Stability question
Thread Starter
Cruising
Joined: Oct 2012
Posts: 10
Likes: 0
From: San Diego CA
Stability question
Yesterday I had my C3 coupe out on the freeway. I spun it up to between 80 and 90 on a nice flat patch and all of a sudden it felt like I was driving in high speed crosswinds or driving on ice. Stayed in my lane but felt very unstable. All went away back down at 75.
I have gone through the front suspension with new lower ball joints, tie rods, idler arm. A frame bushings are good, shocks are new, tires are new (P225 Radial TAs) spin balanced with no shimmy. Power steering components are new (cylinder) or fresh rebuilt (control valve, pump). Factory chin spoiler on the front.
Could some of the experts point me in a direction of where to look next?
Thx
Raymond
I have gone through the front suspension with new lower ball joints, tie rods, idler arm. A frame bushings are good, shocks are new, tires are new (P225 Radial TAs) spin balanced with no shimmy. Power steering components are new (cylinder) or fresh rebuilt (control valve, pump). Factory chin spoiler on the front.
Could some of the experts point me in a direction of where to look next?
Thx
Raymond
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Yesterday I had my C3 coupe out on the freeway. I spun it up to between 80 and 90 on a nice flat patch and all of a sudden it felt like I was driving in high speed crosswinds or driving on ice. Stayed in my lane but felt very unstable. All went away back down at 75.
I have gone through the front suspension with new lower ball joints, tie rods, idler arm. A frame bushings are good, shocks are new, tires are new (P225 Radial TAs) spin balanced with no shimmy. Power steering components are new (cylinder) or fresh rebuilt (control valve, pump). Factory chin spoiler on the front.
Could some of the experts point me in a direction of where to look next?
Thx
Raymond
I have gone through the front suspension with new lower ball joints, tie rods, idler arm. A frame bushings are good, shocks are new, tires are new (P225 Radial TAs) spin balanced with no shimmy. Power steering components are new (cylinder) or fresh rebuilt (control valve, pump). Factory chin spoiler on the front.
Could some of the experts point me in a direction of where to look next?
Thx
Raymond
DUB
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
Make sure the stabilizer bar frame bushings and end links are in good shape, as well. You can replace them with rubber or poly, depending on what you want. If you replace the frame bushings with poly, you may have to shim the mounting brackets so the bar is clamped snugly but not tightly. Tightly just increases the NVH.
Racer
Joined: Apr 2008
Posts: 406
Likes: 46
From: Lebanon OH
My car would kick it's rear end out around a turn if the g-force was high enough. Also, there was some clunking around under there as well. It tuned out to be a number of things, but the most frightening was that two bolts holding the diff to the cross member had backed almost completely out. They were both on the drivers side.
Also, the yokes were worn in the diff and had to be replaced. The driver's side had been ground down and the clip was missing, the passenger side wouldn't hold a clip in spite of the groove.
Finally, there was the assortment of usual dried / worn busings. After repairing all the problems and getting the rear end aligned, the instability went away. Just some things to check. Good luck.
Also, the yokes were worn in the diff and had to be replaced. The driver's side had been ground down and the clip was missing, the passenger side wouldn't hold a clip in spite of the groove.
Finally, there was the assortment of usual dried / worn busings. After repairing all the problems and getting the rear end aligned, the instability went away. Just some things to check. Good luck.
2026 Loser of the Year
Joined: Sep 2013
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From: New Or-leens Loo-z-anna
Burning Brakes
Joined: Sep 2006
Posts: 1,071
Likes: 86
From: Rotonda FL
Modern cars track down the freeway, with its ruts and dips, very well because they typically include more caster than older vehicles. Additionally, C3's are prone to frame sag in the front (especially). This sag reduces the amount of caster, and limits the amount of adjustment available.
Take a look at the size of the shim packs at the front and rear of the each wheels A arm. These are found under the hood, just to the rear of the radiator. If there are no shims, or if the shim packs are the same thickness you have probably found at least part of your trouble (the pack in the front should be thicker than that at the rear, effectively making the axis between the centerline of the upper and lower ball joints less vertical. A bicycle or motorcycle will be much more stable in a straight line with extended forks, compared to one with the forks straight up and down.)
Take a look at the size of the shim packs at the front and rear of the each wheels A arm. These are found under the hood, just to the rear of the radiator. If there are no shims, or if the shim packs are the same thickness you have probably found at least part of your trouble (the pack in the front should be thicker than that at the rear, effectively making the axis between the centerline of the upper and lower ball joints less vertical. A bicycle or motorcycle will be much more stable in a straight line with extended forks, compared to one with the forks straight up and down.)
