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.

Just looked this up and found Husker selling official reman rear axles for around $400. I didn't check the fronts. And the punchline inducing ebay Latvian dealer selling them for sub $300. Not sure if I have the courage to find out if he/she/it is real or if the axles are real or counterfeit.

Forgetting stuff again. Meant to add that I also put out some coin to purchase a new joint assembly (not just boots) from "Febest" as another alternative (they sell direct and through distributors).

I found the parts to be really sketchy - burrs and saw marks where the BMW parts were nicely machined, etc. Ended up pitching them into the scrap metal bin.

"Febest" is cheap chinese junk btw.

Update:
 

3.64 Ratio diffs are on their way! I found a set of O.E. front remaned axles through a chain store. They were remaned by Cardone. Beware!, there are alot of Chinese axles in the reman stock now. I inspected them as best I could without pulling the boots, bringing along the micrometer and calipers.
Everything felt nice and tight and splines looked good. Its a roll of the dice I know. We will see how the install goes.

Good luck Ryan I'm crossing my fingers yours are ok.

Where did you source the diffs?

That's funny! I read that same thread last week, just not all of it. I was hoping Cardone had stayed consistent with their quality control. I was really impressed by the company's response and call to action.

That makes the two of us buddy! I'm prepared for a nut shot, but hoping for the best. The axles were about $120 for the pair (before core charge of 35 an axle)with a lifetime warranty. I will keep my axles as a backup set.

I sourced a pair of diffs from an '03 4.4i out of southern California from flea-bay. 80k miles on the diffs (claimed to be in excellent condition)and a price reduction for buying the pair. All-in-all about 500 bones shipped with a warranty period. ----I think I have figured out why I have such a good time in Vegas. I say, "Roll the dam dice!"

The diffs I'm interested in impressions and how easy the install is as far as bolt on (apparently they should be). As you know I have one less cog so it could be hugely useful on a 5 speed.

Good call on keeping your OE axles. If anything down the line you can reboot them with OEM gkn boot kits like I did (20 bucks a kit per side!) or if you need new outer complete joints it's 150 per side from BMW. Not many people know you can buy just the outer joint from the dealer.

Did you ever meet up with Jim Conforti? Shoot me a pm if so I don't want to get your thread off track homeslice

Update:3.64 ratio diff swap a success!
 

Got everything installed on Friday and refreshed all the drive-line fluids with Redline MTL in the tranny, 75-90 in the diffs. X-drive fluid will be next, just need to get my dealer programming suite up and running first.:thumbup:

Just did a short 400 mile road trip to test everything out. I absolutely love the new ratios! Returned about 25 mpg at 80-85 mph the whole way without even breaking a sweat. (speed limits out here are 75 & 80 on I-15)

Anyone concerned about the 3.64 ratio's being lethargic/slow can put that idea to bed forever. I'm convinced that this should have been the ratio from factory. As the transmission ratios did not change, you still preserve the feel BMW intended, and suits the I-6 3.0 well. I honestly don't think towing performance is an issue at all either. My 0-60 is noticeably quicker as the X5 has more leg under her and requires at least *one less gear change.* I was not expecting this. My wife noticed as well. Time for ECU to get sharked with a 7k rev-limit extension to stay in that gear a wee bit longer!

I'm preparing pics and and slight modifications write up I had to do, as it was not an exact swap with the LCI. Nothing crazy.

All-in-all, I highly recommend this mod for the three pedal guys, especially those with the 5 cogs. I will post some videos as well.;)

Wow Ryan I'm amazed at just the mileage improvements!

Wonder if the diffs are more plug and play on the pre facelift 5 speeds? Looking forward to your write up, looks like a Shark tune and diffs may be in the cards down the line.

This is very interesting. Are these LSD too or no?

No they are stock diffs. You can add an LSD to them, search a thread by "sedc" as he did so.