steel trailing arms. The valving is different as well for the newer heavier cars. The first thing I would check is to see if you are hitting the bump rubbers in the rear shocks. If so cut off one sleeve and try again. Be carefull if the car is too low then you will have to get shorter rear shocks. Koni make an hydraulic rear external adjustable race shock that I like alot. It is shorter and works well on the older cars. What size are the torsion bars? What is the material of the trailing arm bushings? Hope this helps. Thanks Eric

[Neunelfer]

Phil. I'm a modest spring guy. I think stock is 24 back there and I'm running a Turbo set which is 26. I basically did that because of the extra hp (squat) and the slightly heavier 930/07 engine I plan to have finally fill the hole.

I think all Koni's have adjustable dampening. These are brand new but... I didn't see the knob shaft at the top. I didn't think they made the manual adjustable ones any more. I'll look into that further on the weekend but... I like them full soft.

Eric. I'll get a wheel arch measurement. I was going to do that this AM because I know it's relevant. It doesn't seem "that" low but... I'll post a picture so you can see it.

I know about the 14mm bolt issue and even the older Koni's I had were the newer style with the larger sleeve. The rubber bumpers seem like they might be the issue. I'll check that this weekend. I think what might be more relevant is the fact that the lower mount is moved back about 1.5" on the AL arms.

Trailing arm bushings are stock. I kinda like it that way. I have a weird view on suspension. It's not overly sprung (stock front/turbo rear). No huge bars (76 Turbo front and rear sways) and mainly stock bushings throughout.

[JohnT]

for the rear do not have external adjusters.... I believe..... One must remove the bump stops and fully compress the shock in order to adjust them. This adjustment only affects the rebound stroke so firm or soft should have no effect on travel. Too many bump stops under the dust shield (as someone already mentioned) will. You should try to keep one bump stop installed as this is what protects the internal adjuster.

Why not disconnect your shocks and bounce the car? If things are different, you can attack the shock absorbers. Otherwise you need to be looking at torsion bars and/or bushings, or....?

johnt

[pu911rsr]

You may want to check your spring plate bushings as well. They should not cause the kind of problems you are describing but they should be checked. It sounds like something is binding or interfering somewhere.
Phil

[Eric911S]

Hello: If those are 50 series tires and 15'' wheels then I think the rear shocks are hitting the bump stops. Hope this helps. Thanks Eric

[Neunelfer]

Yup... I'll check bump stops this weekend. Sounds and feels like that's it.

I've had the manual adjustable Koni's for quite some time now so I'm intimate with those as well. I was just suprised the new shocks are not externally adjustable. I thought Koni dropped the manual internal adjustment thing a few years back.

Spring plate bushings are Delrin and brand new. Spring plates are plated as are the housings etc. I'm thinking it may be the bump stops or... maybe a tad too low. 225/50-15's