Z4M vs 3.0si vs 3.0i transmission difference

[dre99gsx]

Found another transmission to replace my blown unit, looking for info as I'm too lazy to pull the transmission back out.

I have been on a 3.0i 2003 Z4 M54 trans GS6-37BZ-THEA which has the locator pin right where the starter motor location exists.

I found a 2007 3.0si N52 trans GS6-37BZ-TJES. It bolts right up, but some bolt holes don't line up, while others do on my Collins plate.

The odd thing is it went in like butter, perhaps too easy. I haven't driven it yet, but it seems to catch the clutch if I put in gear, so it must be reaching the clutch disk splines.

My concern is that the input shaft may be a different length. I didn't check because I'm lazy, thought these were all the same.

Here is what I found on bimmerforums:

There's basically 4 versions of the GS6-37BZ
1) M54 version - short input shaft, pilot bearing in flywheel, bellhousing same as all M5x motors
2) S54 version - long input shaft, pilot in crankshaft, bellhousing same as M5x motors
3) N52 version - short input shaft, pilot in flywheel. Bellhousing is slightly different, though not very difficult to modify
4) Diesel version - Different bellhousing pattern and the transmission is clocked differently since BMW diesels sit at 20º rather than 30º

The flipped pilot bearing you found is from the GS6-53BZ and GS6-45BZ in the N54 cars.

Does anyone have any other information on if the input shaft lengths are different between between the M54 and N52 models?

[dre99gsx]

Bah.. I caved in and decided to pull it back out and measure. Takes only 45 minutes to remove the tranny on this car, not too bad.

GS6-37BZ-THEA (M54) from 3.0i 2003
- end of input shaft to end of bellhousing: 1 1/16"
- start of splines to end of bellhousing: 2 3/32"
- pilot bearing OD 15mm

GS6-37BZ-TJES (N52) from 3.0si 2007
- same thing as above
- two of my lower mounting bolt holes don't line up with the Collins plate, I have to drill them out on the bellhousing. Easy to do.
- missing a locating pin on the bellhousing (not machined in there). I can make do without it, Collins plate has two locator bushings that still recess into the bellhousing.

GS6-37BZ-TJEE (S54) from Z4M
- end of input shaft to end of bellhousing: ~3/16" (5mm)
- start of splines to end of bellhousing: ~ 1 3/8" (35mm)
- pilot bearing OD 15mm
(Courtesy of Michael9218)

GS6-37BZ-TJEP (N52) 330i E90
- no idea...

GS6-37BZ-THEG (M54) 520i
- no idea...

There. Now the internets has actual data.

[Steeler]

Originally Posted by dre99gsx

Found another transmission to replace my blown unit, looking for info as I'm too lazy to pull the transmission back out.

I have been on a 3.0i 2003 Z4 M54 trans GS6-37BZ-THEA which has the locator pin right where the starter motor location exists.

I found a 2007 3.0si N52 trans GS6-37BZ-TJES. It bolts right up, but some bolt holes don't line up, while others do on my Collins plate.

The odd thing is it went in like butter, perhaps too easy. I haven't driven it yet, but it seems to catch the clutch if I put in gear, so it must be reaching the clutch disk splines.

My concern is that the input shaft may be a different length. I didn't check because I'm lazy, thought these were all the same.

Here is what I found on bimmerforums:



Does anyone have any other information on if the input shaft lengths are different between between the M54 and N52 models?

Andre, have you had any of the manual boxes apart to see the internals.
The diesel box, specifically the 335D, has some interesting (to me) gear ratios that I would be interested in swapping into my M54 box.

Wondered if the shafts and accompanying bits were the same and just the gear sets different.

[dre99gsx]

I added the dimensions for the Z4M (S54) transmission. Thanks to Michael9218 - it's now obvious they are CAN NOT be swapped between 3.0i/3.0si due to the input shaft being longer.

[ToddBlack88]

Can the input shafts be swapped? Are they the same bearing dimensions and shaft diameter spline size?

Tough question, but wondering if you know.

[Michael9218]

Since we're posting transmission differences, I thought I would share what I know about the differences of the Z4M and ZF 5 speed transmissions for those with a track car that would like to install the lighter 5 speed behind their S54.

These transmissions share the same M5x bellhousing interface. The input shaft has the same dimensions with the exception of the clutch splines. The Z4M has a finer 22 splines while the ZF 5 speed has 10. So to install the 5 speed you simply use an E36 M3 clutch.

The ZF 5 speed is also 100mm shorter, so driveshaft and gear selector rod need to be lengthen. The transmission cross member can be sourced from earlier 5 speed Z4 non-M roadster. Bolts right up with no modification.

As for why you would want to do this, 20 lbs and the ZF 5 speed is said to be stronger (and cheap & readily available). Even with 4.10 diff gearing, you don't need 6th gear on track. They both have a 1:1 5th gear.