A8 Parts Forum  

Go Back   A8 Parts Forum > A8 D2 > D2 - Transmission

D2 - Transmission Gearboxes, diffs, drive shafts.

Reply
 
Thread Tools Display Modes
  #1  
Old 13th August 2018, 07:13 PM
Dakes55 Dakes55 is offline
Member
 
Join Date: Apr 2018
Location: leicester
Posts: 31
Default Gearbox problem after fluid change Help

I recently bought an A8 2.8 2002, and didn't have any service history with it, I have changed the multifunction transmission switch as it had the dreaded PRNDS lights on, after that job was done the car drove great with no problems, I thought I would do a service on the gearbox and change the ATF fluid and filter, but now I have problems, the gearchanges are not smooth, and I am noticing that the rev counter is moving slightly and not stable when in 5th gear, it feels like its slightly jolting, the fluid that was drained off was a dirty red in colour, with no contamination, just a very slight sludge build up, I fitted a new Meyle filter and gasket and filled the transmission with Febi Bilstein atf fluid 29738, this is clear/yellow in colour and according to Febi this fluid is the one for my car, I am concerned that this fluid maybe wrong, the service was carried out exactly to ZF specs, any ideas on this please.
Reply With Quote
  #2  
Old 13th August 2018, 08:18 PM
The_Laird's Avatar
The_Laird The_Laird is offline
Senior Member
 
Join Date: Jun 2009
Location: Redmile: Leics, Notts, Lincs border - near Belvoir Castle
Posts: 5,069
Default

You can’t get all the ATF fluid out by draining it, so you’ll now have a mix. DIY fluid changes have caused problems for others and it’s usually recommended to have them flushed - but this requires specialist equipment. I’m not sure if there’s a ZF specialist near Leicester, but hopefully someone here will be along shortly with a more positive reply!

BTW, was it you at Belvoir Castle a few weeks ago?
__________________
2002 Final Edition S8. Ebony black with Silver Grey leather and myrtle wood trim.
Current mods: solar sun roof, 20mm rear spacers, 15 mm on front, red brembo callipers, 6k headlights, rear view camera, engine remap, alloy dash dial rings, alloy navi rings, tt/phaeton pedal upgrade, (and custom matching foot rest) dension ipod interface & parrot hands free kit (both fully hidden), av input, tv in motion switched thro' PF switch in blanking plug right of steering column, Audi 'quattro' sill covers, repositioned centre console switches, radio clock, .
Planned mods: auto-dimming rear view mirror, dash cam (as steamship's), fit the ski hatch, refit philips drl's (or maybe not - nope, definitely not - horrible botch!).
Reply With Quote
  #3  
Old 13th August 2018, 08:39 PM
Dakes55 Dakes55 is offline
Member
 
Join Date: Apr 2018
Location: leicester
Posts: 31
Default

Hi, thanks for the info, no it wasn't me at Belvoir Castle, I just got back from a run up the A46, I noticed that its driving ok at 60mph and above, but when driving at 40mph or below I noticed that the rev counter is fluctuating slightly and I can feel the car bumping slightly, hard to explain really, I wonder if its the mix of fluid thats causing it. it was fine before I changed the fluid and filter
Reply With Quote
  #4  
Old 14th August 2018, 12:09 PM
lebesset lebesset is offline
Member
 
Join Date: Sep 2012
Posts: 77
Default

my local mechanic [ audi fan but not A8 or auto ] doesn't have a slurpy machine but recommends draining overnight to get as much out as possible , fill up and give it a run for half an hour then drain again , change filter and top up again ensuring correct temperature /fill level

maybe not perfect but with 75% or so fresh ATF gives a reasonable clean box , and using the correct AG52 mannol available in bulk from germany at a reasonable price [ multitronic/steptronic/ tiptronic ] not too expensive

don't forget , getting the level absolutely correct is critical

wonder if mikki could set up to do this , it's a long way to glasgow for us southerners!
Reply With Quote
  #5  
Old 14th August 2018, 05:09 PM
David's8's Avatar
David's8 David's8 is offline
Senior Member
 
Join Date: Jan 2012
Location: Helensburgh, Scotland
Posts: 3,506
Default

Just in case, this is the detailed procedure, Cycling through the gears and checking temps is, apparently, key to getting it right.
Attached Files
File Type: pdf 5HP24 Oil Change procedure.pdf (77.2 KB, 370 views)
__________________
2002 D2 S8 – Ming Blue, Valcona leather, Vavona wood insert, solar sunroof (to be fitted), Heated rear seats, extended leather pack, 18” Avus, ski hatch, Bose, auto dim rear view mirror, rear blind.
Reply With Quote
  #6  
Old 15th August 2018, 02:50 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

The fluctuation in RPM is a common characteristic of the 5HP gearboxes and is supposedly down to the torque converter - a couple of American transmission specialists offer a modified converter to solve it. My S8 does it too at ~1800rpm, just before the converter clutch locks up. Its highly annoying but I just put it in S if it bothers me. Its curious this started for you after a fluid change though. Febi 29738 is the correct specification.

I still haven't figured out why some gearboxes are just fine after a fluid change and some aren't. I have a feeling it could be down to the re-filling period when the level is some 3-litres short due to the stupid design of the filling solution, although I couldn't say what specifically gets upset during that time.
I was going to contrive a device which could get the full load of oil in with the engine stopped so that it didn't have this (albeit short) period of running low on oil, but I've been working on the manual swap instead

The suggestion to refill, run it for a bit then drain and refill again is good, however since the gearbox has to be at 40° to set the level it would be an overnight job so that it could cool down. Still, there are a couple of nice hotels near the workshop
Reply With Quote
  #7  
Old 17th August 2018, 02:20 PM
lebesset lebesset is offline
Member
 
Join Date: Sep 2012
Posts: 77
Default

Quote:
Originally Posted by MikkiJayne View Post
The fluctuation in RPM is a common characteristic of the 5HP gearboxes and is supposedly down to the torque converter - a couple of American transmission specialists offer a modified converter to solve it. My S8 does it too at ~1800rpm, just before the converter clutch locks up. Its highly annoying but I just put it in S if it bothers me. Its curious this started for you after a fluid change though. Febi 29738 is the correct specification.

I still haven't figured out why some gearboxes are just fine after a fluid change and some aren't. I have a feeling it could be down to the re-filling period when the level is some 3-litres short due to the stupid design of the filling solution, although I couldn't say what specifically gets upset during that time.
I was going to contrive a device which could get the full load of oil in with the engine stopped so that it didn't have this (albeit short) period of running low on oil, but I've been working on the manual swap instead

The suggestion to refill, run it for a bit then drain and refill again is good, however since the gearbox has to be at 40° to set the level it would be an overnight job so that it could cool down. Still, there are a couple of nice hotels near the workshop
don't quite follow that mikki ; after it has drained overnight and then filled how is it 3 litres too low for the half hour drive ?

my methodology is
leave on the ramp overnight
first thing in the morning fill
before lunch half hour drive
drain again during 2 hour french lunch at local restaurant [ menu de jour !]
refill at correct temperature in approved manner [ I hope my £10 temperature gun from amazon is accurate enough , works well on brake disc temperatures ]
Reply With Quote
  #8  
Old 17th August 2018, 02:33 PM
MikkiJayne MikkiJayne is offline
Senior Member
 
Join Date: Jan 2012
Posts: 5,017
Default

Its about 3 litres short between when you fill it with the engine off and then top it up with the engine running as it comes up to temperature. Its only a few minutes with it idling, but I still don't like it since if you drove it 3 litres short it would kill the box in pretty short order.

I've never checked to see how long it takes to cool down tbh. If 2 hours will do it then it is practical to flush like that
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 08:29 AM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.