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

[heinzboehmer]

Made this its own thread, to unhide good info.

Nice, thanks for that

I was hoping that would be the case, but not so. The way the flexplate/flywheels are made they are "tuliped" around the the crank flange (if that makes sense). Actually here's a pic.

Damn that's a bummer. Really makes the S6-37 much more appealing now.

[Obioban]

Made this its own thread, to unhide good info.

[George Hill]

I'm glad you mentioned this, I had not even considered this. So the problem is that the flywheel interferes with access to those bolts? If it's just that the bell housing doesn't have holes in the correct spots, then that sounds like an easy fix

I was hoping that would be the case, but not so. The way the flexplate/flywheels are made they are "tuliped" around the the crank flange (if that makes sense). Actually here's a pic.

[heinzboehmer]

*If you bolt the N5x transmission straight to the block without a bell housing adapter you CANNOT take the oil pan off with the transmission installed. The way the flexplate/flywheel is designed you cannot access the oil pan bolts into the RMS.

I'm glad you mentioned this, I had not even considered this. So the problem is that the flywheel interferes with access to those bolts? If it's just that the bell housing doesn't have holes in the correct spots, then that sounds like an easy fix

[George Hill]

Keep in mind all the N5X transmission are not a straight swap onto an S(M)5x engines. Highlights that are likely most important to this group are:
*Starter - Starter bolts to the M/S5x transmission and to the engine on the N5x. I (HPB) make an adapter to bolt the starter to the transmission to solve this issue otherwise you need an adapter plate from Domiworks, Adamat or PMC.
*If you bolt the N5x transmission straight to the block without a bell housing adapter you CANNOT take the oil pan off with the transmission installed. The way the flexplate/flywheel is designed you cannot access the oil pan bolts into the RMS.

[heinzboehmer]

My understanding is it's close enough that it'll all bolt up. I think there is technically a 5mm difference or so, but there's enough slack in the CV to make up for that.

Not something I would bother with personally unless my 420g was dead. And if I were at that point, I'd probably also look into the GS6-45 and GS6-53 from the newer cars.

I have a ton of seat time with an S6-45 and that thing shifts awesome.

However, I've heard of multiple cases where people have experienced catastrophic synchro failure. Close friend of mine had the reverse synchro go in his car (same one I have a bunch of seat time in) and there's multiple reports of the same sort of thing online. Not trying to fearmonger or anything, but that transmission does seem to have a weak point. Think the S6-53 is the better choice.

https://f10.5post.com/forums/showthread.php?t=1672552

https://www.bimmerforums.co.uk/threads/2011-335i-manual-6-speed-broken-reverse-gear-gearbox-teardown-help.575461/

https://www.1addicts.com/forums/showthread.php?t=1382573

https://www.e90post.com/forums/showthread.php?t=1087237

[heinzboehmer]

I know this is a junkyard thread and not a transmission swap thread, but I did some math this morning and figured I'd share.

Here's the difference in rear wheel speed between the 420G and S6-53, all else equal:


Longer 1st-4th, same 5th and shorter 6th.

And here's the difference in rear wheel speed between a 420G with a 3.62 diff and a S6-53 with a 3.81 diff:


Pretty much identical 1st-3rd and shorter 4th-6th.

So, if you like the M3 factory gearing and want to swap in an S6-53, you should budget for a diff gearing change as well.

[terra]

Ah, that's the bit I was missing.

I wonder how the necessary driveshaft length differs with the GS6-37BZ TJEE vs the 420G.

My understanding is it's close enough that it'll all bolt up. I think there is technically a 5mm difference or so, but there's enough slack in the CV to make up for that.

Not something I would bother with personally unless my 420g was dead. And if I were at that point, I'd probably also look into the GS6-45 and GS6-53 from the newer cars.

Edit: Okay so

E46 325i SMG (37BZ, 4-bolt diff) = 1469MM
E46 M3 (420G) = 1404MM

Z4 3.0i (37BZ, M54; 4 bolt diff) = 1230MM
Z4M (37BZ) = 1170MM

So judging based the Z4, the difference between a 37BZ car with the 4 bolt diff and a 37BZ car with the M differential is 60mm.

Difference between 37BZ 4-bolt diff and 420G with M differential is 65mm. So most likely a 5mm difference between the two transmissions, with the 37BZ actually being ever so slightly longer.

Stock vs stock I would say the ZF shifted better than the getrag. The autosolutions SSK'd getrag shifts much better than the stock ZF. I haven't tried the ZF with an autosolutions SSK. Ronald himself says the stock arm is "excellent" and only the shifter itself really needs to be upgraded to for that "ultimate" kit. http://autosolutions.info/applications-1/

[Obioban]

As a data point, ZHP with an M3 subframe and diff uses an M3 driveshaft. Engines should be in the same spot so driveshaft should be fine with the trans swap.

Definitely not a swap worth the effort IMO. My ZHP didn't shift any better (or worse) than my M3.

I actually own a S6-37, it would seem, in my 128i.

I don't think it, stock, shifts better than my 420g with Auto Solutions kit.

If the driveshaft length is the same between the 420g and the S6-37, I'm probably going to stick with the 420G for now.

[discoelk]

As a data point, ZHP with an M3 subframe and diff uses an M3 driveshaft. Engines should be in the same spot so driveshaft should be fine with the trans swap.

Definitely not a swap worth the effort IMO. My ZHP didn't shift any better (or worse) than my M3.

[George Hill]

Any idea what would be involved in installing a S6-37 into an M3? As in...

Its the same as installing in a Non-M E46 minus the driveshaft.
*Clutch and flywheel from the same car as the transmission
*Shifter from the same car as the transmission
*Crossmember from the same car as the transmission
*Driveshaft likely custom length

Would it need a different driveshaft length? If so, any chance you know what it is?

M3 is 40mm longer than the ZHP, what the overall length differences between the two setups are I do not know. I generally do not install used driveshafts on swaps so I would have a custom one made to my specs. Keep in mind the pinion flange is in different locations for the M3 vs Non-M which may effect compatibility as you have two variables to compare. *Physical location of guibo and pinion longitudinally in the car.

Shift-- what is different, exactly?

Check out realoem, the 420g shifter support arm attaches to the transmission at one point where the S6-37 attaches at two points, completely different.

Cross member looks quite different, and has an addition bracket (2 on the diagram). What's the extra bracket do? Does the cross member install in the M3 without any changes?

The S6-37 does not have an integrated crossmember bushing mount like the 420g, ZF320 and 250g. That is an adapter bracket to adapt it to the E46 crossmember.

I suspect a CF driveshaft is in my future, and I already want to change my shifter setup to a 0% reduction AS kit, AND my flywheel is still original at nearly 170,000 miles... so if I was ever going to do this... now might be the time (get it made to length for this swap and get shifter parts that are friendly to the swap).

I'm sure Ronald has a shifter setup to work from a ZHP.

Looks like the Z4M used a different clutch and flywheel than the 330i, but I think the same trans. Thoughts on the Z4M parts?

Edit: Z4M used the same flywheel as M3. Am I wrong in thinking that the Z4M used the same 6mt as the later e46 non Ms?

The Z4M 6MT is a rare bird outside the car, I do not have one in front of me, but I still was thinking the difference is in the input shaft. If you had one I could compare it to my ZHP S6-37s. I would be inclined to use the Z4M clutch parts, but without confirmation on compatibility I wouldn't be worried about using the M54 parts either.

*I would not be afraid to use a 330 S6-37.

[heinzboehmer]

I wonder how the necessary driveshaft length differs with the GS6-37BZ TJEE vs the 420G.

Don't have measurements, but judging from pictures, it'll be very close:

420G:



S6-37:



That S6-37 is out of a 330i, so shifter location should be the same as our cars.

George Hill might have a better answer though. I think he's done a couple of these swaps

[Obioban]

No, Z4M used the GS6-37BZ TJEE, while late M54 E46s used the GS6-37BZ THEG. Mostly input shaft differences between the different S6-37 variations from what I understand. These threads have more info:
- https://www.e46fanatics.com/threads/...stion.1250761/
- https://www.zpost.com/forums/showthread.php?t=1842540

I've been telling myself for the last few years that if my 420G ever comes out, an S6-37/S6-53 is going back in. Likely the Z4M one as it seems to be pretty much entirely plug and play.

Ah, that's the bit I was missing.

I wonder how the necessary driveshaft length differs with the GS6-37BZ TJEE vs the 420G.

[heinzboehmer]

Looks like the Z4M used a different clutch and flywheel than the 330i, but I think the same trans. Thoughts on the Z4M parts?

Edit: Z4M used the same flywheel as M3. Am I wrong in thinking that the Z4M used the same 6mt as the later e46 non Ms?

No, Z4M used the GS6-37BZ TJEE, while late M54 E46s used the GS6-37BZ THEG. Mostly input shaft differences between the different S6-37 variations from what I understand. These threads have more info:
- https://www.e46fanatics.com/threads/...stion.1250761/
- https://www.zpost.com/forums/showthread.php?t=1842540

I've been telling myself for the last few years that if my 420G ever comes out, an S6-37/S6-53 is going back in. Likely the Z4M one as it seems to be pretty much entirely plug and play.

[m3_sancho]

Any idea what would be involved in installing a S6-37 into an M3? As in...

Would it need a different driveshaft length? If so, any chance you know what it is?

Shift-- what is different, exactly?

Cross member looks quite different, and has an addition bracket (2 on the diagram). What's the extra bracket do? Does the cross member install in the M3 without any changes?

I suspect a CF driveshaft is in my future, and I already want to change my shifter setup to a 0% reduction AS kit, AND my flywheel is still original at nearly 170,000 miles... so if I was ever going to do this... now might be the time (get it made to length for this swap and get shifter parts that are friendly to the swap).

I have the same questions regarding the non M 6-speed box. Currently SMG but planning for a conversion and have looked into ZF 5-speed and 6-speed options but was not able to find proper information what is really required. If someone could chime in and give valuable information, I'd be really happy.

Reason for the ZF is the much better feel compared to the Getrag and the ability to rebuild these gearboxes.