Choosing a differential
01-08-2009, 09:14 PM
#1
3rd Gear Member
Thread Starter
Join Date: Oct 2006
Location: Ohio
Posts: 889
Choosing a differential
Figured the 'handling' section was a better place to ask this non-straight line question...
I've been doing a bit of research lately into replacing my stock differential for road racing. The candidates are:
Torsen T2-R: Used in the a number of the FR series racers, can even be purchased through FRPP. High bias (4:1). Sounds good until you read about everyone who has burned a newer one out in 2 or 3 races! Went out to Gleason's website. Hasn't been updated in 2 years. Not a great sign.
Auburn Racer: Different design than the Torsen (uses cones). Bias somewhere between the Torsen T2 (at 2.5:1) and the T2-R (see above). Downside is that this design 'wears' as well and I've seen people reporting blowing these up on hard launches.
Detroit TruTrac: Same basic design as the Torsen but cheaper and apparently bulletproof. The downside seems to be the weight.
Thoughts? Other options? Differing opinions/experiences?
I've been doing a bit of research lately into replacing my stock differential for road racing. The candidates are:
Torsen T2-R: Used in the a number of the FR series racers, can even be purchased through FRPP. High bias (4:1). Sounds good until you read about everyone who has burned a newer one out in 2 or 3 races! Went out to Gleason's website. Hasn't been updated in 2 years. Not a great sign.
Auburn Racer: Different design than the Torsen (uses cones). Bias somewhere between the Torsen T2 (at 2.5:1) and the T2-R (see above). Downside is that this design 'wears' as well and I've seen people reporting blowing these up on hard launches.
Detroit TruTrac: Same basic design as the Torsen but cheaper and apparently bulletproof. The downside seems to be the weight.
Thoughts? Other options? Differing opinions/experiences?
01-08-2009, 09:27 PM
#2
4th Gear Member
Join Date: Dec 2007
Location:
Posts: 1,599
I dont have any experience with aftermarket diffs, but from the information given, i would go with the true trac. A little bit of extra weight over the rear tires wont hurt you that much, and will actually even out the weight distribution a little between f/r. Plus if its cheaper and stronger, i dont see why anyone would get the other diffs.
01-09-2009, 02:20 PM
#4
Former Sponsor
Join Date: Sep 2007
Posts: 1,936
I have lots of experience with differentials. In fact I was just blasted by somone on another forum because I rubbed him the wrong way based on my experience. 
All of the above are units I sell, and more to the point, have used. There are also a few more not on your list you could consider.
What's more, your details are lacking. A Truetrac and Torsen are similar, but not the same. The bias ratios are very different. And all helical diffs add weight due to the gears inside them.
All of the above are units I sell, and more to the point, have used. There are also a few more not on your list you could consider.
What's more, your details are lacking. A Truetrac and Torsen are similar, but not the same. The bias ratios are very different. And all helical diffs add weight due to the gears inside them.
01-10-2009, 12:08 AM
#8
3rd Gear Member
Thread Starter
Join Date: Oct 2006
Location: Ohio
Posts: 889
Thanks for all the great replies (as always) gentlemen.
That's a pretty strong argument in the Truetrac's favor. Although I drive my car mostly on the street (DD) and sometimes at the 'you have to turn the wheel now' track, I might decide to borrow a set DRs and see what we can do 1/4 mile-wise. Don't want to have to worry about grenading the rear (I guess just the stock clutch instead - hee!). Plus, if I'm going through the time and expense of swapping the pumpkin guts I'd like it to stay fixed.
Granted. Differential expert I am not.
My understanding is that the Truetrac has a torque bias range of 2.5 - 3.5 so not too shabby but I saw someone claiming these things weighed 40 lbs. Is there any other downside to a Truetrac? Is there any way to know by manufacturer which are the 2.5s and which are the 3.5s?
The Auburns are intriguing given they are the only one of this set that advertises their warranty as an express selling point. When I look out, though, across the internet wasteland, I find everyone running Truetracs and T2-Rs and Sam running an Auburn. (Not a scientific sample, I know.) I found a graph that claims the Auburn 'Racer' runs a 4.5:1 bias.
You said there are some other choices I didn't consider. Given what I've thrown out for 'requirements' is there something other than the T2-R, Auburn 'Racer', or Truetrac I should be looking at?
Yup. It seems like reported reliability issues aside, the Torsen is definitely the Cadillac in terms of performance. Nobody didn't like how their T2-R worked - just how long it would keep working seemed to be an issue in some cases. From my vantage point behind the keyboard I'm trying to figure out just how big a risk that is.
Very interesting. Reliability aside: How would you compare the performance of the two units?
I dont have any experience with aftermarket diffs, but from the information given, i would go with the true trac. A little bit of extra weight over the rear tires wont hurt you that much, and will actually even out the weight distribution a little between f/r. Plus if its cheaper and stronger, i dont see why anyone would get the other diffs.
I have lots of experience with differentials. In fact I was just blasted by somone on another forum because I rubbed him the wrong way based on my experience.
All of the above are units I sell, and more to the point, have used. There are also a few more not on your list you could consider.
What's more, your details are lacking. A Truetrac and Torsen are similar, but not the same. The bias ratios are very different. And all helical diffs add weight due to the gears inside them.
All of the above are units I sell, and more to the point, have used. There are also a few more not on your list you could consider.
What's more, your details are lacking. A Truetrac and Torsen are similar, but not the same. The bias ratios are very different. And all helical diffs add weight due to the gears inside them.
My understanding is that the Truetrac has a torque bias range of 2.5 - 3.5 so not too shabby but I saw someone claiming these things weighed 40 lbs. Is there any other downside to a Truetrac? Is there any way to know by manufacturer which are the 2.5s and which are the 3.5s?
The Auburns are intriguing given they are the only one of this set that advertises their warranty as an express selling point. When I look out, though, across the internet wasteland, I find everyone running Truetracs and T2-Rs and Sam running an Auburn. (Not a scientific sample, I know.) I found a graph that claims the Auburn 'Racer' runs a 4.5:1 bias.
You said there are some other choices I didn't consider. Given what I've thrown out for 'requirements' is there something other than the T2-R, Auburn 'Racer', or Truetrac I should be looking at?
Very interesting. Reliability aside: How would you compare the performance of the two units?
Last edited by 2007GT/CS; 01-10-2009 at 12:15 AM.
01-10-2009, 05:49 PM
#10
Join Date: May 2008
Location:
Posts: 5
It's a little early to tell, since I've yet to use the Truetrac in the same conditions - concrete w/ DOT-R tires. Street driving, I can't tell a difference (T2R broke on the street btw). Only did one event this past season, but on street tires. I know the T2R has a higher TBR, but the Truetrac felt quite good and didn't feel much difference. If you get back to me, I'll be able to give better feedback by April. Car is no longer street driven, so I may try out a locker in the future?