e36 lsd internals fit into e21 case

[joey79]

I took my diff for a drive today. Put 35 hard miles on it. It ran very quiet and smooth. E36 3.46 188mm build next.

[Beemer Tech]

makes perfect sense. Thanks for the info. At only .1mm increments, I wouldn't think the difference in static lockup would be that significant from 1.9mm to 2.1mm. I wonder what the stock disc thickness was (like anyone could get an accurate measurement at this point)?

I've heard actually adding a clutch disc requires machine work on the e21 diff. I'll know more once I actually get around to tearing mine apart.

yeah the amount of pre load it would add would depend entirely on the spring rate of the cupped washers, the total stack hight and clearance in the carrier. ill get the factory clearances and set up process for our age diffs out of one of my friends at BMW next time i get a chance, we could probably work the stock thicknesses from that.

your right, there would be some required machining to make extra clutches fit. where im not sure yet is where this metal will be removed from to make the extra room, but im guessing it wont be to hard to figure out once i have it in my hand.

[Twelvizm]

Bump for some "down the road" feedback. And a shameless plug for the 2 diff cases I have laying around for sale. $50 plus shipping, with pinion.

[jrcook320]

A diff case probably isn't worth the cost of shipping. A complete open diff in good condition might be worth a few bucks, but not $50.

[jjgbmw323]

I took my diff for a drive today. Put 35 hard miles on it. It ran very quiet and smooth. E36 3.46 188mm build next.

I would be interested in this, as I am wanting to upgrade the diff to handle the 400 hp, m20 2.9 turbo engine build that i will do someday...

[joey79]

Some feedback: I have about 200 miles on the diff so far. Everything seems fine so far. No leaks, sounds, nothing. I'm confident it's going to last. I probably won't be driving it much more until after I do my timing belt.

The e36 diff I'm building is replacing th 3.15 open diff in my e36. I'm not attempting an upgrade to a 188mm diff in the e21 (yet). I would like to hear from anyone who is though. Someday I'd like to have a euro s50 under the hood.

[Abysalone]

Bump an older thread, I need some info.

I have an "early" e21 diff and my output flanges do not have grooves for the snap rings in the e36 LSD diff. Was this only on later model diff's? I also noticed the side covers in your pics have 6 bolts. My e21 and e36 case only have four. Im just a little unclear on what parts from what were used for the swap. I have a 76' 320 open e21 diff and a 95' 318i diff from an e36.

[joey79]

I used the pinion, LSD spool and ring gear from the e36 diff. The case, side covers and output flanges were from a later e21 diff. I wasn't aware of the early e21 output flanges not having the snap ring groove.

[bflan2001]

you shouldn't need the snap ring grooves anyway, it's not like the flanges are going anywhere once the diff is installed.

[Abysalone]

I used the pinion, LSD spool and ring gear from the e36 diff. The case, side covers and output flanges were from a later e21 diff. I wasn't aware of the early e21 output flanges not having the snap ring groove.

no problem man. Just trying to add info to a great thread.

I just re-freshed my diff for now and ill get a donor for the swap.

Bflan, I figured the same, but I would rather do it right.

[german2002]

friends,


I have a BMW E21 318i, right now I am improving engine performance.


I'm going to install a gearbox 5-speed ECO 245.


Now, I have the possibility of placing a core of 168mm E36.


Consultation, as are the relationships?


It is necessary to modify the differential relations to a 3:64?


A great deal of modification?


Thank you very much!

[mcjjordan]

so whats needed is a diff from a 4 cylinder E36
-which models have LSD?
what about E30s?
i think the 318is and 325is have LSD can anyone confirm?

[jjgbmw323]

It was my understanding the large case diffs of the e30 188 mm are different from the smaller case 168 mm diffs, that can be made to work in the case of the e21...

[amarino]

2 years after OP and about 1 year ago, someone at Ireland Engineering had the same idea and did a detailed writeup.

http://www.bmw2002faq.com/articles.h...tial-build-r74

[bflan2001]

The 168mm internals can be found on all 4-cylinder 3-series cars including all E21s, E30 318i and 318is, and the E36 318i and 318ti.

[SkiFree]

The 168mm internals can be found on all 4-cylinder 3-series cars including all E21s, E30 318i and 318is, and the E36 318i and 318ti.

As mentioned in the article linked above.

amarino, for the record at the point I wrote that article Rob (PG) and Rob (Rids) had been doing them this way for nearly a decade.

[Cjp2003]

Bump....

Can you just switch the carriers and keep the e21 ring and pinion?

It's 50 for a carrier and 130 for a rear end at my pick and pull.

[jaredmac11]

Man this is crazy I've never seen this before. I'm curious if folks are still doing this? It looks like, from the pics, the e36 differential has a speedo output. This would provide a lower gear ratio and cover the gap for the speedo output for my E30 m42 swap.

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[idarling]

Earlier in the thread it mentions the speedo wheel doesn't fit and is cut off.

[jaredmac11]

Bumping back up for a question.

So the automatic final gear is a 4.44 ratio. I don't dislike the 3.91 I have currently but I really feel like the gears are just too long for the m42. The e30 is a 4.10 and there really isn't anything that suits that except the auto 4.44.

Maybe it would turn it in to a bit too much of a race car but I drove around the 3.64 before the 3.91 and the shorter gear was noticeable but not drastic. Maybe the 4.44 would be the same. Improved and not drastic. I do think highway cruising would be nearly out of the question but I really like this car for city driving and keep it out of the highways anyways

Long story short. Has anyone tried the open diff in the e21? Would it fit just the same?

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[pofo]

Bumping back up for a question.

So the automatic final gear is a 4.44 ratio. I don't dislike the 3.91 I have currently but I really feel like the gears are just too long for the m42. The e30 is a 4.10 and there really isn't anything that suits that except the auto 4.44.

Maybe it would turn it in to a bit too much of a race car but I drove around the 3.64 before the 3.91 and the shorter gear was noticeable but not drastic. Maybe the 4.44 would be the same. Improved and not drastic. I do think highway cruising would be nearly out of the question but I really like this car for city driving and keep it out of the highways anyways

Long story short. Has anyone tried the open diff in the e21? Would it fit just the same?

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I'm running the 3.91 and have been looking into a better diff as I'm surprised it's lasted this long with the S52 swap. But I think you need an 3.91 LSD case to fit the e36 internals into, I dont think they fit in the auto diffs. I could be wrong I'm sure someone here might correct me.

[jaredmac11]

So to clarify I'm looking at the e36 318i auto diff. I believe it's still a small case diff but I need to confirm. It is a 4.44 ratio which to me is more ideal than 3.91.

Also I had assumed a 3.64 open diff case would work. Does it have to be 3.91 lsd? I know the output flanges are different but I never compared the cases. I assumed it was the same case across the board. I'm less included to rip the guts out of an LSD...

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