Gearbox failure at 90,000mls

[Ronin]

Yes, a lot of parts are NLA if you go to Audi and ask for something, especially unprepared without the part number in hand but...
if you know the right people, a lot of parts are still available or we know of parts from other VAG products (and even BMW) that are like for like replacements, it just takes a little bit more effort. We even have a dedicated section where you can request or ask for part numbers.

Dean (Spanker) is very good at sourcing parts and we even have a dedicated forum section for him, where he doesn't need to hide his services like on a8parts forum who sell tradition parts with 2-3x markup but can't make the forums safe and reliable for its loyal members.

[Spannerrash]

Hi again all
Whilst my car is pretty much a drive ornament at the moment my brain keeps turning over looking for options. Here is one I would like opinions on please.

Is it possible to remove the engine whilst leaving the gearbox in the car?

My initial starting point on this project, should I decide to proceed, was to drop the subframe complete with engine and gearbox. This is going to be a challenge on the drive but I think it's the easiest option mechanically. By that I mean things are easier to access. It does though present a manual handling issue.

So, my brain says why not remove the engine only. If I believe (which I do) that this is an "A" clutch issue only, I can access the front of the gearbox whilst sitting in the engine bay. If I pull the drive shafts out through the wheel arches, remove the front diff and the drive shaft tube, I should be able to remove the gearbox oil pump. The A Drum will then be there for the taking. I could then replace all the "O" rings and thrust bearings.

This is clearly not a full rebuild but a repair. I would also drop the gearbox oil pan before starting any work as any sign of shrapnel in there would make this procedure pointless.

Problems I forsee are.
1 Removing the exhaust down pipes. Is this doable with the engine in the car?
2 Access to the torque converter bolts will mean removing the starter motor. Is this possible with the engine in the car?
3 The bell housing bolts at the top may be difficult to access but I'm thinking of removing the intake Manifold again so hopefully that will give me a chance.

What do you think, doable?

[MikkiJayne]

Not doable I'm afraid, mostly because the gearbox needs to be vertical, sitting on its tailshaft flange, to get it to go back together. Its practically impossible to get the gubbins back inside while gravity is messing with the clutch packs. When I did mine I took it apart on the bench, but to get it back together I had to put the casing on the floor and strap it to one of the legs of the bench so I could drop the A drum back in. ZF had a special tool for rotating the casing to allow it to be assembled.

Its also far more difficult to get the engine out on its own than to just drop it as one chunk. Downpipes aren't too bad - soak them in penetrant for a bit and you can do them from the wheel wells. Bellhousing bolts I've not tried on an auto, but on my manual I just do it with a long extension (5 feet) and a wobbly joint from the back of the gearbox. TC bolts in the car are pretty horrid - the engine mount has to come off to get the starter out

Its worth keeping an eye on FB Marketplace, Gumtree etc for a secondhand pallet truck. This makes dealing with the whole assembly far more practical. It fits nicely on to a lengthways Euro pallet and a few blocks and then you can lift the engine and box off the subframe with an engine crane. Support the gearbox and take the engine off the box, not the other way round. The engine's centre of gravity and inertia are obvious and predictable. The gearbox, not so much.

Plenty of people do take the gearbox out and leave the engine - I've seen it done like that on axle stands, but I wouldn't fancy it myself.

[Spannerrash]

Thanks for that detailed reply MJ, very much appreciated. I'll go back to planning dropping the engine gearbox and subframe complete.

[Spannerrash]

I take your point also about aligning the clutch plates with the box in the horizontal position. I bought a 5hp24 from a BMW to practice stripping and rebuilding with good success. I automatically stood it on it's end in my workshop and so never even considered how much more difficult it would be horizontally. Of course they will drop under gravity. Dumb ass!

[MikkiJayne]

Well, its not that obvious. The 5HP19 for example has to be assembled horizontally as its clutch drums will come apart if you do it vertically. You'd assume it would be the same as the 24, but its quite different inside.

[Spannerrash]

I would appreciate some opinions please.

I removed the gearbox sump pan to inspect the valve block and also to see what shrapnel might be in there. I can't see any shrapnel and I used my prostate camera to inspect the valve body and can't see any evidence of it being cracked. It is just about visible without having to remove it.

No shrapnel, no crack but lots of brass coloured material as I hope you can see in the pictures.

At this point I'm not even sure it's worth fixing just the A Clutch drum. My gut is telling me it's a full gearbox rebuild or it's scrap. If any of the bushings inside the gearbox are worn then it's definitely not something I'm going to be able to fix. It's gonna need some special tooling. I'm not even sure at this point if bushing kits are still available.

It's really starting to look like the end of the road for this car I'm afraid.

[MikkiJayne]

Some interesting and unusual colours in there. Looks like a bushing / bearing has disintegrated, or its shredded a clutch pack, but the oil would smell burnt if that was the case, and its very distinctive. You usually see fur on the magnet and some swirls in the pan, but that brass deposit is not normal, nor is the amount of glittery-looking stuff. In terms of overall wear, 90k is really not much. Mine at 113K was fine inside, negligible wear on any of the bearings etc. Everything I measured was still in tolerance.

As preventative maintenance, I took the A drum out and replaced the thrust bearing which commonly fails, inspected for cracks, and then reassembled with new seals. If your car were mine (and I was still fit and capable), I'd pull the A drum and check whats going on there. If there is an obvious failure, I'd replace the drum & bearings, fit a Transgo pressure valve, and put it back in. If its not the A drum, or there are deeper problems then yes, its probably time to call it a day. However, I recognise 'pull the gearbox and have a look' is considerably easier with a workshop and a lift compared to doing it on the driveway.

[Spannerrash]

Thanks once again for the quick reply MJ, really appreciate it.

I am familiar with the smell of burnt transmission fluid and what came out was fine. This just looks to me like too much bronze (if that's what the bushes are made from).

My biggest feer is that I caused this myself, maybe.

I am quite anal about maintenance and so a few years ago I decided to change the transmission fluid. Realising that you can only change 3-4 litres at a time when dropping the fluid from the drain plug, I did this multiple times. I bought 20ltr of oil from ebay for about £200 and used it all. It was all in 1ltr bottles and looked like the genuine Audi stuff in what looked like genuine Audi bottles but maybe I bought crap / replica.

When I dropped the sump pan a few years ago to do this flush there was no brass / bronze colour at all, just fury magnets so this is new.

Maybe I caused this problem by putting too much fresh fluid in an old gearbox?

Ill post back when I decide my route forward.