Diff Ratios Compatibility

M

Moffmo

Member
 Nottingham
Hi All,

I did a bit of research and read that you can change the diff on your Z4, I would have posted on existing threads but they were all quite old!

I would like to get a 3.73 differential. My question is... Can I only get these off the Z4 autos? or would a diff off a 3 series be interchangeable as well?

I have seen two diffs. One for a E30 325I SPORT 3.73 which has LSD, and E30 325I DIFF 3.73 without LSD.. Would these fit? The LSD one was from a E30 made in 1999.

Hope I haven't confused anybody!

Matt
 
Moffmo said:
Hi All,

I did a bit of research and read that you can change the diff on your Z4, I would have posted on existing threads but they were all quite old!

I would like to get a 3.73 differential. My question is... Can I only get these off the Z4 autos? or would a diff off a 3 series be interchangeable as well?

I have seen two diffs. One for a E30 325I SPORT 3.73 which has LSD, and E30 325I DIFF 3.73 without LSD.. Would these fit? The LSD one was from a E30 made in 1999.

Matt
Click to expand...

BMW stopped making E30s in the very early 1990s and very doubtful if any of those diffs would fit an E85/86. Diff swapping is more common in the US, so I suggest that you do a search to see what others have done successfully to your Z4 variant.

I bought a compatible diff from someone in the US which looked in remarkably good condition and went to all the trouble of fitting new seals before installing it to my Z3MC. Once fitted I discovered that the bloody thing had a whine, so I removed it and stayed with OEM. I wouldn't go down that route again.
 
I must have read the year wrong! - I too highly doubt they would fit.. lol.

I've tried a lot of googling, and alot just point to custom made diffs with LSD. I just want to know if a 3 series diff would fit for example or if I can only get it from the Z4 Auto!
 
Moffmo said:
I just want to know if a 3 series diff would fit for example or if I can only get it from the Z4 Auto!
Click to expand...

These people were recommended to me http://www.geartechltd.co.uk/ although when I decided to ditch the diff I didn't take my differential to them, so I've no experience of them. Give them a call and seek their advice. A crown wheel and pinion swap to your existing diff might be the best alternative.
 
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