Automatic Transmission rebuild?

Matt Simis

Anyone in Ireland doing this? Its a 5speed ZF transmission from an Audi S8.

Anan1

Ouch. I take it you've tried changing the fluid & filter?

Matt Simis

Anan1 wrote: »

Ouch. I take it you've tried changing the fluid & filter?

Ill do that first (ordered parts with Audi today), but no worries, I got the car priced accordingly. Vag Com shows 2 DTCs:

Incorrect Gear Ratio Detected
Transmission Temp Sensor - Implausible signal


Car gets an occasional slamming feeling as it "misses" a gear when coming to a slow stop and, more annoying, gearbox goes to limp mode (or engine cuts out) sometimes on hills stop and starts (up or down).

The last bit and some stuff I read on Audiworld makes me suspect it has insufficient ATF fluid in it (the tilting of a hill making it slip) as well as being worn and old.

Anan1

Good luck with it anyway. I did a lot of homework prior to changing the fluid on my A8 4.2 and I remember people being surprised at how much a fluid & filter change would improve an apparently banjaxed 'box. It's not the easiest to do though, the torque converter holds a lot of fluid.

mullingar

Does the Audi have the so called "tip-tronic" box?

mytime

you could call Pat in autotrans they do full rebuilds. Did a couple of them in for us in my old job. sound fella and knows his stuff


Autotranz, Pat Cassidy, 087 9290669 Ballymount

Matt Simis

mytime wrote: »

you could call Pat in autotrans they do full rebuilds. Did a couple of them in for us in my old job. sound fella and knows his stuff
Autotranz, Pat Cassidy, 087 9290669 Ballymount

I might do thanks!

mullingar wrote: »

Does the Audi have the so called "tip-tronic" box?

Yep, a ZF 5 speed (same as in BMWs), though depending on the pricing I would consider getting a full on manual box put in, seems insane a perfectly good car (any Audi A8 / S8) is ruined by the dying whims of $$ transmission.

daRobot

Is the transmission in the S8/A8 of that era, the same as the e38 740i?

Seems to be a lot of reports of transmission failure from the Audi forums, but not that many from BMW, is my reason for asking.

Matt Simis

daRobot wrote: »

Is the transmission in the S8/A8 of that era, the same as the e38 740i?

Seems to be a lot of reports of transmission failure from the Audi forums, but not that many from BMW, is my reason for asking.

Yes and yes, same box but more commonly reported (seemingly) on Audi's, though I have seen the complaints on BMW forums.
http://en.wikipedia.org/wiki/ZF_5HP24_transmission

On the plus side its a very popular box, so I dont think servicing and parts should present a huge problem even here.

daRobot

Best of luck with it. My next purchase will most likely be an A8 (4.2) or S8 of that era, so it's something I may have to be dealing with myself in the near future.

Stevie Dakota

I'd try Conway Transmissions in Walkinstown first, they pretty much know all there is to know about ZF autos.

I doubt a fluid change is going to solve the problems you describe though.

SouperComputer

What were the VAG code #'s Matt? Mightn't be a bad idea to log whatever block the trans temp sensor is on in VAG-COM and take a look at the results.

I wouldn't condemn it for a rebuild quite yet....

Matt Simis

SouperComputer wrote: »

What were the VAG code #'s Matt? Mightn't be a bad idea to log whatever block the trans temp sensor is on in VAG-COM and take a look at the results.
I wouldn't condemn it for a rebuild quite yet....

That temp sensor is in a wiring harness in the transmission itself, so physically changing it would have to be done at a min when the ATF is changed. Im thinking the "implausible" signal is not actually incorrect, but caused by the below!

Stevie Dakota wrote: »

I'd try Conway Transmissions in Walkinstown first, they pretty much know all there is to know about ZF autos.
I doubt a fluid change is going to solve the problems you describe though.

Talking to them now.. they said it sounds like the Transmission is "chronically" low on oil, which is what I suspected too given the occurrences on hills more than anything else. They would recommend an Oil change first and done the proper way, as I read online (he described their process, nearly identical):
http://www.audipages.com/Tech_Articles/auto_transmission/autotranservicing.html

Matt Simis

So got the Fluid and filter from Audi on Friday and spent the weekend changing the fluid.. its quite involved as one person needs to go through the gears as the car is up on stands as the other pumps (literally pumps) the fluid up so its constantly slightly overflowing.

Draining the fluid.. about 6-7 litres is meant to come out.. just 2.5litres came out of mine. :eek:
I put in about 9litres .

Results:

• Limp mode and cutting out on hills appears to be completely eliminated.
• Smoother, quieter gear changes
• Thumping/slamming (caused by worn Clutch pack) reduced and effect lessened. Possible to feather the throttle when coming to a stop to nearly eliminate it.

I dunno how so little fluid was in it. Im thinking someone (looking at professional mechanics here) changed the fluid before and did it the "normal" Auto trans way, treating the fill hole as a dipstick and filled just the pan without cycling through the gears (it sucks in fluid as you do that) and left it grossly under filled.

Stevie Dakota

Nice result Matt, hard to believe anyone would have filled up previously without cycling but you never know.

I once had an auto go into limp mode on a narrow country road at the exact moment when another car speed by in the opposite direction. Electro magnetic distortion?!