Eaton/Detroit TrueTrac Differential

[Joe66GT]

  Anyone have any experience with a TrueTrac differential? I'm looking to upgrade to 35 spline axles with a TrueTrac diff and am mostly concerned with how it will hold up at the drag strip for the handful of times I make it out to the track each year. I really like their street manners after driving a couple of different cars with them installed and that's why I'm leaning that way. 482, 5 speed (TKX) Fairlane.
Thanks, Joe S.

[pbf777]

      I would not label the True-Trac differential as something actually intended for the drag-strip, nor does it function as well as to other options available; this being relatively true for any of the 'worm-gear resistance' type units.   

      Scott.

[Tunnelwedge]

I'd vote locker.
I've driven a Fairlane "with required third pedal" on the street and track with a locker.
Works perfect.

[galaxiex]

For a mainly street driven car, I like the True-Trac better than any clutch or cone type "posi" differential.


The True-Trac will still "hook" both tires on a hard launch yet allow "normal" open diff action on turns.
They seem to be quite rugged, as the couple dozen or so that I have installed on customers hot rods, trucks, etc,
seemed to hold up just fine for 4X4 Lead Foot Larry, and the "smoke both tires" show off street car dude with more money and HP, than brains.

That's NOT a stab at the OP, those are the kind of customers I get sometimes....


Lockers are in another class and can be noisy on turns and backing up and turning.
Nothing wrong with that, I love the Detroit Locker for the absolute 100% positive locking on launch.


For my 99% street Galaxie I'm using a True-Trac.

[Tunnelwedge]

Lockers are in another class and can be noisy on turns and backing up and turning.
Nothing wrong with that, I love the Detroit Locker for the absolute 100% positive locking on launch.

I use a Yukon locker in my light weight 68 Mustang 482ci 4 Sp car.
The engine makes way more noise than than any unlocking of the gear. The car has Hookers and full exhaust. The engine is loud and I have it turned down.
The OP is thinking 35's. So pretty much full race with aftermarket case and big bearings. Spending his money I would order a Yukon in 35 spline.

[Rory428]

I considered a Tru Trac when I was building my 428CJ 4 speed 59 2 door sedan, but decided on a 31 spline Detroit Locker instead. Main reason was, that I plan on occasional  drag strip passes, and although the Tru Trac has nicer street manners, not really up to hard launches , especially with a clutch. Too many small, moving, internal parts. Detroit Locker is much sturdier for that type of use. I have a later style "soft locker" DL, so much less "Snap, Crackle, Pop" noises than the older Detroit Lockers that I have used in the past, but it will still make the car twitch some, now and then, especially if you give it some throttle before the car is going straight. But after the dismal results that I have had with clutch style Traction Loks in the past, I find the Detroit Locker well worth a bit of grumpiness now and then.

[HTRDHARLEY]

I have run a Tru Trac for many miles, both street & track. On a road course when they start to wear out the unloaded side will spin and lose traction. Coming right off a road course to the drag strip the wore out Tru Trac still hooked both rears. They will fail first in a auto cross / road race envrinoment before the drag strip.

 Do not use synthetic gear oil, dino oil only.

 Street manners are way better than a Detroit Locker.

 The Tru Trac is not rebuilable.

 I am currently running a HD wave trac for the first time. So far I like it, but only has about 2K miles on it and maybe 20 race miles.

 I went from a Trac Lok to a DL to a Tru Trac to a Wave Trac. The DL by far had the worst street manners...

4450# car, TKX, 3:70 - 4:00 gear, 560 HP 561 TQ.

Hope this helps make a decision.

[Joe66GT]

Thanks for the replies everyone.  I like the price of the Yukon Grizzly locker but after running a locker for the past 30 years I was hoping for something with better street manners. I'm concerned with the Truetrac holding up at the drag strip, the Wavetrac on Summit has a ship date of 5/31 and the Strange S-Trac is a whopping $1,100.

[pbf777]

     "Yukon",  off-shore manufacture.   

      Scott.

[Tunnelwedge]

The real question is, how hard are you going to kick it?
Roll up to the line with street tires and a light launch into the clutch?
Or slicks and full launch suspension and a 5000 rpm dump and yank the wheels up?
Either way it's lots of fun. All the best with your pick.

[Falcon67]

I have a "soft locker" DL in a spare 4.11 center section.  It works well and has decent street manners, nicer than a true DL.  Has to do with the way they tuned the springs in the locker, it makes engagement/disengagement a little softer.  It will still clunk - hey, that's a DL.  For street tires at the track, a cone or gear type diff would work, you should be driving around the water box anyway unless you are running Drag Radials.  Any serious burnout on street tires just causes the hard tread compound to ball up, the track rubber to ball up and you launch on bitty rubber marbles.  For decent power leaves on DRs or slicks, locker or spool.  And with a locker, make sure you drive straight to the line from the burnout.  If you get sideways, straighten out, back up and go in straight to be absolutely sure the locker is locked. 

Note - you can hook both tires on the drag strip with an open diff, just do two burnouts.  Seriously - heat one tire, back up a little, burn - Tire 1 will stick and spin Tire 2, stage, go.  Works.

[6667fan]

I went from a True-Trac to a DL when I ordered my complete Strange third member. Reason was the True-Trac diffs were n/a at the time. If the True-Trac was available I would have spec’ed the rear that way. The previous rear with True-Trac performed very well at track. To be fair clutch dumps have only been in the 4K range with both rears.
That is great tip from Chris about how not to wreck a locker at the strip.

[sixty9cobra]

I also have a Tru Track though I'm only going 11s it works just fine on and off the street.


               Harry

[Tunnelwedge]

     "Yukon",  off-shore manufacture.   

      Scott.

Pretty sure Eaton is "off shore". The main office building is in Dublin, Ireland. For tax avoidance.
Very kool Guinness Beer tour if your in town. One of the oldest taverns in the world is just down the street.

[Gaugster]

I upgraded to Moser 31 spline axles and the POWERTRAX® Grip Pro. This is another spiral lock gear system. Great road manners and no complaints. Mine is a pure street car however. I guess a question is do you need the axle upgrade and could you put those funds to better use on a quality center section?