Educate me on Differential Options

[ClayW]

What differentials can be swapped into E3s?

My current 3.65:1 open side loader is leaking from the input shaft, so I’m pulling it anyway. Are there other options from other BMWs? How does the side loader dimensionally compare to medium case diffs from E30s, etc?

 

[HB Chris]

Common diffs for m30 coupes and bavs are 3.25 on euro CSi, 3.45 on early e3 and coupe, 3.64 on all US coupes and later bavs. Sideloaders were used on early e24 and e12 and could have had 3.07, 3.25 or 3.45.

 

[Mike Goble]

I swapped out the entire rear axle in my E3 assembly for an E28 unit. It's much easier to get LSD center sections for these.

 

[m5bb]

That's one of the few things my car does not have. LS diff.
Just pushing it aside hopping one will show up in the mail.......... NOT!

 

[Markos]

Common diffs for m30 coupes and bavs are 3.25 on euro CSi, 3.45 on early e3 and coupe, 3.64 on all US coupes and later bavs. Sideloaders were used on early e24 and e12 and could have had 3.07, 3.25 or 3.45.

Hi Chris,

Do you know which e24's and e12's offered the 3.25? I didn't know they were offered outside of the CSI/CSL.

 

[HB Chris]

Mark, I was Googling info and it popped up. Early series only.

 

[Peter Coomaraswamy]

I have a couple open diffs if anyone wants one- cost's about 100 bucks to ship- maybe a little less- diff is free

 

[Mike Goble]

A new seal is about $15...

 

[Markos]

Mark, I was Googling info and it popped up. Early series only.

Sigh... I had my hopes up! The e23 came in the 3.25 flavor. I was hoping that early e23’s used sideloaders but unfortunately they do not.

 

[ClayW]

A new seal is about $15...

I have the seals and crush ring, but I’ve yet to rebuild a diff on my own. Have you done a sideloader?

 

[Mike Goble]

I've built a lot of rear ends, mostly 9" Fords and Chevy's. If you return the nut to its original position you shouldn't need a new crush ring.

 

[Markos]

Don't forget about the 3.91 sideloader. Not from an e9 but it fits.