Upgrades: differentials and limited slips!

[sedc]

Had a '03 3.0i 5 speed manual for about a year now.

The gearing is awful from the factory!

4.10, waaay too short for comfortable highway cruising and 1st is mostly useless!

So what to do?

Time to swap in better ratios and add a limited slip!

What gearing to use? 3.64 is ideal and available from the factory in 4.4i cars! You could go to 3.46, we did this on an '01 5 speed, but it's a little too tall! You also have to custom build the differentials because there is no factory option for 3.46 X5 medium case!

Why add a limited slip? Because I avoid DSC, much better to have a seamless mechanical torque transfer when there's wheel slip, one that doesn't involve having the engine cut out involuntarily!!!

IN this case, we decided to just add a LS unit to the front differential, because, as we discovered with the '01, having front and rear lockers can cause massive understeer!


Process:

- Sourcing parts: I started working on this 10 months ago, bought a 3.64 rear and a 3.64 front from wrecked early E53 4.4i vehicles. I also bought a small case late limited slip (in this instance a 3.46 from a '93 318) for the front differential.

- I didn't do anything with the rear diff, just verified good bearings and installed new output seals, then installed it. Easy.

- Front diff I shipped to Jim Blanton. He built/machined the small LS to fit the front case!

- Got it back 4 months ago and went to install it, here's the old diff and the 3.64 LS:




- I've discovered that you don't have to drop the subframe to remove the front diff on a 3.0i! TIS is wrong. It can be squeezed in and out past the subframe!

- Once in, the front axles kept popping out. On the highway in the middle of the night. Very inconvenient!!

- also in this pic you can see the spacers I've added to the front drive shaft to help give it better contact with the transfer case splines. highly recommend doing this kind of upgrade on ANY E53 X5 to help preserve the transfer case!!



- The source of the problem was that we machined the front axles to accept circlips fitted in the differential, as is the convention for the early style LS unit. However, it does not produce enough tension to hold the axles in place!

- Long story short, had to pull the front diff 5-10 times and machine various parts to work the way it would have been done from the factory (and as was done on that first one we did), where the clip is on the axle itself!

End result:

The X5 is finally back on the road. There is a small gas mileage improvement! But the real benefits....The 3.64 gearing makes highway cruising much more pleasant! First gear is much more usable! I haven't been able to put a verdict on the LS front because it hasn't snowed yet!

All in all, worth it!


Some more pics from the job: