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self adjusting suspension
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TOPIC: self adjusting suspension

self adjusting suspension 14 years, 2 months ago #7896

  • rd7839
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  • Endurance Racer
  • Posts: 625
Car's been sitting on the trailer untouched since Thunderhill backwards but I pulled it out today to get ready for next weekend and it just didn't feel right in my "cruise" through my private test track(streets built for an abandoned tract housing project). The tires(r888's) are flat spotted probably from being put on the trailer still warm and tied down ever since. That's okay 'cause I have a new set of shaved RA1's but it also handled funny. I couldn't really push it so not sure what was wrong but something about the way it sits bothered me. I didn't get underneath today to take a look but as I was putting the Boxster back in the garage I noticed that the 944 is sitting lower in the right rear than the left. The tape measure shows 5/8" difference and my notes showed they were almost even last corner balancing. Thunderhill backwards I definitely was getting airborne Dukes of Hazard style over turn 5(pictures to prove it!) so I might have broken something on the landing.

Anybody have any thoughts? I'll get it on jackstands tomorrow to see and I'm hoping maybe I just knocked the height adjusters loose.

Re:self adjusting suspension 14 years, 2 months ago #7897

Ron,

What does the left front look like? If the left front spring is off it's seat, the LF will be high and RR potentially low.

I've got two other guesses:

1. Height adjuster moved like you said

2. You have some bind in the suspension bushings and it wasn't fully "down" when you set it up. After the TH jump, the suspension is now fully settled.

Other long shots would be a torsion bar that rotated (damaged spines) or maybe some extreme weight transfer in the car (you didn't load all the beer in that corner did you?). I'd say both are long shots

I always check alignment and ride height after each race BEFORE I jack the car up because I know the suspension is fully settled out. It is hard to get it perfect again just by bouncing and rolling out.

Re:self adjusting suspension 14 years, 2 months ago #7898

  • Big Dog
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In the future, you might not want to leave the car tied down after a race weekend either. I always release all straps so the car sits normally on the suspension, shocks, etc.

Any flat spot on the tires, from being put away "wet", will go away when you run them again. The only time I worry about this is on brand new tires and I don't know if it matters on them either, I just make it a practice to be more careful after scrubbing them in.

Let us know what you find.

Big Dog
Jim Foxx

Re:self adjusting suspension 14 years, 2 months ago #7899

FWIW, my car was about 3/8" low in the right rear today for no particular reason that I could find. The scales supported the fact that the right rear was light. It also had 1/4" of toe out in the rear and I normally run neutral rear toe (that explains the tendency to oversteer at Infineon).

I adjusted the right rear up a little until I got back to 50% cross weight and made a slight camber adjustment on the right rear which also helped the toe.

I don't know why stuff moves but sometimes it does. Everything was torqued to spec last time.

Re:self adjusting suspension 14 years, 2 months ago #7903

  • rd7839
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  • Posts: 625
I got the car on jackstands and once the tires were off I noticed shiny metal on the spring plate where the two pieces come together. Looks like the plate moved up, I can see two scribe marks from where it was originally and where it was adjusted to. The bolts however are tight, with a breaker bar I couldn't loosen them up. The thing is though, the sway bar didn't have any preload(checked b4 I jacked it up) in it that I would expect if one side moved. It's still on the marks from last time I adjusted it.

I don't have scales or any way to measure the alignment specs and probably won't be able to get it to a shop before this weekend so I'll have to live with it.

Re:self adjusting suspension 14 years, 2 months ago #7904

Ron,

I'll have all my tools at the track including alignment stuff. Assuming there is power, I'll fire up the compressor and my impact will easily pop those bolts loose. We can get you fixed up when you get there.

They probably have a setup pad somewhere for alignment but if not, just setting it to the ride height you had will be pretty close.

I'm running with Trackmasters on Friday so I'll be there all day if you come up Friday.
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