E46 M3 6-speed swap guide

[joon]

I just completed swapping an E46M3 6-speed transmission into my car. The car is a Euro RHD 320i sedan with an OBD-1 S52, my buddy has a 4DR Euro S50B30 3.0 M3 and we did the swap together. I couldn't find any definitive information online so I'll post everything here. The cheapest source for these transmissions is in the UK, I saw a deal for 2 and purchased them immediately for my buddy and I. I also had a very worn Euro E36 M3 6-speed which I was hesistant to install due to the high mileage. In contrast most E46 M3 6-speeders are relatively low mileage and are starting to get plentiful.

Some other informative threads:

http://www.uucmotorwerks.com/98M3/up...6SPD/index.htm

http://forums.bimmerforums.com/forum....php?t=1213732

http://forums.bimmerforums.com/forum...d.php?t=918288

Transmission
The S6S 420G from the E46M3 is IDENTICAL in exterior dimensions to the S6S 420G from the Euro E36M3 EVO 3.2. The transmission itself weighs about 100lbs dry and takes 1.9L of transmission fluid (about 2 quarts). By most estimates the 6-speed is about 10-12lbs heavier than my ZF 5-speed. There are subtle differences between the two 6-speeders (the E46 one has provision for a gear indicator I believe) but they are largely similar, except that the E46M3 version has a bigger input shaft.

Crossmember
To bolt this onto an E36, you'll need the E36 M3 EVO crossmember P/N 23702227892

Shifter
Based on the advice from the E46 folks, I used the shifter from the Euro 330d, it gives a much shorter throw. Together with UUC's delrin carrier bushings, this is a very economical and extremely effective combination.

Driveshaft
The E36 M3 EVO CV-jointed 6-bolt driveshaft bolts RIGHT ON if you have a 6-bolt flanged differential. The length is an exact fit. This particular driveshaft has no slip joint, no sliding section in the middle, to separate it you remove the M8 bolt in the middle and pull it apart (to replace the support bearing)

UUC's writeup says "E36 M3 Evolution driveshaft can be used, but is not exactly the right length... the sliding section accomodates the difference, but technically the Zionsville Autosport driveshaft is a better choice and is comparably priced."

This is technically incorrect. The EVO driveshaft is a direct fit with a 6-bolt flanged differential. It has no sliding section in the middle, the CV joint accomodates some movement in the long axis of the car. If you're using the 4-bolt flanged differential, you can't use the EVO driveshaft anyway.

If you're indeed using the 4-bolt flanged differential, you can use the USDM Automatic M3 driveshaft. The 4-bolt driveshafts have a splined sliding section in the middle, you release the big hex nut to adjust the length. The auto driveshaft needs to slide out about 20-21mm to make up the difference, around 0.7-0.8".

To summarise
Option A: Use a 6-bolt flanged differential + EVO driveshaft = DIRECT FIT
Option B: Use a 4-bolt flanged differential + USDM Auto M3 driveshaft = slide out center section by 0.7-0.8"

Flywheel / Clutch
You can use the entire E46 M3 clutch kit including the E46 M3 dual-mass flywheel.. any E46 M3 LTW flywheel + clutch combo will fit

As a side note, my pals in the UK are only changing the clutch disc, they're using back their E36 M3 dual-mass flywheel + E36 M3 pressure plate and just swapping out the E36 clutch disc (they call it drive plate in the UK) for the E46 M3 one. Together with the E46 M3 throwout bearing, this appears to work pretty well with many of them clocking regular track days and tens of thousands of DD miles.. If you use their method, all you need is the E46 M3 clutch disc. I have not tested this as I'm using a complete E46 M3 flywheel + clutch.

Slave cylinder and other parts
Everything else bolts right in.. I used back my E36 M3 slave cylinder (22mm). This results in a very light clutch pedal pressure.. those who like firmer pedals can swap to the smaller 325i slave

Borrowed some pictures from my UK counterparts.. The first 2 are UK pictures, the rest are mine..

Please feel free to add your own experiences to this thread

[NeilM]

Nice info Peter.

Neil
96 M3, E36 M3 Evo 6-spd

[joon]

I forgot to add, I used the ball pin from the E31 850i V12.. this replaces the white plastic one that always breaks

P/N 21 51 1 223 281

[GT110]

Damn,, already bought and replaced with a new plastic one.

[PCarroll]

Having done this I would also add a couple of points...

It's not E36/E46 6-speed. It's actually early/late 6-speed. Some of the early E46 M3s came with the small spline input shaft. I think the changeover was some time in 2002. The small spline transmission takes an identical clutch to the E36 5-speed. I swapped between early or late transmissions and only had to use the corresponding clutch plates to match the shaft. The rest is the same.

Beware the 325 clutch slave cylinder. We tried that and I had problems with the pin falling out of the arm - leaving you stranded with no clutch. You have to weld an extension to make the pin longer. In the end, I prefer it with just the E36M3/E46M3 slave. I recall they are identical. I did use a pressure plate with a higher clamping force. So this might have changed the swing a bit for me.

Also worth noting that you cam easily convert an SMG 6-speed to a manual if you have a dead donor manual 6-speed. After removing the hydraulics, the only differences are the spring centered shifter and the reverse sensor for the backup lights. Easy solution for the spring is to swap the bell housing from a dead 6-speed. No need to machine anything. Dead 6-speeds are a dime a dozen. You also need to swap the reverse switch from the dead manual. It's just pressed in and the SMG has a plug. I did not try this as a race car doesn't need reverse lights... I found SMGs are a cheap source of otherwise well looked after transmissions. The computer is kinder usually to the synchros than human.

Worth noting that the same bell housing swap should work to convert a E39 540 6-speed to a compatible manual. Never tried but those transmissions are easy to find and cheap too. E39s will have a lot more small spline input shafts due to the earlier years.

Peter

[MotionMotorsport]

Excellent, valuable tips, Peter. I have often been curious about the SMG/6MT swap points, and very good point on the syncros.

[joon]

Great info on the SMG's, I might pick up one as a spare

Anything particular to look out for when swapping bell housings?

[iceman2007]

Hello Peter,
i know this maybe a long shot since we are 10 yes forward but could you let me know if I could use e46 2003-2006 gs6 37bz 6 speed transmission in replacing 92 325is getrag 250g?