High Speed Vibration???

Dustin Yenny

Registered User
My car has had a vibration ever since I purchased it. Its getting worse about 2K miles later. At first it would not really shake the rear end of the car/driveline but I could feel it in the seats at say 70 and it seemed to get worse at higher speeds. It feels like it is a vibe per one revolution of the tires. Its NOT like a steady vibration/shimmy. I have brand new tires and they have been rotated and rebalanced days ago. That did not help anything and actually may have made it worse. I checked the u-joints back a few weeks or so and they seemed tight. The car was aligned before I bought it but the rear was not aligned as they could not lossen the rear adjustment screws or something!?!?! Below are the rear alignment numbers from the printout sheet. Could the alignment cause this vibration? I have noted just minutes ago that the vibe is worse when I get on the gas. If I get on the gas it feels like something back there really shakes but once I let off the gas it isn't as bad. I had both motor mounts replaced and I know the rear end gears were stepped up to 3.27's by a previous owner.


LEFT REAR

Actual Camber -0.6* Specified Range (-1.0* -- 0.0*)
Actual Toe 0.28* Specified Range (-0.07* -- 0.18*)


RIGHT REAR

Actual Camber -0.8* Specified Range (-1.0* -- 0.0*)
Actual Toe 0.22* Specified Range (-0.07* -- 0.18*)

REAR

Total Toe 0.50* Specified Range (-0.13* -- 0.37*)
Thrust Angel 0.03* Specified Range (?????)


The camber was off but according to the printouts it looks like that was fixed.

Any ideas on what to check?
 
These cars have drive shalft balance problems. If the whole car virbates and not just the fromt end, check the shaft. One thing you can do is re-orintate the rear u joint a half turn and see if its better or worse. If that doesn't make any difference, start looking at rear wheel bearings etc. Another trick is to position the valve stem one lug hole ahead of the painted lug all towards the front of the car.
 
Whats this trick with the rims?? I have the valve stem on them all towards the front of the car?? I've never seen a painted lug on eithe of my SC's! I'll take a look but before I jack the car up again I want to be sure what to do.
 
Hmmmm.......

My car does the same thing man! Every since a Ford Stealership so call "balanced" my driveshaft! I think mine also needs u-joints though.:(
Is yours an auto or a stick??? Mine is an AOD.;)
 
Re: painted lug

The factory paints one lug on each of the front wheels. If you don't see any painted ones, you'll need to just mark one as a referrence and move the wheel around and see if you feel any difference. It's a real pain to do but it's worth it in the end.
 
One last question. When you said position the valve stem on lug ahead of the painted lug. Do you mean on lug hole to the right, left or what?
 
Valve/lug position

Position the wheel so the valve stem is just one hole ahead of the painted lug, both sides towards the front of the vehicle.
 
I must be thinking with my ass again but I still don't understand where to position the wheel. I'm assuming one lug to the right of the painted lug. I can't see how you can position it one lug ahead of the painted one.

I drew a picture so you can tell me which colored lug you consider ahead of the red painted lug with the F inside. Asuume the red lug with the "F" in it is the factory painted lug. Also assume we are looking at the driver's side front wheel.

Thanks

lug.jpg
 
Re: painted lug

Position the valve stem ahead of the painted lug. That is, put it between the red and green . And if it where the passenger side it would go between the red and the brown.
 
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