e21 differential

[giorgio2g]

Hello, i am a new member here and this is my first post. I own a '81 315 and i am looking to swap the gearbox from 4speed that it is now to 5speed. I have already found a getrag245 gearbox at a good condition and in a fair price. However i have a question. Do i also have to change the differential or not? Sorry if the question is kind of silly, but i am still learning about the technical stuff of my car.

[petroscf]

No you don't have if the studs mate does the gearbox have the propelershaft as well? is it 3 or 4 stud? if both diff and prop shaft have the same number you are ok

[giorgio2g]

Thanks for the quick response! Both my current gearbox and the one i am about to buy, are 3 stud. I have one more question, the seller has told me that the gearbox is from an m10 engine, is there a way to make sure whether it's indeed from an m10 engine or an m20?

[joe14]

The getrag 240 from my m10 has some stamps or serial numbers that started with 240.xxxxx
I think there's a thread in the FAQ's or top techs about identifying gearboxs

[giorgio2g]

Thanks mate. I found the thread you mentioned and what i understood reading it, is that i am looking for a gearbox that has NO m60 sign on it, that has a mechanical speedo and of course the extension of the 5th gear.

[Jeroen]

Sounds good then!

[petroscf]

Oh, and WELCOME here!!!!
(forgot to...)

[petroscf]

I guess that what differs between M10 and M20 gearboxes is just the bell housing? Which means that a swap can fairly easily be done (by someone who knows how to do it of course)

[E21noob]

If you find the markings "T" or "BO" on it, its a M10 sport.

If you find the markings "GH", "ME" og "GL" on it, its a M10 overdrive.

Like this:



Check out my write up:
http://www.bmwe21.net/forum/viewtopic.php?f=38&t=13418

245 M10 five speed Sport:
245/2.00 T (part number 23001205711)
245/10.00 BO (part number 23001207146)

Recognised by:
- three piece case
- Mechanical speedo output
- Shift pattern: 1st down left, 5th bottom right, reverse same
- Markings should include "245" (follow by more numbers), six unidentified numbers, and the letters "T", or "BO".
- 87mm longer than the 4 speed (requires shorter drive shaft part number 2611120860)
- Four or three bolt output flange 23211208536 or 23211209612
- 120mm between the two top bolts of the bellhousing, as opposed to 140mm for M20 boxes.
- the two top bolts of the bellhousing are M8 (as opposed to M12 on M20 transmissions)
- reverse light switch up top

245 M10 5 speed Overdrive:
245/4.30-GH (part number 23001209775)
245/5.30 ME (part number 23001220421)
245/4.13-GL (part number 23001209891)

Recognised by:
- three piece case
- Mechanical speedo output
- Shift pattern: as 4 speed, 5th top right
- Markings should include "245" (follow by more numbers), six unidentified numbers, and the letters "GH", "GL", or "ME".
- 87mm longer than the 4 speed (requires shorter drive shaft part number 26111208608 (same as sport))
- Four or three bolt output flange 23211208536 or 23211209612
- 120mm between the two top bolts of the bellhousing, as opposed to 140mm for M20 boxes.
- the two top bolts of the bellhousing are M8 (as opposed to M12 on M20 transmissions)
- reverse light switch up top

[E21noob]

Yes welcome

Remember, you will also need the parts for the gear shifting linkage and the matching propshaft (or have yours shortened) to make it all fit.

[giorgio2g]

Thanks a lot everyone for the awesome informations you have provided me. I am very happy to be part of this community and be able to share my passion about my car with other e21 lovers!

[giorgio2g]

[That's the gearbox i am about to buy.
http://imgur.com/a/NZBIt

[petroscf]

Giorgo I think the link does not work

[giorgio2g]

How about now?

Giorgo I think the link does not work

[petroscf]