Posi units

[Stangman]

So I have a traction lock posi unit for years and it’s starting to make noises going around turns. So I have been looking into a True track unit with the helical gears to get rid of the clutches. There’s a couple of different manufacturers is the Eaton one a good unit.

[cammerfe]

Eaton has a good name. Others here will undoubtedly chime in with info as to the likelihood of it being best for your purpose.

KS

[Jb427]

My truetrac is silent I hear one click when I exit my driveway it has a high cross slope I can't tell if it is the truetrac or my caltrac's when I turn and cross centre and it dose not make any sound turning into the near lane that makes me think it is more my caltrac's

no sound even doing the tightest of turns

I think Eaton is the go to brand

[HTRDHARLEY]

Tru Trac is a good unit although now manufactuered off shore. DO NOT use synthetic fluid. Only time they have not worked well is during Auto-X in a heavy car.

 At the drag strip or street use they are great.

 I also use the Wavetrac with great results and it is American Made. This has been my go to the last few years. I have wore out several Trutracs, but I also put allot of race miles on my stuff under some tough conditions.

[Rory428]

I have never owned, or driven a vehicle with a Tru Trac, or any other helical style locking differential, although I have talked to some people that did like them. However, none of them race their cars at the dragstrip, with slicks, and a manual transmission, my concern is all those small gears being able to stand up to hard, clutch drop dragstrip launches, so I have a 31 spline Detroit Locker in my 428 4 speed, 4000 pound 59, that sees one or 2 dragstrip outings per year (with slicks), and my drag only cars always get a spool. The Detroit Locker is clunky and noisy at times, but it always locks at the dragstrip. And it will pull to one side quite noticeably if you get on the throttle before ensuring the car is pointed straight long enough for it to lock after a curve or corner. Ford Traction Loks are barely worthy of consideration, between the weak, crack prone side covers, low number of clutch plates, compared to most other limited slip units for other rearends, mainly due to the design of the 9", which prevents the ability to have clutches on both sides, like every other differential, due to the rear pinion support being in the way. The cone style units, like the Auburn units can work well for a while, but once they wear out, they are unrebuildable, as they essentially eats themselves up as they wear. Again, they don`t seem to like the higher shock loads of a stickshift car with a clutch on slicks, a buddy destroyed a brand new Auburn "Pro" series in 3 passes in his 5 speed 12 second 5.0 Mustang at the dragstrip. Does anybody actually have any experiences with a Tru Trac on a stick car that gets raced , on slicks, at a dragstrip on a regular or semi regular basis?

[gregb]

I put Eaton Truetracks in both my cars, Mustang and a Chevelle.  Quiet.  I would never go back to a clutch pack unit.  Both street cars.

[HTRDHARLEY]

As mentioned, I have many laps on all kinds of traction devices. Im 4430# without the driver. 700+ HP Fe with a TKX currently. Gear ratios are anywhere from 3:70 to 4:30 depending where I race.

 I have broken several TKO 600 transmisions, but never the rear. I have wore out the helical gear units, with many race miles on a road course.

 Part of what I do also requires some drag strip passes. I have to run a 200 or 100 tread wear tire, so not exactly like a slick. I do dump the clutch anywhere from 2800-3600+ depending on how the track is hooking.

 Would I run a Trutrac in a drag car on slicks? No. I always ran spools or lockers. Would I run it on a street car with a few passes per year at the drag strip? Yes. The street manners are really good, cornering is improved over any clucth type or locker differential.

 For what I do, so far the toughest and most relaible has been the Detroit Locker, although I sacarfice some handling in the corners.

 Every unit has its application, if its only a set of drag radials a few times at a drag strip per year, little or no road racing or auto -X I would recomend a helical unit just based on street manners.

[6667fan]

Ran a TrueTrac for several years, including passes at track with slicks and 4K clutch dumps. The unit was in a Ford housing which kept crushing spring perches, ( including reinforced ones).So when I upgraded to a complete Strange third member I asked them to put a TrueTrac in it. They were n/a at the time so I went with a Detroit Locker. I can’t say if the newer TrueTracs have any issues.
Guess it’s up to Joe to figure out how many trips to the track are in car’s future vs the arguably more bulletproof but noisy Locker unit.

(I get a little twitchy when I hear the word posi in this discussion, lol).

[pbf777]

      Any rear differential equipped with pinion & side gears in its' design is going to be more sensitive to shock-loading than those without.  And this is a problem with Auburn units, along with the issue of their steel on steel conical clutching which can be damaged.   

      The worm gear units suffer less often from their internal breakage, but not totally, because of the greater surface interaction of the gear sets, including the surround support of the case which supports the worm gears from defection, and the fact that a great sum of the resultant force is a compressive thrust loading in in their length rather than so much a deflective force.  Unfortunately these type units are not immune to wear and their function is greatly reliant on friction which is sensitive to the surface texture of the gear sets.  If not broken, but only failing to provide the "posi" effect as was when the unit was newer, I have found that a good abrasive blasting of the gears, ruffing-up the drive face surfaces will usually bring them back to functioning reasonably.   

      Though remember, the only "differential" (not a spool) that when your spinning the rears, that both tires are turning together at the same rate is the Detroit Locker; and as it doesn't contain spiders & side gears it doesn't suffer from that failure problem and is probably the least failure prone unit available other than a spool.  But O.K., maybe not the quietest.   

      Scott.

     

[cleandan]

I have driven with Detroit Lockers, Detroit Tru-Tracs, Trac-Loc's, Equa-loc's, Auburn street and Auburn Pro's, and quite a few others that don't matter here.

I recently installed a 28 spline Tru-Trac in a 1965 Shelby GT350 with 3.70:1 gears that also got a T5, 5spd manual.
Prior to this it was stock with a T10, 4spd and 3.89:1 Detroit Locker.

The Detroit Locker, at least in my opinion, is the clear winner in the traction and durability area if you also want some differential action in the rear end.
The Yukon Locker is a good option in a Detroit Locker style unit as well.

The D-Locker does exibit some driving quirks that must be understood so they don't catch the driver off guard....like on/off throttle in a curve (highway on/off ramp is a great example)
The D-Locker can impart odd steering responses if it either locks, or unlocks, during a corner under power application.

The D-Tru-Trac does not have this issue.
As a matter of fact I have found the street driving manners of the car to have improved over the D-Locker with the Tru-Trac.

The Tru-Trac will still scuff a tire around a sharper corner, (think right turn at intersection), while getting on the throttle to pull out into traffic....Not hard throttle, just moderate throttle to pull out and get going.
This also causes chirps as the tires go over the painted cross walks and turn arrows.

But getting on, or off, the throttle during a longer curve (think long curved on/off ramp but not quite a cloverleaf) does not exibit any steer like a D-Locker does.

They are also quiet, basically silent compared to a D-Locker.

The version I installed is from Eaton and I used the supplied Lucas 85W-90 standard gear lube....Lucas is a good product so no issues there.
But this unit was clunky and noisy at first so after about 500 miles of break in I changed out the fluid for 85W-140 and things are happy, silent, and running well.

I've only got about 1,500 miles on it so far so I can not give any long term use in the vehicle.

The Auburns I have dealt with were behind a 408 stroker in a Fox Mustang with slicks, or drag radials, running in the mid 10's in the 1/4 mile.
The standard Auburn was ruined in two passes, and it was suggested to switch to the "Pro".
The "Pro" lasted about 8-10 passes before it started having issues.

But, seeing as it was otherwise new I decided to try to rebuild it just to see if I could.
I did rebuild that "Pro" and it has been working perfectly in a less powerful, street tire vehicle ever since.

If you need ultimate traction, along with some differential action, the D-Locker is your huckleberry.
If you are working with less HP, (under 400) and less traction, (tires that will spin rather than try to hook hard) in a street driven vehicle...even a spirited street vehicle, the Tru-Trac is a great option.

[pbf777]

The standard Auburn was ruined in two passes, and it was suggested to switch to the "Pro".
The "Pro" lasted about 8-10 passes before it started having issues.

     Basically the difference is only that the "Pro" presents a greater spring preload so as to resist an initial single-side event which then would cause a reduction in the loading and effectiveness of the cone-clutch.   

     Scott. 

[Stangman]

I used to have a Detroit locker and yes it was clunky but I really didn’t mind it much. My car is fairly light around 3500 with me in it and I am running an automatic. I dont really drive a lot of miles maybe only 300 to 400 a year but I do drive it a lot. A lot of 10 mile trips for a ride. I was going to the track like 3 or 4 times a year but the last few years only once a year. I’m leaning towards the true trac but the locker is only 50 dollars more.

[6667fan]

Joe, for that amount of driving the TrueTrac will likely do everything you want with less “personality”
JMHO

[69ramair]

I only have about 300 miles on my Eaton tru trac 3.89 gear set in a 1969 mustang 464 automatic 275 50 15 Mickey Thompson drag radials. Mostly hard use. No issues so far excellent manners on the road   As mentioned above no synthetic oils or additives

[Stangman]

I only have about 300 miles on my Eaton tru trac 3.89 gear set in a 1969 mustang 464 automatic 275 50 15 Mickey Thompson drag radials. Mostly hard use. No issues so far excellent manners on the road   As mentioned above no synthetic oils or additives

So regular 80-90 weight. Obviously no additive because no clutches.