5 replies to this topic

[SteveS]

Hi Guys, I'm new at all this, and love these cars now. My car is a 1993 with the original viscous diff.  The car has a high speed severe vibration, and I got black flagged at the Glen due to a rr tire wobble. I've checked everything, and replaced the rr half shaft which had some slop but was not the problem. The car shows over 150k mileage.  The diff has slop in both axle stubs, enough to hear a clunk and see movement chucking them back and forth. The vibration is less severe when up in the air and no weight on the tires.  Should I replace the diff with a used one of the same type? Should I upgrade?  Exactly what parts would be required to upgrade and keep the same track so I could run with NASA or SCCA?  This car will not be a front runner, but a great car to learn and hone skills in.  Thanks in advance for all the expertise...

[Bench Racer]

Hi Guys, I'm new at all this, and love these cars now. My car is a 1993 with the original viscous diff.  The car has a high speed severe vibration, and I got black flagged at the Glen due to a rr tire wobble. 

With the car jacked up and if you put one hand at the top of the tire and one hand at the bottom of the tire and push and pull with opposite hands do you get some free play, wobble? Try same thing with hands at sides of tire.

 

If play/wobble occurs it could be the wheel bearing which is pressed into the hub. 

 

Are the rear control arms/bushings/bolts/cam bolts good?

 

Is the shock leaking fluid, is the shock good?

[EMatoy]

With the car jacked up and if you put one hand at the top of the tire and one hand at the bottom of the tire and push and pull with opposite hands do you get some free play, wobble? Try same thing with hands at sides of tire.

If play/wobble occurs it could be the wheel bearing which is pressed into the hub.

Are the rear control arms/bushings/bolts/cam bolts good?

Is the shock leaking fluid, is the shock good?

In addition to what bench said above loosen the big nut that holds the CV shaft into the hub and check for play. I had a wheel bearing come apart and actually crack the race - it felt fine until I loosened the nut. Then the wheel fell offf!!

[SteveS]

With the car jacked up and if you put one hand at the top of the tire and one hand at the bottom of the tire and push and pull with opposite hands do you get some free play, wobble? Try same thing with hands at sides of tire.

 

If play/wobble occurs it could be the wheel bearing which is pressed into the hub. 

 

Are the rear control arms/bushings/bolts/cam bolts good?

 

Is the shock leaking fluid, is the shock good?

 

Thanks for the suggestions. The wheel bearing is good, the shocks are new, no leaks, and I've tried prying on all the bushings and can't find any slop.  I can't find any reference to how much play axle stubs are allowed to have, but it seems like too much.  

[SteveS]

In addition to what bench said above loosen the big nut that holds the CV shaft into the hub and check for play. I had a wheel bearing come apart and actually crack the race - it felt fine until I loosened the nut. Then the wheel fell offf!!

 

Interesting!  I can try this suggestion, but I did replace the axle shaft with a Mazda one and didn't notice anything.  Again, wish I could find how much play the axle shafts are allowed.  But, I'll take the nut off again and inspect.  Thanks

[Bench Racer]

Let's go back to the get-go.

 

How did the black flag officials describe the RR tire wobble? This must have been a big wobble for them to view, which side of the car?

 

"The car high speed severe vibration."

 

 "The vibration is less severe when up in the air and no weight on the tires."

 

From the officials black flag/sound, you know which side of the car has the issue.

 

You tried a different axle shaft and didn't notice a difference.

 

Vibration at how many miles per hour when jacked up?

 

Measure the end play of the 4 bolt wheel hub. Maximum allowable is .002 inch

 

The axle nut is tightened to 159-217 ft. lb.

 

You'll need a buddy to complete this task. With a mechanics stethoscope listen to the sound at the non rotating output end of the differential and at the knuckle. Do this on both sides of the car for noise difference. For example if the noise is growly one place compared to the other, that would be an indicator of an issue.

 

I've never had an issue with a drive/half shaft. Don't know anything.

 

There are videos out there for many vehicle issues.