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914World.com _ 914World Garage _ Transmission question

Posted by: Marty Yeoman Oct 5 2006, 01:33 PM

I have started to notice noises that I attribute to excesive differential clearance.
When shifting up I can generate a "clunk" type sound. Also while driving I can generate the same thing by feathering the throttle. I can eliminate the noise by being excessivly smooth on acceleration. I seem to be able to duplicate the sound by raising the rear wheels off the ground and rotating the rear tire.

My questions are: How is the pinnion/ring gear clearance set? Can it be adjusted with the dirve train still in the car? How long can I let this go?

Posted by: Joe Ricard Oct 5 2006, 01:50 PM

Sure it's not the CV's ?

Posted by: Matt Romanowski Oct 5 2006, 01:50 PM

Are you sure it's the pinion / ring clearance? In my experience, when they start to wear bad, they usually resolve themselves rather quickly.

It could be the cv joints or the spiders.

Posted by: Joe Ricard Oct 5 2006, 01:52 PM

Pinions get shims for depth and also via paper gaskets between intermediate plate and case.

Guys like Dr. Evil can hi-lite where I am wrong. He does lots of these transmissions. I have only fumbled through one so far.

Posted by: Marty Yeoman Oct 5 2006, 06:09 PM

Any quick tests for CV diagnosis????????????

Posted by: r_towle Oct 5 2006, 06:44 PM

in this order

Front and rear engine mounts.
If newer type with a side shifter you need to make sure the front mounts on the outer part of the bar, where the bar attaches to the body are nice and tight.
The front inner ones are rubber with a bolt glued inside and are not repairable, just replacable.
I am guessing that might be the issue.
Aslo look at the rear mounts from tranny to body, but these are pretty solid
The clunk could be from the engine rising up on one side due to the amazing amount ot torque that these little monsters produce...seriously it will make that sound.

Easiest check, have someone do it while you watch from outside, and look into the engine bay...if the motor moves when the engage the clutch...its the mounts.

CV joints will click while going forward or backwards just a little bit, again easier to hear from outside the car.

Rich

Posted by: Dr Evil Oct 5 2006, 10:13 PM

Joe, you are right as well (thanks for the honorable mention ).

To check CVs you can jack up one side at a time and rotate the up wheel for and aft. You should not hear or feel a click after some motion (clear?).

I REALY doubt your ring and pinion are that far gone If so you would be in a worse shape. However, if the roller bearing on the pinion shaft goes, you can have some symptoms of the clearance changing.

But, I am thinking that the simplest explanation is what Rich suggested. Check and get back to us so we can see what to do next.

Posted by: McMark Oct 6 2006, 12:29 AM

Lay down at the back of the car, reach underneath, grab the axle and try to bang it into the transmission, then try to bang it into the wheel side. If you hear it hit, that CV is shot.

There has been some debate as to this technique, but I think it works and I've used it on multiple cars.

Posted by: Marty Yeoman Oct 6 2006, 01:20 PM

Thanks for all the suggestions.
I try them and check back.

Posted by: Marty Yeoman Feb 23 2007, 03:26 PM

Well, I just completed my rear axle rebuild. I replaced all four CVs and both wheel bearings. Man what a difference. No more clunk. Just smooth power to the ground now. Weeeeeeeeeeeeeee!!!!!!!!!!!!!!!

Posted by: Eric_Shea Feb 23 2007, 05:40 PM

Cool... so now we can hijack your thread! Arrrrrrrrrrrrrrrrrgibra.

Rich, what ever happened to your front end issue on your sons car?