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Official Automatic to 6-speed Swap

288135 Views 446 Replies 100 Participants Last post by  oijuma
First off, I would like thank Neil1138, ivegotissues666, and xmltok. Without their DIY’s and information from posts I probably wouldn’t have decided to do this. My intention with this DIY thread is not to dwell on what has already been covered but to share my experience, reinforce things I found necessary, point out differences in my conversion, and above all explain the wiring piece well.

Second, if you are fairly skilled mechanically, can assemble Legos, and have a desire to solve complex puzzles, you will probably do well at this. While you don’t have to be an OCD perfectionist, it might help.
Before you get started there are several things you must do, no matter whether want to or not. If you plan on doing this yourself you must research realOEM.com and find out mechanically where all these pieces are and why you need them. As model years progressed, some parts on the cars also changed slightly so the parts required may be slightly different from one build to another. Know your own vehicle well prior to starting.

Overall once I got started this took me 4 days. I did all the work myself, with a few emails with knowledgeable members.

All the photos for this are in my media library here: TitaniumCranium
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6 speed in 325i auto?

Has anyone done this swap from a 325i auto? I just bought a complete 6 speed setup from a ZHP off of eBay (don't have my hands on it yet), and after I bought it I read something that insinuated that the ZHP/M54B30 flywheel might not fit or otherwise be appropriate when bolted up to an M54B25. Does anyone have any experience with this? If not experience, insight? This will be going into my 2004 325iT that currently has the auto trans.

I naively assumed that this howto would probably carry over exactly to my setup, but upon closer inspection, it seems that putting a 6 speed manual into a 325i is quite rare. Most examples are 330i's. And most 325i manual swaps are 5 speeds.
I did a 6 speed swap on my 325. We needed a new flywheel. In addition to a 330 driveshaft, you'll also need a differential flange from a 330 -- the 325 uses a 4-bolt flange and the 330 uses a 6-bolt.
Awesome -- thanks for the reply Zach. That's just the kind of info I was looking for. Which flywheel did you end up using?
We pulled a flywheel from a manual transmission 330 -- the engine blocks on both models are the same size, so it bolts right in.
Ahh OK. The 330 flywheel came with the transmission I bought so I should be set there.
Another option is to use the 325 SMG driveshaft if you don't want to swap flanges. Rare to find used though
That's an interesting option that I never would have thought of. A cursory look though confirms that they are indeed rare! I came up empty.
So I finally got the transmission I got off ebay...and to my surprise, it's a Getrag, not a ZF. The seller insisted it came out of a 330i ZHP. Does anyone know whether the ZHP ever came with a Getrag transmission?
Pretty sure the only Getrags were the 5 speed used in the 323/325 and the 6 speed used in the M3/M5/540.
Thanks blarf. In the meantime, I found this thread:


which reports that there is a GS6-37BG (instead of GS6-37BZ) that is manufactured by Getrag and that made it into some non-M 3-series. Visually, the transmission is basically the same as the ZF 6-speed you posted, but has a Getrag tag/serial number on it:


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So I bought a "low profile" transmission jack, and I have some basic geometry questions. The transmission measures ~15" from the bottom to the top of the bell housing. The jack measures ~9" from the ground to the mounting plate. A cursory measure of my jack stands tells me I might be able to get the car ~18" off the ground. You see where this is going. How have people been making this work? With 15" of transmission and no more than 18" of clearance, I'm not sure how to get the transmission on a jack, under the car and then up into position.

I've got most of the parts and tools now, I'm just taking things slow and staging things as much as possible to try and make sure things go smoothly.
The way I did it, three times now, is to slide the tranny under the car, position yourself right under where the tranny goes, pull it up onto your chest, using your knees steady it and just push it up into position. It only weighs about 80 lbs, plus you can feel it slip on to the pilot bearing and the splines. It only takes about a minute to get it in place, put a couple bolts in finger tight and proceed as normal.
This was awesome. I like to think of this as the "Mad Max" way to do a tranny swap.
Got the swap completed about a week ago and so far, so good. Maybe a dumb question: with the AT, you have a sport mode that changes shifting behavior but (as far as I can tell) also throttle responsiveness. Is there a MT version of this "sport mode" that would make the throttle response a little more aggressive? Is it just automatically in "sport mode" all the time once you code out the AT stuff?
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