murrayg

Hi all,

I’m doing preventive maintenance on my transaxle ring and pinion. It had a bit of a whine, especially when lifting off the throttle. Since I have the trans out anyway (to fix cracks in top of gas tank) I figure I’d have a look at the R&P bearings. The pinion is OK, but both bearings on the ring gear are showing signs of wear. The races are dull in color, with some pits. I’m thinking if I replace the bearings and races now, it may quiet it down, and more importantly, may help the R&P survive a bit longer with the “spirited” driving the car sees. Can I just replace the race and bearings with exact parts and insure any shims are re-installed as they were?
Thanks,
Gord.

Oddjob

You might be able to get away with using the existing shims, but really should check the ring gear (differential) backlash and preload per the factory service manual when you replace the diff bearings.

murrayg

sounds complicated...is it difficult?

944Ross

The tolerances on this type of bearing are in the tens of thousandths, as long as you reassemble carefully there shouldn't be an issue. On the other hand, some of the noise is likely because the r&p contact is off due to wear in the gears, not just slop in the bearings. Like Oddjob says, you should reset the contact surfaces. But you will do no harm just replacing the bearings.

Oddjob

Trans noise when lifting is generally the front pinion bearing, not the diff bearings. I would double check the condition of those. If you can, post pics of the wear patterns on the bearings and R/P teeth.

Unfortunately, the tolerance for a caged tapered roller bearing isnt within the tolerance of the R/P gear mesh, so they really should be checked. The rollers and the races will be within a very tight tolerance, but the apparent problem is the stamped cage that retains the rollers does not hold the rollers at the same contact plane within the races, from bearing to bearing. So thats why its important to check preload and lash.

Get a copy of the transmission section of the factory service manual and review the measuring and shimming requirements for bearing replacement, to see if its within your scope.

Potomac-Greg

I'll bet a buck that you do all the work and it makes the same whining noise. It's virtually universal. The gears are all right under the floor behind your head, with a glass hatch reflecting the noise. But if you're in there anyway...

murrayg

I've checked the manual and on pg 39-14 - Adjustment Survey, it states that replacing differential roller bearings requires only S1 and S2 shims be set. Looks rather straight forward. I think I'll go ahead with this. These bearings are not great, much better than the pinion bearing, which, by the way looks MUCH more complex to replace. Wear patterns and contact patch on the R&P look quite good.

On an related note, anyone know what "VW sealing compound D3" is? Is there an equivalent more available sealer that I can use here?

Thanks as always!
Gord.