I suffered an excruciatingly long return to Paris yesterday, with traffic backed up for long intervals. During this stop start driving, with transmission in Drive, I was frequently around 20 kph. What I kept seeing (feeling) was a sharp kick at around 20 kph as the box shifted up - almost like taking backlash up - as car went from semi coast to drive.

Did some research, and it seems the GM5L40 is known for a less than perfect shift from 1st to 2nd.

In normal driving, when accelerating, it is still not "smooth" but less noticable and not enough to raise suspicions.

Is this correct, or is this symptomatic of an issue?

For information, the box has done 150k km, and I flushed the transmission oil at 140k - while fairly black, the oil was otherwise clean (no slurry or metal filings etc)

Any input as to experience with this type of issue appreciated.

This is supposedly normal and the BMW diesel X5's are well documented in the forums for suffering it with even owners selling their X5's over it

hi steven i have the same gearbox but i dont have this problem.. but there are more members on here better to advise you.my input is mine dont kick in any gear or any speed.

Start budgeting for a new gearbox.

I think its a characteristic of the gearbox, especially after being in slow moving traffic, maybe its excessive drive fluid pressure or something, but after being in traffic, I used to get a clunk on take up, not sure if it was between 1 and 2 or 2 and 3. I wouldn't worrry about it unless you have got far worse symptoms

I get something similar in my TDV8 TBH, Range Rovers since the dawn of time have had transmission clunk so I just accept it and try to adjust the way I drive to make it less noticeable if I can.

Hope that helps allay your fears of impending doom! THE INVENTOR OF THE TERM "FULL-FAT RANGE ROVER" :
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Hi Steven,
This is the beginning of the typical GM gearbox probs. I posted my findings on this gearbox several times now - after worrying over exactly the same problem as you. Basically the crux of the issue is that the alloy used in casting the valve body on the 5L40E is too soft. The valve bores wear, shifting becomes erratic and, at some point, the box dies. You'll notice that if you go into sport mode, 1-2 shifts are much nicer: you're spinning the pump faster hence more pressure.

I'd do a trans fluid flush or 2-3 fluid changes. Your gearbox will likely still hold up a while. I've gone 50k kms since mine started showing these symptoms. When you do a rebuild, make sure you get valve bore inserts installed. Supposedly makes the transmissions better than new.

Here is the synopsis of the transmission research (quoted from a thread about transmission fluid on RR.net):

Quote:

Daniel wrote:Yep, despite all the conjecture in respect of the correct fluid to use, any high quality latest spec auto transmission fluid is OK.
The industry specs are there for all to see and it's just oil companies attempting to claim that their fluids are better than others.
And at the time of the td6 release LR had some sort of collusive deal with Texaco hence their promotion of that brand at that time.

Thanks everyone for your input.

Steve,
I have trawled the net and various manuals and found a couple of things of interest, which have not been covered on the RR forums as I can see.

1. The RR 5l40 underwent an upgrade at the end of 2003, at the same time as the BMW box. The complete gearbox changed part number at around 3A000xxx, but the valve body changed at 3A111xxx. At the same time, the BMW box went from XF to XW. The question is, did they change the valve body then? If so, it would appear to be backward compatible from the step change, although this is not listed as an OSI supercede.

2. The RR box is always listed as a 5l40, but the BMW box (X5) was in fact a 5l50 (A5S390 instead of the 5l40 which is A5S360) - improved torque rating but identical ratios and form factor. Would it be possible to fit a 5l50 to a RR???


I tend to agree with the valve body diagnostic - sitting in hot weather crawling along, must push the fluid temp up, and therefore lower its viscosity slightly, so that any wear effects will be more exagerated.

A question I asked when I first got the car, and am now resurrecting - if the valve body is the cause, would changing it for a new (or refurbed as you suggest) significantly prolong the life of the box, if there are no other signs of wear (muck, swarf or bits in the sump)? If the wear pattern is leaking valves, increased clutch wear, increased wear on valves, torque converter failure - then changing the valve body early on should stop the rot! I guess its interesting to note that the valve body is one of the only replaceable parts that LR (or BMW) supply in the transmission.

Finally, re the oil, I read early on your thread, and changed mine (complete flush) with the genuine article, at a reasonable price, 10k km ago.

Hi Steven,
If I ever found the time, I ought to run up to Strasbourg and see if I can find these things out at the source rather than second hand. I drive by the plant regularly (not GM anymore tho)...

To address your points:
1. I asked the people I spoke to (in this case mainly Sonnax and Mackey) about retrofitting later, improved pieces to earlier boxes. Consensus was it wouldn't make a significant difference. The later gearboxes had about the same failure rate as earlier boxes.

2. General consensus here was that torque was not the main issue but wear and the resulting pressure loss. And as far as swapping boxes goes, nobody I spoke to had any significant experience with this (or was willing to tell me about it).

I've thought long and hard about swapping out the valve body too. The thing is, purchasing a modified valve body costs about €800-1000. An auto trans' biggest enemy is dirt/particulate from wear. Even with a flush, you'll never get all the crud, so you'd be tossing your expensive new valve body into a questionable environment - and if the trans still ends up going out you either write off the new valve body completely or end up with the reverse situation: a brand new trans and a questionable valve body. You could, theoretically, also add a filter to the pressure side, but that brings a whole new set of problems (which is why they're not there to begin with).

I decided it would make more sense to wait (also the easy solution ). If and when I need a new transmission, I'll go about installing uprated pieces then.

It might be interesting to find out what can be done to build the 'ultimate' 5L40e. Ian Ashcroft complained about the 'toilet-paper-roll' shaft which is manufactured like a toilet paper roll in that a strip of steel is spirally wound to make a hollow shaft. This unwinds itself and expands inside the transmission making it impossible to dismantle the box = a total loss (he was the only one, tho). Finding out which pieces were superseded and what can otherwise be done to make the gearbox stronger... 
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P38, and LM
(wife thinks I'm nuts - prob right, too)

Thanks Steve.

I thought the plant was still with GM (GMC)?

I think that we are of the same opinion - damned if you do and damned if you don't!

I have found a reasonably priced valve body which has Sonnex valve inserts, and so I propose to drop the sump again, and if the oil condition is still good, to change the valve body and the cooler. This should minimise the muck in the system (although changing the Torque concerter would be even better) and hopefully, the wear caused by any remaining "contamination" will be minimised by the inserts.

That being said, I am not sure that the valve body is that worn - this jerky change from 1st to second seems symptomatic of these boxes, and BMW even issued a firmware upgrade to address the problem of jerking when starting off from a "rolling stop", as in crawling traffic!

So the intention is to gain piece of mind by hopefully avoiding the sudden failures that these boxes are known for, as well as to avoid putting my neck out idling along in French traffic jams

Thanks again for your input

does anyone know where the gearbox control module is fitted on the FF? Current: TDV8 Vogue Zambezi Silver

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Under the bonnet on the drivers side in the box with the rest of the electronics 

thanks for that..  Current: TDV8 Vogue Zambezi Silver

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Tourque converter this is the cause of all gearbox problems replace and flush also check input shaft they wear too

the BMW X5 has similar problems to the TD6, the torque convertors go at about 50k, this was a known problem on the earlier cars. BMW knew about it but tended to do nothing. it would break down quicker if you used the car to tow with!!

the only way around it is to uprate the convertor and this cost about £2k all in via a transmition specialist.

it is a good idea though, instead of replaceing with stock parts, go for something more heavy duty, wouldn't cost that much more. Current: TDV8 Vogue Zambezi Silver

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