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

[Bry5on]

That is weird. Realoem lists the e46 "zhp" manual gs6-37 driveshaft at 1444mm, while the M3 is 1404mm. I'm assuming the bellhousing mounting location is in the exact same spot between the two - where is the 20mm?

I looked for a gs6-37 transmission for my "daughter's" 330i, but they were either more than I'd want to spend or had a million miles. I ended up sourcing a 420g M3 6spd and will be using an M3 driveshaft, m3 clutch kit, and an non-m 3.48 diff from an automatic 330i.

Unfortunately that setup won’t work! You’ll need to use the 330i driveshaft (and potentially guibo) because as George said above, the diff input flange is in a different axial location on the non-m vs the bigger diff in the M

[liam821]

Unfortunately that setup won’t work! You’ll need to use the 330i driveshaft (and potentially guibo) because as George said above, the diff input flange is in a different axial location on the non-m vs the bigger diff in the M

The M3 diff is longer, making that distance shorter.

OOHH! Well shooooooot. I didn't know those two were in a different location. Thanks!

[George Hill]

IIRC the M3 guibo is thicker than a Non-M so I would plan on using the M3 guibo as well.

[bigjae46]

IIRC the M3 guibo is thicker than a Non-M so I would plan on using the M3 guibo as well.

.3" thicker to be exact.

[Tomba]

I'm in the same boat. Have an S50B32 fitted in my E30 with the Getrag S6S 420G. 4th gear synchro is out with fast shifting.


N52/N53 gearbox?
Was thinking to put a N52/N53 gearbox behind it but you need a different flywheel for it as noted.
They sell them here,

https://pmcmotorsport-shop.com/eng_m_Swap-Solutions-Adapter-Kits-Clutch-Kits_Full-Adapter-Kits_BMW-M50-S50-M52-S52-M54-S54_ZF-6-speed-manual-Adapter-Kits-3984.html

It looks like the N5x gearbox needs slight machining to make the upper 2 bolts fit.

Still rated from €600 - 1300,-

N47/N57 gearbox?
Availability a lot, and cheap. But doubt the gearing would suit the S5X engines


M5x 6 speed
GS637BZ from M54 are getting more and more expensive here, €1750,- minimum and without service history. Don't think its worth the gamble for that amount of money. Quite a shame BMW doesn't deliver parts for these gearboxes.

Refurb?
Do some of you know companies that refurbish the S6S-420G? Europe would be my preferred location as I suspect high shipping costs. A RMFD one from the dealer costs €4600,-.
Seems ALLGEARS in the UK does them.

8HP / DKG
Another option would be to go automatic, but I like the "old school" manual, and I think its character matches better for the car.

[George Hill]

Was thinking to put a N52/N53 gearbox behind it but you need a different flywheel for it as noted.

N5x generations bolt the starter to the block and of course our S54s bolt the starter to the transmission. When you put an N5x transmission on an S54 there is no location for the starter. There are a couple ways to solve this issue but no matter which way your go here the N5x generation transmissions require much more work/customization to bolt into an E46.

It looks like the N5x gearbox needs slight machining to make the upper 2 bolts fit.

The upper (2) bolt holes for the N5x transmissions are just slightly offset from the M/S5x engines. With a dremel/die grinder you can easily slot the holes and make it work. The lower (2) bolt holes are doweled and do the locating so these upper are just to hold everything tight.

N47/N57 gearbox?

IRC Diesel transmission are tilted at a different angle than gas transmissions. It can be adjusted with adapters but seems less than ideal and as you noted the gearing is generally less than ideal for gas RPM bands as well.

Do some of you know companies that refurbish the S6S-420G?

The 420G is NLA from BMW (I checked last week).

In the US, Diffsonline used to rebuild them but no longer offers that service. Metric Mechanic still advertises it but I have no experience (first or secondhand) with this service.

Another option would be to go automatic

There is still no good option for running the 8HP with an MSS54 DME.

[ac427]

I've not considered transmission swaps. However, when i bought my E46 M3 i couldn't believe how bad the first to second change was, how crashy the ride was and how poor the brakes were.

Not really knowing anything about them but had always wanted one. I decided to get AP brakes, Bilstein PSS10 suspension but what to do with the gearchange.

Luckily, i knew a Mastertech and i had BMW Warranty. He agreed it was as it should be and i got a new gearbox under warranty.

It was better but not great. I then got an Auto Solutions SSK with 30% shift throw which made a massive difference. Thank you Mad Russian.

A change in the gearbox to Redline 70

The shift is great. I have tried lots of other options in the 150k miles since i bought the car, including Rogue SSK and UUC DSSR shift rod but it's the oil and the shifter that will get you 90% of the way there. Well unless your transmission is knackered.

Redline Synthetic Manual Transmission MT-LV 70W/75W is the best i have tried and i have tried them all more or less.

Slightly off topic but i thought it might help a bit.