S6-37 6mt swap info (broken off from junk yard thread)

[tnord]

probably the smart thing, I just don't like the idea of spending all of that money and not "upgrading" to a better shifting, serviceable gearbox. I should probably talk to a shop that does SMG -> manual conversions and have them set aside a good unit for me.

[Slideways]

say you had a car with 111k miles, and worn 2nd/3rd synchros that caused gears to grind unless you were very deliberate with your shifts. When it came time to replace a clutch, what would you do?

I'd have a hard time putting my same transmission back in, but I also don't see anything else that's the clear choice. I'm guessing if I could find someone qualified, that rebuilding my existing one would be the most economical.

Reman GS6-37 doesn't seem terribly expensive from the dealerships I'm finding online. It looks like that was the transmission I had in my E90 330, and I could bang through gears way faster than the M3. But potentially having to get a custom driveshaft doesn't sound great, and if you need the flywheel setup also things are getting more complicated and more expensive.

Most cost effective option is the get a good working sub-100k SMG unit and convert it to manual. It is even less when swapping over your manual bellhousing. Also, the shift detent, spring guide pin, and compression spring need to be transferred over to the SMG unit. Big plus is you keep the clutch assembly, driveshaft and shift linkage, so no cost there other than renewing the clutch disc and pressure plate.

Rebuilding service is rather expensive by comparison, like 4-5x, and very few companies can do it.

[tnord]

I have to think finding a used box out of a Z4M is nearly impossible.

the reman units I was finding through dealer websites was about $3k. Add in a flywheel, clutch, and shifter setup and this project follows my rule that modifying anything on this car is about $5k to do it right.

Used units appear to be available for about $1000-$1500, but of course are of unknown condition. Add in a rebuild on those units and you're probably right at the $3k number you can get a reman unit from BMW for.

[terra]

Should be able to get away with the stock driveshaft. Flywheel stuff is a bit of a complication for sure if you're not using the box out of a Z4M

[tnord]

say you had a car with 111k miles, and worn 2nd/3rd synchros that caused gears to grind unless you were very deliberate with your shifts. When it came time to replace a clutch, what would you do?

I'd have a hard time putting my same transmission back in, but I also don't see anything else that's the clear choice. I'm guessing if I could find someone qualified, that rebuilding my existing one would be the most economical.

Reman GS6-37 doesn't seem terribly expensive from the dealerships I'm finding online. It looks like that was the transmission I had in my E90 330, and I could bang through gears way faster than the M3. But potentially having to get a custom driveshaft doesn't sound great, and if you need the flywheel setup also things are getting more complicated and more expensive.

[Lee_Enfield]

I had to replace the GS6-37 because of an engine failure taking out the bellhousing, it was excellent! It was also a BMW reman. Hard to say how a used gearbox will shift.

A reman GS6-37 used to be about $3k which I think makes more sense than swapping in a used gearbox. Nowadays...not sure where prices are. I know the 420g has doubled over the past 8 years.

Was the reman from BMW or a third party? I seen that some BMW parts places charge a notable core charge that is not really returnable if your trying to replace a different box.

[bigjae46]

How big an improvement is the GS6-37? The standard E46 M3 gearbox is really the only thing I don't care for about the car.

I had to replace the GS6-37 because of an engine failure taking out the bellhousing, it was excellent! It was also a BMW reman. Hard to say how a used gearbox will shift.

A reman GS6-37 used to be about $3k which I think makes more sense than swapping in a used gearbox. Nowadays...not sure where prices are. I know the 420g has doubled over the past 8 years.

[D-O]

How big an improvement is the GS6-37? The standard E46 M3 gearbox is really the only thing I don't care for about the car.

[discoelk]

E46 M3 DS is what you use when putting an M3 subframe/diff in a 6 speed 330i so it should work fine in the M3 with the GS6-37.

[George Hill]

I thought the 330i driveshaft is the same as an E46 M3 driveshaft?

I think the rear length is the same, but I am not sure about the front.

I'll dig out some driveshafts later and take a pic comparing them.

[EthanolTurbo]

The transmission tunnel and transmission placement is exactly the same on all US RWD E46s.

Other than the driveshaft this will bolt in exactly like it would to its native engine.

IE to put the E46 GS6-37 trans in from a 330 you would use the 330 clutch, flywheel, TOB, Ford, shifter assembly and crossmember. I don't know how the driveshafts compare but I would imagine you would need either the 330/6MT driveshaft or a custom one. Hydraulics are all the same so you don't have to make any changes there.

I thought the 330i driveshaft is the same as an E46 M3 driveshaft?

[George Hill]

The transmission tunnel and transmission placement is exactly the same on all US RWD E46s.

Other than the driveshaft this will bolt in exactly like it would to its native engine.

IE to put the E46 GS6-37 trans in from a 330 you would use the 330 clutch, flywheel, TOB, Ford, shifter assembly and crossmember. I don't know how the driveshafts compare but I would imagine you would need either the 330/6MT driveshaft or a custom one. Hydraulics are all the same so you don't have to make any changes there.

[e46IX]

Did you ever make the tranny swap? Any reviews/insight you can provide would be appreciated. Thanks...

I'm probably still a month or two away before I bring the E46 M3 back home to finish the build. Just waiting on my engine builder to get the motor back together and I'll be sure to post updates here for everyone.

I have since acquired a few more transmissions. One of them is from a Z4M, one from an E60 530i, and the other 2 from E46 330's.

Apparently the Z4M input shaft is a bit longer than the 330 variant, I'll get em all side by side and carefully inspect the differences. From the outside they look identical, also the Z4M uses the same flywheel as the E46 M3, but has a unique clutch setup.

[BMWE46M3]

This just got shipped in, snuck this one from a wrecker who had it priced for cheap. Contacted Ronald to see if he can make an SSK for me hoping to get one from him by end of January.

Just so you guys know, the ZF 6-Speed in the E46 330i is also used in those early E60 525/30's with the M54 engine. I think it was 04-06 E60. I found mine like this priced under market value from car-part.

Did you ever make the tranny swap? Any reviews/insight you can provide would be appreciated. Thanks...

[BMWE46M3]

Just to confirm, are you planning on putting this transmission in an E46 M3? I’d love to hear your reviews if this is the case after you install it. If anything, there should be a great improvement just by installing the Autosolutions shifter.