318ti diff flange distance narrower than small case e30?

[captain awesome]

So I snatched up a 318ti 4.44 lsd and it appears to be about an inch narrower overall than the 318is small case I have. Does anyone know if the shafts have enough stretch to pull the 1/2" per side safely or do I need to swap flanges? I was hoping to bolt the thing in and be ready for an autocross meet this Sunday, but I'm not sure that's possible now. I could have sworn these were a direct swap, but I can't seem to find the thread where it was mentioned.

Quoted from the home page 318is article:

Rear end gear - The 318iS is equipped with a 4.10 limited slip from the factory, but you can do better. The desired gears out there are the 4.27 and the 4.45. You will find the 4.27 in E30 318i convertible 5 speed’s and the 4.45 is in E36 318i automatics. The 4.45 is a wicked, wicked street gear but will stick your RPM way up there on the highway. The 4.27 is a good compromise of performance and everyday use. It should be known that to make a 4.45 work, you have to swap the gearset into your E30’s differential, or find an automatic 318ti, which has a 4.45 and also has trailing arm rear suspension! So the E36 318ti 4.45 bolts right onto an E30, though finding an automatic 318ti with LSD may be difficult.

318ti diff width 10 1/8"

Untitled by hatchethairy, on Flickr

318is diff width 11 1/8"

Untitled by hatchethairy, on Flickr

318ti flange width 7/8"

Untitled by hatchethairy, on Flickr

318is flange width 1 3/8"

Untitled by hatchethairy, on Flickr

[captain awesome]

Looks like I just need to swap flanges. Apparently it's easily done even without a puller.

[TobyB]

Yeah, just tug. It can take an impact to 'pop' them out. Dead blow or copper face hammer,
copper drift. Or slide hammer on the face.

Sometimes, you have to tip the thing so the hole is facing straight up
and center the clip inside to get the flanges to go back in, tho,
so do the swap on the bench before you drop it in.

easy, yah.

t

[captain awesome]

I found this video shortly after posting this and gave it a shot. Just a 7/8" wrench with an abrupt bump did the trick. Super quick and easy. Sliding them back in was equally simple. Love the grip with the LSD compared to the open and the jump from 4.10 to 4.44 doesn't seem as dramatic as I expected. We'll see how noticeable it all is at autocross tomorrow. Unfortunately now my speedometer isn't working and at this point I think it's obviously something to do with the speed sensor plug.

https://www.youtube.com/watch?v=8FymJmCbtEk

[loki_]

I literally came here to post this exact same question. Thanks x100!


If you’re installing a small case diff from an e36, you only have to swap the cover and the output flanges? Do you have to do anything with the input flange and where it connects to the driveshaft?

[captain awesome]

I don't think standard small case e36 is a direct bolt in. I think the cases had to be swapped?

The e36 318ti utilizes e30 mounting for the case as well as some of the z cars if I understand it correctly. The internals will swap, but the standard e36 cases mount differently to the subframe.

Does yours have mounting holes on the top of the case like mine above?

[loki_]

From everything I’ve read, the 318ti diff should be the same as the small case e30 carrier.

http://www.318ti.org/notebook/diff_conversion/index.html

That outlines swapping an e30 small case into a 318ti. If you can do it one way, you should be able to do it the opposite.

[captain awesome]

Right. Not all smallcase e36 cases are the same though. The 318ti has the same mounting holes on the case as an e30. A standard 318i or is will not have the same case, but the internals are the same.

Is your case from a TI? If so you are fine, if not it will require more work.

[loki_]

My situation was e36 318ti small case diff going into e30 rear subframe. I just wanted to confirm I only needed to swap the cover and output flanges. Thanks :)

[captain awesome]

You are good to go then. Sorry I think I read e36 and wanted to make sure you had a TI case.

What ratio did you get?

[loki_]

I think said just e36 and not 318ti, my mistake. I was looking for a 4.45 ring and pinion to swap into a 3.73 medium case I had laying around but that’s next to impossible but the 318ti ones are much more common. Not a crazy amount of power, just looking to use what I have more effectively.