L322 5HP24 gearbox misbehaving

Hey folks. My 4.4 L322 (ZF 5HP24 'box) is not driving as smoothly as she should.

At low to medium speeds (20-50mph), I get the occasional judder from the gearbox/drivetrain, which is usually followed by a loud humming/vibration, which passes if I accelerate. I've narrowed it down to being the gearbox (I think), as the noise goes away immediately if I slip the gear selector into neutral.

Additional information: When selecting reverse, there is often (but not always) a jolt as the car moves backwards. The judder/vibration/noise/jolting is worse when the car is up to temperature.

I had the gearbox oil drained & refilled (filter done at the same time), but it's made absolutely no difference.

In all other respects, the car drives wonderfully, and changes gear without issue - it's just the juddering and the vibration/loud humming noise that worries me.

If anyone's got any advice on what this could be, I'd be most grateful. Had a quote today from a recon gearbox specialist, who tell me they'll happily rebuild my gearbox for the thick end of two grand... I'd like to avoid a bill like that if possible.

Thanks in advance for any help/advice.

That is the classic symptoms of a failed/failing Torque Converter Lock Up Clutch.....

The L322 uses a 'continuous' slip mode to prevent torsional vibration as they never fitted a damper in the engine to gearbox connection!!

So what the LUC does is allows the Torque Converter to slip by about 3% and is controlled by a modulating valve that controls the hydraulic pressure to the LUC piston.

Over time the friction material wears away until there is nothing left and you get a judder.....most evident around 30-40mph on light acceleration and more so on a slight gradient.

Cure is to fit a new/remanufactured Torque Converter......if left for a prolonged period, it will slowly wear the individual clutch pack friction plates as the oil get filthy with all the debris in it.

An oil and filter change in the box will buy you some time but the Torqe Converter will need to be replaced at some time.

Research the issue, it is super common on the V8 L322's from 2002-2005

Thanks for the speedy and comprehensive response, Saint.

Forgive my ignorance, but can I purchase a replacement torque converter as a separate part, without the need to replace/recondition the entire gearbox?

Also, is the LUC a separate part, or is it integrated into the torque converter?

I'd really like to nail this one, as other than the gearbox issue, my L322 really is a spot-on car.

LUC is integral to the Torque Converter.

TQ can be replaced as a seperate unit without the need to open the gearbox at all.....all you need to do is seperate the engine and gearbox and then take out and replace the TQ and put back.....

If you are handy with the spanners and have paitience, it can be done yourself....although the box is heavy with the transfer gearbox in place.

I'm not particularly handy with the spanners, but I know a man who is.

I'll look into getting my hands on a remanufactured torque converter.

Thanks again for the advice, Saint. Fingers crossed, you may just have saved me a HUGE amount of money.

Whilst you can just replace the torque convertor, if you see lots of what looks like glitter in the transmission oil and all over the internals of the gearbox then you may find the replacement torque convertor a short lived fix as what will have happened is that the friction material has worn away completely and the TC is now chewing up the disc that previously had the friction material. This gets into the valve block of the transmission and wears that too resulting in a failed transmission down the line.

If you're lucky you may have caught it in time before the metal glitter is produced but look carefully at the gearbox internals when you drain the oil.

Fortunately the Sachs WA4/W260S-2GWK torque converter used in the ’02-’05 V8 Range Rover gives plenty of warning before the friction material is worn through. I left mine for quite a few weeks from when it started making the cattle grid noise before I got round to replacing it and there was still plenty of material left on the friction plate.



The story is quite different with the GM 5L40-E transmission used in the TD6, where usually the first warning you get that the LUC has worn through to the metal is when the transmission grinds to a halt.

The reason the 5HP24 LUC is so sensitive is because the total piston movement from ‘off’ to ‘on’ is only 1mm so only a small amount of wear can upset the preload.

Don’t leave it too long though because even the 5HP24 LUC will wear through to the metal eventually

These refurbished my TC and all very good after a few thousand miles
http://www.sussexautos.co.uk/mobile/index.php
JPAT are the original and possibly best
http://www.jpat.co.uk/