A8 Parts Forum  

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

D2 - Transmission Gearboxes, diffs, drive shafts.

Thread Tools Display Modes
Old 12th October 2017, 06:55 AM
spannerrash spannerrash is offline
Junior Member
Join Date: Dec 2016
Posts: 14
Default Valve body replace, easy?

2002 Audi S8 D2 86000mls

Hello all

I have owned the above car for about 8 months and am spending a small fortune in trying to make it the best it can be (for a 15 year old car). I have already done lots to the car, new front susspension links, front brake pads and discs, new catt on one side, water ingress sorted, gearbox output shaft oil leak sorted etc, etc. I am now thinking about some preventative maintenance for the gearbox. I have changed the gearbox oil and strainer, to be fair, the previous owner told me that it had been done previously 20,000 mls ago. The oil actuall looked pretty good and I could see evidence that some one had at least had the pan off at some point. So to my question. Would you guys recomend preventative valve body work? the car has absolutley no gearbox issues at this point, well none that I can pick up on anyhow. I have an official version of VCDS and there are no transmission codes. All is good.

Would you?
leave well alone?
Remove the front lower valve body to have the pressure regulator valve upgraded (aprox 350) with new valve body?
Replace the whole valve body assy for a new genuine part (aprox 1200)?

I am prefering the latter as clearly this will also incl new springs, seals, stariners, dampers, solenoids etc. What do you guys think? is swapping a complete valve body whilst the tranny is still in the car as easy as it looks? If I go just for the lower front valve body only, can this be removed whilst leaving the rest of the valve body still in place?

Any help / points to other threads much appreciated.
Reply With Quote
Old 12th October 2017, 01:25 PM
Joe2.0E Joe2.0E is offline
Senior Member
Join Date: Feb 2012
Location: Ireland
Posts: 341

Would you consider a big road trip/short holiday and take it to ZF in Germany ?
It sounds mad but they seem to offer a fantastic service.
Lots of positive reviews if you google "zf dortmund gearbox service"
Reply With Quote
Old 12th October 2017, 05:41 PM
spannerrash spannerrash is offline
Junior Member
Join Date: Dec 2016
Posts: 14

Sounds like a long way to go. I'm looking more for a diy solution. I bought the car originally as a hobby and enjoy doing the work myself. It really hurts when I have to take the car to another mechanic. Clearly I would have to do so if the gearbox needed a rebuild. This would be way out of my comfort zone but in terms of doing something preventative, I think I would like to do it myself. I get a great feeling when I manage to fix / improve something myself
Reply With Quote
Old 12th October 2017, 05:58 PM
HPsauce HPsauce is offline
Senior Member
Join Date: Sep 2011
Location: About 250m from HS2!
Posts: 6,097

Minor point, but this is in the D3 section.......

Assuming you are talking about a D2 the valve body doesn't seem to crop up much as an issue, so apart from the usual preventive ATF/filter change why touch it?
2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions, ski hatch retrofit; extended leather.
2016 Volvo V40 T5 Cross Country (4WD) with ALL the toys including adaptive cruise etc. etc. Osmium Grey with Blonde/Charcoal leather interior.
Finally: gone, but not forgotten.....
1998 D2 PF S8. AgateGrey/Platinum. Every option (I think) except electric rear seats, tiptronic steering wheel, ski hatch, towbar & dimming door mirrors.
e.g. Cruise control, NavPlus/TV, Bose, GSM, Xenons, Solar roof, Parking sensors, Alcantara/leather everywhere of course. (internal dimming mirror added later)
1998 (very early) Ford Focus 1.8 Zetec; ABS/TCS, Heated screen/mirrors, Aircon, Auto-dim mirror, Leather, Trip computer, Cruise control, OEM Ford SatNav with CD changer.
Reply With Quote
Old 12th October 2017, 09:54 PM
spannerrash spannerrash is offline
Junior Member
Join Date: Dec 2016
Posts: 14

OK, fairly new to the whole forum thing and not sure how it ended up in the D3 section. I thought I posted in the D2

Any advice from long term D2 S8 owners would be very welcome and please correct me if I am wrong. I understand that these 5hp24A gearboxs are prone to A clutch drum failure caused by pressure spikes which in turn is caused by valve body wear. Searching the net, this seems like quite a common problem. Is this not the case?
Reply With Quote
Old 13th October 2017, 04:52 PM
MikkiJayne MikkiJayne is offline
Senior Member
Join Date: Jan 2012
Location: Devon
Posts: 1,273

The early ones are. The later ones like the FBG in your 2002 seem to be more affected by the A-drum roller bearing collapsing which then causes the clutch pack to slip and shreds an o-ring which releases line pressure causing all the other clutches to also slip.

Changing the valve body is simple if you are meticulous about detail and cleanliness although its a very messy job in the car since it holds a lot of oil which will drop on you I would argue though that if its shifting ok then changing it is a waste of money. The best preventive maintenance on it is to change the bearing, but that's inside the box behind the oil pump so is a considerably bigger job. Still, its pretty obvious when that bearing has failed (clutches slipping) and if you get to it immediately it won't do any lasting damage.

Treat it to a new MAF if you haven't already - that has a surprising impact on the gearbox behaviour and longevity

I'll ask a mod to move the thread to the D2 section for you

Pecuariam felis
Reply With Quote
Old 14th October 2017, 07:17 PM
Architex_mA8tey's Avatar
Architex_mA8tey Architex_mA8tey is offline
Join Date: Jan 2009
Location: London/Oxford/Swindon
Posts: 7,013

Originally Posted by MikkiJayne View Post
I'll ask a mod to move the thread to the D2 section for you
Already moved!

Confidence is the feeling you have before you know better . . . .
Audi A8 D2 3.7 Quattro Sport 1999 FL - Melange
20" x 9" Bentley GTC Wheels with 385mm W12 Front Discs & Bentley Caliper Covers, Front Lowered on Coilovers, Xenons, Combined DRLs and LED Foglights to modified OEM front fog lamp position, Alcantara/Leather, Full Black Alcantara headlining + pillars and blind shelf, Bespoke Flat Bottomed Sports Steering Wheel, Dark Myrtle Wood, Autodim Mirrors, Bose, Blinds, Digital TV, Ski Hatch, Modified rear exhaust section for extra V8 Burble
Next - Clean Car, Phantom Aeriel, Clean Car again, Fit Variable Back Box with remote control on/off Loudness, RNS-e, Clean Car again!
Audi A8L D3 4.2 Petrol with LPG - Oyster Grey
and some other A8's A8L's and Mercs
Reply With Quote
Old 15th October 2017, 02:21 PM
spannerrash spannerrash is offline
Junior Member
Join Date: Dec 2016
Posts: 14

Thanks for the advice. Why is it that a MAF sensor will have such a big impact on the gearbox. I have a reasonable knowledge of car ecu control systems and components but just thinking about it I can't get my head around why it should be. I understand that MAF sensors get sluggish with age. They measure air volume and mass entering the engine. If sluggish you can get an incorrect reading and this a weak or rich fuel mixture. This will though be picked up by the O2 sensors and the fuel trims altered to bring back to spec.

I'm sure you are right with what you say as I know engine management systems and components do all kinds of less obvious stuff. If you could help me understand I would much appreciate it, just for my future knowledge.

Reply With Quote
Old 15th October 2017, 09:15 PM
spannerrash spannerrash is offline
Junior Member
Join Date: Dec 2016
Posts: 14

I have scanned through quite a few different forms and it does seem a common opinion that the MAF sensor will inpact shift quality and timing. As I said in my first post, I don't have any transmission issues but I do believe in preventative maintenance. The transmission is by far one of the most expensive things that can go wrong and so justifies some preventative expense. I do more research and will let you know where I go with this.

Just as a side note, I also plan to change the timing chains and adjusters next spring. Also a preventative measure.
Reply With Quote
Old 16th October 2017, 01:40 AM
27litres's Avatar
27litres 27litres is offline
Senior Member
Join Date: Jan 2014
Location: Belgrave, Australia
Posts: 367

The ECU measures (or estimates) torque loading on the engine using the MAF and then uses this information along with the TCU to optimise shifts.

If your MAF is past it, you can get some very rough shifting on moderate to heavy throttle.

Mine threw a code right on max rpm on the highway one day.
It banged into 3rd gear and I thought I'd broken something.
Gave me ESP and ABS fault lights - I thought the ESP might have chucked a wobbly!
Only on running a scan did I spot the faulty MAF.
Replaced it and everything got better!


2001 Audi S8 - Brilliant Black with Black interior, C5 RS6 rims (whenever I actually put them on...), Solar Sunroof, Tinted side and rear glass, RNS-D, XCarLink, Bose, clunky old phone in arm rest!
2002 Audi S8 - Project
Replacement head coming arrived thanks to MJ
Silver with Black interior. All features as the '01, with the 'S' mode auto shifter. Dodgey rear tint (need to find a way to get rid of that).
2009 Volvo XC90 V8 R Design
- has a louder more obnoxious exhaust than the S8, sounds great! Love this thing - Q7 was double the price, and certainly not double the car!

1997 Audi A4
- Hamilton's Club Sport, Achat Grey (will miss the old girl)
Reply With Quote

5hp24, gearbox service, transmission, valve body

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 01:58 PM.

Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.