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Transaxle/Drive Gear grinding sound - post repair, upgrades

Posted: Thu Jun 04, 2020 6:54 pm
by Marktt
Hi all,
Looking for some support - Concerns a 1967 type 1 swing axle transmission.

Following repair and part replacements and upgrades, all listed below, there is a somewhat mid to high tone grinding noise – seems to be coming from the drivers side axle but maybe not as I’m sitting closest to that side

It occurs during wheel rotation, neutral or not, not constant in whole of 360 degree rotation. Turning the axles when on jacks, there’s more resistance that prior to all the work performed and parts installed. New spider gears, diff, and such possibly a given. Disc conversion, done along with transaxle work; rotors/pads are not binding.

I searched for a long time and could not find any discussion concerning this issue and I’ll be thorough as possible for the benefit of responders and others seeking resolves.

Here’s a summary of work and parts installed in diagnosing potential cause:

Firstly, transaxle was not opened up; only the nose cone, differential and final gear was worked on.

New nose cone
New Wendell Ind thrust plate
New super duty side covers
New spider gear set ... -gear-set/
New front trans mount
New side cover retainers ... D301%2D145
New axle spacers (see note 1)
New Rotohub disc brake kit

Start with Thrust Plate:
I installed a Wendell bearing thrust plate, sandwiched between the nose cone and the main case.

Per instruction when using the thrust plate, the same thickness the plate represents had to be removed from the face flange of the nose cone; I did so using a belt sander, flat sanding. No leaks.

Question though: If I didn’t remove enough material from the nose cone, the amount representing the thrust plate thickness then the total length of the transaxle would be greater and upon install would have resulted in pressing or compressing if you will, the transaxle. Could the grinding issue be associated with such an event? How would I check? By relaxing slightly the transaxle mounting– backing out the frame horn bolts a bit?

Next up; new superdiff (clip type):
The prior superdiff, screw type, failed when a couple of spider gear teeth sheered/snapped off. Some of the material (the teeth) made its way to the axle and along with chewing up both fulcrum plates; some of the material became embedded/smashed into the axle (paddle portion). I was able to grind the material out of the spade, polish it and replaced both fulcrum plates. The superdiff was installed professionally, set up by a long time vw shop owner here in town, setting preload, clearances and such.

My limited rear end experience but best guess is either the transaxles compressed in the mounts or the differential is rubbing on the cover (prior one showed scars it had once chewed up inside of cover via diff bolts), my axle tube is too tight, insufficient clearance (shouldn’t create noise though I’d imagine) or the spider gear set and axle were installed wrong or?

Any ideas or help is greatly appreciated. Where I go from here determines if I begin pulling motor, then tranny or direct attention to axle, tubes, etc.

Note 1: There was a slight variation in the outboard racer spacers (thickness was greater) and it affected the axle tube final assembly so I used the stock ones.

Re: Transaxle/Drive Gear grinding sound - post repair, upgrades

Posted: Tue Jun 30, 2020 2:47 am
by Marktt
FOLLOW Up: Ended up being a fulcrum plate had slipped behind the axle .

Re: Transaxle/Drive Gear grinding sound - post repair, upgrades

Posted: Tue Jun 30, 2020 7:05 am
by doc
Thx for follow up.