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Ford Performance FR500S Differential - 31 Spline 8.8 in. (11-14 V6; 86-14 V8, Excluding 13-14 GT500)

Item 50300
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      Product Information

      Features, Description, Reviews, Q&A, Specs & Installation


      • Used in the FR500S Race Car
      • Type T-2R Torsen Differential
      • High Bias Ratio of 4.0
      • Preloaded Clutch
      • Perfect for Street or Track
      • 8.8" Differential
      • Requires 31 Spline Axles
      • Fits 1986-2014 V8 and 2011-2014 V6, Excluding IRS Models


      FR500S. Does your factory rear end just leave you spinning your wheels? Then upgrade to the same exact differential used in the Ford Racing "FR500S" race car. This limited slip differential (LSD) uses a worm gear friction system that ensure your engine's power is transferred to the wheels for maximum traction.

      Torsen T-2R Differential.
      Built off the T-2 differential, the Torsen T-2R uses friction enhancing plates that allows for improved mobility and traction even under the most extreme conditions. The T-2R is always active and responds instantly to torque feedback from all driving conditions.

      Application. This Ford Racing FR500s 8.8" Differential will fit solid axle V8 Mustangs from 1986-2014 and 2011-2014 V6 Mustangs. Requires 31 spline axles.

      Application Note: 1986-2004 V8 Mustangs came factory equipped with 28 spline axles, except for 2003-2004 SVT Cobras which were 31 spline. All 2005 and newer V8 Mustangs come equipped with 31 spline axles.

      • 8.8" Limited Slip Differential
      • Preloaded Clutch
      • Will accept anti-lock exciter ring
      • Requires 31 spline axles
      • Requires 3 quarts Gear Oil
      • Requires 4 ounces of CM-19546-A1 friction modifier with initial fill
      • Fits solid rear suspension
      • Does not fit IRS applications

      Technical Note. You will need to reuse your factory 8.8” gear set, or upgrade to a new set of our 8.8" rear gears for this Limited Slip Differential. No aftermarket gears are included. For normal driving conditions, we recommend you use 75W 90 rear gear oil. This will give you the same oil weight as factory. For colder temps or race use, try 75w 140.

      Fitment: 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Details

      MPN# M-4204-T31H

      CA Residents: WARNING: Cancer and Reproductive Harm -


      Customer Reviews (10)

      Write a Review

      Ratings Summary

      4.9 out of 5 overall rating from 10 customers

      Installation Time: Weekend

      Installation Cost: $250-$500

      • July 21, 2018

        5 2003 Mach 1 - TimothyN Installation Time: Shop Install Installation Cost: $500-$1000

        FR500S Diff

        Amazing product. Worth the money. Noticeable difference when even regular driving. Love pushing the car more in twists and turns. Can't wait to try out in the next autox season. One of the few things I didn't trust myself to install. If you don't know whether you can install or not watch Eric the car guy on youtube work on a Ford 8.8.

        Helpful (8)
      • February 22, 2018

        5 2007 GT - DarrenF Installation Time: Shop Install Installation Cost: $500-$1000


        I notice the difference on the first corner leaving the shop. The rear feels like it rotates some much better.

        Helpful (10)
      • July 29, 2017

        5 1992 LX - DerickP Installation Time: Afternoon

        Definitely an upgrade!

        Mustang handles in twisties soooo much better! Install was straightforward, no hassles, everything bolted right up and fit great.

        Helpful (12)
      • July 28, 2017

        5 2014 GT - WadeW Installation Time: Shop Install Installation Cost: $100-$250

        HOLY COW!!!!!

        WOW!!! I had high hopes for this part, but I really didn't understand the level of performance that this provides. I RARELY write reviews on products unless they are really bad or really good. I use my 14 GT for fun, it is not a daily driver. I have lots of suspension mods. I will give the short list: Watts Link, Upper and Lower control arms, Koni yellows, front sway bar, relocation brackets. All but the Koni's are BMR. This car is stiff and had the ability to go around a turn at a very high level with my Nitto NT05's for grip (amazing as well). When negotiating a turn, there is a point where you could tell that the factory rear end was stressed and at it's limit. FR500S to the rescue...while pushing through a turn now, the Mustang is just asking for more and more. Very hard to explain, the car just curves through the corner now, allowing me, the driver, to push harder and harder. The limits I haven't found yet due to my pucker factor, lol. Strongly suggest this modification is you have a road coarse car, you will not regret it. WOW!!

        Helpful (11)
      • June 22, 2016

        5 2006 GT - Andrew

        Way better than the Trak-Lok

        After installing this, I've noticed a substantial reduction in understeer. Powering through a corner makes it feel like the rear axle is steering too. Incredibly confidence inspiring, not just on the track, but on the street too, dry or wet. The diff is very quiet and has smooth, fast, and predictable operation. This also doesn't have clutches to wear out, so if you're on the fence between this or a trak-lok, this one is the only way to go, unless you're strictly into drag racing.

        Helpful (13)
      • December 23, 2014

        5 2007 GT - NicNak Installation Time: Weekend

        Best money ever spent on a mod

        Car handles completely different. No longer clumsy around corners. Transfers every bit of torque from the driveshaft to the wheels with's the key "perfect instintaious differential action". Theriatically a zero wear item. This is the most ingenious LSD available. I am a repeat offender(customer) and this is by far the best money I have spent to date. It's no wonder these torsens come standard on the track pack 2015 mustangs and the earlier boss'. I wonder why those cars put down the best circuit and drag times compared to other variants?

        Helpful (11)
      • October 01, 2014

        5 2011 V6 - MUSTANGTT Installation Time: Weekend

        Excellent product

        Installed the FR500S this week along with new 3.55 gears and aluminum drive shaft. Still breaking in the gears, etc., so I don't have performance input at this time. The install went really well and the quality of the unit was excellent. Compared with the original differential this Torsen unit is a big improvement. It was installed in a 2011 3.7 that has twin turbos and loads of torque (in excess of 400 ft pounds to the wheels). Should hook up a lot better out of the corners now.

        Helpful (13)
      • August 08, 2013

        4 2011 GT - JohnH1775 Installation Time: Shop Install Installation Cost: $500-$1000

        T2R differential

        If you auto cross or road race your mustang this is a must have. I went from the T2 to the T2R and my inside wheel spin issues seem to have vanished. If you're on the fence between the two, I'd go with the T2R and be done with it.

        Helpful (17)
      • May 26, 2013

        5 2012 GT - csamsh1 Installation Time: Shop Install Installation Cost: $250-$500

        Wow! This is a must for some people....

        I recently had this differential installed when the stock one was burned up from too much use with R-comp tires. The car now puts power down out of turns incredibly well, and it rotates like never before. It took me by surprise the first time I took a corner after I'd picked the car up. If you do any track or autocross work- look no further. Slicks WILL toast the stock diff. The torsen has no clutches to rebuild, so it *should* be a zero-wear item! Expensive price of entry, but worth every penny IMO. Get it now!

        Helpful (13)
      • April 28, 2012

        5 2012 GT - BLee403 Installation Time: Shop Install Installation Cost: $250-$500

        Let's Go Racing

        Had my new FR 500S Differential installed in my 2012 Mustang GT. Took my car to the track at Buttonwillow Raceway near Bakersfield, Ca and it had tremendous hook up both in the turns and the straights. My ability to pass other cars increased and it was and absolute pleasure to drive at the track and to and from the track. I would highly recommend this upgrade to anyone wanting to put more power to the pavement. It feels as if the differential spins much more freely than before as if there is nothing dragging or hindering it at all. Like your getting free horsepower.

        Helpful (19)

      Questions & Answers (9 answers)

      5 Top Rated Questions

      Just wondering if this differential is any stronger than the original T2 Torsen? Also I see in the description this one has friction plates, does that mean that it would wear out faster than a T2 based on the higher torque bias? Thanks

      Will this fit my 2011 GT Automatic?

      • This would fit for GT as long as you have 31 spline axles.

      Helpful (0)

      Is this the newer style T-2R with the parallel split gear setup?

      • This Ford Performance FR500S Differential is a T2R differential. The Ford Performance Part number is M-4204-T31H.

      Helpful (0)

      Will this be good for drag racing while still maintaining streetability?

      • The Ford Performance FR500S Differential will maintain street manners, however this is not ideal or recommended for drag racing.

      Helpful (0)

      would this product also work for a 2010 v6 mustang if i changed the axles to the appropriate 31 spline 8.8 inch axles

      • The Ford Performance FR500S Differential would require you to remove the 7.5" rear, and install an 8.8 rear with 31 spline axles.

      Helpful (0)
      Post Your Question
      4 More Questions
      I see 2.0 2.7 4.0 etc. for the bias... What does this mean? the amount of slip? what would help me out more if I say had one wheel up in the air and needed the other cause my wife put the car in a ditch? 1 answer
      do you need to change out your axle bearings and seals when installing this part? thanks ! Do you have to pull out your axles when installing? 1 answer
      Will this go good with a sn95 GT ? I have a few bolt on and in currently Rebuilding my transmission with a complete beefed up kit Along with the torque converter . I'm swapping out the rear end as well and Installing a 4.10 . Will this be to much ? Or will this be okay. 1 answer
      Manual or Auto Does this work with both manual trans and auto? 2 answers

      Installation & What's in the Box

      Installation Info

      What's in the Box

      • (1) Limited Slip Differential

      Tech Specs

      Will It Fit My Mustang

      • Boss 302 - 12, 13
      • Bullitt - 01, 08, 09
      • Cobra - 93, 94, 95, 96, 97, 98, 99, 00, 01, 03, 04
      • Cobra R - 93, 95, 00
      • GT - 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14
      • GT500 - 07, 08, 09, 10, 11, 12
      • LX - 87, 88, 89, 90, 91, 92, 93
      • Mach 1 - 03, 04
      • Other - 86
      • V6 - 11, 12, 13, 14

      Requires 8.8" rear and 31 spline axles. Does not fit IRS applications

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