AUDI auto gearbox service tips

Road-race engines and ancillaries - general discussion
Post Reply
Nobby
Posts: 87
Joined: Tue Aug 24, 2010 11:58 am
Contact:

AUDI auto gearbox service tips

Post by Nobby » Mon Sep 30, 2013 1:48 pm

Hi all!

I'm after a few tips please. I'm going to be changing my gearbox (auto) oil in the next few weeks and I'm after a couple of tips. The gearbox on my car Audi RS6 is a ZF HP24A and they fail quite often. Although its stated as a 'sealed' box numerous cars all over the world have experienced premature failure, brakedown of Torque Converter, stuck valve bodies and cracked internals. This wouldn't normally bother me too much, but they cost around £5k to replace. I know I could take it to Audi (or a Specialist) but these aren't common cars (so I don't necessarily trust Audi anyway) and believe it or not I'm keen to do everything myself. The instructions themselves are quite complicated involving plugging a computer, monitoring temperatures and filling to an exact level.

Anyway I digress.

Potential problem number 1: The filter is inside the sump and bolted vertically into the valve body. I've yet to find out the tightening torque, nor any mention of threadlock. Its gotta have threadlock on surely? If the nut falls out the filter with fall into the sump (only a few mm) and pickup will be touching the bottom and could starve the gearbox. What do you guys reckon?

Potential problem number 2: And this is a biggy. I have ordered all the genuine parts from Audi, but reputable specialists (of ZF gearboxes) have noted that supplied kits often contain a filter with a longer pickup than needed. I don't yet know whether mine filter is one of them, but the solution is rather worryingly to saw the end of the pipe. Its a metal pipe (steel I'm guessing) and I don't want any particles getting free'd. Do you think its a good idea to do this and just bung up the end then clean away all the swarf? One line of thinking is that the filter fits a similar gearbox (the non 4wd ZFHP24 - note no 'A' at the end).

Potential problem number 3: Many people have recommended cleaning the valve body a little. Now, the valve body is an A4 sized lump of aluminium with lots of pipes, O-rings, valves, etc.. I don't have any industrial equipment to clean it with like a steam cleaner - I dont even have a dishwasher - so I'm a little reluctant to get busy with the JIZER, Brake cleaner or elbow grease if I might leave some residue. I also don't want to damage any internal seals. Are there any cleaning products that definately won't damage rubber seals? I assume that hot water might be the best thing to be careful. The other alternative I can think of is to flush all the oil out with more oil. I don't like the idea of this as it would take ages and another £100 in oil (yes it takes 10 litres of oil which costs over £10 per litre).

So in summary: A - Threadlock just to be sure, B - To cut or not to cut & C - To clean or not to clean.

Thanks for looking.
Chris
Chris Burgess
GC 01

Urbancamo
Posts: 318
Joined: Mon Aug 08, 2011 1:04 pm
Location: Finland
Contact:

Re: AUDI auto gearbox service tips

Post by Urbancamo » Wed Oct 02, 2013 7:14 pm

Hi Chris

I'm not any gearbox specilist but I think these can be answered just by using common sense and some mechanical knowledge.

1) In places like that the torque comes from skilled mechanics wrist, there usually is not any torque settings for fasteners like that. Just snug them slightly with very small spanner/ratchet and that's it. Tiny amount of threadlock cannot hurt a thing. Use a medium strenght compound.

2) I checked the pictures from that filter and I definitely wouldn't modify a part like that if it's not absolutely vital. There must be perfect fitting OE parts available.

3) Valve body is really a soul of the whole automatic transmission. I really wouldn't touch that if I wouldn't have proper equipment to clean that. It's really a jigsaw puzzle at it's best.

Generally any major work with automatic transmission is beyond any ordinary enthusiast's skills.

Too bad many manufacturers will produce weak automatic transmissions today. I know one old Aisin-Warner gearbox witch stripped the splines off from the turbine/input shaft, but it had done 550.000 km's with regular 60.000 km oil change interwalls. It would be almost criminal act to produce such a durable things today!

Tommi
GC_25

Nobby
Posts: 87
Joined: Tue Aug 24, 2010 11:58 am
Contact:

Re: AUDI auto gearbox service tips

Post by Nobby » Fri Oct 04, 2013 1:44 pm

Thanks Tommi

I knew common sense would prevail, but I just thought I'd check. Funnily enough all the parts have arrived and it seems the filter just might be the right one (phew!). Now just need to get the car level, drain overnight and give it a go - oh and find a few hours spare to do the work.

The modern ZF gearboxes are hugely complicated. I wouldn't even dream of taking one appart.
Chris Burgess
GC 01

Rallyroller
Posts: 87
Joined: Tue May 31, 2011 2:40 pm
Contact:

Re: AUDI auto gearbox service tips

Post by Rallyroller » Sun Oct 06, 2013 1:39 am

Hi Nobby.

I agree with common sense prevails. Just a bit of info on the manufacturing process.

In my business we deal with the automotive manufacturers. ZF are one of our customers, and I am currently reading your thread while in transit after visiting a large Far Eastern Auto Gearbox manufacturer for a week.

Yes - modern gearboxes are very complex. What is interesting is that the level of cleanliness in the manufacturing and assembly process is bordering on surgical. The whole assembly area is off limits to most people, and there are air locks to get in and out. The complexity of the castings and valve system is incredible. 9 speed in production now and they are now talking of 12 speed versions!

The reason they are “sealed for life” is that no garage can match the clean conditions of initial assembly, so the manufacturers know that if the oil lasts the life of the gearbox, then there is no reason to jeopardise the “sterile” interior by opening it up.

Having said all that, if it goes wrong or there is a known weakness then alternative actions have to be considered. As other posters have said, just make sure everything is clean. Re cutting the pipe, do ensure no swarf is left. We are talking surgical standards here, not just a wipe with a rag. Clean everything and bag it while it is stored.
Out of interest what are the know problems with this box? You mention breakages and torque converter.

My last motor was a 4.2 Jag S type with ZF 6 speed box. Again sealed for life, but there was a known fault of clutch squeak on down shifts. Solution was an additive that dealers added to the box (so partly blows my theory about not trusting dealers and cleanliness). Apparently the noise was due to a soft ware issue that was rectified in later models. Shows how times are changing if computers can make noises go away. Good luck and let us all know how it goes.
GC_13

Nobby
Posts: 87
Joined: Tue Aug 24, 2010 11:58 am
Contact:

Re: AUDI auto gearbox service tips

Post by Nobby » Mon Oct 07, 2013 12:31 pm

Of the 60 odd cars surveyed approximately 50% had experienced some form of failure, but this usually leads to a complete rebuild or new gearbox. The symptons were some or all of; banging into gear, slip at full throttle, failing to engage gear (automatically or manually) or at worst going into limp mode where the gearbox won't do anything.

Around 50% of those cars where also modified - and its quite straight forward to unleash horrendous amounts of torque (850Nm+) with a simple remap. Of the ones that failed very few had been serviced and the average failure rate was 55,000 miles, whilst the average mileage of good gearboxes was 67k miles. They were also spread across the 3 years the car was produced so there's no evidence to say early ones where better etc.. It should be noted that some failed again after rebuild but this could be down to poor rebuild quality.

Most of the failures reported a failure in the Torque Converter of some kind, and often brought up an error 17125 - Torque Converter Clutch Circuit Performance or Stuck Off. It is often believed that failure in the torque coverter can then lead to failure of other components due to swarf in the oil so this could account for the resultant damage to clutch plates etc.. Quite a few people in the states have fitted higher rated Torque Converters from a US company (not so easy for us in the UK).

Ofcourse a number of these failures could be attributed to leaks, driver mechanical sympathy and warm up procedure, but unless there is a very detailed investigation its unlikely we will ever know what is happening. Unfortunately a number of failures are sorted with warranty claims so the full problems are never communicated. Indeed my own car has done nearly 88k miles and as far as I can tell it has never had the gearbox serviced, but the oil cooler looks relatively new so some top ups MUST have happened.

It seems the best course of action is to keep them serviced. This doesn't ensure the boxes longevity as, in some cases, the boxes may already be damaged or beyond saving.
Chris Burgess
GC 01

Nobby
Posts: 87
Joined: Tue Aug 24, 2010 11:58 am
Contact:

Re: AUDI auto gearbox service tips

Post by Nobby » Fri Oct 11, 2013 1:07 pm

I'm hopefully going to do this next week - if the weather doesn't get worse.

The filter looks like it might be right one according research on the net and I will obviously compare against the one on the car.

As a rule of thumb how far should the pick up be from the bottom of the sump? (5mm) I shall employ the time honoured plasticine method and give it a measure (of both old and new). Ideally I hope the one fitted is definately correct and I can just compare, but worst case is the one fitted is too long and I'm only copying incorrect fitment.
Chris Burgess
GC 01

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest