which 6 speed transmission fits an m20?

[lukeADE335i]

The e46 320d gearbox is an option too - the angle is similar to the M20.

[The Dark Side of Will]

I've heard the diesel gearboxes have the same angle as the M20 and will install "straight up". There are quite a few of those in Europe and if you can find a seller willing to ship, reasonably easy to find on www.ebay.de. I recently bought an E46 2.35 ratio 188mm diff from Lithuania and it was surprisingly painless.

i'm going to assume this isn't going to work for an iX or will it?

The GS6x37BZ/DZ can work with a T-case, just not the original T-case.

This is a GS6-53DZ, but you get the idea:

Hope so. :D

More bolt-on stuff here. E9x 335i Gs6-53bz and e70 x5 (6 cylinder) atc700 transfer case (compared to e30 ix stuff):

[mr2peak]

Diesel gearing sucks.

The g420 from the e46 m3 has almost the exact same ratios as the coveted 265/5 dogleg. Seriously. 265/5 with a 4.10 vs g420 with a 3.25 is off by 1 mph in 2nd, 2mph in 3rd, and 4 mph in 4th, and the trend continues simarly.

I want a g420 on my M20.

E36 M3 auto driveshaft, what else is required? Can an e46 clutch be used with an m20 flywheel? Pressure plate will probably need to be e46, I know a 260 pressure plate is too small for a 240mm disc.

Clutch slave?
Throughout bearing?
Trans mount isn't difficult.

Someone must have done this, but I can't find the info.

[Wanganstyle]

Diesel gearing sucks.

The g420 from the e46 m3 has almost the exact same ratios as the coveted 265/5 dogleg. Seriously. 265/5 with a 4.10 vs g420 with a 3.25 is off by 1 mph in 2nd, 2mph in 3rd, and 4 mph in 4th, and the trend continues simarly.

I want a g420 on my M20.

E36 M3 auto driveshaft, what else is required? Can an e46 clutch be used with an m20 flywheel? Pressure plate will probably need to be e46, I know a 260 pressure plate is too small for a 240mm disc.

Clutch slave?
Throughout bearing?
Trans mount isn't difficult.
Someone must have done this, but I can't find the info.

data is all on this forum; keep looking.

there are a few 320d box m20 e30's running around the bay area. Owners are happy; both had budget to buy any other box but choose to go 320d due to angle.

tilted wrong is tilted wrong; if you want to tilt wrong then use the 5 speedZF sg320 and a 3.15-3.46 final - its cheapest and newest and best performance as 6th is not needed for lap time in norcal tracks; even with a 3.91 final

[Wanganstyle]

The E46 M3, E46 330 or the Z4 trans would be the better option since the Euro 6-spd is more costly .

When I was looking around for prices last summer I saw them as low as $1500 which is very doable .


YOu would need a custom shortened driveshaft and the trans would be rotated 10degrees off .
You'd have to compensate that with a bent shift linkage .

Other than that it seems pretty straightforward .

Euro 320D 6mt costs LESS honestly; at least the ones I've had my hands on.
no rotation
driveshaft bolt on affair and avail in usa.

[mr2peak]

Made a mistake comparing ratios, the ZF 6 and g420 have the same ratios as the close ratio 260, not the (262 265/5 dogleg).

This is not a track car, and it's not boosted. It's a nice higher compression m20 stroker. The 320d ratios are wide: fine if you have a turbo to stay in boost, terrible if you need to stay on cam.

The 6th is a nicety for keeping revs down. I like taking road trips in this car, and it's currently quite loud on the highway.

[Wanganstyle]

Made a mistake comparing ratios, the ZF 6 and g420 have the same ratios as the close ratio 260, not the (262 265/5 dogleg).

This is not a track car, and it's not boosted. It's a nice higher compression m20 stroker. The 320d ratios are wide: fine if you have a turbo to stay in boost, terrible if you need to stay on cam.

The 6th is a nicety for keeping revs down. I like taking road trips in this car, and it's currently quite loud on the highway.

ZF6 petrol is 1:1 5th gear
ZF6 diesel is 1:1 5th
g420 is 1:1 5th
ZF5 is 1:1 5th

G260 is 1:1 4th
G265 is 1:1 4th

the gear spacing is alot wider as referenced by the OEM final drives equipped

zf5 for s52b32 or m52b28 is 3.23 - 2.93
zf6 petrol for m54b30 is 2.93 or 3.07
zf6 petrol for s54b32 is 3.62
G420 for s54b32 is 3.62
zf6 diesel for euro 320d is 2.65 or 2.35 range


the spacing on the older g265 and 260 is wider 1-4; thus the need for a shorter final drive - 4 speed + 1 overdrive vs 5 speed ZF5 (with no overdrive) or 6 speed zf which is a 5 speed ZF + overdrive.


1-5 are supposed to be close; 6th is for long hauls.

[mr2peak]

The 320d has a 5.14 1st gear, while the 420G has a 4.22 1st. That's a big difference, quite a rev drop between gears. A step in the opposite direction of a performance N/A gearbox

[Wanganstyle]

The 320d has a 5.14 1st gear, while the 420G has a 4.22 1st. That's a big difference, quite a rev drop between gears. A step in the opposite direction of a performance N/A gearbox

its a diesel gearbox; its also 1/2 the price of a petrol box. - pick an appropriate final drive to make your 1st gear useful - OR NOT; just use 2/3/4/5 and 6 overdrive




if you want to pick your gears;

Samsonas makes a 6 speed setup you can install into the housing of a ZF 5 speed;

https://store.vacmotorsports.com/samsonas-dogbox-kit-bmw-m3-e36e46-6spd-p2992.aspx

[mr2peak]

A cheaper (non-UUC) conversion kit for the ZF6 or 420g to sit with an M20 would be great. Good ratios for an N/A engine and gearboxes are newer and easily available.

I don't have $8k for a custom transmission for a street car..

[Wanganstyle]

A cheaper (non-UUC) conversion kit for the ZF6 or 420g to sit with an M20 would be great. Good ratios for an N/A engine and gearboxes are newer and easily available.

I don't have $8k for a custom transmission for a street car..

sadly there is no such thing from the factory that fits the tilt and gearing setup perfectly;

otherwise I would have NOT gone through the effort to gamble on a radom oil burner 4 banger turbo gearbox from europe years ago when I had both G420 and ZF6 from e46 330 in front of my face


if you have the skills to do it and insane amount of free time; the internals from a e46 330i zf6 will fit in side the housing of the e46 euro 320D gearbox so you could swap all the bits over and have your ideal item.

the petrol ZF5 speed is rather ideal IMO; even with a 1:1 5th no overdrive and a 3,91 my 36m still gets about 20mpg commuting to and from the track; unless you do really long hauls then the 6th is not really that needed.

[mr2peak]

I wish I had the skills to swap transmission cases, but sadly u don't. I also don't see buying 2 gearboxes and the work to combine them coming any cheaper than the UUC kit, seeing as you would still need a clutch kit. It definitely is an interesting idea, and a challenging project.

ZF5 certainly is cheaper and easier, with a nice change is ratios. Same lean issues, but I honestly think that's a non-issue. Plenty of M5x cars with 240 and 260 boxes running around just fine. A trans crossmember is an easy thing to fabricate.

[Wanganstyle]

I wish I had the skills to swap transmission cases, but sadly u don't. I also don't see buying 2 gearboxes and the work to combine them coming any cheaper than the UUC kit, seeing as you would still need a clutch kit. It definitely is an interesting idea, and a challenging project.



ZF5 certainly is cheaper and easier, with a nice change is ratios. Same lean issues, but I honestly think that's a non-issue. Plenty of M5x cars with 240 and 260 boxes running around just fine. A trans crossmember is an easy thing to fabricate.

One Pm to either tiny t or gunmetal grey should solve the x member

I run the original zf5 speed in my 36m global time attack car. It runs 1+ second faster than my well prepared s2000 on similar courses so something has gone correct.

[Delanoso]

Did you end up putting a 6-speed on your M20? I keep seeing "I hear that . . . " but I don't see threads on any forum where anyone seems to have actually done it. Feel free to point me in the right direction if I'm missing anything.

According to Real OEM, the e46 320d did have 6-speed manual which is a 4.35 1st gear. The Getrag 260 is 3.83, correct? I'm considering options here because I like the diff swap I did for lower gears but wish I had an extra gear for the highway. If I've done the math correctly, swapping back to my original diff and using the ZF GS6-37DZ would put me almost exactly there.

320d Gear Ratios for reference:
https://en.wikipedia.org/wiki/ZF_S6-37_transmission

My big question is, how do I know that a transmission mated to an e46 engine will bolt up to my M20? Working out the flywheel/clutch/TOB/drive shaft/support etc. is do able if dumb things like bolt patterns work. Is there someplace I can see engineering drawings? OEM doesn't seem to have that kind of information. And with all due respect, answers like "because that's how it works" don't give me much confidence.