Questions on building an LSD for MkII IRS 1065 carrier

Hello all, I'm new to post on TB but I've been learning a lot from all the knowledgeable forum members.

I have a '97 V90 with some power upgrades and I'm looking to replace the ALD (Eaton Auto Locker G80) diff with a true LSD diff using my 1065 carrier (MkII IRS). The on/off nature of the ALD makes this car a riot to drive but isn't ideal for smooth traction and putting down power.

Yes I know this topic has been asked dozens of times (and yes I did my research first), but hear me out. I have tried to swap a Ford 8.8 IRS carrier into a V90 rear but the fabrication of the aluminum cradle is a bit over my head. So I'm back to the option of trying to convert my 1065 carrier to accept an LSD diff.

Bakaxel in Sweden has an Torsen-type LSD unit with 27 spline side gears to fit 1030/1031/1041 solid axle carriers, also claimed to fit IRS carriers 1045/1065. They also sell a custom 27 spline output shaft with a flanged end, which connects with MkI IRS axle shafts (normally 26 spline). I contacted their tech support and they seemed think this should work with the proper MkI axle parts.
Torsen LSD diff: http://bakaxel.se/torsendiff-dana-30-27-splines-volvo.html
Output shaft 27 spline conversion: http://bakaxel.se/hubb-gavel-27-splines-volvo-multilink.html
So with these parts I should THEORETICALLY be able to put a Torsen LSD diff into a MkII IRS 1065 carrier and have flanged MkI IRS style output that can be attached to MkI axle shafts. So far so good... right?

I need help with some of the details, mainly making MkI axle shafts work with MkII carrier.

1) MkI (1045) output flanges use adjusting nuts on diff housing, can these nuts be used on MkII (1065) diff housing?

2) Likely I won't be able to just bolt on MkI axle shafts onto the Bakaxle conversion flanges (it's never that easy) due to width differences between 1045 to 1065 diff housings. Maybe custom or modified MkI axles needed? Any insight on this?

3) Speedometer signal still possible using 1031 style differential? I'm sure Bakaxle sells a compatible tone ring but I don't have much faith in my Swedish translation skills.

Like I said I'm naive and motivated, so please steer me in the right direction... even if that advice is to just learn to love the ALD cuz there's no easy way out!
Thanks in advance!

My friend got BMW pumpkin under his 960 mk II. Can ask details if you are intrested.

Absolutely, I'd love to see your friend's 960 install. I'd imagine it would require a similar level of fab work as a ford 8.8 but maybe there are applications that are simpler than others. Thanks for the help!

you need to adapt 27 spline axles to fit the irs if you are gonna use a live axle rear.

Cool, that Truetrac from Summit is much cheaper than unit from Bakaxel (not to mention the shipping from Sweden!). As Ben noted, still need to convert the 27 spline output to the IRS axle flanges.

So far Bakaxel & Sellholm are the only sources I've found for those conversion 27 spline adapters:


And since this is a 1065 MkII housing, those adapter flanges would (I'm assuming here) need to be used with 1045 MKI style adjusting nuts, bearings, etc. That's the puzzle I'm trying to piece together.

vishmutzy said:

Cool, that Truetrac from Summit is much cheaper than unit from Bakaxel (not to mention the shipping from Sweden!). As Ben noted, still need to convert the 27 spline output to the IRS axle flanges.

So far Bakaxel & Sellholm are the only sources I've found for those conversion 27 spline adapters:

And since this is a 1065 MkII housing, those adapter flanges would (I'm assuming here) need to be used with 1045 MKI style adjusting nuts, bearings, etc. That's the puzzle I'm trying to piece together.

Click to expand...

this i used myself not long ago .. have some Pictures here?

http://www.smct.se/965/nya
http://www.smct.se/965/bakvagn

also loads of Pictures of retrofitting the irs to an old 965 that had live axle


what needs to be done

use original bearings crushsleeve and seals

next the bakaxel adapter and stock mk1 irs driveshafts then it's a bolt on setup

one minor thing needs to be done to the gears inside the differential

and that's to grind off the egde to allow removal of the adapters. otherwise the lockring will permanently lock the adapter inside

Thank you moon_walk, your post and the photos are very helpful. It's reassuring to see that it HAS been done! Some grinding and few tack welds to retrofit the 1065 housing sure beats weeks of measuring & fabrication to mount a completely different pumpkin!

I'd like to understand more about the modification to the diff side gears. I get that the lockring on the adapters' splines could get permanently clipped into the side gears, but can you explain exactly what needs to be done?
I'm sure I could figure it out with the parts in front of me... after getting the adapters jammed in first of course! Is it just a matter of smoothing the radius on the lockring groove so the adapters can be pulled out if needed?

Time to order some adapters from Bakaxel and a Trutrac from Summit!

Thank you sir, I am forever grateful!

That 960 MkII got 760 IRS halfhafts and carrier from E34 (type 210) BMW. adapter plate for drive shaft.