Please note – The following applies to the ZF 5HP24 transmission fitted in the ’02-’05MY 4.4 BMW V8 L322. The GM 5L40-E transmission fitted in ’02-‘06MY 3.0 TD6 and the ZF 6HP26 transmission fitted post-‘06 (to both petrol & diesel models) will have different characteristics.

To save length and weight ZF (very unusually) didn’t fit a torsional vibration damper to the 5HP24 torque converter lock-up clutch. Instead, at low engine speeds, the LUC is controlled to continuously slip to absorb the driveline vibration. The LUC therefore has 3 modes of operation – off, ‘continuous slip’ & locked.

Anytime that you’re driving at light to medium throttle openings in 3rd gear or above at speeds less than 56mph the LUC will be operating in continuous slip mode. The LUC never locks at speeds below 56mph (higher speeds at larger throttle openings). If the vibration you’re feeling immediately disappears when you reach 56mph on a light throttle, in either 4th or 5th gears (doesn’t matter which) then the LUC or its control system is faulty. If the vibration disappears when you select ‘Sport’ or ‘Manual’ mode then, again, this implicates the LUC.

It costs around £200 to have the torque converter remanufactured (not including the cost of getting the thing out & then back into the vehicle again). The transmission has to be removed but doesn't have to be disassembled.

Phil

Thanks Phil what if there's no difference when you engage sports or manual
I tried both today still I get a humming/ resonating same goes if I engage cruise when it's happening
I thought with cruise activated the luc was locked ??
I can even replicate the humming at 70 ish on the motorway

The 56mph ‘rule’ still applies even with the cruise control activated (see measured result below). If the cruise control is activated below 56mph the LUC will be in continuous slip mode (where its application pressure is modulated according to engine torque to maintain a continuous slip speed of around 3%). Above 56mph the LUC will be locked solid.

Click image to enlarge

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Thanks for your input Phil.

I have a 2005 TD6, so I presume this doesn't apply to me?

The guy that looked at mine insists it's not gearbox related and wants me to have the diff work completed before any further investigation.

Shall I accept this or insist on letting someone else check it out?

Thanks again.

Cheers

Paul

Hi Paul,

The GM 5L40-E transmission used in your TD6 does operate on a similar principle to the 5HP24 i.e. the torque converter lock-up clutch has a ‘continuous slip’ mode - as well as ‘on’ or ‘off’ - to allow the lock-up clutch to be activated at lower engine/vehicle speeds for improved fuel efficiency. Unlike the 5-speed ZF unit, however, the GM ‘box does have a torsional vibration damper built in to the LUC :

Click image to enlarge

Click image to enlarge

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phil are you the famous 'phil' from the rangeroversnet site that rebuilds gearboxs ..

I think he is Scarey

Ermm, yes – but I’m pretty sure that I’m not famous

you defo know your stuff mate..welcome ...

Thanks for taking the time to explain Phil.

Finally got out for a long drive around Anglesea and much of north wales the other day and the vibration is still very much there.. after I though I'd fixed it with the tire pressures

Will be going back to the stealer next week and hopefully come back fixed, shall pass that info on Phil! many thanks!

JonP wrote:

Thanks Phil what if there's no difference when you engage sports or manual
I tried both today still I get a humming/ resonating same goes if I engage cruise when it's happening
I thought with cruise activated the luc was locked ??
I can even replicate the humming at 70 ish on the motorway

Hi Jon, Sorry I've been away and have only just caught up on forum posts

The official diff recall was carried out having previously had 2 earlier attempts at solving "diff issues" so it definately wont be that! When I first had the car it appeared to have the symptoms you are referring too and it turned out to be "cupped" Goodyear tyres I switched to Michelin Synchrones and never had the problem again, very smooth and very quiet - I thought there was a reasonable amount of tread left of the "Michy's" but maybe they are now suffering the same fate

Andy. 2015 L405 SDV8 Autobiography, Indus Silver with Black Pack.
SWMBO: 22MY Defender 110 HSE X Dynamic, Gondwana Stone.
Gone: 2014 Discovery 4 HSE Luxury Firenze Red
Gone: 2006MY Java Black TD6 Autobiography
Gone: 2013 Jaguar XKR Convertible, Italian Racing Red with Ivory Seats
Gone: 2010MY Stornoway Grey TDV8 Vogue SE with RSE
Gone: 2008 Disco 3 HSE, Hybrid Tv + Retro-fit RSE System & DVD
Gone: 2003 Epsom Green 4.4i Vogue, LPG, Mk4 Nav, BMW Bluetooth Phone, Hybrid Tv Tuner,

Ajay(UK) wrote:

JonP wrote:

Thanks Phil what if there's no difference when you engage sports or manual
I tried both today still I get a humming/ resonating same goes if I engage cruise when it's happening
I thought with cruise activated the luc was locked ??
I can even replicate the humming at 70 ish on the motorway

Hi Jon, Sorry I've been away and have only just caught up on forum posts

The official diff recall was carried out having previously had 2 earlier attempts at solving "diff issues" so it definately wont be that! When I first had the car it appeared to have the symptoms you are referring too and it turned out to be "cupped" Goodyear tyres I switched to Michelin Synchrones and never had the problem again, very smooth and very quiet - I thought there was a reasonable amount of tread left of the "Michy's" but maybe they are now suffering the same fate

Andy.

Just an update following fluid and filter change last Friday
The fluid was black and apparently smelt burnt although apart from some sludge in the pan there was no discernible evidence of metal chunks or debris
The filter and fluid were changed and upon test drive no more vibrations or resonating inside the cabin space
So fingers crossed I have bought myself some more time and I will monitor closely
Hi Andy I will keep my eye on the tyres thanks mate hope you had a great time away

Best regards
Jon

Mikeyjd wrote:

"cupped tyres" are often caused by worn shocks. If that is the cause of cupping, fitting new tyres will eventually result in the new tyres getting cupped as well, unless the cause of the original problem is rectified.