The complete automotive resource for buyers, sellers, and owners like you.
Car, Truck and SUV Forums at Roadfly
+ Bentley Forums
+ BMW Forums
+ Cadillac Forums
+ Chevrolet Forums
+ Ferrari Forums
+ Jaguar Forums
+ Lamborghini Forums
+ Lotus Forums
+ Mercedes-Benz Forums
+ Maserati Forums
+ MINI Forums
+ Porsche Forums
+ General Discussion
+ Marketplace Forums
You cannot compare 528 & 540 Diff's (archive)
[ Follow Ups ] [ 5-series (E39) Message Board ] [ Msg. Board FAQ ]
Posted by Larry on June 26, 2000 at 13:39:44:

In Reply to: Pardon my ignorance.. Can this be done to a 528ia? posted by Abdoul Wane on June 26, 2000 at 01:21:59:

: : As I mentioned a couple of weeks ago, I bit the bullet and ordered the 3.15 differential. This weekend I put her up on stands and began the project. I quickly came to the realization that I am nowhere near as young as I used to be. I won't torture you with the difficulty I had getting the the old 2.81 out (unless someone would like to learn from my experience - It WILL help); Suffice it to say, it was tough.

: : After discovering the secret to removal and achieving victory in droping the old unit, I had the new 3.15 installed in a matter of minutes. Moments later, still with a large grin upon my face, I attempted to re-install the half-shafts to the new diff. and abruptly wiped away my thrill of victory - THEY DON'T FIT. Needless to say, I was quite disappointed.

: : Finally, to my request: Has anyone out there put a 3.15 into a 540iA non-sport? If so, how did you overcome this obstacle? I vaguely remember a post with someone mentioning swapping the hubs on the diff. I think this would be a big project, as it would clearly require at least a partial, if not complete, disassembly of the diff.

: : It appears that I will have to buy new half-shafts with CV joints. I could really use some help with some recommendations from someone who has encountered and dealt with this issue. I will call Pacific BMW tomorrow and have them compare the part #'s of all of the related components for the Sport and the non-sport.

: : JIMMY, I know you had a 3.15 added to your non-sport, do you know what they did about this?

: : I am embarassed to say that I should have known better. The increase in gearing will create greater stress, through the increase of actual torque, and therefore require a stronger shaft. I should have asked. I guess it is possible that two types of hubs are available on that diff and I got the wrong one. I sure am hoping!!

: : Thanks in advance for your assistance.


The gearing used in the 528 four speed and the 540 five speed are very different and assume a given, in this case different, ratio at the rear-end.

Remember, for each gear, the actual ratio between the engine flywheel and the tires is based upon a combination of the transmission (different for each "gear") AND the differential. They are engineered to work in conjunction with one another. You can see this by examining the transmission gear ratios on your brochure.

Good luck.

Follow Ups:


[ Follow Ups ] [ 5-series (E39) Message Board ] [ Msg. Board FAQ ]
Questions, comments, or problems, please visit the Roadfly help desk.
Roadfly.com Logo © 1997 - 2009 Jump Internet Inc. All rights reserved.