Author Topic: e36 M3 LSD into e36 318 (Read 6334 times)

szed03 · « **on:** May 26, 2008, 11:00:14 PM »

I'd like to know what's involved in the swap.

I know I'm going to have to swap output flanges or halfshafts.

Can anyone confirm that the driveshaft needs to be swapped to the M3? Is the driveshaft swap a hard job to tackle?

Thanks a lot guys!

szed03 · « **Reply #1 on:** May 28, 2008, 01:50:50 PM »

No one?

Master · « **Reply #2 on:** May 28, 2008, 02:59:02 PM »

You only need drive shaft, the diff itself, and output shafts and you're done!
Gonna do a similar conversion myself soon...

szed03 · « **Reply #3 on:** May 28, 2008, 08:59:02 PM »

Ahh so I do need a driveshaft. Rats!

I think you can actually just swap the output flanges as opposed to switching out the entire halfshafts. It's easier...just a matter of prying the old flanges off and replacing with the M3. They should have the same teeth count.

With saying that, the 6cyl halfshafts are beefier however.

christophbmw · « **Reply #4 on:** May 28, 2008, 10:21:38 PM »

what ratio is the E36 M3 LSD if you dont mind me asking?

sumyungguy · « **Reply #5 on:** May 28, 2008, 10:26:52 PM »

So for an e36 318is, to put a LSD from a 6cyl car you need to change the driveshaft and half shafts? Its not just a simple diff swap like the e30? Doesnt make much sense to have separate driveshaft and half shafts for the low production 318's, seems like they would have just changed the diff like the e30.

tjts1 · « **Reply #6 on:** May 29, 2008, 01:47:03 AM »

Look up the part number on realoem

nicknikolovski · « **Reply #7 on:** May 29, 2008, 04:05:42 AM »

Part no's are different.

E36 318is - 26111227463-BOE (driveshaft)
E36 318is - 33-21-1-227-606-M60 (output shafts)
E36 M3 - 26112227222-BOE (driveshaft)
E36 M3 - 33-21-2-228-156-BOE (output shafts)

szed03 · « **Reply #8 on:** May 30, 2008, 03:00:01 AM »

Quote from: christophbmw;50219

what ratio is the E36 M3 LSD if you dont mind me asking?

It's a 3.91 from an automatic M3.

Quote from: sumyungguy;50221

So for an e36 318is, to put a LSD from a 6cyl car you need to change the driveshaft and half shafts? Its not just a simple diff swap like the e30? Doesnt make much sense to have separate driveshaft and half shafts for the low production 318's, seems like they would have just changed the diff like the e30.

Nope...different transmissions and case sizes.

168mm "small" case diff for the 318 and 188mm "large" case diff for the 6cyls. Also the 318 and 325 both used the Getrag transmission where as the 328 and m3s used the ZF, requiring shorter drive shafts for the latter two. Also the small case diff being narrower, the 318 halfshafts are slightly longer than the 6cyl.

I did some research and what I'll need is a 325 manual driveshaft, 6cyl non-M output flanges and halfshafts.

My next question now is...will M3 halfshafts fit my hub? I wonder if the splines on the hub end are the same...I'll report back with what I find.

sumyungguy · « **Reply #9 on:** May 30, 2008, 04:02:40 AM »

Yeah I found the same info.. But some e36 318is came with LSD, so that would be the easiest but hard to find.

szed03 · « **Reply #10 on:** May 30, 2008, 12:06:57 PM »

Quote from: sumyungguy;50291

Yeah I found the same info.. But some e36 318is came with LSD, so that would be the easiest but hard to find.

Yea but I'm looking to swap in a 3.91 lsd.

Edit: Oh yea and M3 halfshafts won't fit...the diameter of the splined end seems to be bigger as it uses an M27 nut as opposed to the 4cyl/6cyl non-M halfshafts which use M24

tjts1 · « **Reply #11 on:** May 30, 2008, 12:30:13 PM »

Quote from: szed03;50313

Yea but I'm looking to swap in a 3.91 lsd.

You might want to reconsider that decision. The engine will be doing 3000rpm at 57mph in 5th and 4000rpm at 76mph. If you raise your rev limiter to 7000rpm, your shift points with 3.91 diff will be:
1st -> 2nd = 26mph
2nd -> 3rd = 53mph
With stock rev limit the shift points will be even earlier. On SoCal freeways you'll be the guy in the slow lane trying to keep your ears from bleeding.
E36 318is gear ratios:
1st 4.23
2nd 2.52
3rd 1.66
4th 1.22
5th 1
Plug them in and try it.
http://www.et-studios.com/motorsports/gears/gears.html
For a street driven car you want the 2-3 shift to happen just after 60mph. Shifting to 3rd kills acceleration like nothing else.

szed03 · « **Reply #12 on:** May 30, 2008, 11:24:56 PM »

Quote from: tjts1;50315

You might want to reconsider that decision. The engine will be doing 3000rpm at 57mph in 5th and 4000rpm at 76mph. If you raise your rev limiter to 7000rpm, your shift points with 3.91 diff will be:
1st -> 2nd = 26mph
2nd -> 3rd = 53mph
With stock rev limit the shift points will be even earlier. On SoCal freeways you'll be the guy in the slow lane trying to keep your ears from bleeding.
E36 318is gear ratios:
1st 4.23
2nd 2.52
3rd 1.66
4th 1.22
5th 1
Plug them in and try it.
http://www.et-studios.com/motorsports/gears/gears.html
For a street driven car you want the 2-3 shift to happen just after 60mph. Shifting to 3rd kills acceleration like nothing else.

Thanks for the heads up but I've already plugged in the numbers and analyzed the shift points. I do have a Turner Motorsport chip so the rev limit is at 6900. I want better acceleration out of 2nd gear corners on an autox course and this is the best option at the moment.

If I had the money, I would've gone with a 3.73 built diff but I just don't have the cash right now.

Besides, I'm pretty hardcore about things such as noise, vibration, harshness ect...The M42 is a pleasure at 4k+ RPMs and the sound level isn't all that loud to me. I can careless about what my passengers think. :p