Rear Diff Lock Actuator --> Toast
Thread Starter
Audiworld Junior Member
Joined: Apr 2009
Posts: 99
Likes: 0
From: Wisconsin
Rear Diff Lock Actuator --> Toast
Go figure, a 19 year old plastic vacuum actuator will only stand up to one winter of Wisconsin hooliganry and road salt. I found the blue line snapped off of its nipple over the weekend.
Anyone know where I can find a new one? I have access to a couple of 100Qs at the local salvage yard, do they use the same part?
Anyone know where I can find a new one? I have access to a couple of 100Qs at the local salvage yard, do they use the same part?
Audiworld Junior Member
Joined: Sep 2005
Posts: 70
Likes: 0
easy to fix, impossible to replace as they are no longer made. The fix is also quite strong, and I have done this many times on 2 of my quattros, 2 other quattros, and also several other vacuum operated units on other cars, such as cruise control units etc. the plastics get brittle over the years. Vacuum units on audi transmissions get overlooked when clutches and bushes are done, and usually suffer.
you need 3/16inch brake pipe, like cunifer. copper pipe is ok. In the UK i found some normal copper pipe from a hardware store was a little narrow. About an inch and half long, max.
cut the broken stub so it is smooth. Makes for easier working
drill out with a suitable drill bit, slightly larger than the pipe stub that you will insert, so that a decent length of pipe can be inserted.
Use thread lock or bearing fit/retainer loctite to keep the new copper stub in place.
The longest part of this job is getting the white plastic vacuum unit off (audi call it a manifold in their parts list)
cutting the pipe, drilling the counterbore to fit it, and loctiting the stub in will take you about 15minutes, tops.
photo guidance- this is the vacuum operated cruise control for my GTO, and next to it is the difflock that I repaired in similar manner
Hopefully this is useful
you need 3/16inch brake pipe, like cunifer. copper pipe is ok. In the UK i found some normal copper pipe from a hardware store was a little narrow. About an inch and half long, max.
cut the broken stub so it is smooth. Makes for easier working
drill out with a suitable drill bit, slightly larger than the pipe stub that you will insert, so that a decent length of pipe can be inserted.
Use thread lock or bearing fit/retainer loctite to keep the new copper stub in place.
The longest part of this job is getting the white plastic vacuum unit off (audi call it a manifold in their parts list)
cutting the pipe, drilling the counterbore to fit it, and loctiting the stub in will take you about 15minutes, tops.
photo guidance- this is the vacuum operated cruise control for my GTO, and next to it is the difflock that I repaired in similar manner
Hopefully this is useful
Audiworld Junior Member
Joined: Sep 2005
Posts: 70
Likes: 0
Sorry, forgot to answer the other part of your post. the same module is common across all the audis with lockable diffs. 857711995A, also known as throttle control element in some parts catalogues. This number appears in quattro and 100q 200q parts lists.
If they are available in the scrap yard, grab them. I would suggest that the repair also be used. The internal diaphragm is subject to perishing, and is much harder to repair, as any effort to glue a rubber patch makes them very stiff internally.
If they are available in the scrap yard, grab them. I would suggest that the repair also be used. The internal diaphragm is subject to perishing, and is much harder to repair, as any effort to glue a rubber patch makes them very stiff internally.
Thread Starter
Audiworld Junior Member
Joined: Apr 2009
Posts: 99
Likes: 0
From: Wisconsin
I'm glad you mentioned the part number, I found this little gem on the 4000 forum. A late Mercedes W123 door lock actuator should do the trick.
http://search.audiworld.com/showthread.php?t=2224062
http://mercedessource.com/node/1286
http://search.audiworld.com/showthread.php?t=2224062
http://mercedessource.com/node/1286
Thread Starter
Audiworld Junior Member
Joined: Apr 2009
Posts: 99
Likes: 0
From: Wisconsin
Sorry to bring this one back from the dead, but I finally got around to fixing it
The Benz part works perfectly but it takes a little effort to get it installed. Some precision machining (i.e. dynafile) was required to turn down the end of the shaft to accept the die, and only 2 of the three mounting holes line up, not bad according to Meatloaf's standards.
AudiWorld Newcomer
Joined: Jan 2013
Posts: 5
Likes: 0
if it's only the bellows on the shaft and especially if the collar on the shaft end is intact, I have just repaired mine with a wrap of loom tape (rubberised and sticks to itself) and some small zip ties : )
AudiWorld Newcomer
Joined: Jan 2013
Posts: 5
Likes: 0
Sorry, forgot to answer the other part of your post. the same module is common across all the audis with lockable diffs. 857711995A, also known as throttle control element in some parts catalogues. This number appears in quattro and 100q 200q parts lists.
If they are available in the scrap yard, grab them. I would suggest that the repair also be used. The internal diaphragm is subject to perishing, and is much harder to repair, as any effort to glue a rubber patch makes them very stiff internally.
If they are available in the scrap yard, grab them. I would suggest that the repair also be used. The internal diaphragm is subject to perishing, and is much harder to repair, as any effort to glue a rubber patch makes them very stiff internally.
Trending Topics
AudiWorld Stories
Bringing Audi to Life for Audi Fans
Top 10 Most Expensive Audis Ever Sold on Bring-A-Trailer
Brett Foote
10 Audi Features & Options We Miss the Most!
Joe Kucinski
Audi Recreates Crazy-Looking Speed Record Breaker From 1935
Verdad Gallardo
Coachbuilder Recreates the 1995 Audi TTS Concept
Verdad Gallardo
Every Audi V10 Car Ranked!
Joe Kucinski
9 Audi Designs That Aged Like Fine Wine
Verdad Gallardo
2026 Audi Q5 Buyer's Guide (Every Model Explained)
Brett Foote
Ranking Every Current Audi 'S' Model From Worst to First!
Joe Kucinski
10 Best Audis That are FINALLY LEGAL to Import to the U.S.!
Joe Kucinski
AudiWorld Newcomer
Joined: Jan 2013
Posts: 5
Likes: 0
if it's only the perished bellows on the acctuator shaft/rod losing vacuum (won't engage) and especially if the collar on the shaft end is intact, I have just repaired mine with a wrap of loom tape (rubberised and sticks to itself) and some small zip ties, you have to leave the tape over-long and baggy so it can concertina in and out with the rod : )
Thread
Thread Starter
Forum
Replies
Last Post
ibennett
Audi 4000 / Coupe GT Discussion
1
Mar 28, 2017 02:18 PM
SRTst
Audi 90 / 80 / Coupe quattro / Cabriolet
5
May 11, 2003 04:40 AM
rocketaudi
Audi 4000 / Coupe GT Discussion
4
Dec 23, 2002 04:43 PM
