[BlackBarchetta]

Anyone have experience with this differential and can compare to the standard traction lock differential?

 

[JBert]

No direct experience, but as I understand it: the Torsen is better for a road track car because it is a little "freer" in the corners and can take more cornering under power. The regular traction lock diff is better for maintaining traction in a straight line and I think it transfers torque better / more evenly across the two wheels.

Maybe someone else can chime in with a better explanation but I think that is fairly close.

Why are you interested, what are you doing with the car and what shortcoming are you seeing now or what improvement are you looking for?

 

[BlackBarchetta]

Right, that has been my understanding as well... which is what I really don't want for what I do (straight line). I was hoping that the Torsen differentials would have better slip sensing and locking capability for straight line racing. If one get wheel gets slips, it diverts power to the other wheel to help along. But they say the math for the slip on these Torsen differentials may get you stuck in an ice or snow situation since there is 0 resistance or force to divert if either of the wheels is spinning. It's more about compensating inside rotation on a turn to keep the front end from skipping over itself in the Torsens I think... seem to lean more on the "limited slip" side where traction lok seems to be more traditional like posi.

I was flirting with the idea of having an eLocker installed where I could keep it in limited slip for normal driving and then electronically lock the differential for straight line racing. I just feel like I am asking for trouble with that type of an install, though.

 

[Blazin72]

If you already had it in your car then I'd say don't bother changing it out because plenty of Boss 302s and TrackPack GTs are drag raced it. Since it sounds like you don't have it - keep or upgrade your limited slip. You can buy springs and clutches or complete assemblies to better match what you are looking for.

And no, it wont leave you completely stranded in bad weather.

 

[GLOCKer]

I kind of hate to hijack this thread, but I see a great learning opportunity here for me. I have the most base level GT sold in 2014. I think I have a 3.31 rear end (according to a VIN look up I used when I first bought the car) and the MT-82. I'm also running a ProCharger P-1SC-1 (575 rwhp on a DynoJet). Drag racing isn't my thing; I mainly enjoy street driving the car, club "mountain cruises" at places like The Tail of the Dragon, and an occasion track day. Would my car benefit from a rear end upgrade? Should I consider a rear end upgrade or would my money be better served upgrading the brakes (non-Brembo right now), transmission cooler, and oil cooler? And here is where I'm probably going to sound very stupid; when I'm overly aggressive with the go-pedal, do both of my wheels spin or just one? (I hate that I sound so ignorant - I'm still learning!)
Thank you guys!

 

[BlackBarchetta]

I kind of hate to hijack this thread, but I see a great learning opportunity here for me. I have the most base level GT sold in 2014. I think I have a 3.31 rear end (according to a VIN look up I used when I first bought the car) and the MT-82. I'm also running a ProCharger P-1SC-1 (575 rwhp on a DynoJet). Drag racing isn't my thing; I mainly enjoy street driving the car, club "mountain cruises" at places like The Tail of the Dragon, and an occasion track day. Would my car benefit from a rear end upgrade? Should I consider a rear end upgrade or would my money be better served upgrading the brakes (non-Brembo right now), transmission cooler, and oil cooler? And here is where I'm probably going to sound very stupid; when I'm overly aggressive with the go-pedal, do both of my wheels spin or just one? (I hate that I sound so ignorant - I'm still learning!)
Thank you guys!

I had 3.55 gears in my last car with 19"x10" rims in the rear and still got tire spin under heavy throttle.
In my opinion, these cars have plenty of power as is... getting that power to push the car along without spinning is the biggest battle. Efficiency is everything.

BUT the first thing you should do is upgrade your shifter assembly and clutch setup. The stock clutch, pressure plate, and throw out bearing suck. Also replace do the clutch line between the pedal and throw out bearing- replace it with a steel line.


After that, I recommend working on the rear end differential to ensure maximum traction for launch... granted you have good rims and tires, etc..

 

[BlackBarchetta]

I did some reading today and learned a bit from Torsen.


They measure power/friction output in "biasing ratio", which indicates how much torque can be transferred to the wheel with better traction in terms of a ratio. The FR500S T2-R differential can send 4x torque to the better-tractioned wheel and keep 1x on the less-tractioned wheel (5x to work with total in that ratio); the Boss 302 differential can only send 2.7x torque to the better wheel (3.7x total available), and the basic T2 will only send 2x (3x total available).


So with the FR500S, if both wheels get equal traction, it becomes a 1:1 ratio, where 1.5x is pulled from the one axle and diverted back to the other ( 4-1.5= 2.5; 1.5+1= 2.5; 2.5:2.5= 1:1 ). Or you could look at 4:1 as a n 80%/20% split, where 30% can be diverted back to the other making it 50%/50% in equal power distribution.
I think a high bias ratio is ideal for "turning" applications like road racing, but not for drag racing in a straight line.
Best bet is to get both axles locked and make sure you have good traction.

 

[CDN5.0]

The Torsen uses gears instead of clutches to move torque to the wheel that is gripping as opposed to the trac lok using clutches to perform the same function. The torsen is far superior to the trac lok when road racing as it handles side slip much better. It is a road racing rear end. You will find that most drag racers switch it out for the trac loc clutch type because the clutch type handles straight line torque better and the spider gears in the torsen are prone to breakage under wheel hop, whereas the clutches will take the twist, hop, twist abuse much better. Drag racers almost always switch out the torsen for the trac loc clutch type for that reason.
If you are a dedicated drag racer you should switch to trac lok for durability. Ultimately you will want to upgrade to a rear suspension system that eliminates wheel hop but the trac lok clutch type diff does deal with it better than the torsen, just like the torsen puts power down through the corners better than the trac lok. Ultimately it depends on what you do with your car.

Scott

 

[JBert]

Thanks BlackBarchetta and CDN5.0 for the helpful insights on the workings of these differentials.

. . . . I think I have a 3.31 rear end (according to a VIN look up I used when I first bought the car) and the MT-82. I'm also running a ProCharger P-1SC-1 (575 rwhp on a DynoJet). . . . . I mainly enjoy street driving the car, club "mountain cruises" at places like The Tail of the Dragon, and an occasion track day. Would my car benefit from a rear end upgrade? Should I consider a rear end upgrade or would my money be better served upgrading the brakes (non-Brembo right now), transmission cooler, and oil cooler? . . . I'm overly aggressive with the go-pedal, do both of my wheels spin or just one? . . .

I would leave the rear end ratio alone because I think you will have plenty of torque from that setup and I don't know why you would want a lower first gear. The transmission ratios are fairly close in the MT-82 so I think you should be able to find a gear that matches the situation pretty much all the time.

For the road track days it sounds like the Torsen differential might be a benefit in the corners. I wonder if the standard trac-loc contributes a little to unpredictable behavior in corners when near the limit. I am starting to think that I might want a Torsen myself; even though I cannot point to any definite instances where I have had a problem with the trac-loc . . . I am a fairly novice track driver so I can't really tell the difference on some of these fine points.

In your situation I think I would do the brakes first. The SVT GT500 Brembo kit is the "best buy" in my opinion, though you might be able to save some money by piecing together the parts rather than buying the complete kit. There are some threads on here with the details about that.
https://www.americanmuscle.com/svt-brakekit-0509gt.html

I had an issue with my rear brakes getting really hot during road track sessions and cured it by installing the larger GT500 rotors with adapter brackets from the guy on e-bay . . . very cost effective and easy upgrade.

Then I would at cooling if you are having any overheating issues. I have heard from several guys driving the 13-14 GT's on the road track that they do have issues with the oil getting too hot. Also have heard that the Boss oil cooler is not the best solution.

The purpose of the "limited slip" differential is to make sure that both wheels spin, not just one -- so you should be getting two-wheel burnouts, not one wheel.

 

[GLOCKer]

I had 3.55 gears in my last car with 19"x10" rims in the rear and still got tire spin under heavy throttle.
In my opinion, these cars have plenty of power as is... getting that power to push the car along without spinning is the biggest battle. Efficiency is everything.

BUT the first thing you should do is upgrade your shifter assembly and clutch setup. The stock clutch, pressure plate, and throw out bearing suck. Also replace do the clutch line between the pedal and throw out bearing- replace it with a steel line.


After that, I recommend working on the rear end differential to ensure maximum traction for launch... granted you have good rims and tires, etc..

I've got the MGW Race Spec shifter and the stock clutch with the Steeda clutch pedal spring. The car has been unbelievably more enjoyable to drive since these upgrades. I was previously running the American Muscle SR Performance shifter with the bushing; it sucked royally. I was getting 2nd gear lock-out in all conditions!

I've been interested in the steel line as I've heard it makes a great difference in feel.

 

[BlackBarchetta]

If you are road racing, I think your best option is just to get a 2015+ model because they have independent rear suspension! Watts link can help as well as limited slip, but neither are a replacement for IRS because at the end of the day, solid axle is solid and both sides are tied together at the differential.

I actually avoided 2015+ models when looking to replace my 2011. IRS will just wheel hop around in a drag scenario. Ford 9" can take it better than a GM, but still not advised.


As for me, I am kind of looking for something opposite from what exists... something that stays locked until it senses one is turning and only then does it compensate for the difference in rotation from wheel to wheel. Even if "slipping" during straight steering, I want both rear wheels to have equal power distribution. Win/win for everyone I think.

 

[Blazin72]

Then buy a Detroit Locker or equivalent.

 

[BlackBarchetta]

Then buy a Detroit Locker or equivalent.

A Detroit locker is always locked, is it not? This is dangerous for normal driving conditions when you have to turn... say on an interstate at 70-80 miles per hour. Having a locked axle during turning will cause skipping, not unlike driving over a speed bump while turning (rear end kicks out because the wheels are travelling different distances despite being tied together).


When it's not locked/not under acceleration, it is "open". There is no limited slip!

 

[Blazin72]

It is always locked until you enter a turn. The vehicle understeers a bit until it unlocks but once that happens it turns like any other vehicle. A spool always locks the axles together.

Ever driven a Jeep with a locker? It's an adventure at times but far from dangerous.

If you are uncomfortable with the idea of a locker then the best bet for you is probably upgrading the spring and clutches in the differential you already have. If you are still having tire spin then buy better tires.

 

[BlackBarchetta]

Well, been through the tire and rim game already and found what works best regarding that aspect. There is no room for improvement there.

I was just talking to my rear end mechanic and he talked about a locking differential that goes limited slip when cornering. He said it's noisy (I don't care about noise, I'm not John Q. Public/lowrider man) as it clicks when in limited slip, but works. The name he gave me didn't sound familiar, so I have some research to do I guess. The newer Detroit Lockers are supposed to be like this as well, but I am not convinced until I hear it from one of the guys who lives at the track that uses them.

Part of winning every battle is the element of surprise. Catching your opponent off guard is wonderful. I don't want to swap differentials every time I go to the strip and then back on the street.

 

[John1]

Before I purchased my 2014 GT with the Track Pack, I did some research on the Torsen differential and found a short animation on youtube (see video below). I know how the clutch type differential works since I had to rebuild the one I had on my 93 Lightning. I like the idea of the Torsen since clutches can fail as mine did in my Lightning. I hope this helps...

 

[GLOCKer]

Before I purchased my 2014 GT with the Track Pack, I did some research on the Torsen differential and found a short animation on youtube (see video below). I know how the clutch type differential works since I had to rebuild the one I had on my 93 Lightning. I like the idea of the Torsen since clutches can fail as mine did in my Lightning. I hope this helps...

That was pretty neat! Thank you!

 

[JBert]

Cool video!

but, even though I am a mechanical engineer, I still don't really get how it works to allow the car to go around corners . . . does the outside wheel basically free-wheel; with all power transmitted to the inside wheel?

I guess I need to watch it again, LOL

 

[Pete Grimaldi]

Mine works great!

Pete

 

[Blazin72]

Cool video!

but, even though I am a mechanical engineer, I still don't really get how it works to allow the car to go around corners . . . does the outside wheel basically free-wheel; with all power transmitted to the inside wheel?

Even in a turn it sends torque to both wheels but the amount of torque sent to each wheel is based on the bias ratio of the differential.