Differentials--for corner carving

[AutoXRacer]

Oh...thats easy...

Easton makes the Detroit Truetrac and the Detroit POSI LSD...
See link below for all the diffs:
http://www.eaton.com/EatonCom/ProductsServices/PerformanceProducts/Products/Differentials/index.htm

 

[_M_]

yeah, i actually have a truetrac in my car. Im confused as to which one Sam is using, or going to use? I've noticed a slight improvement in mine, but nothing outrageous...maybe cant tell as much on the street?

 

[_M_]

im also concerned that perhaps it wasnt installed correctly...im getting a lot of backlash in the drivetrain and some highway whine (could be gears)...was installed by a shop i decided to try that gave a decent price..dumb move on my part

 

[Sam Strano]

I was just confused by Sams post. In one post he says he wouldnt use truetrac, and in another he said he was going with Eaton.

I have now successfully confused myself

Because you are assuming they are the same thing, they aren't.

Eaton makes the Eaton LSD, TrueTrac, and Detroit Locker. An Easton LSD is not related to a TrueTrac--they are no more the same than a Mustang and an F150 just because both are Fords.

I won't run the TrueTrac. Generally recommend Eaton's for S197's these days because the other option that I often use which is a Auburn Racer's is not available in 31 spline versions.

 

[Sam Strano]

yeah, i actually have a truetrac in my car. Im confused as to which one Sam is using, or going to use? I've noticed a slight improvement in mine, but nothing outrageous...maybe cant tell as much on the street?

I'm going to go with a Eaton. You wouldn't notice anything outrageous because it's not that good at biasing power around--which is why my car won't get one. In fact, excepting that it won't wear it's similar in how it applies power to a carbon clutches t-lok.

 

[AutoXRacer]

I'm going to go with a Eaton. You wouldn't notice anything outrageous because it's not that good at biasing power around--which is why my car won't get one. In fact, excepting that it won't wear it's similar in how it applies power to a carbon clutches t-lok.

If thats the case, then I'll probably try the carbon clutches and maybe upgrade to the one Sam decides on...?

Though, the important question is, is the one Sam is going with streetable for everyday driving...?

 

[_M_]

Thats a good question..is it streetable? And Sam can you post a link to the unit you are going to use?

 

[Sam Strano]

http://www.stranoparts.com/partdetails.php?PartID=442&CategoryID=49&ModelID=5

This is what I am going to use. It's very streetable. Tight, but streetable. I don't run lockers or anything that works like a spool---not very good for turning. The idea is that you have some differential wheel speed when you need it, but less when you try to apply power (but not locked, that's bad).

I've already made my decision, just a matter of when I put it in this winter. I've got experience with these units in the smaller GM axles and they get power down really, really, really well.

 

[projectRudeAwakening]

torque and torsen T2 do not mix

No I was NOT drag launching the car either

 

[AutoXRacer]

Eaton Posi LSD
http://www.eaton.com/EatonCom/Produ...ucts/Products/Differentials/PosiLSD/index.htm


Called Roush and both the Truetrac and Posi-Trac are both 31 spline!!!
http://store.roushperformance.com/detail.aspx?ID=1296

 

[_M_]

Thanks for the link. I wish I was still lived in Butler, I would just drive up and have you go over my car with me and get this thing fine tuned they way I want.

 

[AutoXRacer]

I ended up ordering the Truetrac... Roush put them in their Trak Pak cars, so its good enough for me. The POSI is a little too aggressive, plus I don't want to be changing clutches every season or half season.

Roush is having some really good sales on these Truetrac and POSI units...that is until the inventory is gone!! $350 for either, that at least $100 off from anyone else online for the Truetrac and $150 off the POSI...

Get them now!!!

Anyway, I'll be installing mine in December... We'll see how this thing performs. According to everyone I've talked to (regular owners), they claim it feels like the car has more power since it actually moves forward instead of spinning...

Works for me!!! They also say in corners it hooks up, no more one wheel burnouts exiting a corner, though you will oversteer if you are too aggressive with the throttle.

 

[Sam Strano]

I think you made a mistake... but then I didn't have much say in it.

I'm doing the Eaton LSD, the Truetrac has way too little bias ratio, and worse the diff works on an autox car the looser is becomes (also the less power you get down).

 

[AutoXRacer]

What do you mean by too little bias ratio?

I chose it because Roush put it in his Trak Pak race cars...they have a Trak Pak national race series and no one has found the need to replace it. Also, for the most part, my car is a daily driver then an autocross car; although its not a good autocross car...

Anyway, everyone I've spoken to loves their Truetrac...they say its bulletproof...

I just compete in autocross for fun... So I can drive the car in a way I can not on the street. Its just an outlet for aggressive driving and also to improve my driving skills.

So on a scale of 1 to 10...10 being the POSI and the T-Lok being a 1, in your opinion, where do you rate the Truetrac?

 

[Sam Strano]

Where do you see these Roush cars racing exactly? Further you autox, something I not only do, but excel at. And my car is street driven as well. In fact I drove it to work today in the 40 degree rain....

I was just tryin' to help. You seem pretty set on thinking that since Roush uses it then it must be the best. I've tried to use them and get way too much inside rear wheelspin. I'm sure I make more grip than they do considering what I can pull on a car with little wheels. And if you are talking about Koni Challenge series cars they run on a much harder tire than autocrossers do, carry less side load, and run bigger radius corners in relatively higher gears..... All of the above makes life a lot easier for any limited slip, and what works ok for that ain't so hot for me.

If I have to explain bias ratio, then frankly you didn't do your homework on the differential. You also seem to think that an Eaton is not streetable, which is completely untrue. And a good differential makes a car better, regardless of it being a street car or a full out autox car.

Does the TrueTrac suck for a street car? No, in fact it's fine for a street only car. But when you add more aggressive driving to it, it's weak bias ratio starts to show and it only gets worse the more grip and the more power you add.

 

[Pony DNA]

What do you mean by too little bias ratio?

I chose it because Roush put it in his Trak Pak race cars...they have a Trak Pak national race series and no one has found the need to replace it. Also, for the most part, my car is a daily driver then an autocross car; although its not a good autocross car...

Anyway, everyone I've spoken to loves their Truetrac...they say its bulletproof...

I just compete in autocross for fun... So I can drive the car in a way I can not on the street. Its just an outlet for aggressive driving and also to improve my driving skills.

So on a scale of 1 to 10...10 being the POSI and the T-Lok being a 1, in your opinion, where do you rate the Truetrac?

Hey X,

Do not take this too personally, Sam is trying to help you here and I gotta agree with him. This is something he KNOWS COLD no ifs ands or butts. IF your actually plan race your car in a parking lot it would be foolish not to seriously consider what he has to say, make and possibly more importantly change your suspension part list.

HTH!

 

[AutoXRacer]

I don't think the Truetrac is the best out there... My reference to Roush installing them in their Trak Paks is just saying that higher caliber drivers race in the Trak Paks and they have no issues with the TrueTrac diff...so if its good enough for them, its definitely more than what I need; since I'm not that great of a driver.

Though you do have valid points regarding the environment a vehicle sees in autocross versus road racing; and totally agree with you.

I spoke with Eaton (Torque Group) and they described the Truetrac as locking as soon as increased torque (throttle) is sensed. They even warned me that upon exiting a corner under aggressive throttle the vehicle will oversteer; to especially be careful in inclement weather. Reassuring me that as soon as you mash the throttle, both wheels will spin. The only way this will not happen is if one wheel is up in the air or on ice. They even said it is more aggressive in biasing than the POSI... Thats what they said...I don't know first hand, nor will I probably ever know... This is where Sam's experience comes in...

Eaton did state that they do not recommend synthetic fluid, but that if there are no noises/chattering heard in corners that its OK to use. But the Truetrac will be much more aggressive with petroleum based oils. They said for maximum biasing to make sure there is no friction modifier in the oil...

I was flip flipping between the POSI (your choice) and the Truetrac. I was concerned with the POSI since its a cltuch type of LSD. I am pretty aggressive with the throttle in corners...many times trying to make the vehicle drift (not the fast way around) and I thought since its still a limited slip that I would potentially prematurely wear the POSI clutches. I did not want to have to service the POSI every season or so.

We'll see how I feel about the Truetrac. I'm sure I can sell it if I don't like it. But from other forum reviews, it seems to do pretty well and forum members seem to really be happy with it.

Remember, I'm not trying to compete in or win the nationals, just want to improve rear end traction. My requirements are much lower than yours.

Maybe I should have gone with the POSI... I'll just have to see how this Truetrac performs compare to what I have now (OEM T-Lok).

I really appreciate your contribution to this thread; especially from a multi national champion caliber driver!!
Keep them coming, I'm sure this will help a future member that may be in my shoes someday.

 

[Sam Strano]

Ok, clearly it doens't matter what I know. I've run TrueTrac and Eaton's back to back, I know which puts power down better. I don't care what Eaton says. There is no substitute for testing these things, which I have done.... In fact I'd bet I've run more different combinations (and not just limited slips either) than anyone around.

I know what you thought, but frankly what you think has been pretty far off the mark. Carbon clutches are super tough and don't wear fast at all. You can't compare a stock T-lok to an Eaton, they aren't the same and don't have same clutch material or pre-load.

And again, I'm curious as to where all these Roush cars are being raced.... Cause I sure don't know.

You bought into marketing, pure and simple. I hate to say that, but it's pretty much the case. And if you think that any aggressive driver has no need for an excellent limited slip, you are incorrect. How the car puts power down effects not only the speed of the car out of corners, but the balance of it as well. In fact a huge portion of what separates an F-stock car from an ESP car on time is the limited slip change that are allowed.

TrueTracs are fine for street cars that never see any other action. They are friction devices, and despite claims, they do wear. That's why they work better without friction modifiers.

 

[AutoXRacer]

OK...

One of the race series that Trak Paks race is in the ASA Road Racing program among others...

 

[Sam Strano]

ASA? Isn't that a stock car series? Did you mean NASA?