mcm95403

Not sure how to ask this but.......

I'm having an intermittent vibration issue at freeway speeds.

• Just had the tires/wheels rebalanced
• the u-joints are all good/tight
• the driveshaft and half shafts appear to not be bent - best as I could tell without using a dial indicator

I've just replaced all the rear control arms and seem to notice a little more vibration than before.

Here's what I'm thinking/wondering - is it possible that the batwing bushings are worn to the point where the differential can move enough to throw the half shafts to an odd angle causing the vibration? Those are now the only original bushings left in the back of the car aside from the sway bar bushings. I kind of doubt it with the C-beam in there, but I'm curious if anyone else has run into this.

JackDidley

Sounds to me like a tire problem. Can you rotate the tires and see if the vibration moves. Most every time Ive had a vibration it was a tire or a U joint. Look for red rust around the U joints. Just because they seem tight doesnt mean they are good. My 2 cents.

mcm95403

I just had them rotated and balanced - no change at all. Next time I get under there I can ghcek the u-joints more carefully, but they seemed to all be tight and nice.

383vett

Might want to pull the driveshaft and have the balance checked. It's not too hard to do. If that's ok, concentrate on the wheels/tires.

Pwnage1337

train tracks

ddahlgren

It is the old deal did it ever not vibrate and if there was a time what did you or someone else do to the car and then it vibrated...
Dave

powerpigz-51

I read somewhere that the driveline has to go in the same way it came out....maybe it is 180 out?

samsonb

I've heard that. But then wonder what if you install a brand new shaft?

M. Schumacher

What do you mean by "intermittent"??

Bluewasp

use a dial indicator and check for Wheel run out

mcm95403

Sometimes it's there and other times, it's not there at all. That's why I'm thinking that it's something that "tweaks" and causes a vibration.

powerpigz-51

Is the vibration throttle sensitive or just out of the blue at any speed/RPM/throttle position?

corvette95

Tires, you rotated them, you can balance a square brick, but it still wont be round. Rotate tires again in a "x" pattern and see if there is ANY difference, I bet there is, not saying it will be gone but different, that will prove tires. Rule of thumb, if you feel shake in steering wheel its balance, if you feel it and hear it in body, it a trueness (roundness) issue.
(BTW - I was Goodyear Tire Corporate Manager - 5 years)

Also, changing rear gears causing higher driveline speeds will do it too.

gp85

I chased an intermittent balance problem for a whole summer.Sometimes it was in the steering wheel and then sometimes I felt it in the seat then on the floor.Turned out to be worn shocks. I could'nt believe what the car felt like after.

GREGGPENN

I also have to think tire, u-joint, or driveline. Engine don't vibrate (unless the RA wasn't balanced from the get-go). Tire's can have wear patterns and/or out-of-round that balancing won't cure.

Most people say the driveline's not that sensitive to being installed backwards, but one or two posters have said it can cause vibration. That's I'd believe wouldn't be intermittent -- but it could oscillate in/out.

If you feel it in the body and not the steering wheel (with both tire locations) front or rear, I'd be more inclinded to suspect the driveshaft or u-joints. If it was constant and got louder with speed -- wheel bearing.

I suppose a shock could even do it -- if the isolation is SO far gone that it's transmitting road texture depending on how the shock (piston) is setting at any given moment.

powerpigz-51

You can check the wheel bearings (hubs) by jacking up the car and see if there is play by yanking on the wheel and tire to see if there is any play.....

mcm95403

The wheel bearings are new as well. Tire wear is very normal.

I can easily beleive however that it could be the shocks. I've heard some odd sounds comming from the rear lately and it's also bouncier than when the schocks first went in. I have a set of Z-51 Bilsteins on the way. I also still have the KYB's that were on the car when I got it up front.

Give me till next weekend to get the shocks swapped and I'll let y'all know how it is.

corvette95

shocks should not do what you are describing even if they are completely shot.

frenchyoliver

In case the balance between tire and wheel is high with a lot of lead, it can reach a rebound frequence at crusing speed. a dead shock will emplify it. Check if you can rotate the tire 180 to have less lead as possible. Sometimes they dont take the time to do it properly for cheap.

C4 are very sensitive when it comes to shocks. Good ones make a hell of difference in car's various vibrations.

When I changed for 4 new F1GSD3, Rotating 180 the front right solved my intermitent vibrations problems at cruise.

twin540

I had a vibration at 4,000 rpm it was my exhaust pipes hitting the dana 44, i guess when the *** off the car would sink at wot it would get close enough to cause that annoying vibration. Took me awhile to find it i changed u-joints had the tires balanced it felt like my motor was out of balance.