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Discussion Starter · #1 ·
Hi all,
After the dreaded failure of the gearbox in my 1996 XK8, Idecided to have a go at repairing it myself. The problem turned out to be theclassic 'A Drum' failure. To fix this, I replaced the drum, but also did ageneral reconditioning to reduce the need to do all this again.
There's plenty online to advise the budding amateur, but Ithought I'd supplement this by sharing some lessons learned to help anyone elseconsidering this.
1. ZF have a repair manual freely available online.In reading it, don't be put off by all the specialist tools that are used. Idid not need a single specialist tool to do the job. It just takes a littlelonger.
http://www.jagrepair.com/images/AutoRepairPhotos/ZF%205HP24%201%20Repair%20Manual.pdf
2. I found YouTube videos far more useful than the ZFmanual. My new best friend became a guy called Gary Ferraro. His channel has 'teardowns'of ZF 5HP24 from a Jaguar, a Land Rover and a BMW X5. All useful. Research theseso that you know exactly what to expect when stripping down the gearbox. Thereis a video where he also partially re-assembles one. Useful.
3. There is a poorer quality YouTube video of anXJ8 'box being rebuilt. It's quite detailed and worth a look. However, there isa point where they state that they had to make a tool to lower rebuilt partsback into the 'box. You don't need this tool if you reassemble it verticallyrather than horizontally on a bench. Here's a link to the first of 9 videos:
4. It sounds obvious, but the ZF 5HP24 was fittedin several cars, so don't limit your internet search to "XK8 transmission".There's a wealth of advice and images on other forums. I used forums for RangerRover, BMW and Audi. Here's a couple:
http://www.rangerovers.net/forum/6-range-rover-mark-iii-l322/27361-zf-5hp24-teardown.html
http://bimmernut.com/5hp24show/
5. Another obvious point, but this whole projectlooks daunting if you don't break it down into mini-projects. Disciplineyourself to recondition only one clutch at a time. That way, you don't losetrack of the rebuild.
6. I found the following faults: The A Drum hadsplit. An O-ring on the A/B clutch had torn.
7. To recondition the gearbox, I bought the following- listed in order of importance:
· 'A' Clutch Drum (This A clutch drum replaces theblown one and - so I hear - is an upgraded part to reduce the chances of thefault reoccurring)
· TransGo 5HP-24-PR Pressure Regulator ValveRepair Kit (The story goes that the 'A' Clutch Drum fails because of a surge inpressure caused by this valve wearing. Mine looked fine, but a worn one won'tbe that easy to see. So I had this valve imported all the way from US America.)
· Overhaul Kit Genuine ZF OE (Contains dozens anddozens of O-rings, scarf rings, etc. All are in separate packets so that youcan work your way through the gearbox in a logical order)
· Friction Kit Exedy (These are the clutch rings.Mine looked fine, but with a blown A drum, clutch rings can become contaminatedwith embedded metal fragments, so I changed them.)
· Bearing Case A/C (there is a needle bearingbetween clutch A and clutch C that has a habit of failing. Mine looked fine,but I changed it for the sake of £10.
· F Piston (This F clutch piston can fail,resulting in a loss of reverse gear. Again, mine looked okay, but I bought thisin anyway)
· Filter
· 10 Litre of Mobil Esso LT71141 ATF AutomaticTransmission Fluid
· Blue Goo (Proper transmission assembly gel.Worth buying as it's so much better than vasoline or standard grease. Itprevents damage during assembly and seats all O-rings and seals properly)
8. Most of the parts were bought from one-stop-gearbox-shop on eBay.
9. The Exedy Friction Kit Ibought contained one clutch ring too many. This panicked the hell out of me atthe time, as I thought I'd failed to fit all of them. I revisited all the workI'd done to confirm I hadn't made a mistake. Perhaps this was a one-off errorwith the friction kit I bought, but if not, don't worry about it.
10. Don't skimp on parts. Some people just replacethe 'blown' A Drum. Trouble is, when it blew, where did all those little shardsof metal go? I probably spent a few hundred pounds to replace parts that Icould have just reused, but as the time and effort of researching and doingthis work is so great I'd never entertain the idea of just changing the A Drum.
11. The most awkward bit of the job is compressingthe circular springs that hold the clutch pistons in place. You'll need to takeyour time to improvise tools for this. ZF has special tools, but I found thatusing G-clamps, inverted pullers and the like worked just as well.
12. I found that nuts and bolts freed off quiteeasily, with exception of…
13. …There are two oil cooler pipes that must beremoved. I think that they are aluminium going into steel. Either way, minewere corroded in tight. After much effort, one was undone but it wrecked thepipe. The other required the gearbox casing to be sent away for drilling and anew thread cutting in. Not cheap and really delayed progress. Of course, bothpipes needed to be replaced too.
14. If you do need to replace the oil cooler pipes,avoid second hand ones. There is a small bracket behind the air con compressorthat holds the pipes in place. This is a recipe for localised corrosion on apipe that can otherwise look good. One of the second hand pipes I boughtleaked. I ended up buying new from Jaguar. Double the price but worth it. I thenwrapped the bracket in plastic tape to prevent future corrosion.
Of note, my gearbox failed at122,000 miles. This is despite servicing the gearbox at 120,000 miles. So,sadly, servicing is no guarantee against failure - particularly when it's doneas belatedly as mine.
 

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The Exedy Friction Kit Ibought contained one clutch ring too many. This panicked the hell out of me atthe time, as I thought I'd failed to fit all of them. I revisited all the workI'd done to confirm I hadn't made a mistake. Perhaps this was a one-off errorwith the friction kit I bought, but if not, don't worry about it.
All 24 models of the 5HP24 have 6 plates in the A clutch, 6 plates in the B clutch, 4 plates in the C clutch and 6 plates in the F brake.



However, for the D & E brakes (which are used in 2nd, 3rd & 5th gears) the number of clutch plates used depends on the engine torque. The 034 model for the BMW X5 4.6is (480Nm) and the 035 model for the Alpina V8 Roadster/B10 V8S 4.8 (510Nm) both had an additional plate in the D brake, which is why you had one left over from the kit as your 009 model has 'only' 4 plates in the D-brake.



If you'd been repairing a 5HP24 from a 3.2 litre XJ8 (or a 3.5 litre BMW) you would have had 3 plates left over from the kit as both the D & E brakes have one less plate in them.

In case you're wondering how this is achieved, ZF simply machine the snap ring groove in a different position in the clutch drum.




Phil
 

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Discussion Starter · #4 ·
"The 034 model for the BMW X5 4.6is (480Nm) and the 035 model for the Alpina V8 Roadster/B10 V8S 4.8 (510Nm) both had an additional plate in the D brake, which is why you had one left over from the kit as your 009 model has 'only' 4 plates in the D-brake"

I think that this will be very valuable to anyone else searching the forums to compile info before attempting the work. The Friction Packs themselves contain no instructions, and Phil's is the first clear info I've seen on this. A great addition to the thread. Many thanks.
 

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Thank you very very much for sharing all that info and your experience.
I want to perform a transmission fluid change (1 liter out / 1 liter in top filling) on my 96 xk8 109kmiles to carry on trouble shooting my intermittent "gearbox fault", does anyone know if Shell Spirax S2 ATF AX is adequate or not for a ZF5HP24
thank you.
 

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It's essential that the fluid you use has the correct friction modifier pack - particularly for the operation of the torque converter lock-up clutch - otherwise the controller may push the solenoids to the extremes of their adaption limits and still be unable to achieve acceptable shift times.

The only approved fluids for the 5HP24 are ZF Lifeguard Fluid 5, Pentosin ATF1 and Mobil ATF LT71141. The Mobil fluid is by far the easiest & least costly of the three to source here in the UK, though it will still set you back around £10.50/litre.



In case you're thinking of trying to save a few pounds by risking using the wrong fluid, just a reminder that a replacement/re-manufactured transmission will cost you around £2000.

Phil
 

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Good evening Phil
Thank you for taking the time to answer, + picture, i really appreciate. I will get one of those. Great technical info as well, knowing why is as important as knowing how.
Trying to save on oil ? never :) Do people do that ? :0
 
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