Place for a gearbox swap?

[4004]

Long story short(ish) - my E46 has the GM 5L40 mated to an M57. It's obviously not going to hold up when I go above stock power/torque levels.

It looks like my options boil down to:
- rebuild when it fails, or preventatively, like an oil service. Seems like a waste of time and money
- get a TCU mod for earlier TC lock up - good in theory, but no long term data and hard to find a good place to do it
- rebuild using "uprated" IPT etc components. This seems like a good option, but the basic design remains the same, and it is not clear how much more reliable the "uprated" stuff is
- try a swap - hence this topic.
I've seen successful swaps from GM to the ZF 5HP24. Both were E46 standard issue, so probably easier to achieve.
A ZF6HP21 would've been nice, but I can't even imagine where to start swapping an old GM 5 speed to a newer ZF 6 speed. Marrying the TCU/DME would be tricky.
Then again, people are installing DCTs into E36/E46s, so anything is possible huh

Anyone happen to know of a place (in the South/SW ideally) that would take on a swap (should be easier), reinforcement or a DCT conversion, including all of the machining required?

[aka_kerrly]

Have you seen the GM >nissan 350z gearbox conversion kits. The 350 box is supposed to be pretty tough and relatively cheap/ easy to source

[4004]

Do you mean the Z33? I haven't seen any kits, and even then would've thought this would be for jdm people that swap JZ/RB's into drift shells

[helix402]

The E46 petrol 6s used the ZF5HP19. I’m pretty sure it doesn’t have a higher torque rating than the GM box, probably lower. Even the 5HP30 has a max torque of 560Nm. My tuned 184hp 330d has 550Nm, will be returned to at least 606Nm when I put the 6 speed in.

I’ve replaced a failed GM box in a 330d with a 5 speed manual box. (Whole thread on here). That flywheel is fine for a modest torque increase. My current 330d has a lot more torque so is getting a 6 speed box and flywheel.

My advice would be to go for a 6 speed manual conversion.

Edited by helix402 on Saturday 13th June 10:10

[4004]

helix402 said:

The E46 petrol 6s used the ZF5HP19. I’m pretty sure it doesn’t have a higher torque rating than the GM box, probably lower. Even the 5HP30 has a max torque of 560Nm

None of the standard E46 boxes are strong enough, but with the HP24 there are much more reinforcement options, from what I know

helix402 said:

My advice would be to go for a 6 speed manual conversion.

I knew that would be suggested. My routes are better suited to an auto, and that's what I wanted for the car. I don't intend to do the manual swap