RX-8 LSD in a '91 B2600i 4x4 rear axle
 

Not really rotary related yet, but I've got a '91 B2600i 4x4 that I am prepping for a rotary swap next year. I did the swap a few weeks before christmas and its still driving great. I don't plan to do much offroading so I'm not worried about those characteristics, but it should be great for a street truck with no weight in the rear.


I'd heard that FC Rx7 owners have used Rx-8 LSDs. I'd heard that the Rx7 LSD can be used in the B2600i axles with a little fab. So, my deducing brain got me started on a project to get a low cost LSD in my truck for winter. The Rx-8 LSD is a Tochigi-Fuji "Super LSD" torque-sensing carrier similar to Mazda's "Torsen" units in function. They allow an amount of slip before engaging. Where they differ from the helical Torsens is that they use conical clutch packs. Rx-8s use them with good success so I imagine them to be great for the street, thought I have no experience with their offroad capability. Mine came from a 2006 with 30k miles. Enjoy!

Stock Diff (open diff with ABS ring on carrier)
https://lh5.googleusercontent.com/-5...0/IMAG0548.jpg

Rx-8 diff housing
https://lh6.googleusercontent.com/-o...0/IMAG0536.jpg


RX-8 Carrier
https://lh3.googleusercontent.com/-K...0/IMAG0542.jpg
https://lh6.googleusercontent.com/-x...0/IMAG0539.jpg


Mounted into B2600i housing with B2600i 4.3 ring gear (you lose the ABS ring, but it doesn't trip the ABS light. I did not try to swap them)
https://lh5.googleusercontent.com/-5...0/IMAG0557.jpg

Through axle tube
https://lh4.googleusercontent.com/-0...0/IMAG0561.jpg

Axle Extension - 2 washers +/- some welding/ grinding (Adjusted endplay by adding/grinding material at end of axle)
https://lh6.googleusercontent.com/-x...0/IMAG0567.jpg

https://lh6.googleusercontent.com/-p...0/IMAG0568.jpg

https://lh6.googleusercontent.com/-O...0/IMAG0573.jpg

Reinstall axle
https://lh3.googleusercontent.com/-r...0/IMAG0574.jpg

Dirty pic from when I first got it
http://a7.sphotos.ak.fbcdn.net/hphot...56478747_n.jpg

if your interested in selling your truck send me a pm..

Very very interesting...