After trying to find a bulleproof version of the Td6's 5L40E auto or a replacement box I found this gem.
I had been looking at ZF 6HP24 variants and found that BMW fitted this gearbox (first variant not the 2nd in new LR's) to the TD6 (M57) in the 730d sold in Europe between 2002-2005. Also it was used again behind the M57 in the E63/64 6 series coupes from 2003-2007
It was not made available to the Range Rover and other BMW vehicles; because they were marketed as the prestige vehicles in the BMW lineup.
Surely these boxes were communicating on the old canbus system ? I e-mailed ZF a few weeks ago, but have had no reply, so I thought I would put it out for discussion

Is it worth more investigation ?

Laurie

I would be interested to know the answer....

You can do anything with enough time and money, but even if the bus system for the ECUs is the same, the transmission ECU will need to be programmed to match the parameters presented by the RR and will need to present and understand all the correct status messages that it encounters in comms with the other vehicle systems. I would be extremely surprised if ZF gives you an answer simply because it has never been done - they will not be likely to start venturing guesses.

The main problem with the 5L40E is not that it is weak, underrated, or any of the other descriptions floating around the net. The main problem is that the valve body was cast in a soft alloy. This can be repaired by sleeving the valve bores. Do a search for valvebody+sonax. There are 5L40Es running behind relatively high hp motors in the US.

Spend a little more building the transmission right and you'll have a nearly bulletproof solution. 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)

+1 SteveMFr. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

As above it would take a lot of time and if you were good coding and diagnosing these types of systems then maybe a few hours here and there if you had another car to use would be ok but not really.

The biggest irk i have about the chocolate box is the lockup is so poo. mine never locks up below 30 where as all the new box's will lock up even in 1st! wish we could get a software mod for that  FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
Mantec Sump Guard, Rigid Load liner, MY10 BT upgrade.

HAving a quick look round the web and the sonnax things ...

there are places in the US that offer a sonnax valve body rebuild for less than $500 ... are all the 5L40E valve bodies the same across the cars they were installed in? Or is a RR valve body different from another vehicles make?

Would a fitting of a sonnax valve body be a worth while future-protection measure for the Td6 gearbox? V8 or else ...

Have to express my ignorance kingpleb, what do you mean by lock up ? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

The conditions causing the torque converter to lock and the clutches as well. I'm sure rrphil could explain it better but compared to the latest boxes the gm slips all the way upto 30ish and at light throttle as well. Try a new disco 4 on a test drive and see what I mean  FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
Mantec Sump Guard, Rigid Load liner, MY10 BT upgrade.

From Wikipedia:
Torque converter

In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load. The torque converter normally takes the place of a mechanical clutch in a vehicle with an automatic transmission, allowing the load to be separated from the power source. It is usually located between the engine's flexplate and the transmission.
The key characteristic of a torque converter is its ability to multiply torque when there is a substantial difference between input and output rotational speed, thus providing the equivalent of a reduction gear. Some of these devices are also equipped with a temporary locking mechanism which rigidly binds the engine to the transmission when their speeds are nearly equal, to avoid slippage and a resulting loss of efficiency.


From Steve:
The lock-up clutch in the TC is the wear item that causes the most probs in the 5L40E. Due to insufficient pressure, the clutch slips and dumps its lining into the trans fluid - resulting in more probs and accelerated wear.


Fisha, to answer your question: a couple of us have considered this (see the end of RRPhil's '5L40E tear down' thread on RR.net). Flushing the transmission thoughroughly and replacing the TC and the valve body modified with Sonax bits could possibly be a 'transmission saver' solution. StevenA - member here too - seriously considered doing this. I came to the conclusion that before I R&R the transmission and spend 1000+ on parts only to find that the transmission fails anyway due to a worn pump or contamination not flushed out, etc. I would just do a solid rebuild when the time comes. StevenA solved his problem by selling the TD6 and buying a TDV8

Last edited by SteveMFr on 29th Sep 2012 1:00pm. Edited 3 times in total

I am no longer so ignorant and pleased to say that so far have not experienced this effect ? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

We have the 5L40E in locallly built Commodores, but like the BMW X5's all the valve bodies are different. The one thing that is consistant across all variants here is that the torque converter is usally the first point of failure. One local specialist stated that GM had a batch of badly bonded T/C clutch linings; if you look at most failures you will find failure of the T/C clutch linings was the start,and the valve wear just exacerbated the problem. As was stated here on the forum if you go thru LR part numbers there have been 3 different numbers for the T/C's.between 2002-2006.
The main reason I wanted to upgrade the box was the increased performance available with the Td6; the L322 version of the M57 was the lowest rating motor specification. If you get the chance to drive later model X5's you realise how restricted the TD6 is, even taking the EXTRA WEIGHT of the L322.
BUT when you read the spec's for the 5L40E it shouldn't have been put into the L322 at all !!! today LR & BMW would be liable in court for repairs under todays consumer laws here. The auto was under spec in the first instance,
The maximum torque rating of the GM 5L40E is rated at 340Nm yet the TD6 output is 390Nm in stock form !!!

The 5L50E version was never available in Australia so it's 25% increase in ratings can't be easily compared, but it did have a different output shaft spline to the 5L40E, so it's not a straight swap.
If only we could get a better auto