My 5L40E gearbox is on its last legs

I changed oil 20k kms ago using proper Texaco ATF HD 389, few days I dropped the oil again as gearbox suffered a flare when changing from 4th to 5th and it was black and full of glitters

I need a new gearbox and I don't want another 5L40E

I wondered about any possible replacement:

-Fully rebuilt 5L40E with sonnificated valve body and oil pump -> Too expensive and I don't like that it locks TC only at very high speed, while driving between 30 and 45mph is a pain and a waste of diesel

-Engine swap with M57N along with ZF 6HP26 gearbox -> Probably would be the best option to deeply improve the whole car but it's a lot of work and here in Italy would make the car not road legal hence the engine number would differ from what is stated on the V5 (306D1 vs 306D2)

-Gearbox swap with 8HP70 -> The best gearbox you could fit but apart from the gearbox cost, it would need two adapter plates and a stand alone gearbox ecu definetely too much also considering that the TD6 differentials ratio would not let enjoy all the benefits of having 8 gears


Apart from the rebuilt 5L40E, the other two options require heavy modifications but there's one that is the closest to a stock fitment

The 5HP24 gearbox has been fitted as standard on M57 on 730d E38 and Alpina D10 biturbo E39 and obviously on 4.4 V8 L322

Those aspect are crucial for the costs and easiness of the swap, all the parts are available as spares or used parts and even the gearbox ecu is straight replacement

The only downside appears to be that bell housing that fits M57 is not available as spare but I will have to buy a whole 1058000023 or 1058000033 gearbox

This is the shopping list until now:

-1058000032 from Range Rover L322 M62 engine
-1058000023 gearbox from 730d E38 or 1058000033 gearbox from Alpina D10 biturbo E39 and its torque converter
-24401423298 flywheel driving plate from 730d or Alpina D10
-24607508401 Bosch GS60.8.2 gearbox ecu from 730d or Alpina D10
-gearbox loom from 730d or Alpina D10 (can't finda part number but already found used)

To cut down costs I could source a rear epicyclic carrier along with the output shaft and its housing rather than buy a whole V8 L322 gearbox

Despite the large hike in power between the BMW 730d and the Alpina D10 Biturbo (135kW to 180kW), the only physical difference between the 023 and the 033/036 transmission was the torque converter. The 023 transmission had the H35 model and the 033/036 had the D61. Presumably the H35 would be a better match to your engine. I guess that the transmission controllers may have been programmed differently?

Both the L322 032 and the diesel 023/033/036 transmissions have the same number of clutch plates (6A, 6B, 4C, 4D, 5E & 6F) and, in my view, it would be much easier to simply swap the diesel bellhousing and torque converter over onto an 032 transmission. The BMW transmissions have their selector mechanism and inhibitor switch on the opposite side of the casing.

I don’t know off the top of my head if the 5HP24 and 5L40-E transmissions are identical lengths, so there may be some installation issues if not.

I’d be very interested to hear of your progress with this, and any issues that arise. Good luck!

Phil

Top gear will be slightly shorter (26.8mph/1000rpm for the 5HP24 compared with 28.7mph/1000rpm for the 5L40-E) but certainly nothing drastic.

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