L322 TDV8 '56 Plate Gearbox Knackered. Options?

myfirstl322 said:

@Bemble is the wizard of the ZF five speed but is also up on the 6 speeder which you have.

Quite robust I believe, but there are a couple of 'fixable' issues.

Have you looked at the oil condition and level?

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Bemble said:

"...I'm in the predictable situation of a totalled TDV8 6 speed gearbox"

Nothing predictable about that – the ZF 6HP26 transmission has an enviable reputation for reliability. Having said that, these are the known issues that occasionally affect this transmission :

1. Transmission won’t shift into 4th, 5th & 6th gears (E clutch slipping due to stator shaft bush wear/leakage)
2. Erratic gearshifts – particularly 3-4 (faulty solenoids)
3. Clunky 2–1 rollout shifts (requires software update)
4. Drops into neutral when accelerating hard/turning corner from stationary (clamp bolt for shift cable seized in shift lever)
5. Failure of output shaft spline through fretting corrosion (lack of lubrication during assembly at factory)
6. Clutch packs destroy themselves following fluid change and adaption reset (never reset adaptions unless mechatronic/solenoids are replaced)

Phil

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myfirstl322 said:

When I said a couple of issue of course I meant six.

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gstuart said:

....just really concerning as ive bought some ATF oil and will be changing my ATF oil soon and was going to clear the adaptive settings and then install a software update for the transfer case

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Bemble said:

If you’re resetting the adaptions because new software is being flashed then just follow the appropriate adaption drive cycle afterwards until the new solenoid settings are learned. Don’t change the fluid at the same time, change it at a later date.

The idea of the long-term adaptions is to allow the transmission controller to compensate for changes in the clutch performances over the whole life of the vehicle. The adaptions allow the solenoid currents to be incrementally ramped up (or down) over a long period of time (i.e. years) to ensure that the shift times remain constant and therefore the shift energies seen by the clutch packs remain within spec. while compensating for wear.

The issue that wasn’t foreseen is that the six proportional pressure solenoids in the mechatronic unit have turned out to be very problematic in the 6HP26 and the mechatronic controller ends up having to use the adaptions to try to compensate for the unreliability of the solenoids. Sometimes, therefore, the solenoids may be operating at the extreme ends of the adaption range to hide their faults.

If the transmission adaptions are then reset, and the fluid is also changed at the same time, the combination of the changed coefficient of friction and the much-reduced solenoid current can lead to a situation where the transmission cannot learn the new settings before the clutches slip to such an extent that they overheat and the transmission is then permanently damaged.

For that reason, Land Rover issued an instruction to their dealerships not to reset the adaptions at the same time as a fluid change. The change in friction coefficient is potentially even greater if a non-Land Rover workshop (or individual owner) decides to use any fluid other than Lifeguard Fluid 6, usually because it’s less expensive. Saving £30 may end up costing the owner £3000.

I’m not certain why people feel the need to reset the adaptions anyway (unless, of course, a new software revision is being installed). I wonder if this is sometimes because they believe that the controller has learnt the driving style of a previous owner or something? This is absolutely not the case. Driving modes and styles are cleared each time the engine is turned off and on again. Only the long-term adaptions are stored, which are essential to compensate for wear.

It tickles me each time someone on a forum drags up the old myth about ‘resetting the adaptions’ by holding your foot hard down on the accelerator while turning on the ignition and holding it there for a number of seconds. In reality, this just temporarily puts the transmission into ‘sport’ mode (because it senses wide-open throttle) which is then cancelled anyway when the ignition is switched off. People sometimes report that this ‘fix’ has completely transformed the feel and performance of their vehicle! Just shows the power of suggestion.

In summary, if your solenoids are performing to spec. and you reset the adaptions at the same time as changing the fluid then all should be fine. On the other hand, if one or more of the solenoids is at its adaption limit due to a fault, then resetting its adaption to ‘nominal’ may prevent it generating sufficient pressure to stop the clutch that it is controlling from burning up before it gets chance to find its new setting. Land Rover are understandably not prepared to take the risk of trashing a customer’s transmission.

Phil

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Bemble said:

If you’re resetting the adaptions because new software is being flashed then just follow the appropriate adaption drive cycle afterwards until the new solenoid settings are learned. Don’t change the fluid at the same time, change it at a later date.

The idea of the long-term adaptions is to allow the transmission controller to compensate for changes in the clutch performances over the whole life of the vehicle. The adaptions allow the solenoid currents to be incrementally ramped up (or down) over a long period of time (i.e. years) to ensure that the shift times remain constant and therefore the shift energies seen by the clutch packs remain within spec. while compensating for wear.

The issue that wasn’t foreseen is that the six proportional pressure solenoids in the mechatronic unit have turned out to be very problematic in the 6HP26 and the mechatronic controller ends up having to use the adaptions to try to compensate for the unreliability of the solenoids. Sometimes, therefore, the solenoids may be operating at the extreme ends of the adaption range to hide their faults.

If the transmission adaptions are then reset, and the fluid is also changed at the same time, the combination of the changed coefficient of friction and the much-reduced solenoid current can lead to a situation where the transmission cannot learn the new settings before the clutches slip to such an extent that they overheat and the transmission is then permanently damaged.

For that reason, Land Rover issued an instruction to their dealerships not to reset the adaptions at the same time as a fluid change. The change in friction coefficient is potentially even greater if a non-Land Rover workshop (or individual owner) decides to use any fluid other than Lifeguard Fluid 6, usually because it’s less expensive. Saving £30 may end up costing the owner £3000.

I’m not certain why people feel the need to reset the adaptions anyway (unless, of course, a new software revision is being installed). I wonder if this is sometimes because they believe that the controller has learnt the driving style of a previous owner or something? This is absolutely not the case. Driving modes and styles are cleared each time the engine is turned off and on again. Only the long-term adaptions are stored, which are essential to compensate for wear.

It tickles me each time someone on a forum drags up the old myth about ‘resetting the adaptions’ by holding your foot hard down on the accelerator while turning on the ignition and holding it there for a number of seconds. In reality, this just temporarily puts the transmission into ‘sport’ mode (because it senses wide-open throttle) which is then cancelled anyway when the ignition is switched off. People sometimes report that this ‘fix’ has completely transformed the feel and performance of their vehicle! Just shows the power of suggestion.

In summary, if your solenoids are performing to spec. and you reset the adaptions at the same time as changing the fluid then all should be fine. On the other hand, if one or more of the solenoids is at its adaption limit due to a fault, then resetting its adaption to ‘nominal’ may prevent it generating sufficient pressure to stop the clutch that it is controlling from burning up before it gets chance to find its new setting. Land Rover are understandably not prepared to take the risk of trashing a customer’s transmission.

Phil

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seansmith said:

Hi Phil,
Just reading your review above and now your comprehensive response.
I have a 3.6tdv8 Range Rover that has developed a judder that is mainly present going up hill. It has 125k miles so I’m prepared to have it reconditioned, is this some you do? I have no knowledge round gearboxes so forgive my ignorance but what parts are there to recondition? Am I correct to say gearbox, haldex, torque converter, mechatronic?

Im in Northern Ireland so if you could recommend anyone here would be great or advise someone in GB I’d consider bringing the vehicle over or can the box be removed and sent over for recon?

Any other advise around this is appreciated.

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