car shakes at 65mph plus
 

I need some help. My car shakes real bad at speeds above 65. At first I thought it may be the tires and since I had a set I wanted to put on the front I tried that. It is better than it was but still has a problem. The car is a 96 with 40k on it. The rotors where turned a couple of months ago. My guess is the steering rack,ball joints or wheel bearings. Is one more common than the other for that age and milage of a car? Also since it looks like I will be taking the front end apart and upgrades I should plan on while it is apart. The plan is it it is the ball points I would go ahad and lower the car at that time.

I replaced my front ball joints at around this mileage. It sounds like you are closing in on an answer. Have you put each front corner on a jack and checked for "play" by trying to wiggle them? You know, a hand on top and one on the bottom of the tire and then checked for slop?

This has got to be a balance issue. It could be complicated by worn ball joints, usually lowers, and/or bearings. Years ago I had a vibration problem that turned out to be water in a tire that came from an air compressor that must of had some water in it. The best thing to do is get the wheels balanced on the car by someone who has knowledge and experience.

JMHO but I think you're going to find it's tire balance/variation causing the problem.

Find someone with a Hunter GSP9700 (IIRC) and have them do a 'Road Force Variation' on your tires along with a dynamic balance on them.
That's the only balancer that is capable of doing this test AFAIK.

I bought THREE sets of BFG tires and none of them would balance satisfactory for EITHER of my C4's. They would shake at various speeds.........
Put the SAME tires on my Z28 and they were ok on it.
Go figure...

I figure our Vettes are REALLY sensitive to tire variations.
Tires that aren't really close may be ok on other vehicles bvut they will give Vettes the shakes.

It's not alignment and I can't say with certainty but it's probably not ball joints, bushings or tire rod ends.

My 84 has 154,000 miles on the original ball joints and they are still in good condition.
Ditto on my '91 that just turned 111,000. Origina; BJ's top and bottom and still good.

At 40,000 yours are likely still ok. That's not a lot of miles at all.
You can easily check them for wear as someone posted above.
There's a visual inspection for the bottom one's as well.
THe 'shell' retracts as the ball wears and there's a spec. on how much should be showing on the lower ones.

Tie rods, ball joints,spindles,control arms, etc are , by nature, overdesigned because it's impossible to know what stresses they may experience (bumping into curbs, etc) in day to day operation that can load them far beyond the 'normal' stresses.


Lubrication is another element that can drastically affect the life of ball joints and tie rod ends. I lubricate mine every 3 thousand miles when I change the oil.
That's beyond any service reccomendations but I figure 'too much too soon' is better than 'too little too late'.

BTW, rotors 'usually' will only cause a pulsation in the brake pedal or steering wheel when the brakes are applied.
I reckon a BADLY warped one 'could' contact the caliper piston and cause a 'shake feedback' into the vehicle but it's not likely at all.
If you feel pulsations or shudder when you apply the brakes, it's the rotors and in most cases it's the front ones.
To test the reat rotors slowly apply the parking brake while driving 30~40. Keep your finger on the brake release when doing this.

Thanks for all the info. I will try and check it out some more tonight.

I would be suprised if it's ball joints at 40K unless they have been negleted. If you have worn a pattern in your tires that could be part of the problem. Most of the time this is a tire/wheel issue. Rotate the tires when you get the balance rechecked.

I should add a couple of details I should have on the first post. The first time this came up it was so bad I thought I had a flat and had to get off the highway. On a different road it seemed to be better. I then had different tire mounted on the front because I was planning to do anyway. It is not as bad as before. The steering wheels jerks real hard left and right until I slow down.

The ball joints on my '85 were shot with not much more mileage then yours - but then mine are 11 years older. GM ball joints have wear indicators - so its easy to see whether its time to replace them or not (Mine were overdue- and actually fell to pieces when I tried to remove them).

That said - I think you need a balance and alignment.

:iagree:

:iagree: :iagree: :iagree:

I just booked an aligment for tomorrow and am going to have them rebalance the tires.

It still could be a tire issue but...judging from the preceding imformation I'd reccomend taking it to a good garage for inspection of ALL the front end components.
It could be a tie rod with some 'play' in it or ball joint or control arm bushing.
None of those are major repairs.

In any case if there are forces developed strong enough to move the steering wheel then it's going to beat your front end components to death.
Needs to be fixed before you drive it much more.

It didn't initially sound like such a problem but the nature and severance of the wheel shake makes me think it needs to be inspected by a knowledgeable mechanic.

If you anywhere near Columbus, Ga. I'll look it over for you free.
Whoops, I see you're in Ks.

Well that's COMPLETELY different. Take it to a good front end shop to be sure.

Update I have the car in the air and the ball joints and tie rod ends are fine. However when I rock the wheels back and fourth the steering rack is moving and makes a noise.

I have no idea whats wrong but keep us posted! Ask them if you can watch them balance your tires, that you think the last place did an unsatisfactory job. Also ask them if they have this...http://www.gsp9700.com/index.cfm

any update on the steering problem?

How are the shocks?

Check your U- joints. I had a similar problem with my Tahoe. Raise the car and check for play in the drive shaft.

ed89

I ended up changing all the ball joints since I had it apart. One of the lower ones was bad. Since I had it all apart I lowered the front with a VB&P adjustable front spring. I had the car up to 100 mph and rode great.

Good report. :thumbs: Which ball joint was it?