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Best Differential For Road Racing


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I've been trying to find some information on the stock differential, but am not having any luck. I've been talking talking to a few guys about putting a new piece in since I already have the cover off for a homemade RBST. I've gotten recommendations on every type of diff on the market (Detroit locker, posi, gold trac) but without any reasons as to why. Guys are always talking about their buddy that uses this diff and that diff, but they can never tell you why that is the "best." So please when giving recommendations also say why you feel that is the best choice. I want to have the best, but I don't want to waste my mod budget buying multiple diffs to find what seems to work best.

 

The car is seeing an increasing amount of track days (went from 2-3 a year to 7+ with sometime hour long run sessions), but it is also an everyday car so I'm still have to balance the two. I don't mind the side effects of performance parts on the street I just don't want to have a chattering problems or have issues when trying to get through tight parking lots.

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JT , based upon what you have on your car and what you want to use it for , I'd recommend going with an Auburn Gear Pro Series Limited Slip Differential. It will work good for you on both street and track . Cheaper than a torque bias differential , less chance of inducing an understeer issue in the car , strong enough to handle your mods . As far as chatter goes - you need to have a quality diff fluid that keeps the discs wet in the diff. JMO

 

Note: Torque bias differentials are meant more for racing , more exspensive , come in different bias ratios based upon horsepower , vehicle weight , etc...

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I have an Eaton TrueTrac with 3.73 gears… works perfectly on street and track (my stock unit would overheat on the track and start "clicking" around turns), but it has that "famous Eaton whine"….

 

 

 

Jer

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I have an Eaton TrueTrac with 3.73 gears… works perfectly on street and track (my stock unit would overheat on the track and start "clicking" around turns), but it has that "famous Eaton whine"….

 

 

 

Jer

Uh Jer I think that whining noise you hear is from the engine compartment . :lol: But , yeah another good choice still cheaper than a Torson which I use but I'm more for the track !

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Uh Jer I think that whining noise you hear is from the engine compartment . :lol: But , yeah another good choice still cheaper than a Torson which I use but I'm more for the track !

 

Aw, hell, no… with the upgraded UCA and mount, I became VERY familiar with the location of my diff whine… LOL

 

 

Jer

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I have an Eaton TrueTrac with 3.73 gears… works perfectly on street and track (my stock unit would overheat on the track and start "clicking" around turns), but it has that "famous Eaton whine"….

 

 

 

Jer

I run a Roush Black Jack on the Track and this the set up the guys are really pushing on me. Big positive reviews from the folks that have them.

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I run a Roush Black Jack on the Track and this the set up the guys are really pushing on me. Big positive reviews from the folks that have them.

 

I'm very happy with it.

 

 

Jer

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The 2.7 ratio unit (2012-13 Boss) and I take it's for your SGT/SC right?

 

Yes, That's the plan. The car is in the shop right now a UPS in running around with the unit and can't figure out what to do with it :banghead:

 

Do the 13/14' GT500s and Boss 302 use the same unit?

 

WHat is the maximum HP recommendation?

.

 

It is my understanding that it is the same unit that is available in the SVT performance package . So I would assume it's good for at least 662 hp

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From what I understand is that there are 3 different ratios of bias. 2.0 , 2.7(used in the 2012-13 Boss LS models and13-14 GT500 SVTPP) and a 4.0 ratio (used in the FR500S and C - "not for use in drag racing applications- for use in performance street or road race applications" - per Ford Racing) .

 

dh777 - good luck with UPS :drop:

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Sorry for the delay, I had a family member pass away last week and there has been no down time trying to make their final wishes come true.

 

I have an Eaton TrueTrac with 3.73 gears… works perfectly on street and track (my stock unit would overheat on the track and start "clicking" around turns), but it has that "famous Eaton whine"….

 

 

 

Jer

 

I've been looking at this piece, but would stay with the 3.55 gears due to the conversations we had in Dearborn last year.

 

 

From what I understand is that there are 3 different ratios of bias. 2.0 , 2.7(used in the 2012-13 Boss LS models and13-14 GT500 SVTPP) and a 4.0 ratio (used in the FR500S and C - "not for use in drag racing applications- for use in performance street or road race applications" - per Ford Racing) .

 

dh777 - good luck with UPS :drop:

 

I've been debating between these three options since the beginning. I've heard a lot of good things about the 2.7 and 4.0 ratio. Since I won't be doing any drag racing with the car I was thinking about the 4.0 ratio Some has said that having the bigger ratio will cause the car to want to spin out, but I can't see how this would happen since it automatically even back out once it senses the rear is gaining more traction.

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I have an Eaton TrueTrac with 3.73 gears… works perfectly on street and track (my stock unit would overheat on the track and start "clicking" around turns), but it has that "famous Eaton whine"….

 

 

 

Jer

 

I second or third the Eaton TrueTrac, also with the 3.73's

Owner and believer since 2009 and won't be without it :)

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  • 3 weeks later...

Order my rear end build parts today, with a few extras… :whistling:

 

FR500S Diff

2013 GT500 Diff Cover

3.73 Gear set w/ install kit

ARP studs all around with new hubs up front

 

Hopefully the one piece driveshaft and new axles will be on the way soon. Being under a crap of snow, I've lost count on the amount after the first 5 feet, as long as they're here by July 4th I should be all set. :drop:

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I am gathering my stuff as well

 

TruTrac Differential (in my shopping cart)

KR Differential cover (on the way)

Moser Axles, new bearings and seal kit and new ABS rings (here)

ARP 3" Wheel Studs (here)

Shelby/Fays2 Watts link (on the way)

 

Contemplating swapping my 4.10 gears for 3.73 at this time

 

Andrew

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I'm hoping to get the Watts Link ordered soon. I'm trying to get the rear end back up into the car soon it can be pushed out of the garage to get some electrical work done. Between the RBST and the rebuild it's been out of the car since the fall.

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