(I first posted this thread elsewhere in Nov 2012)

Having invested a thick wedge in my new toy (88k mile 53 plate TD6 L322) and due to me planning on keeping the car (as I did my Soft dash) for apprx 5 years I have decided the following

I will be very shortly having a new torque convertor fitted

I have no current issues with the gearbox or gearchange but at 88k it wont be long before "issues arise"

Whilst reading previous threads and the excellent gearbox strip article linked to by others it appears to me the weak link is the plates within the convertor

My theory is that the oil pump draws in the oil through the filter and then into the TC which then pressurises the oil within the gearbox and valve system and oil cooler so should or more importantly WHEN the TC fails it dumps its swarf under pressure into the workings of the gearbox and as the box is not longer protected by the filter (after the TC) major failure is guaranteed.

So my plan is to have fitted a new TC, filter, cooler and a full strip, clean, inspect and rebuild of the gearbox - fill up with correct spec Texaco Texamatic 7045E oil BEFORE anything fails !!!

Have contacted VMTP in Cannock regarding the work to be carried out as a drive in - drive out service with them reporting back to me once box is stripped.

I run my own small MOT Service and repair business and VMTP have on previous occasions been no problem whatsoever to deal with and I have had no issues with work carried out by them for me.

Sorry meant to add that I will be regularly towing my track car all over the country and want to reduce where possible any risk of failure when out on the road.

OK - 1st Update

Driven to VMTP - had a long chat with Nigel and made him aware of my reasons for new TC, new gen LR oil cooller, strip, clean and rebuild

He says he has seen many RR Auto boxes eat themselves and has no problems with what I want to achieve

One thing they were not happy with though was the quality of my gearbox oil filter and I have subsequently swapped the item for a genuine LR item

They said they have seen non-gen filters collapse under high flow as no internal supports inbetween the filter element - £117.00 + vat gen LR £55.00 inc pattern part

Box will soon be removed stripped and I am going to inspect the stripped box tomorrow.

Just been to VMTP to inspect the stripped gearbox

For me it is a great result

Oil burnt and sludge residue
A couple of hot spots on a couple of the plate rings
Most if not all friction plates have sufficient material left on them
Black oil residue coming out of TC
NO SWARF OR DEBRIS IN SUMP PAN
NO SPARKLY OIL

Conclusion

TC beginning to break up on its internal friction plates as suspected at 88,000 miles and no internal damage to gearbox internals whatsoever - valve block to be pressure tested, stripped and resealed

I reckon TC was within a couple of thousand mile from total failure and subsequent internal damage to gearbox

Plenty of pics taken and will be uploaded later

Current results are what I hoped for so am happy bunny !

Update later

Returned to VMTP tonight to deliver the Gen LR oil filter

Box now rebuilt

The valve block assy was stripped, inspected and re-sealed and as NO swarf had circulated through the system the bores were totally serviceable and no discernible wear was evident

BUT

an accumulator spring was found to be snapped (see pic below that was taken from another thread elsewhere and it lists the accumulator as being "overdrive clutch 4-5 shift"

All other pics are my own box stripped and then rebuilt

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Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated

You may want to look at the ecotune ecu for the gearbox so as to lockup the TC sooner and avoid less wear on it and the clutches within the box  FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
Mantec Sump Guard, Rigid Load liner, MY10 BT upgrade.

There is a thread running on AULRO currently.
A trans workshop in Melbourne has started to experiment with better/stronger components within the areas that cause failures in this trans.
I dont have a Diesel I took the Petrol option on my L322, these failures were one of the major reasons why........

Not to be critical, but when I see shots of the underside of UK vehicles,,,,WOW they are in really poor condition, corrosion,oil leaks, dirt etc. There must be a lot of damage done to the underside of vehicles in winter with salt on the roads.
I guess our out back red/bull dust is not as damaging as one might think.

The 5L40 is not that bad. You have to know its shortcomings. That said, as I want to keep my TD6, building a tougher box is on my long list as well.

RS, sounds like you've done nearly everything to stave off a failure in the short term. It is a bit late now but one thing I would have done is a valve body upgrade. This is from another thread I posted to a while back:

I did considerable research on this transmission and spoke to all sorts of people from Ian Ashcroft, to John Mackey, to some very competent folks at Sonnax Transmissions.

The 5l40E has some very real problems - nearly all of which are pressure related. In a nutshell, the biggest wear issues stem from wear in the valve body bores and in the torque converter clutch valve bore. It seems that, for whatever reason, the aluminum used by GM in the casting of these pieces is softer than the material used in other (older) GM transmissions. This wear leads to improper shift/lock-up pressures which in turn leads to premature wear in the rest of the transmission components (which drop particulates into the fluid and exacerbate the wear in the valve bores) and, at some point, transmission failure.

All of the people I spoke to concurred on a number of items:
-'sealed for life' is not a good thing.As the filter is on the suction side of the system, it can't be made too fine as otherwise it would cause cavitation in the pump. These means that wear causing particulates, once in the transmission fluid, are there to cause damage till removed - or transmission failure. Early, regular fluid changes are good and necessary.
- using the proper transmission fluid is vital. The valves tend to oscillate relatively rapidly in their bores and the GM engineers put considerable effort into the interaction of the materials vs. pressures vs. wear problems. Use only the recommended fluid - not all fluid is alike.
- when transmissions are rebuilt, cleanliness is vital as is checking the tolerances in the valves and the pump
- after a rebuild, changing the fluid is almost more necessary than before to reduce the likelihood of a repeat failure

There used to be a more complete article on pressure loss in the 5L40 due to valve body wear on the Sonnax website but it has since been removed. Nevertheless these articles are good for info as well.
http://www.sonnax.com/publications/transmi...rse-or-tcc
http://www.sonnax.com/system/pdfs/177/orig...09-RCW.pdf 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)