Swap Your Differential

[fdagen]

It was my understanding that the z4m already had lsd. Can you upgrade the gearing, without upgrading the lsd? I am assuming from the early post yes?

[StickMon]

The ///M does have LSD, which I assumed is why it was >$2k.

[angelr]

Originally Posted by fdagen

It was my understanding that the z4m already had lsd. Can you upgrade the gearing, without upgrading the lsd? I am assuming from the early post yes?

Yes it has an lsd, and yes you can upgrade the ring and pinion to either a 3.91 or 4.10 ratio. Uses the same R&P as the e46 m3

[Sterling Roadster]

Originally Posted by angelr

Yes it has an lsd, and yes you can upgrade the ring and pinion to either a 3.91 or 4.10 ratio. Uses the same R&P as the e46 m3

Now that's interesting. Is it much more labor intensive than just swapping a new diff in, requiring more skill?

[Aaron Maguire]

Originally Posted by Sterling Roadster

Just wanted to ad to this subject. The diff swap is a must on these cars, especially if you have a 3.0 with the stock 3.07 gearing. I went to 3.46. It's not as significant as forced induction of course but the torque feels like it's always there with no low points whatsoever. I notice my DSC light coming on more often due to the extra torque.

The gears are closer together and it feels even more like a true sports car. However on the highway i'm still under 3,000 RPM so not a big trade off. If I had to sum up the difference i'd say it makes the car feel lighter overall. I was on the fence about this and now it's the first thing i'd recommend.

I spent $500 CDN for the whole job including all new seals and anything replaceable was replaced. DIY would be less than $300. What a DIFFerence it makes in the car. tehehe. Hopefully this helps.

I'm looking at getting the 3.46 (Part number ending 131) for my 3.0 Manual which has a blown diff 3.07 (Part number ending 129).
Can you confirm that they bolt straight in?
My supplier is reluctant to sell me one because the VIN doesn't match with the 3.46 (131) diff.
My mechanic and I have studied the images of both diffs and are sure they would fit but I'm struggling to find anyone who can 100% say that their bolt patterns are the same.
Cheers.

[Steeler]

Originally Posted by Aaron Maguire

I'm looking at getting the 3.46 (Part number ending 131) for my 3.0 Manual which has a blown diff 3.07 (Part number ending 129).
Can you confirm that they bolt straight in?
My supplier is reluctant to sell me one because the VIN doesn't match with the 3.46 (131) diff.
My mechanic and I have studied the images of both diffs and are sure they would fit but I'm struggling to find anyone who can 100% say that their bolt patterns are the same.
Cheers.

Hello Aaron,

I can confirm that the diffs from certain E46 will ffit your 3.0 manual.

I have not had a problem fitting 4 different diffs to my car.

I have used a 3.64 from an E46 a 3.73 from an SMG Z4 and for a very short time even a 3.91 and a 4.44 from E83 X3's circa 2006 ish.
Currently running an aftermarket 3.64 LSD.

Do your research on which E46 diffs fit, I physically looked at the diffs I was buying to ensure both the input and output shafts were the same.
To my knowledge the cases and mounting points are the same, save for possibly the ear on the diff cover which you can use your original part.

You say "supplier"....if you are buying new I would look into an LSD from an aftermarket supplier before plonking down money at the dealer/supplier.

Here is a list of ratios that might be of interest.

Also pics of your car would interest the group.

Good luck.

[WickedNy]

Have a 3.91 from an automatic z 2.5 in my 3.0si. Found a low mile front end total, and the junkyard almost refused to sell because it didn't list my vin as compatible…just because the computer doesn't list it as a fit, doesn't mean it won't