Thought on AWD Bevel gear failures

Post by **wizechatmgr** » 21 Nov 2023, 14:38

I also happen to have an XC, the vibration damper under the angle gear has a scoop that "should" cause air to be passed over the angle gear. As others have mentioned, I think it's the VC going that ultimately causes these to shred because they typically don't nail the aluminum coupler but rather shred the angle gear.

I think the south main auto YT channel did a replacement of a VC bearing not too many years ago - I'm guessing he likely replaced the fluid in it and knew what to use if he was already pulling a bearing. My guess is these leak, then corrosion & heat locks them up tight. Then it becomes a solid 4WD which it isn't designed for. I believe the rear wheels are usually left to freewheel most of the time when working correctly.

Post by **scot850** » 21 Nov 2023, 19:08

I'm not clear, are you saying he replaced the VC fluid? I'd be interested to see how you do that and what fluid was used to refill as I thought the VC unit was a sealed unit? There is what I call a 'nose' bearing at the front of the VC housing that can fail, just as you can get a knocking from the bush on the VC casing when it wears out.

Neil.

Post by **wizechatmgr** » 21 Nov 2023, 19:14

scot850 wrote: ↑21 Nov 2023, 19:08 I'm not clear, are you saying he replaced the VC fluid? I'd be interested to see how you do that and what fluid was used to refill as I thought the VC unit was a sealed unit? There is what I call a 'nose' bearing at the front of the VC housing that can fail, just as you can get a knocking from the bush on the VC casing when it wears out.

Neil.

Yes, I believe he did. Let me see if I can find the video...

Update:
Was a Kia and it was just the bearing on the VC he replaced.
https://www.youtube.com/watch?v=ZOIJNC42QwI

There is something similar:
https://www.youtube.com/watch?v=VObmA-DE-6U

Just reached out to these guys to see if they would entertain servicing Volvo VC's... https://vw-kern.at/unser-pruefstand

Post by **scot850** » 22 Nov 2023, 08:29

It would be interesting to see if they can. The challenge is the Volvo VC unit is sealed as I recall and non-serviceable. The other challenge is that I have known these units to fail out the box, even when fitted by the dealer depending on how they were stored. The must not be stored flat or the silicon fluid leaves dry areas in the VC unit which destroys the friction materials on start up.

Neil.

Post by **abscate** » 23 Nov 2023, 01:22

From the Kat…

Pacolamerguez · Post by **Pacolamerguez** » 24 Nov 2023, 17:43

Hello everyone,

I've also looked at the videos on the viscous coupling and it's true that it could be the cause of this noise at stabilised speed and also on deceleration (the whistling is not heard on acceleration).

This video also explains how the viscous coupler works and how to 'test' it.

So how do you go about repairing the viscous coupler? It's quite a problem

Post by **abscate** » 29 Nov 2023, 04:07

We are asking a group in Austria if they can do this, see up thread.

That’s a nice road trip for you!

Thought on AWD Bevel gear failures

Re: Thought on AWD Bevel gear failures