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

FerociousP · 01-03-2012, 04:36 PM

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)

Rx-8 diff housing

RX-8 Carrier

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)

Through axle tube

Axle Extension - 2 washers +/- some welding/ grinding (Adjusted endplay by adding/grinding material at end of axle)

Reinstall axle

Dirty pic from when I first got it

Judge Ito · 01-03-2012, 06:03 PM

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

85rx-7gsl-se · 01-03-2012, 06:10 PM

Very very interesting...

01-03-2012, 04:36 PM	#1
FerociousP I-had-a-bad-experience... Join Date: Feb 2008 Location: M'boro iTrader: (2) Posts: 1,046 Rep Power: 18	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) Rx-8 diff housing RX-8 Carrier 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) Through axle tube Axle Extension - 2 washers +/- some welding/ grinding (Adjusted endplay by adding/grinding material at end of axle) Reinstall axle Dirty pic from when I first got it __________________ '15 Juke Nismo '06 MX-5 GT SOLD '04 S Silver RX-8 GT Track Day Use SOLD '90 Black TII vert w/ Sprint RE stock port/turbo DD dyno (242.6whp@5500rpm @12psi 8psi@redline) and (250ftlbtq@4800rpm @13psi) SOLD '89 GTUs 6p TII SOLD, '87 sport SOLD, '79 SA stock SOLD '91 B2600i 4x4 w/ Rx-8 LSD SOLD Last edited by FerociousP; 01-03-2012 at 04:41 PM..

01-03-2012, 06:03 PM	#2
Judge Ito Porting Master Join Date: Mar 2009 Location: North Jersey, USA iTrader: (0) Posts: 154 Rep Power: 16	if your interested in selling your truck send me a pm..