I have a question for those of you that are "Torsen Diff rear end professionals".
This spare wheel (235/50/18), when mounted on the rear, will actually perform 750 revs per mile while the stock rear wheel (285/35/19) on the other side will go 750. So we are talking about a 10 revs per mile difference here. To which extend could this potentially hurt the Torsen Diff? Is it a matter of speed and distance? Distance only? I knew this from scratch, but thought it was only a minor difference. Could I be wrong?
Thanks for your insight on this.
Assuming you ment to type 740 or 760 and the difference is 10 revolutions per mile, this would be 1 revolution per 1/10 mile. This does not seam to be much, but if you go to the Torsen website, they are pretty set on same diameter rear wheels.
The Torsen does limit slip, but it does it with gears and is much different than a traditional limited slip diff with clutch packs. It is a torque sensing and multiplier, and it acts as an open differential until it senses slippage, (different speed of rear tires) so your set up with running the spare tire will make your Torsen work overtime.
Remember, the Torsen is also a torque multiplier, so when it does sense wheel slippage, (the smaller tire), it will multiply X 2.5 the amout of torque to the opposite side. (Note: Torsen T2 diff = X 2.5 and the Race Spec T2R = X 10).
So, it could be working more than we think. Best thing to do if used on the rear is to limit the speed and distance of the spare use on the rear axle.
With that said, I would recommend that you contact Toresn Manufacturing, they will give you the best information. Have the exact wheel/tire diameter ready for each tire. Maybe the difference is so slight the Torsen wouldn't pick up or sence a wheel slip condition? This I don't know, but contact them to make sure you don't run the risk of overheating your rear diff gear lub. That is when the real damage will occur and is why speed and distance are important factors.
Hope this helps,
PS: I'm not a Torsen expert by any means.
2012 KB Boss 302 MC: 500A | Boss Production Line Assembly Number 2800. Vehicle Special Ordered with Recaro Sport Seats & 3.73:1 Torsen Option | Engine: FRPP 84.5MM TB, Peterson CJ Vent Can, TracKey Activated, AirAid CF PJ CAI, FRPP 84.5MM TB | Drivetrain: AE 4.0" Aluminum DS, MGW Gen 3 Race Spec Shifter, GT500 Clutch Pedal Box, FRPP Stainless Clutch Line, Dedicated Clutch Fluid Reservoir, FRPP Trans Cooler Scoop. | Exhaust: Silver Ceramic Kooks Super Street Headers, MagnaFlow Street/Comp 3.0" SS CB X-Pipe System, Open Kooks SS Boss Side Pipes. | Suspension: FRPP "T" Springs (alternate Steeda Boss Rear Springs), Koni Sports (Yellow) Adjustable Struts/Shocks, Steeda HD Camber Plates, Cortex Watts Link, Steeda Billet KB Poly/Spherical LCA's, KB LCA Relo Brkts, Steeda Adj. UCA & Energy Suspension Sys. Upper Diff Housing Bush, OEM Boss Rear Sway Bar | FRPP GT500 Forged wheels, (19X9.0 F & 19X10.0" R) | Brakes: FRPP Boss 302 Cooling Duct Kit, Steeda SS/Kevlar Brake Lines, GT500 13.8" Rear Rotors, GT500 Rear Brake Pads, Dot 4 Motul 600 HT Fluid | Body: FRPP Boss 302S Grill, FRPP Boss 302 LS Front Splitter, FRPP GT500 Rear Spoiler & Serviceable Gurney Strip, BFR Front Tow Hook, Jacking Plates, 3M Window Tint, (35/20), OEM Boss 302 Floor Mats & Boss 302 Car Cover, Pioneer TS-D6802R Speaker System, Auto Dim, Home Link & Compass Mirror. Notes: Current Intake System - Ram Air thru Front Grill Fog Light, OEM CAI Box and AEM Aluminum Intake Tube with Drop-In High Flow Filter. In Testing Spring 2016. SCT-X4 Tuner used exclusively for Data-Logging AFR/Timing Curves Only. FRPP TracKey is Preferred PCM Tune.