upgrading differential on 318is

[nobrakese36]

hello, what would need to be done to upgrade the differential on a 318is, to a differential from a 325, would i need to change the subframe/carrier in the rear, thanks

[auto3251]

I see no point in changing to to a 325diff unless yours just died.

[tomt30273]

I think all E36 diffs interchange (but I could be wrong). Check this website: www.diffsonline.com (http://www.diffsonline.com). They should be able to answer any questions you have.

[kalimot]

has anyone done this? not necessarily from a 325 but upgrading a 318's differential to something like a 3.91, 'cause i'd love to improve my M42's accelaration a little more. thanks

[318is4life]

if not from a 325 what were u going to swap from? a M or somenthing like a 328?

[kalimot]

yes. or is there an aftermarket we can use?

[auto3251]

318 and 6cly e36 differential's aren't interchangable (not directly anyways). you have to change out axies, rear subframe and a few extra things. Not worth it, you're better off just buying a aftermarket.

[m3ltw98]

318 and 6cly e36 differential's aren't interchangable (not directly anyways). you have to change out axies, rear subframe and a few extra things. Not worth it, you're better off just buying a aftermarket.

I believe you have to swap out the subframe, axles etc. if you have a 318Ti. He has a 318is which has rear suspension like the 325, 328 and M3.

[auto3251]

I believe you have to swap out the subframe, axles etc. if you have a 318Ti. He has a 318is which has rear suspension like the 325, 328 and M3.
no I think that applies to the 318 as well, the suspension is the same, but the differential housing and flanges are different. I'm pretty sure you have to change out the axies, but I'm not sure about the subframe.

[m3ltw98]

Yes, the subframes are the same according to the ETK but the diff casings and even the diff cover have different part #s like you mentioned. I guess if you switched to 325axles,flanges etc.. you could swap one in. By that point, you'd be better off getting a M3 diff w/ LSD

[auto3251]

Yes, the subframes are the same according to the ETK but the diff casings and even the diff cover have different part #s like you mentioned. I guess if you switched to 325axles,flanges etc.. you could swap one in. By that point, you'd be better off getting a M3 diff w/ LSD
yeah, pretty much the only thing that's the same with the 318 diff and 6cly diff is the mounting point to the subframe, everything else is different.

[nuvola rossa]

So if I want upgrade my 318is diff to a ///M3 or 6 cyl LSD I need to swap "only" the axis? And the drive shaft, must be changed?

[Alpine 318is]

from what i remember 4 cyl and 6 cyl diffs are not interchanglable. if you want to upgrade you diff get a 3.45 lsd for diffsonline.com

[Jeffrie]

So if I want upgrade my 318is diff to a ///M3 or 6 cyl LSD I need to swap "only" the axis? And the drive shaft, must be changed?

You wouldn't have to change either.
Out put flanges from the bigger diff can be swapped with the output flanges off the smaller diff (which lets you use the 318 axles).
Both use the 4 bolt drivshaft so that part is a simple bolt on.
Some M3's & 328 use the 6 bolt drive shaft which would mean you would have to change the input flange from the 4-6 bolt.
Rear subframe has to be changed between the two different size casings to bolt up.
I have installed a smaller lsd in my 318.
Cheapest way to go to upgrade your 318 diff is take your current diff, tear it apart and replace the gear set with one out of a small diff e30 from a wreakers. Buy new shims from BMW, use slicone the diff seal, and you'll be good to go.