Okay guys I'm lost here. I just got my new rear spring on a week or two ago and now I have a bad vibration at freeway speed. It feels like the tires are out of balance, but it was fine before I put the new spring on.
That is the only thing I did was to change the spring out.
I just checked and everything looked good and was tight.
I'm thinking bad things like u-joints because the ride height is not the same as before...
Any ideas??

It could be a u-joint, but I would first get an alignment. Any suspension work should be followed by a good 4 wheel alignment.

Just my $.02

the answer may lie somewhere in the middle, but im inclined to agree with silver69. if your u joints were bad, they would have given you clues before the leaf spring changeout. the ride height would change the rear alignment specs enough to notice.
stevep3162007-05-19 15:44:04

Yeah I agree, but to cause a vibration? It's bad enought that I don't feel comfortable driving it.
I'm going to lube up the u-joints and see if it changes, but will also get an alignmemt done soon..before Carson City anyway.
Thanks

If the height is raised significantly with the new spring, you're half shafts may be at too much of an angle and the vibaration could be a sign of a slight bind. Longer spring bolts lowering the ride height a bit may cure that. LukesVette2007-05-19 16:15:23

Thanks Paul,
It came with the new 8 inch bolts and the nut is all the way down to where the key goes in...it's not real high, but the old spring was so bad it is higher than it used to be.
If I keep spending money Momma is going to make me sleep in it...

The frequency of the vibration and rpm of the tire can narrow down the culprit. Does it do it at all speeds? Would you call it high frequency(buzz) or is it low frequency( more of a lope)? High frequency would definitely point to the u-joints. If it is more of a lope that increases frequency with tire rotation it would point more to a tire.

Scott

Scott I only notice it at high speed (freeway speed) and there is no noise. It fells just like the tires are out of balance..but I don't think they are because they are less than a year old and were fine before the spring change. It's bad enough to make everything inside rattle. I can also feel it in the steering wheel. Yesterday I put in new front bearings, I need to bleed the brakes before I drive it...but don't want to take it to the aligment shop yet because I still have to put the new front springs on. I'll find it...but it just seems odd to me.
Thanks

It really is puzzling that it did not do it before the spring change. The only thing I can think of are; A change in the spring rate with in combinaion with the rear camber. Maybe the tires are ridng on a different contact patch and one tire has a high ot low spot in it. As a test I would lower the air pressure to about 22 psi and do a test drive. See if that dampens the vibration any at all. It it does, it may indicate an out of balance or alignment problem. If it were u-joints I would expect a viration at all speeds with an increase in frequency as speed increases. It truly sounds like an out of balance tire but don't understand how the sping changed that unless the spring rate is a tad harsher.

Scott

How are your rear bearings? Any play on the rear tires -  left to right and/or in and out? That was my problem with vibration at highway speeds -  bad bearings on left side side, had both T-arms rebuilt complete; no more vibrations.
Good Luck!
Phill's Vette2007-05-20 21:25:25