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996 C4S --rear sag problem

PostPosted: Sat Oct 27, 2007 1:24 pm
by elcap00
The drivers side rear of car is 1/4 lower than the pass. side. this is an issue that has happened in the last 2000 miles. The car has been lowered by previous owner ---it has Gemballa springs (non adjustible)---I imagine that these are aftermarket.

There is no manual way to adjust rear ride height. Could this be a shock issue? A tired spring? The car only has 30K on it--so it wouldnt seem that a spring would get tired that fast.

Any ideas ???
Thanks
Toby

PostPosted: Sat Oct 27, 2007 2:33 pm
by kurquhart
I assume you have checked air pressures and tread wear?

Re: 996 C4S --rear sag problem

PostPosted: Sat Oct 27, 2007 3:20 pm
by ttweed
elcap00 wrote:The drivers side rear of car is 1/4 lower than the pass. side. this is an issue that has happened in the last 2000 miles.

Are you saying it dropped 1/4" (one quarter of an inch) in the last 2000 miles? That is a pretty small amount, and I have to say I would probably be too oblivious to even notice that by eyeball. Are you actually measuring this every 2000 miles? Has the handling changed?

If there is no ride height adjustment on the 996, how the heck do you corner-balance one of them new-fangled, water-pumping thangs?

TT

PostPosted: Sat Oct 27, 2007 3:25 pm
by Steve Grosekemper
Toby,

The ride height spec for your car is 10mm +/- side to side so at 1/4-inch (6.35mm) you are in spec.
Also the surface you are measuring on may not be 100% level. 1/4-inch over 10-feet is going to be tough to see.
While the height is not "officially" adjustable there is a provision to set corner balance on Boxsters, 996 & 997 cars. This uses a 3.0 or 6.5mm spring length compensation shim (rubber spacer) that can be used to correct ride height.

However, I would just check corner balance and if it is good, then leave it alone. If not, the C/B figures and height will tell you where the problem is located.

PostPosted: Sun Oct 28, 2007 8:59 am
by elcap00
As mentioned the car is lowered and I have 19" HRE's on all 4 corners. The space between the top of the tire and the fender is about 1/2" on the passenger side---on the sagging side it is about 1/4" (tire to fender). It is very easy to eyeball. Because it looks like I am rubbing the tire.

For clarity ---when I am saying that it dropped "sagged" 1/4 between sides----I am saying that the difference between L and R sides is 1/4" lower. I am just not sure how this happened and how to fix it. I am running Pilot Sport 315/25/19's and they are $480 each--and I would rather not ruin 1 tire and have to buy 2.

Where does the shim go and how easy is it to corner balance my car?
Thanks

PostPosted: Mon Oct 29, 2007 9:57 am
by Steve Grosekemper
The shims are between the top of the spring and the spring perch.
So it is spring R&R for each change.

Best left to someone who has done lots of 986/996/997 cars and is aware of how much weight change is how many pounds of change per mm of shim. It will be cheaper in the long run.

For the whole deal including re-alignment, you are looking at about 8 hours of shop time and two days on the alignment rack.