Driveline shunt

Bandycoot · 21-09-16, 04:31 AM

Has anyone successfully managed to cure driveline shunt on Quattro's? My 90q is doing it and all my previous ones did. I've tried all sorts of things to cure it without success.

20vcqdriver · 21-09-16, 11:58 AM

Quote:

Originally Posted by Bandycoot

Has anyone successfully managed to cure driveline shunt on Quattro's? My 90q is doing it and all my previous ones did. I've tried all sorts of things to cure it without success.

I cannot say I've noticed it on mine, however I suspect it is caused by a worn or failed diff /gearbox mount or propshaft coupling or support bush. Certainly worth starting here. Diffs and gearboxes themselves are pretty bombproof so long as you check oil levels periodically and use top quality oils in them

jimh · 21-09-16, 05:48 PM

Mine was the CV joint at the rear end of the prop shaft where it meets the rear diff.

I could barely feel any movement at all, but if I held the outside of the CV joint with one hand and twisted the prop shaft back & forth with the other hand, I could hear the same metallic sound I got on the road.
What surprised me was the the wear was not in the ball race of the CV joint, but in the inner splines of the CV joint where it slides over the end of the prop shaft. New CV joint sorted it.
I don't think the CV joint is available from Audi who want you to buy a whole new prop shaft, but IIRC the same CV joint is used on Porsches.

Bandycoot · 21-09-16, 09:57 PM

Thanks very much. Inner rear Cv joints were my thoughts. I checked mine recently and was getting slight movement and noise. I'll have a look on line to find a pair. Thanks again.

Andy10v · 22-09-16, 06:11 PM

If you can track down the play it could save a fair bit of money. If you turn a wheel back and forth there is normally a fair bit of accumulative play in most old quattros these days.

Engine mounts
Gearbox mounts
Diff mounts

prop bearing

Stiffening the above will often make play in the below feel even worse

outer cv x4
inner cv x4
prop cv x2

prop X joint

Torsen centre diff backlash

Front diff backlash
rear diff backlash

gearbox backlash

Ensuring all the rubber mounts and driveline CV joints are in good order is a good start without getting silly.

Bandycoot · 05-10-16, 10:21 AM

Thanks Andy. On my previous 90q I started with the gearbox mounts and then moved on to the subframe and diff mounts. Made no difference. Not sure where to begin with this one. It's tempting to start with inner Cv joints and see what's happens.

20vcqdriver · 05-10-16, 10:29 AM

Quote:

Originally Posted by Bandycoot

Thanks Andy. On my previous 90q I started with the gearbox mounts and then moved on to the subframe and diff mounts. Made no difference. Not sure where to begin with this one. It's tempting to start with inner Cv joints and see what's happens.

Now you mention it, I remember a friend with a 100Avant Quattro who was complaining of shunt and had been advised it was the diff, but when I investigated he actually had excessive play (very excessive up and down as well as rotation play) in his rear inner CV's. Replaced these and all sorted

Well worth starting here.

Bandycoot · 05-10-16, 04:25 PM

This is my thoughts as well. Previously I changed everything apart from the inner CV joints. I'm getting a strong feeling this could well be the issue.

steve briance · 06-11-16, 10:54 PM

The single biggest improvement I have seen in my quest to cure shunt was to modify the engine front snub mount. The mk1 golf gearbox mount works as a perfect solution to 5 cylinder snub mount woes. Granted it needs welding in but it holds the rubber buffer perfectly and transformed my car. Sadly it is NLA so look on eBay or old school scrapyards. Incidentally in it also used on the sport Quattro!

SorenR · 07-11-16, 12:58 AM

https://store.034motorsport.com/snub...lications.html

22-09-16, 06:11 PM	#5
Andy10v Grown up member Classic Audi Club Member Join Date: Dec 2008 Location: Stirling Posts: 861	If you can track down the play it could save a fair bit of money. If you turn a wheel back and forth there is normally a fair bit of accumulative play in most old quattros these days. Engine mounts Gearbox mounts Diff mounts prop bearing Stiffening the above will often make play in the below feel even worse outer cv x4 inner cv x4 prop cv x2 prop X joint Torsen centre diff backlash Front diff backlash rear diff backlash gearbox backlash Ensuring all the rubber mounts and driveline CV joints are in good order is a good start without getting silly. __________________ 2005 350z GT Sold-1992 3B S2 coupe-RS2+, 996s, konis, forged rods, rear torsen.... Sold-1993 ABY coupe

21-09-16, 05:48 PM	#3
jimh Grown up member Classic Audi Club Member Join Date: Dec 2008 Posts: 122	Mine was the CV joint at the rear end of the prop shaft where it meets the rear diff. I could barely feel any movement at all, but if I held the outside of the CV joint with one hand and twisted the prop shaft back & forth with the other hand, I could hear the same metallic sound I got on the road. What surprised me was the the wear was not in the ball race of the CV joint, but in the inner splines of the CV joint where it slides over the end of the prop shaft. New CV joint sorted it. I don't think the CV joint is available from Audi who want you to buy a whole new prop shaft, but IIRC the same CV joint is used on Porsches.

21-09-16, 09:57 PM	#4
Bandycoot Grown up member Join Date: May 2015 Posts: 24	Thanks very much. Inner rear Cv joints were my thoughts. I checked mine recently and was getting slight movement and noise. I'll have a look on line to find a pair. Thanks again.

05-10-16, 10:21 AM	#6
Bandycoot Grown up member Join Date: May 2015 Posts: 24	Thanks Andy. On my previous 90q I started with the gearbox mounts and then moved on to the subframe and diff mounts. Made no difference. Not sure where to begin with this one. It's tempting to start with inner Cv joints and see what's happens.

05-10-16, 04:25 PM	#8
Bandycoot Grown up member Join Date: May 2015 Posts: 24	This is my thoughts as well. Previously I changed everything apart from the inner CV joints. I'm getting a strong feeling this could well be the issue.

06-11-16, 10:54 PM	#9
steve briance Newbie! Join Date: Oct 2016 Posts: 18	The single biggest improvement I have seen in my quest to cure shunt was to modify the engine front snub mount. The mk1 golf gearbox mount works as a perfect solution to 5 cylinder snub mount woes. Granted it needs welding in but it holds the rubber buffer perfectly and transformed my car. Sadly it is NLA so look on eBay or old school scrapyards. Incidentally in it also used on the sport Quattro!

07-11-16, 12:58 AM	#10
SorenR Grown up member Join Date: Oct 2010 Location: Vesterlyng/Föllenslev, Denmark Posts: 563	https://store.034motorsport.com/snub...lications.html