Transmission from n55 335i Direct Bolt On For n55 135i?

[135iMike]

Based on realoem.com the part number are exactly the same for the similar year (n55) 335i transmissions and the 135i transmissions (GS6-45BZ - THD4)... Just looking to see if anyone has done this or if there's something else needed/won't fit/whatever else..

I tried searching for this and was surprised I couldn't find anything. I'm looking at 335i box's because they're much more common than our 1s.


Quick backstory if anyone has any advice:

Reversed out of my driveway this morning, drove 30 minutes to work, pulled in parking lot, went to back into a parking space and reverse was gone.

Stick would go over, and up half way, but not settle into the gear, like hitting a wall. Mirrors moved as if it was in reverse but no luck. No noises, bangs, booms, clunks, nothing. Drove 100% normal, but reverse vanished.

I got into work and Google'd "135i reverse broken", etc.. and I see a TON of threads about the same thing, all leading to you need a completely new unit, no fixes, no linkage issues or the like.. I'm shocked I haven't heard of this being a thing before.

The car only has 60k miles on it and is a 2012, sadly CPO has run out

I'm looking on Ebay for boxes now and see used units for around $800 - just need to make sure they'll bolt right up.

Thanks for your time and the long read!

[christofis135i]

Sorry to hear about this. Exact same thing happened to me in November last year. Reverse one minute, the next it was gone.

Dealer investigated it to be a reverse gear synchro. I was shocked, I've experienced a bad synchro before and this didn't feel anything like it before. Had to replace my transmission as that's the only way to fix the issue it seems like.

You are correct. The 335i n54/55 trans will bolt up to a 135i. I ended up getting a brand new trans from the dealer for a steal. Usually wrecked cars have high mileage, not even worth it.

[Gangplank]

Sorry to hear about this happening to both of you.

You might want to try a transmission shop to see if they can get a used remanufactured unit vs a junk yard used.

[Lucky1]

What models and years are affected? 128i's also? Is there a TSB for the issue? Thats certainly bad news.

[135iMike]

Originally Posted by Lucky1

What models and years are affected? 128i's also? Is there a TSB for the issue? Thats certainly bad news.

Seems like n55 cars with the box part number: GS6-45BZ - THD4