Differential Assembly

[QuebecTransit]

So... turns out it's NOT my bearings which are making a whining noise, but the differential assembly. I can't find it anywhere online (need to ship it to Canada).
I have a mk4 with the type 51 axle. Part number 1669120.

Any ideas on where to find one?

[QuebecTransit]

Additionnal information:

I've been to two garages. The first one claimed it was the differential bearings. The second one is claiming it's the differential assembly.

The internet is claiming it's the pinion and ring that are improperly adjusted or worn out and need replacing.

FYI I'm hearing a humming or whirring sound coming from the differential above 15-20 km/h and it's significant on the highway. No ticking or clunking or grinding. Any ides on solving this other than just replacing everything?

[Chug]

https://www.ebay.de/itm/126047058125

(caveat, not for the faint hearted or sensible types) But I would get it on some sturdy axle stands and chock the front wheels and get someone to run it in gear whilst very carefully having a listen around the axle.

[QuebecTransit]

Thank you for the link!

I think I'm going to indeed have to diagnose it myself as I have learned that neither garage has actually opened up the diff to take a look at it!

[MinorMatt]

I would open the casing, check the lash, and adjust it before doing anything else.

Remove rear cover, and rotate the crownwheel (make sure your out of gear!) by hand. The outer edge should only move 0.1-0.2mm - i.e. perceptible but not much more.

If its moving much more, undo the 2 locking screws and tabs, and rotate the 2 "nuts" (threaded inserts with holes in the top) to take out the slack. Both of them should be moved the same amount, in the same direction, to maintain the preload. Then re-install the locking tabs and rear cover.

[QuebecTransit]

Thank you! I have the Haynes manual. This procedure doesn't seem to be in there. Before opening the differential I'd like to find a diagram. Do you happen to have a link to one? I'm not seeing the two screws on any diagrams int he Haynes manual.