bmwe21.net forums

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.

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

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?

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

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.

Sounds good then!

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

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)

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

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.

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!

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

Giorgo I think the link does not work

How about now?

petroscf wrote:Giorgo I think the link does not work