4.10 gears

[jpiazzam3]

Probably a stupid question but are the 4.10 gears strictly aftermarket or do they come out of another Bmw. I’m looking into doing the conversion but I’m having trouble justifying 1000$ for a gear set

[see.m3.go]

I believe the 4.10 is a motorsport only gear ratio. The e34 m5 before 6/94 had a 3.91 diff though

[jpiazzam3]

I’m seeing they were in the old e30/e28s. I’m just curious if they are interchangeable

[see.m3.go]

I’m seeing they were in the old e30/e28s. I’m just curious if they are interchangeable

They have a different size diff (medium case - 188mm). Our cars have the large case diff (210mm), so any ring and pinion you find would have to be 210mm to work in our diffs. Like the 3.91 from the e34 m5 is a 210mm

[DoubleSidedTape]

There's also 3.85 from the manual e9x M3, and I believe 3.91 from the X5 4.6 and 4.8 is.

[Cubieman]

I've got 4.10s on my car and kinda wish it was a 3.91, 4.10 is almost too much for what I do with the car.

[Feffman]

I've got 4.10s on my car and kinda wish it was a 3.91, 4.10 is almost too much for what I do with the car.

I exchanged 4.10 for 3.91 because 1st gear was virtually unusable on the race car. On longer straights, Roads America & Atlanta, I'd run out of 5th gear with 4.10.

Feff

[Cubieman]

I exchanged 4.10 for 3.91 because 1st gear was virtually unusable on the race car. On longer straights, Roads America & Atlanta, I'd run out of 5th gear with 4.10.

Feff

I can only imagine that on a track. Hell, I'm out of first gear in a parking lot most of the time, unless I want to cruise around at 5K!

[M3KVU]

Absolutely love my 4.1 diff , car should have came from the factory like it.

[Cubieman]

Absolutely love my 4.1 diff , car should have came from the factory like it.

She does pull!

[mrgizmo04]

Here are some notes I assembled when I was looking for shorter gearing. I currently run 4.10.

http://oppositelock.kinja.com/the-cheap-er-e46-m3-final-drive-upgrade-1503641554

Below list needs to be double checked for accuracy, pulled from various threads/sources.
3.91 from e32/e34 m5
e28 535, m5 has 210mm
e31 850csi has 210mm
E32/E34/E31/E28M5/E24M6/M635CSI(3.73LSD)210mm
e24 m6 has 3.9
e34 535 3.64
525i A 92-95 M50 4.1
Type 210 cars:
E46 M3 and E36 4door M3
E34 M5 and 540i
E32 740i and 750i
All E38 models
E39 V8 models, could be all models but not sure

[M3AZ]

I'm running a 3.91 from an E28 M5. Just needed reducing sleeves for the ring gear bolt holes to go from M14 to M12.

[J. Beez]

Looking into running either 4.10 or 3.91... my first E46M had a Dinan 3.91 and even that was a decent upgrade from the stock 3.62. Car is mostly for weekend track use, but even so I'm somewhat skeptical about the useability of the 4.10 on certain tracks and on the freeway...

[donutroidz]

4.10 is a BMW motorsport option, but I don't remember it coming on any car.
I personally have the 4.10 And it's pretty short. I like it, but damn cruising anything over 80 is crazy.
It's like driving a Honda gear ratio. First gear is useless. If you're just doing it for a sports car purpose and not short track racing, 3.9 is a nice little upgrade.
I personally would do a 3.9 if I could do it all over.

[oceansize]

I'm in the middle of a complete rear end bushing and ball joint refresh plus 3.91 diff install and I'm excited for the slight bump. I was going to go 4.1 and then I got into a car that had 4.1 and while I didn't mind it I realized pretty quick I needed to keep at 3.91. There was nothing wrong with 4.1 and I can certainly see the appeal some people have for it but I think I would get tired of it. Who knows, I may get tired of 3.91 gearing.