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rjff Member Since: 28 Oct 2017 Location: Cambridgeshire Posts: 1196 ![]() ![]() ![]() |
I've a sneaking suspicion that maybe RRPhil may be along sometime soon, and he's sure to help if you do some homework.
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Life is an Adventure Member Since: 04 Feb 2013 Location: Trawsfynydd, Wales Posts: 4 ![]() ![]() |
Thank you
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rjff Member Since: 28 Oct 2017 Location: Cambridgeshire Posts: 1196 ![]() ![]() ![]() |
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Fox889 Member Since: 04 Jun 2019 Location: Bury St Edmunds. Suffolk Posts: 696 ![]() ![]() ![]() |
You could start by having a 'mega flush' of the gearbox, this apparently flushes out 99% of the oil versus 60% of the by only doing a filter change.
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Life is an Adventure Member Since: 04 Feb 2013 Location: Trawsfynydd, Wales Posts: 4 ![]() ![]() |
I’ve let it drained for 2 days. It took 8.4lts to refill the box. A
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Alistair Member Since: 11 Feb 2011 Location: Peterborough / Bordeaux / Andorra Posts: 7979 ![]() ![]() ![]() |
RRPhil is your man - I wouldn't waste time talking to anyone else
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RRPhil Member Since: 22 Aug 2011 Location: Blackburn, Lancashire Posts: 993 ![]() ![]() |
It’s true. The post-2002 5HP24 does have a couple of vulnerabilities i.e. wear of the torque converter lock-up clutch friction plate, and failure of the B-clutch hub/C-clutch drum axial needle roller bearing. However, both these tend to fail at around the 100,000 mile mark and their replacement will then give you another 100,000 miles of use from the same transmission.
With the torque converter, the lock-up clutch operation is highly sensitive to the friction modifier pack in the fluid (particularly when operating in controlled-slip mode where the LUC continually slips at around 3% to absorb torsional vibration due to the fact there is no spring damper in the clutch). It is critical, therefore, that only Mobil ATF LT71141/Lifeguard Fluid 5/Pentosin ATF1 fluid is used.
Although the 5HP24 was originally designed for 420Nm and the M62 4.4V8 engine produces 210kW/440Nm, the ZF 5HP24A transmission (which uses the same internal running gear, clutch packs, etc.) was used in the VW Phaeton behind the mighty 6.0 litre W12 engine and in the Audi RS6 Plus, whose Cosworth-developed engine produced 353kW/560Nm. Consequently, the post-2002 5HP24 (putting aside the two vulnerabilities already discussed) is a highly durable transmission in the L322 application with capacity to spare, and I personally don’t see the need to uprate it. Phil |
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fanders Member Since: 10 Jul 2013 Location: Hants, UK Posts: 318 ![]() ![]() ![]() |
This is why this forum is so good.
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Life is an Adventure Member Since: 04 Feb 2013 Location: Trawsfynydd, Wales Posts: 4 ![]() ![]() |
Thank you for this information. That answered all my questions and put my mind to rest. So a new torque converter and a rebuild gearbox will see me back on the road again 😀 |
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pcourtney Member Since: 14 Jan 2020 Location: Stansted Posts: 897 ![]() ![]() ![]() |
might need to do this on my car
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RRPhil Member Since: 22 Aug 2011 Location: Blackburn, Lancashire Posts: 993 ![]() ![]() |
The transmission has to be removed from the vehicle to access the torque converter, but it isn’t necessary to dismantle the transmission, so no specialist knowledge of automatic transmissions is required. Any competent mechanic could do this bit.
![]() The spring retainer for the LUC piston is friction welded into position on the centre tower so this weld also has to be cut off to allow the piston to be removed to provide access to the friction plate.
Once the friction plate is replaced, the spring retainer has to be very accurately re-welded back into position (total piston movement is only around 1mm) before the complete assembly can be welded back together, pressure tested and balanced. There are few companies in the UK capable of doing this. Those with the capability include JPAT, Sussex Autoparts & Mackie Transmissions. When the B-clutch hub/C-clutch drum axial needle roller bearing fails it will cause an O-ring between the input shaft and B-clutch drum to split and this causes a hydraulic leak in the A-clutch circuit. You’ll know if this happens because, once the fluid gets warm, the failsafe message will be displayed and the transmission will lock in 5th gear. Phil |
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pcourtney Member Since: 14 Jan 2020 Location: Stansted Posts: 897 ![]() ![]() ![]() |
thanks Phil - really appreciate the info - top man ! |
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