Operation differential swap is a go!
 

Well, my front diff decided to eat itself this weekend. Not quite catastrophic, but close enough. Hit a small bump on an overpass, blew both R&L inner cv boots off from the rings, and made a hellish grinding noise. Tried to creep the car forward but felt quite a bit of resistance from front end. Flat bedded to my shop. What ever is bouncing around inside the diff is dislodged at the moment and I now have a 3 wheel drive. I have no drive to the driver-left side axle. I haven't looked at the fluid yet, but I'm sure its gonna look like metallic grape nuts. Transfer-case and drive shaft splines seem to be fine.

Sooo... I here's my opportunity to swap out my 4.10s in favor of a set of 3.64 ratio diffs. A rear LSD is in the works.

Time for the axles to go as well. My question being, what recommendations do you have on CV axle replacement? OE or aftermarket,and what are your experiences? I don't have a ton of coin to drop on the project as school starts next week. Thanks for your help and suggestions.

Your acceleration will suffer probably quite substantially with the taller diff ratios. And the transmission ratios are intended for use with the shorter diffs.

If you can live with those consequences, all good.

I would still be trying to identify how a "small bump" can "blow" inner CV boots. Sounds to me like there is something unusual going on there.

Ryan, I don't recommend aftermarket axles.

I recommend oem or if you want a bulletproof solution check out www.raxles.com, used them on my VW's back in the day and they are ridiculously well engineered. Think UUC but for axles. Built on OE cores, all new joints that are USA made, new grease high quality boots etc. Should be about 250 per side if my memory serves me right.

Give Marty at Raxles a call you won't be disappointed!

Anthony, The 3.64 ratios will be just fine for a manual tranny. Like everything, there are compromises involved, but as luck would have it, I am not the first to do this. Also, My wife's X3 runs these with similar trans ratios.
http://www.xoutpost.com/bmw-sav-foru...ted-slips.html

Yeah, defiantly odd about the boots, but an internal shock load between the ring gear and spider gears connecting the front trans-axles due to a broken piece lodging itself is my suspect culprit. Wasn't enough to blow the case apart. Just my theory, but a postmortem autopsy will be performed to confirm.


Jay, Thanks for the heads up on Raxles! Checking them out now.

I tried the cheap import axles and returned them - splines wouldn't fit and the joints were rattling new out of the box.

Turner Motorsports sells the real OEM axles (GKN Loebro) for $280 for the fronts (at least for my 2001 4.4i). Seemed like the best value (price for non-junk) around.

I could not find any alternative to the factory axles (ignoring the cheap imports) for the rear and ended up simply rebooting my rears axles.

David, Thanks for the input and heads up on turner's set. I was tempted to try the import route, but I ordered in a set of remans to check out as well. If my axles are rebuild-able, I can have them rebuilt for 169 a side locally. The Turner Motorsports are tempting and much more reasonable.

BTW, Raxles does not do BMW axles.

FWIW, ask what they mean by rebuilding - if it is just cleaning, regreasing and rebooting, it is a pretty easy DIY. Certainly no harder than getting the axle out if you are willing to do that. Replace the e-torx-head bolts on the differential while you are doing all this, too.

There are several YouTube videos that show the process - nothing particularly hard. I had always avoided it, but didn't feel like laying out 2x$550 for new dealer rear axles when the boots went south, so BMW sort of forced my hand and it turned out to be pretty easy. But only for those not ashamed to be covered elbow-deep in CV grease...

It's been a year, so I guess it worked. For the heck of it, I used Redline's synthetic CV grease - very gooey, high-melting stuff.

Sorry about the Raxles boys, I emailed them over a year ago and they said they had X5 axles for 250 per side, maybe stock levels changed and they don't sell them anymore bc they weren't a big seller. Not sure.