Thread: TD6 reliability gear box

Really? Not sure I agree after several conversations with rebuilders.

From what I read Don is not using the heavier planetary gear set or the new main shaft (which is a weakness). Correct me if I’m wrong here, I have asked this before and its not been answered.

Having a lower stall speed TC is attractive, and heavier clutch packs as well, but the major difference between the 40 and 50 is the planetary set and shaft?? The TC is application specific. There is even different planetary sets found in early or late 40s and lord knows what else was upgraded post 03/2004 - (for example the post 3/04 valve block has the same part number as the 5L50e...)

So what is wrong with a GOOD rebuild that doesn’t leave half the bits out? New clutch packs, TC clutch that doesn’t disintegrate (later 5L40 don’t have this issue) new valve block, new pump, new main shaft that won’t toilet roll out.

Yes there are lots of people having issues with their rebuilt transmissions but there are lots of cheap half arsed rebuilds being done.

Where is Rhys? I had a good chat with him month or so ago and was very interested to hear what he’s seeing in these boxes weather they be out of holdens, volvos, BMWs or RRs

Hats off to Don for an amazing exercise, $3700 cost, he’s way in front, but tally the real cost to a consumer and it’s concerning, We won’t be able to get those parts for anywhere near that figure. By all accounts the uprated TC is a very custom job, which for the masses will come at a premium price with no support and backing. The estimate of 3k for labour puts this near 7k, add a few more K for labour as this is a custom exercise, add few more k for the real price of parts and realistically we are up to 10k with the old planetary set and shaft?

If you’re looking at a solution that has no backing for this price, it brings up an old discussion - I can get a 20k old 6 speed ZF (from a TDV8) delivered for about 1.5k, wonder how much the software dev and module would cost…

you'd need the TDv8 to pull the .69 sixth

Harlie
The other problems apart from the software are that the ZF is 30mm shorter and the output spline (I believe) is different. So transfer case input problems.
This box is in the 05+ BMW X5 with the TD6, but I don't know what type of Canbus etc they use? If it was the same it shouldn't be too hard to do if you have a faultmate etc. So a box from an X5 will bolt straight up, no bell-housing mods, there are a few for sale at BMW wreckers here in Oz.
I also toyed with the idea of a ZF and aux box from a S/C L322, with a diesel TC and hopefully getting away with it with just a new tail-shaft !!!
But the X5 solution would be the best especially if you could use the BMW transfer case ???

Laurie

5L50 planetary outer gears only about 3mm wider than 5L40; all other parts same- shafts, bushes, splines. I've never seen a planetary set collapse/fail in other boxes, eg BW and ZF.
I had no qualms using my "old" 5L40 set as 220,000km and no appreciable wear/slop compared to tolerances of the new 5L50 set.
The output drive splines on both planetaries same; the RR output shaft heavier duty; the spline drive on RR thicker/stronger.
Main shaft? don't know which you mean as all other shafts 5L50; all shafts and drive dogs same diameters/thickness both boxes; just minor length differences.
The main wearing parts are the clutch packs and 5L50 are "heavier" only in having extra drive and friction discs.
The valve blocks identical externally, but no doubt slightly different springs/pressures
internally?
5L50 T/C- had to slide on a spacer spigot as the Caddy obviously smaller bore in flywheel. Added 6mm spacers to the mounting blocks (flywheel to TC) of T/C.
Made up a 4mm thick spring steel drive plate with smaller bolt PCD to match T/C.
My original drive plate was a piddling 2mm thick! and cracked almost right thru one "arm"!
The flywheel had the clearance holes enlarged for the smaller PCD; the engine back plate ( thin gal steel) was cut with tinsnips to give clearance for socket.

The 5L50 gear change and filler plug on opposite side to 5L40 but there was no problem here. I would have liked to fit a dipstick, but only one I had was a ZF but not correct size/thread/shape! In my previous RR soft dash LSE with TD5/electronic 4HP24, I fitted a dipstick in lieu of the "sealed-for-life" arrangement"of Disco.
The electronics? Same plugs/sockets; just plug-and-play/drive away!

To be honest Laurie, (as you and I have concluded re this before) I still think it is cost prohibitive – and I think the 5L50 hybrid custom build is (to the average consumer) as well , hence my question about GOOD rebuilt.

For what it’s worth. A 6 speed ZF (or any non standard transmission) transplant would need a custom ECU. Either use the trans ECU from the donor car, and a custom ECU to translate between the foreign ECU and the car. Or have a full custom ECU developed. First option would be heaps cheaper, you would also need one of the diagnostic developers on side (best plp to build the custom ECU) because you would also need a custom software module for your diagnostic tool to read the new foreign ECU. It’s not going to happen unless someone like the GAP guys get interested. From research I’ve done, the 6 speed ECU won’t work with the car as is.

What’s a trans from an X5 worth? BMW transfer case is single speed.

Thanks Don, from what you have seen, is it possible to fit the heavier clutch packs to a rebuild?

I didn't try the 5L50 clutch packs in 5L40 but I think yes,
but you'll need the 5L50 hollow shafts as there are different lengths, albeit same diameters/thickness, as the 2 cases are same overall length (same casting).

Although it all works as it should, I still haven't studied/got my head around how they can get 5 speeds from only ONE planetary set!!!!!!!! And I'm not going to worry about NOT knowing!

Harlie as we've said before "cost" is the stumbling block. And thanks for reminding me about the BMW X5 transfer case being single ratio, I completely forgot about that could have been expensive mistake.

I've seen Td6 ZF 6 speed from X5's from $2500 onwards advertised from local BMW wreckers apparently little interest so far, as the later X5's are going along ok, so far.

I'm still looking at the GM 6L90E. There are a few US suppliers that are now making conversion kits so I'm keeping a eye on this at the moment If only vehicles used a common electronic language Have you any idea what Canbus the later GM vehicles are using , compared to the 02-06 Td6 L322's ?
Example of what's happening in the US With retro-fitting these autos.

PSI // Performance Systems Integration // 732.691.6531

Laurie