2002 A8L Transmisson ZF5HP24A rebuild
 

Hello all,
Sooooooooo I purchased this '02 A8L only a few months ago and was told it needed nothing at all done to it, so I bet you can imagine my surprise when it began slipping within the first few miles of me owning it :mad:! When it's cold it runs fine, but as soon as it heats up it begins slipping. As you continue to drive it it slipps worse, and will eventually go into limp mode in which case I've got to pull over, shut it off and start it again. I got several codes when I scanned it, for incorrect gear ratio in general and then specifically for 3rd I believe. Also there was a P0730. I tried all manner of diagnosing the problem: checked fluid levels, electrical connections etc. plus poking around this and other Audi forums in addition to bringing it to a friends garage and still no joy. So after debating and going round and round about options, it's out and being pulled apart.

I found two very inspiring threads by a guy named Mickey on motorgeek and rs246, one for an S8 and the other an RS6 both w/dead trannys, and have since gotten up the courage to delve into the unknown myself. I really like the car a lot and look forward to actually driving it in the very near future, and I guess it will build character (I thought I had enough already).

This is my 6th Audi. I've been very satisfied owning them (up to now lol) and have done a lot of different kinds of stuff to the ones I've owned but this will be the first automatic transmission I've got my hands into ever. May the force be w/ me. I do apologize if I'm repeating this topic, did a brief search and came up dry so here goes. Varying opinions w/ tackling such a task, ZF saying it's "a very complicated tranny" and the converse of "just like any other."

On the workbench. What's transmission repair without some tasty snacks?

Next step, remove the diff cover. The small Torx in the center comes out plus all around the outer ring

To reveal the diff itself. Careful, cuz it will fall out easily. Keep it clean

Sorry for each separate post. I can't figure out how to attache multiple images :o

Now for the other side....
Three more Torx

Once that's off, back around to the other side to tap that tube out. Gently.

Take a small deep well socket and tap these rubber plugs out as there are more Torx behind them holding the drum in place. All the Torx attaching the drum are T27

Face on w/ 8 bolts out

I forgot to mention there is a circlip holding the tube in place, and must be removed before it is able to be tapped out,

Good work. Keep the pictures coming.

Thanks JoePGT5S, will do. I'm just gettin' started :D

Forgot to mention my car has 172k on it

Btw here are the threads which I am following. This guy Mickey is awesome!

http://www.motorgeek.com/viewtopic.p...f376e1c358bff4

http://forum.rs246.com/viewtopic.php...2b9441e25499bf


So continuing, we removed the valve body. The larger size head screws, T27 are the ones that connect it to the bottom of the transmission. We thought we could get the intermediate plate off by pushing on it from the back, but couldn't see how this worked for the other guy...

We ended up just using two vise grips! It pulled out easily :)

Now out with the first clutch pack

Removal of the first clutch pack

Fascinating stuff

This circlip comes out easily

Continuing, remove this..... thing. I'm not sure what it's called :o

Remove the next piece and a quick flip shows the bearing is in good order

Removal of another circlip and the smaller clutch housing is removable

And the culprit is found! The same stupid O-ring has failed in another gearbox.

I wonder how often our transmission problems are just this o-ring.

Tozo - it would be great to hear some of your feedback on this.

It seems to happen a lot based on how often this comes up online. We're gonna delve deeper obviously to see if there is wear on any of the other clutch packs or hardware, but so far the only problem has been the O-ring and some minor ware here.

The bearing there is also missing one roller. Thankfully I found it sitting there in the fluid. Second part I'll need to order

Close up

Just curious: has anybody researched adding clutches to the clutch packs for more durability? I remember speaking w/ a guy at ZF America and him saying something to that effect. I figured I'd ask just to see if anybody ever did it

I can't imagine there being any clearance for additional clutch packs, unless ZF offer thinner discs (weaker?).

Curious to know how the rebuild is proceeding.

Joe

It's that exactly Joe. ZF said the clutch basket is different on the RS6 allowing for more clutch discs. Also some differences in the VB and a different torque converter.

I'm currently waiting on the new gasket kit and bearing from the CTSC, so right now the tranny's just sitting patiently on the bench. I think I've decided not to dig any further into the tranny cuz reverse works fine, and I don't want to replace parts that are working ok. If it gives me trouble in the future, I'll just have to pull it out again. Although I'd prob just pull the trans by itself. And my dad has told me in no uncertain terms that he doesn't want any part of that :D Cross that bridge when I come to it :)

ATM I'm working on the motor. It was burning oil pretty bad and knocking so we bought a 4.2 from an '03 last week and spent most of the weekend swapping parts to the new one but are finding it doesn't seem to be an "A" grade as advertised (sigh). Oh well, at least forward progress is being made, albeit seemingly kinda slow.

Can't wait to drive it OOOOh

Sorry for all the time in between posts the last few weeks have been crazy. Anyway...
Where was I?

The kit arrived from the CTSC; this plus the bearing was $270 including shipping.
All OEM, made in Germany

The new O-ring installed.

Since this piece has failed on so many gearboxes I asked a tech at ZF if the material it was made of had been changed or improved to possbliy make it more durable. He said no, it hadn't been changed :( So I guess I'll be waiting for it's failure to happen sometime in the future

The old bearing and race. This rides on the tower behind the A-clutch assembly.

The race had worn significantly compared to new one. It was razor thin. The replacement was $17

We had to turn the transmission on the tailshaft to realign the clutch discs

The A-housing back in place. We had to gently twist it when the trans was vertical to ensure it was fully seated.

We also used a small round file to align the oil assembly

The assembly back in

You sir have balls of steel! Excellent job and you know these things are $5k to fix.

Was in the shop that did my tranny in 2009 today and they mentioned that they did some "upgrades" when re-building the transmission - not sure what they meant but my tranny is still working - apart from the output flange seal that they replaced today, leaking badly for the past year or so.

Hey thanks ThaboTheWuff. That price alone is enough to make me want to do the work myself; I just can't afford to pay it! I'm getting to the point where I simply can't trust that a garage will necessarily follow or even know the exact procedure to maintain said piece of equipment, even when it's as serious an issue as this. I would rather trust a group of fellow enthusiasts who WANT their car to last and are borderline anal w/ their methods of keeping it running:) instead of a garage whose business to be in business. Plus their are so many different steps and procedures that must be done correctly according to spec. There might be a new mechanic on duty or one having a bad day when I drop off my vehicle who's simply not focused. Do they know what they're doing? :eek:

Regarding digging into an auto gearbox, I found a great quote form a guy on a Land Rover forum, he's Bemble on this one and RRPhil on another, seems to know these boxes like the back of his hand. He said

"People are funny about automatic transmissions. They see them as a black box into which no one should dare to delve. In reality, they're a darn sight easier to fix than an engine for example, yet people seem perfectly prepared to strip engines down."

I find that was really my opinion as well, like Pandora's box. But it in my very limited experience it just isn't the case.


All better! New seals around all the output shafts were installed (sorry, forgot to photo). This transmission is going back in

Truly great work!! And thanks for documenting this for the forum. Looking forward to hearing how the car drives once it's all back together.

How many hours do you estimate putting into this?

Joe