BMW Turbo Discussion  - BMW 745i and BMW Turbo Project Forums
User Name:
Password:
Save Password
Forgot your Password?
Home | Active Topics (0) | Members | Online Users | Statistics | File Library | Search | Avatar Legend
 All Forums
 The e23 745i and Turbocharged BMW Motor Topics
 BMW M106/M102/M30 Turbo Topics
 What are our diff option?
Next Page
 New Topic |  Reply to Topic |  Bookmark Topic |  Printer Friendly
Author Previous Topic Topic Next Topic
Page: of 5

cd745igo
Starting Member

Status: offline


16 Posts

Posted - Sep 30 2004 :  07:34:04  Show Profile  Visit cd745igo's Homepage  Reply with Quote
Hello all,

Wondering what diff everyone is running. My 293 is making noise and I would like to replace it. I did have a 391 out of an e28 m5 for awhile but the trnany didn't care for it much and my mileage went south.
I am alos wondering about putting a standard cased diff in from either another e23 or e28. Is it possible and what needs to be done to complete the transfer.

Rgrds,
David
84 745i Bismark

scottie
System Administrator

Status: offline


3845 Posts

Posted - Sep 30 2004 :  09:23:47   View scottie's Photo Gallery  Show Profile  Visit scottie's Homepage  Send scottie an AOL message  Reply with Quote
What did you do with the 3.9? I may have a 2.9 avail for you if you wish. Frankly, you can put any diff from any 80s BMW in there, but you probably want to stick with a big diff. They were avail in 2.9, 3.4, 3.9. If you go with a standard size diff, you have other options, but nothing outside of 2.9 to 3.9. I'm not 100% sure on these #. Somebody correct me if I'm wrong.

Scottie Sharpe
San Jose CA
Discussion Board SYSOP


88 Dinan M5
1968 2002


FOLLOW ME ON FACEBOOK
My Profile
Go To Top Of Page

cd745igo
Starting Member

Status: offline


16 Posts

Posted - Sep 30 2004 :  09:48:05  Show Profile  Visit cd745igo's Homepage  Reply with Quote
Sold the 3.9 to a 6 series guy. I would like something in 3.4 range but haven't found anything. I have a 3.07 from a 81 745i it just seems such a little advantage over the 2.9.
What else needs to change to use a standard diff?
Or, anyone have a 3.4 large case diff they would like to part with?

David
Go To Top Of Page

scottie
System Administrator

Status: offline


3845 Posts

Posted - Sep 30 2004 :  10:27:58   View scottie's Photo Gallery  Show Profile  Visit scottie's Homepage  Send scottie an AOL message  Reply with Quote
The 3.07 is very close to the 2.9. We just experimented with this on Don's car.

Scottie Sharpe
San Jose CA
Discussion Board SYSOP


88 Dinan M5
1968 2002


FOLLOW ME ON FACEBOOK
My Profile
Go To Top Of Page

Jon 86 745 MS
Over 745 Posts!

Status: offline


1423 Posts

Posted - Sep 30 2004 :  19:34:46  Show Profile  Reply with Quote
Big diff came in the following ratios:

2.93
3.07
3.25
3.46
3.64
3.91
4.11 ? Not super sure on this one. I however have been told that they exist. As for the smaller diff, I would not go there. First you would have to drill new mount holes in the subframe. The axels would have to be changed due to the different flange size/bolt pattern. Doubtfull that the smaller diff would hold the torque for a long period of time. Just does not make since to go smaller. There are lots of 2.93 around and 3.07's. These are fairly cheap.

Jon Jacobs
85 Korman 745i (AKA Das Borg) R.I.P.
86 745i (Die Rakete)(no mas :(
1.2 bar + Boost with
Team WWW.745i.com Performance Parts
Go To Top Of Page

dnliii
Over 745 Posts!

Status: offline

1405 Posts

Posted - Sep 30 2004 :  20:40:57  Show Profile  Reply with Quote
If you do a delta calculation of 2.93 to 3.07 you will get a figure of 4.78%. That is a pretty small change. Maybe better to go with a 3.25 diff- that is 10.92%. Most will say that 7% is a good target. Your choice- 5% or 11%....
Don
Go To Top Of Page

ARINUTS
Master Technician

Status: offline

236 Posts

Posted - Sep 30 2004 :  21:43:26   View ARINUTS's Photo Gallery  Show Profile  Reply with Quote
ALL Euro E28 with Big 6(M30) , E24 and E23 have big diffs. Find a Euro car and see what rear it has.
Go To Top Of Page

E23 Norway
Starting Member

Status: offline


32 Posts

Posted - Sep 30 2004 :  21:56:01  Show Profile  Reply with Quote
The "small" diffs that was used up to 732i will fit a 735/745i because the subframe is the same. The diff from a 81 mod or older however would'nt fit on a E23 with the new E28 type undercariage that came 09/81. There was also a change of the rear subframe and trailingarms 09/82, but I don't know how big the difference is between them.
Go To Top Of Page

cd745igo
Starting Member

Status: offline


16 Posts

Posted - Oct 01 2004 :  06:28:55  Show Profile  Visit cd745igo's Homepage  Reply with Quote
Well in that case does anyone have a 3.25 large case diff that would like to part with?

Jon, When are you coming out this way.

David
Go To Top Of Page

BIGANT
Gas-fueled God

Status: offline


341 Posts

Posted - Oct 01 2004 :  10:43:36  Show Profile  Send BIGANT an AOL message  Send BIGANT a Yahoo! Message  Reply with Quote
No one has mentioned the 3.73 diff? I have the LSD 3.73 in my E24. Im going to take it out and install it in my E23! Should make a difference. Same diff as the others right? Looks the same


Thanks,
Anthony '85 745i

'84 745i with 17" Racing Dynamics wheels
'88 735i with 18" M Parallel
Go To Top Of Page

Jon 86 745 MS
Over 745 Posts!

Status: offline


1423 Posts

Posted - Oct 01 2004 :  12:59:01  Show Profile  Reply with Quote
I have never seen a big diff in that ratio. Is it the large diff with 8 bolt axel flange?

Jon Jacobs
85 Korman 745i (AKA Das Borg) R.I.P.
86 745i (Die Rakete)(no mas :(
1.2 bar + Boost with
Team WWW.745i.com Performance Parts
Go To Top Of Page
Page: of 5 Previous Topic Topic Next Topic  
 New Topic |  Reply to Topic |  Bookmark Topic |  Printer Friendly
Next Page
Jump To:

Please consider donating to help keep BMW Turbos! online.
Donate now using the link below. Thank you for helping keep the M102/M106 discussion forum alive!

BMW Turbo Discussion - BMW 745i and BMW Turbo Project Forums © Scottie Sharpe Go To Top Of Page
BMW TURBOS! generated this page in 0.67 secs. Snitz Forums 2000