a lot of vibrations at 50mph and more

[mickeypowa]

Hi guys !
I have an issue that I would like to solve on my car : when I drive, as soon as I get to 50mph and more I have lots of vibrations. I make lots of resonance in the car and it's pretty disturbing and it doesn't feel safe at all.

But if I withdraw the foot from the throttle, the vibration decrease a lot even if I'm still at high speed.

So I think maybe I have a problem with the driveshaft or something like that rather than with suspension or wheels ?
Or maybe I have a problem with both driveshaft and suspension/wheels ! ahah (because I have still a problem of rear swinging a little at very low speed : under 10mph)

What do you think it could be ? what could I check/test/change? The driveshaft ? the u-joint at the reat of the driveshaft ?

thanks a lot

Mickeypowa

 

[Jeff L]

There are a few things you can do to check for vibrations.

If you have access to a car lift it would help and save you a bunch if time.

When the car's rear end is off the ground you can put the car in drive and see if the driveshaft is working correctly and if there is any vibrating. Safety is key here. Please make sure the car is secure if you plan to jack up the car yourself and put it on jack stands to see if you have a driveline vibration. Have a friend or two on hand to help. Make sure those front tires are blocked securely if you only lift the back end. If you have enough jack stands getting the whole car off the ground is so much better. But safety first. Again if you can get it on a lift it is si much safer.

Go to a tire shop and have your wheels checked for balance. You might have a bent rim, tire going bad, a wheel weight fell off.

Front wheel bearings going bad can cause a vibration.

My guess from what you said is it could be something to do with your driveshaft and u joints.

Good luck and hope you find the problem.

 

[lilbowtie]

No vibration till 50 ?? I would pull the driveshaft and check the universals. Make sure the shaft isn't bent and feel how much play is in your rear end. Lose the spacers in the rear springs - they mess with the spring geometry. You never said if you checked the swing arm bushings, and you have new ones!

 

[awdblazer]

i had the same thing, was my tires were seperating?

 

[mickeypowa]

I haven't many vibrations until 50, they come very quickly a soon as I arrive at 50.

my tires seem to be in good shape. I will go to a tire shop to check for balance though.

For the spacers that I had in the rear springs, I withdrew them few month ago.

I have found an american car mechanic, I am going to let him the car to change the bushings but I wanted to know if I have maybe a u joint/driveshaft issue before, in order to tell him.
I will try to jack up and check if shaft is vibrating this week end

thanks for your help 😉

 

[UMI Sales]

Have you checked Pinion Angle?

Craig

 

[somaphox]

im thinking driveshaft as well,have fun sweating those nylocks out of the old ujoints..< your gonna need a b.f.h,a large socket or if you have a bench press it goes much more quickly but you will have to have a oxy/acetylene torch or a mapp gas blow torch.careful how long you heat it though the ends can explode off...found that out the hard way

 

[mickeypowa]

how can I check the pinion angle ? what is the correct value ?

 

[UNGN]

how can I check the pinion angle ? what is the correct value ?

Just look at it. If the angle doesn't look excessive, its probably fine. Drive shafts can have a lot of misalignment and not vibrate @ 50 mph ,but they cant have a worn tailshaft bushing or a bend/dent and NOT vibrate @ 50 mph.

Put the rear on jackstands and run the car above 50 mph indicated, and watch the drive shaft for whip. You'll probably see it/hear it if you can feel it at only 50 mph.

I burned up the tailshaft bushing on my 2+2 during a race and back end would practically hop off the ground above 150 mph from the drive shaft whip.

If the drive shaft is whipping, pull it out and look at the tailshaft for damage. It should be smooth shiny, oily and not discolored.