V8 - Is it worth proactively overhauling gearbox before it blows up ?

Saint.V8 said:

A replacement TC will have better friction material, but with the wear in the valve block, whilst it will last longer than the original, may still be prone to exponential wear eventully....but should be good for 100k at least.

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and that sir will do me fine lol

I aim to keep the TD6 for apprx 5 years or till it bankrupts me and I average 12,000 mile a year so 60k will do it for me - lol

So feedback from Mackie was same as Dave's. Just do the maintenance as having it stripped and reconditioned internally is just as expensive as actually waiting for it to fail and do it then. Good consistent feedback so will be the course of action and Strathearn have been asked to service gearbox this week whilst it's in for the diff fix.

Conclusion though : I will ask for a spare reconditioned gearbox for Christmas from Santa as it can't do any harm to have one stored away.

So : where do I source ? Do I go for one from breaker and get one of the good gents here to refurb & upgrade or do I go buy a recon one and sacrifice the exchange cost ?

2.0_hippo said:

i cant understand why LR put an overrated engine in with an underrated gearbox ??

it goes against all science and concepts !!!

why not keep the same ZF gearbox in the TD6 too ???!?! :scratching_chin:

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Because BMW wanted them to cut costs.

But LR/RR have a history of underrated gearboxes. All of the L322 suffer the same problem. To a lesser extent at the EoL, but still exists. Of course until they get older no one really knows by how much.

The L405 is supposed to have addressed all of these shortcomings and is the first properly built RR ever. But again, only time will tell. Based on a write up I saw t'other day the L405 still suffers battery drain issues.

Ok so now found a box from 2002 V8 at not a bad price.

Who do you guys recommend I contact to get it reconditioned to have as a nice spare in the background ?

Mackies in Glasgow are top drawer.

VMTP are also a ZF agent.....

K Motors in Preston do a good Job.....

Also a member on here - Bemble (RRPhil as he is known on other forums) is a guy who rebuilds these things for a hobby, all he will charge you is parts aslong as you can get the box to and from him and are willing to wait a couple/few weeks for the work as he does it part time as a hobby.....but by feck does he know his mustard on these boxes!!

Check out this:

ZF 5HP24 teardown

2.0_hippo said:

i cant understand why LR put an overrated engine in with an underrated gearbox ??

it goes against all science and concepts !!!

why not keep the same ZF gearbox in the TD6 too ???!?! :scratching_chin:

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Perhaps BMW aren't the technical geniuses everyone makes them out to be - they fitted the same crap GM box to the X5 diesel too. It's called penny-pinching.

StuckAgainSteve said:

Perhaps BMW aren't the technical geniuses everyone makes them out to be - they fitted the same crap GM box to the X5 diesel too. It's called penny-pinching.

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So if they fitted the GM box to the x5 ... The x5 puts out more horsepower than the td6 in the l322

So in theory the gearboxes should last longer in the range rover in compared ton the X5's ?

2.0_hippo said:

So if they fitted the GM box to the x5 ... The x5 puts out more horsepower than the td6 in the l322

So in theory the gearboxes should last longer in the range rover in compared ton the X5's ?

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We've had this conversation before - excessive torque destroys transmissions and gearboxes - not horsepower.

2.0_hippo said:

So if they fitted the GM box to the x5 ... The x5 puts out more horsepower than the td6 in the l322

So in theory the gearboxes should last longer in the range rover in compared ton the X5's ?

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The L322 is about half a ton heavier than the X5. Horsepower is a by-product of creating torque and torque is what kills things.

HP = RPM x Torque / 5252

StuckAgainSteve said:

We've had this conversation before - excessive torque destroys transmissions and gearboxes - not horsepower.

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Well I think the x5 gives it more torque anyway

Haven't got the actual statistics to hand

2.0_hippo said:

Well I think the x5 gives it more torque anyway

Haven't got the actual statistics to hand

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The X5 being half a tonne lighter helps the box.

Bix said:

The L322 is about half a ton heavier than the X5. Horsepower is a by-product of creating torque and torque is what kills

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Ohh good point !!

2.0_hippo said:

Well I think the x5 gives it more torque anyway

Haven't got the actual statistics to hand

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It probably has but if the post above about the L322 being half a tonne heavier - there's your answer to the increased failures the torque loadings felt by the box will be higher. That said GM transmission failures in BMW X5s are quite common as they are in L322s. What's much more common on the X5 compared to the Rangie is transfer box failure - the Range Rover one is much stronger.

Tried to PM Bemble but his acct is switched to not accept. Anyone got any idea on how best to contact him ?

tonymccandless said:

Tried to PM Bemble but his acct is switched to not accept. Anyone got any idea on how best to contact him ?

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Go onto www.rangerovers.net he is called RRPhil on there....he frequents that more than here!

Thanks, did just that.

Another twist on this thread....

I am considering a petrol V8 L322 which has high mileage (115K) but is cheap...

It has recently had a new torque converter. Is this a good thing, or a bad thing?! I am just a bit concerned that if the old TC was failing it could have contaminated the gearbox. It seems to all work OK at the moment.

Would it be a good idea to drain and refill gearbox as a preventative measure, observing the quality of the oil? I presume installing a new TC would have required new fluid anyway, so not sure if this would reveal much...

Or (being more positive) is the TC the problem on the ZF gearbox anyway, so having a new one should give me many miles of trouble free motoring


Any input gratefully received...

Cheers

Jerry

jerrytlr said:

Another twist on this thread....

I am considering a petrol V8 L322 which has high mileage (115K) but is cheap...

It has recently had a new torque converter. Is this a good thing, or a bad thing?! I am just a bit concerned that if the old TC was failing it could have contaminated the gearbox. It seems to all work OK at the moment.

Would it be a good idea to drain and refill gearbox as a preventative measure, observing the quality of the oil? I presume installing a new TC would have required new fluid anyway, so not sure if this would reveal much...

Or (being more positive) is the TC the problem on the ZF gearbox anyway, so having a new one should give me many miles of trouble free motoring


Any input gratefully received...

Cheers

Jerry

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I would give it an oil and filter change and check the condition of the oil like you suggested.

you will then know if / when the torque conv. was changed.

have you proof of these works ?

The issue on the ZF box is failure of the bearing between B and C clutches....this fails and allows the B clutch drum to move on the along the shaft wearing out the O ring underneath...when this O ring fails, hydraulic pressure is reduced in the A clutch (which this O ring is there to prevent).

When the A clutch starts to slip, the Lock Up Clutch in the TC starts to work harder as the system is designed to limit TC slippage to around 3%....with the A clutch (which is used in all gears bar 5th and I think Reverse) slipping, the LUC has to work over time prematurly wearing out the LUC friction material leading to debris in the Oil and filter...this then gets into the box and acts like a fine cutting paste wearing out the gearbox clutch packs friction plates....

In the best case you can replace just the bearing. O ring, TC and the A clutch friction plates (as they wear due to this excessive slippage)....

Worst case, replaceing all the friction plates in the box....plus TC, O ring and bearing....

The worst case is better than the GM box which trashes the whole box in the worst case and needs a whole replacment box...the ZF can be got away with a rebuild.

Images to digest.....

Faild Bearing.....




Failed O Ring.....


Phots by RRPhil (Bemble)

jerrytlr said:

It has recently had a new torque converter. Is this a good thing, or a bad thing?! I am just a bit concerned that if the old TC was failing it could have contaminated the gearbox. It seems to all work OK at the moment.

Would it be a good idea to drain and refill gearbox as a preventative measure, observing the quality of the oil? I presume installing a new TC would have required new fluid anyway, so not sure if this would reveal much...

Or (being more positive) is the TC the problem on the ZF gearbox anyway, so having a new one should give me many miles of trouble free motoring


Any input gratefully received...

Click to expand...

It’s common for the torque converter lock-up clutch in the ZF 5HP24 transmission to wear just sufficiently to cause it produce the characteristic ‘cattle grid’ noise/vibration during the engagement & disengagement of its continuous slip mode – usually once the vehicle mileage gets to around the 100k mark. The fluid is not unduly contaminated as there’s still sufficient friction material left on the plate to prevent metal-to-metal contact. A replacement torque converter fixes the vibration issue and hopefully the fluid would have been replaced at the same time too. I had mine done around 20k miles ago and all is still well. The photo below shows the LUC friction plate from my old converter.



Note however that this only applies to the ZF transmission. For the GM 5L40-E transmission used in the TD6, failure of the lock-up clutch is not only common but also disastrous. It results in the generation of huge quantities of metallic debris and the subsequent failure of the whole transmission.