Replacing leaking rear suspension air bag - Audi Allroad

[paul b]

Hi all

I've read posts about replacing leaking bags on the Allroads, has anybody changed them on the rear?

It's my friend's 2001 Allroad 2.7T with the problem, it sags on the nearside rear when left parked for a period of time. I'm thinking about doing the job for him. No doubt it's best to do it now before the compressor packs up!

Any hints and tips would be greatly appreciated.
Cheers
Paul

[kite]

Search for posts by "bagpiping Andy, he the allroad man !!

[paul b]

Cheers Kite, I have done a search, but have only found information regarding changing a front air bag.

The rear will be different and hopefully easier.

So anybody?

[snugglebum]

Hi Paul

Ive replaced both the front air bags on my Allroad. The most difficult part was the bloody top pinch bolt. I used the Arnott replacements and followed there instuctions which were easy.
Im waiting for the weather to get a little warmer and im going to replace both the rear ones. Heres the link to there guide for the rear air bags.
Hope it helps.

Cheers
Lee

[mickmcvw]

Have done both front and rear in the past few weeks and if you get lucky with the pinch bolt at the front, the fronts are easier to do.

The problem with the rears in my experience was getting the assembled unit back into place afterwards. This was probably due to the fact that I had replaced the shocks with Bilsteins at the same time and these were a lot more difficult to compress enough to get them back in. I did take a lot of photos with the intention of doing a write up but the camera is currently a few thousand miles away, sorry...

There are a few things to watch out for and this depends whether you're going OEM or Arnott. From the top of my head (apologies for anything I've missed out on):

Put suspension into Jack Mode
Remove tyre
Axle stand onto jacking point just in front of wheel arch.
Remove plastic/rubber protection, brake air flow guide (2x 10mm head bolts I think, really easy to cross-thread on reinsertion)
Disconnect airlines, the feed and the pipe between the air bag and shock (10mm open ended spanner)
Undo nut/bolt from bottom of shock & remove (for some reason I think these were 18mm instead of the usual 17 or 19mm)
Undo 2 bolts at top of spring. The shock/spring assembly is now totally free from the rest of the suspension.
From here, there are a couple of options in removing the assembly. I removed the top wishbone bolt, freeing up the wishbone to move upwards.
You can now compress the assembly by pulling down the top of the air spring. While it's compressed, lift the bottom of the shock out of its recess in the lower wishbone. When you get to this stage, you'll see why the upper wishbone needs to be pushed upwards... Very difficult to explain this without the pictures.

Anyway, once the assembly is out, remove the cap at the top (large hex/allen key, can't remember if it's 12 or 14mm) to expose the top nut.
You will really need an impact gun to get the nut at the top of the shock off as otherwise the nyloc nut will just spin with the shock itself as you can't grip the shaft anywhere.

Once the nut is off, don't do as I did and assume it's just stuck together and a good belt will separate the shock and spring... You need to turn one of them by 90 degrees to free a flimsy nylon locking mechanism that will break off and cost you an air spring if you're not careful.

Once they're apart, reassembling is just the reverse. Proper grease on all the o-rings is vital, relocking the OEM shock and spring with the 90 degree twist can be a b**ch but having the nylon base of the air spring caught in a vise will help a lot. Again, air gun is the best way to redo the nyloc nut at the top and assuming you're not putting in Bilsteins, putting back in the assembly shouldn't be too bad.

One final tip for the moment - don't over-tighten the air connections into the bottom of the OEM air spring. It's only nylon and the threads will be gone in no time if you over tighten. Very badly designed in my book...

Just found a couple of photos on my phone that might help a little. Apologies for all the words and lack of proper pictures/tool list etc. but I will do a decent 'How to' when I get my camera back...

[bagpipingandy]

Hi all, Sorry cannot help with this one, no experience (as yet) on removal/refitting the rears, looks like Mickmcvw is the man for this, good work Mickmcvw, looks like we will need to follow this guide at some point, hopefully not too soon!!

Andy

[paul b]

Many thanks for the responses guys. The job certainly looks do-able, but not easy as nothing's easy on Audis! Not like in my Toyota days...

With the days getting shorter and my lack of a garage and therefore a roof over my head at the moment, I think I'll let my friend find his own mechanic to do the job, as freezing my nips off in the Manchester rain doesn't appeal to me! Besides, he can afford his own mechanic...

Unless of course he asks me specifically, then I'll do it. I'd do it on my own car but I've got a standard A6 with no air suspension!

Once more, thanks for the info, particularly Lee and mickmcvw. No doubt it will certainly come in handy for those doing the job, and maybe even me yet!

Regards,
Paul