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Car feels unstable

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Old Sep 2, 2006 | 09:16 AM
  #1  
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Default Car feels unstable

I bought my first 993 about 3 months ago. 1995 lowered upgraded shocks and springs,RS sway bar, 18 inch turbo twists etc. I've driven it about 1500 miles so far.

Anyway I notice that over bumps the car feels like it wants to move laterally,I feel it more in the in the rear. In the dry it's not bad,but noticable. yesterday I drove it in the rain for the first time. The lateral movement was very noticeable especially in the front. Very unnerving. Whats the likely culprit. The shocks and springs are onlyh about 5000 miles old,tires have about 65% tread left. The car is lowered.

Any thoughts?

Thanks
Jeff
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Last edited by slvr993; Sep 2, 2006 at 09:39 AM.
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Old Sep 2, 2006 | 10:19 AM
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First thing to check is alignment... maybe when it was lowered, they set a very aggressive negative camber. This will make the car stable in the turns, but a little 'darty' in a straight line.
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Old Sep 2, 2006 | 10:30 AM
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Classic alignment - but I would only expect to pick this up at relatively high speeds.

PJC
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Old Sep 2, 2006 | 10:46 AM
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Jeff,

Are you 100% sure that the shocks only have 5,000 miles? Are they "new" stock shocks or Bisltein HD's? It sounds like it's an alignment issue, as the others have said, but if these are crappy shocks that have had the mileage "dialed back" by someone on ebay, they could be the culprit. I had a similar feeling when I first got my car a few years ago. At the time, my shocks had approx 30,000 miles on them. Good luck.
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Old Sep 2, 2006 | 11:05 AM
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Thanks Guys

It does only happen at high speeds. I do 80-85 on the way to and from work. Although in the wet it was anything over 60-65.

As for the shocks, I'll have to have them checked out. The previous owner had the suspension work done by Peter Dawe and when I had the PPI done my mechanic commented that the components did look new. Oh well I'll start with the alignment and go from there.

Jeff
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Old Sep 2, 2006 | 11:12 AM
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The oem bushings don't last forever, check all of your links and arms.
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Old Sep 2, 2006 | 11:28 AM
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Could it be bump steer from possibly being too low?
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Old Sep 2, 2006 | 11:43 AM
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I had the same problems and it was an alignment issue where the rear toe settings were way out. Got it "straightened out", problem solved.
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Old Sep 2, 2006 | 11:45 AM
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I have a 993S and a 85 carrera. Untill 3 days ago I thought the twitchness of my car was just the power steering. once I came so close to the jersy barrier answering the cell phone it really woke me up . I loved the way the 85 carrera tracked down the road and almost avoided driving the 993. 3 days ago i took it into our local race shop to check the alignment. I was standing around watching and at one point heard the guy saying this thing is F%$^#& up. I am in awe the way it tracks now. funny thing is the guy I got the car from had it aligned at the same place before not to long ago.
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Old Sep 2, 2006 | 11:50 AM
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Autosea

I was having the same thought yesterday. I was thinking back to my recently sold, and dearly missed 81 SC w/3.6 . That thing tracked dead straight..the faster I went the more it seemed to hunker down and go. I was very surprised when my 993 didn't feel as good. I'll get it to the shop next week and see whats up.

Thanks

Jeff
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Old Sep 2, 2006 | 12:17 PM
  #11  
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If the car feels 'twitchy', most likely an alignment.
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Old Sep 2, 2006 | 02:37 PM
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i had a similar problem with something as simple as tire pressure. with such low profile tires the tire can still look good to the eye with half the pressure in it.
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Old Sep 2, 2006 | 03:11 PM
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Check all four shocks for leaks. If one has lost its 'charge', it will create a monster out of it. Like mentioned above, tire pressures can do the same.
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Old Sep 2, 2006 | 04:11 PM
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The front being twitchy or nervous can be two things, too much toe out or bump steer... since your car is lowered, toe out makes the car more nervous. You don't mention tire sizes, if you have 245s by any chance, you might want to go narrower (or more toe-in)

The rear, you need to check out your kinematic toe adjustment (and all others too). Assuming your tire pressures are not too high, that is.. No need to go with factory recommendations, you can drop pressures a bit.
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Old Sep 5, 2006 | 01:40 PM
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twitchiness can be caused by tire pressure being low, especially if one rear tire is lower than the other...check this first
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