Narrow IRS LSD?

I'm trying to figure out how to put LSD into a BMW 2002 without breaking the bank. I can get common LSDs at the local you pull it for $80 and even better on half off days or all you can carry. I measure the BMW diff at 9 inch or so flange to flange. I checked the R200 and 8.8 I have but they're both too wide. Anyone know of something narrower than 9 inches?  Power won't be more than 300hp in a turbo 4 so not a torque monster. I'm not we worried about input driveshaft issues as we're going to need a custom driveshaft anyway. 

I can measure my mk3 Supra 8" LSD when I get home, but it's narrower than the Ford 7.5" it's replacing, so those might be worth a look.

Stampie said:

I'm trying to figure out how to put LSD into a BMW 2002 without breaking the bank. I can get common LSDs at the local you pull it for $80 and even better on half off days or all you can carry. I measure the BMW diff at 9 inch or so flange to flange. I checked the R200 and 8.8 I have but they're both too wide. Anyone know of something narrower than 9 inches?  Power won't be more than 300hp in a turbo 4 so not a torque monster. I'm not we worried about input driveshaft issues as we're going to need a custom driveshaft anyway. 

I have nothing technically usefull to add.  But the fact you're working on this car (or at least planning to) makes me giggle.

You might check out the RX8 LSD rear end as there should be multitudes of "low compression" rotaries in the boneyard with this setup.

none of the commonly available BMW diffs fit, even the "small" cases?

subaru rear diff's are pretty narrow but dont use the flange ends like it seems you are looking for.

Miata?

I don't know the width (could take a tape to it if it's useful), but just to clarify, the E21 LSD that's a near drop-in (have to change inner CVs to match, and actually IIRC add spacers between flanges and CVs) is a no-go? That is, this isn't just putting an LSD in a 2002, this is a narrow LSD needed for an unusual application that just happens to have a 2002 wrapped around it?

In reply to ¯\_(ツ)_/¯ :

Thanks.

In reply to Indy-Guy:

I like making you giggle.

In reply to 84FSP:

Those are actually hard to find in my two yards.

In reply to mad_machine:

There's some special combo involving putting E30 LSD pumpkin in an E21 open case with the E10 rear cover. Just about impossible to find in local yards.

In reply to edizzle89:

R180?  That looks like it should work. Any special models to look for the LSD?  

In reply to Dusterbd13 :

On the list just need to measure width.

In reply to Ransom:

It's a 2002 but for Challenge it's cheaper to build a bracket for another diff than going all BMW. 

Miata is the answer?

Miata with 2nd gen RX7 output hubs if you need flanges. I have one on the ground at home and will measure it tonight.

edizzle89 said:

subaru rear diff's are pretty narrow but dont use the flange ends like it seems you are looking for.

you can get flanges from the Datsun folks. Not sure the R160 would take that much power though.

Stampie said:

In reply to edizzle89:

R180?  That looks like it should work. Any special models to look for the LSD?  

no idea lol i just knew the subaru diff's were pretty narrow, im sure you can look toward STI stuff to find a LSD option

A subaru R180 is beefier, still not super strong, but pretty rare.  I believe some nissans used it as well.  Mine came from a JDM STi with an LSD.  I think the USDM STi have it with LSD, you may be able to find one of those, but it will likely be $$$$.

You may look at the Nissan version they put into the G37 and 370Z. You can get those with the VLSD and it's basicallly an R200 so a lot of head room on there for HP growth. They are all over for about $300 if you can't find one at the u-pull it.  I can get some measurements if you absolutely need them. 

Definitely look at old Datsun diffs. My z was r180, barrow like the subie pic above and flanged for axles. 

http://forums.hybridz.org/topic/50499-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount-faq/

In reply to bmw88rider :

That's actually the R200 I measured. It's about 13 inches flange to flange vs ~9 inches for the BMW diff. I'm wanting narrow so that I can just adapt the flanges without custom half shafts. 

Weld the stock diff?  Doesn't get cheaper than that.

MK3 Supra diff is approximately 10.25" flange to flange, sorry!

I don't feel like jacking up my wrx in the cold rain, but it's an r160 lsd.  Long nose even.  They're pretty narrow.  

nocones said:

Miata with 2nd gen RX7 output hubs if you need flanges. I have one on the ground at home and will measure it tonight.

Or Miata two-piece halfshafts, as seen from 1994-95 IIRC.

In reply to pimpm3 :

That's what it has now. It's the back up plan if I can't figure this out. 

​​​​​In reply to Patrick:

About to text you. 

In reply to ¯\_(ツ)_/¯ :

Thanks, that's close.  Aren't they a variant of the R180?