Diff for 6 speed and m20 stroker

[adam.nonis]

I made a spreadsheet calculator that may be helpful. I was trying to figure out diff ratios for my N52 swap. Seems like I can't upload it here directly. If you're interested, DM me your email address. You can input tire size and rear ratio, change RPM and it'll output MPH and RPM after shift for G260, GS6-17BG and GS6-37BZ

[digger]

digger There has been many hinderances and distractions over the past years I've just brought the car and all the parts to where I live 10 months ago, to be fair washed it for the first time since 2016.

I've decided to start with 3.07 as well because if I build a fresh LSD it can be switched to higher ratios later and with the other offset casing I can only go 3.15 and lower.

Almost got the shifter/linkage sorted out.

i have a spare diff it was originally a 3.91, so 3.07 is the lowest that fits in the housing?

digger Got another option for a driveshaft ready e36 rear half + e46 front half: http://bmwfans.info/parts-catalog/26117518375/.
Got some stainless cut, bent and welded to start with the gearbox mount according to this (yet to confirm the fittment): https://hobby.farit.ru/custom-bracke...on-in-bmw-e30/
Right before Christmas got this from Australia: https://racehead.com.au/product/bmw-...e-molly-steel/
Need to measure things out, I'd love to fit clutch/pressure plate/release bearing from the Valeo kit I got in 2017. When this is confirmed and I find some spare time I'll rip the old gearbox out (need to change the rear main seal carrier as well).

thanks i also saw this FW in my research which starter should be used?

when you mix and match halves of the driveshaft i presume it need to be rebalanced?

[raudonis]

i have a spare diff it was originally a 3.91, so 3.07 is the lowest that fits in the housing?

I assume the diff housings are the same, but it has to be checked.
Satellite housings are definitely different both open diffs and LSD for ratios of 3.07 and less, because they increased the pinion gear diameter and had to offset the ring gear more.

thanks i also saw this FW in my research which starter should be used?

Not confirmed by assembly, but by cross-referencing gearbox, flywheel, etc. partnumbers and starter specs I found this starter to be the lightest smallest bolt on option, I have it ready in my pile of parts:

http://bmwfans.info/parts-catalog/12412354693/

https://www.elstock.com/en/product-search/?pid=26-3376

when you mix and match halves of the driveshaft i presume it need to be rebalanced?

Yes, driveshafts are balanced as a whole, so when putting halves from different driveshafts together, the new hybrid assembly has to be balanced.

[digger]

I assume the diff housings are the same, but it has to be checked.
Satellite housings are definitely different both open diffs and LSD for ratios of 3.07 and less, because they increased the pinion gear diameter and had to offset the ring gear more.


Not confirmed by assembly, but by cross-referencing gearbox, flywheel, etc. partnumbers and starter specs I found this starter to be the lightest smallest bolt on option, I have it ready in my pile of parts:

http://bmwfans.info/parts-catalog/12412354693/

https://www.elstock.com/en/product-search/?pid=26-3376

Yes, driveshafts are balanced as a whole, so when putting halves from different driveshafts together, the new hybrid assembly has to be balanced.

oh, so the limit is 3.15 with my original 3.91 unit? and its the lsd unit that differs not the housing?

[raudonis]

oh, so the limit is 3.15 with my original 3.91 unit? and its the lsd unit that differs not the housing?

I'm aware only of the satelite housing difference. ⩽3.07 housing can be used with ⩾3.15 ratio with an offset spacer for the ring gear, but not all diff builders will endorse such spacer.

[digger]

I'm aware only of the satelite housing difference. ⩽3.07 housing can be used with ⩾3.15 ratio with an offset spacer for the ring gear, but not all diff builders will endorse such spacer.

ok i presume the guts inside the satellite housing are the same so i should be able to use my spare

[bmw444]

How did you end up going with getting the gs6-37bz gearbox attached to your M20?
I have thought of using a gs6-17bg instead as it's a fair bit smaller and lighter sand should still be able to handle a decent amount of torque. I'm not concerned with the angle problem as that's just the same problem people used to get with a zf320...

[digger]

I have heard that it is possible to swap the gearsets from a gs6-37BZ into a gs6-37DZ.

Is it possible to only change one (1) or more gears rather than the entie contents? for example i would want the longer 1st from the BZ to put into the DZ.

Has one seen a writeup of this, even if in part ? Has one seen a good parts list?

[hasa]

I believe the front bellhousing could be swapped from DZ to BZ if one wants the correct angle. But I can't confirm this.

[TobyB]

I have heard that it is possible to swap the gearsets from a gs6-37BZ into a gs6-37DZ.

Is it possible to only change one (1) or more gears rather than the entie contents? for example i would want the longer 1st from the BZ to put into the DZ.

Has one seen a writeup of this, even if in part ? Has one seen a good parts list?

Seems highly unlikely, as the countergear usually has 1st- 4th all ground onto the same blank.
I mean, cutting and welding not withstanding, of course. Sometimes the overdrive ratio will swap-
and sometimes, depending on the input to countergear ratio, it comes out kinda useful...

I've found that the Aisin J160 was offered with some downright fantastic (for racing) ratios for the Toyota IS200 in Europe-
they're dirt cheap over there, if you can smuggle one back in your carryon...
anyone wanna go in on a pallet of them on a tramp freighter?

t