Detroit TrueTrac in a 10.25 rear
- Thread starter runaway!
- Start date
bobracing
Full Access Member
Can't say I've run one but am a fan of the TrueTrac, seen them at work and they do work well. It's a gear driven LS that doesn't require any special gear lube.
Wouldn't have a problem running them for street use, front and/or rear.
Wouldn't have a problem running them for street use, front and/or rear.
GOOSE
Happy IDI'er
I had the old fashioned Detroit Locker in my F100. I wouldn't think twice about running that in my crew cab. It makes the truck a whole new animal in the snow and off road.
Had one in the rear of my F250 for about 6 years or so. Love it. Works much better than the factory LS's and no friction modifier to add to the gear oil. It will occasionally bark the rears on sharp turns, but not nearly as bad as a full Detroit Locker.
Highly recommend.
Heath
Highly recommend.
Heath
PwrSmoke
Full Access Member
I have one too since about 2005. Love it fully and completely! It has a high bias but because it's gear driven, it doesn't bark much (if at all) unless you power out of a turn hard. It's really good in snow because it doesn't have to break away as a clutch type unit does. In order to differentiate in a turn, the clutches have to slip... break away. What happens when there isn't enough grip at the tire to break the clutches away? Tire slippage and a possible loss of control. The TruTrac will keep both tires rolling... providing grip... unless you it the foot feed a little too hard. In the dirt, it's very positive as well. The only place where falls down a little is when you lift a tire. Since it doesn't have those preloaded clutches, it goes a little more "open" with a lifted tire. A little application of the parking brake or the foot brake helps it bias better (just like an older Hummer, which used these types of diffs). No FM additive needed, but Eaton wants you to use mineral gear oil and not synthetics.
That strikes me as odd...any idea what the reasoning is behind that?
Also, just out of curiosity, can this be installed as a DIY, or does the install involve setting ring & pinion lash and whatnot?
PwrSmoke
Full Access Member
It's all about the friction characteristics. The gears use a combination of friction and helix angles to provide the "braking" to bias torque. Most syns have less friction, so it alters the bias ratio. They have also noted that some syn oils cause a squeaking noise. I ran Amsoil in mine for a while and noted no odd behaviors or noise.
As to installation, you have to remove the carrier. You need to know enough and have tools enough to reproduce the original settings (reuse the shims) and press new bearings onto the carrier. At the minimum, you need a dial indicator with a magnetic base for checking backlash, a torque meter, torque wrench and a case spreader is very helpful. It ain't brain surgery but you have to do it right.
i was recently researching LS devices and this is the one that really stood out at me.
only one issue,and it's not a minor one.
can't use synthetic gear oil!
with these fuel prices,id rather just keep chaining up than swap back to the old sludge in the rear.
wish we had an e-locker solution.perhaps the ones offered in the new super duties can be swapped in......if you can find one from a totaled truck or something.
only one issue,and it's not a minor one.
can't use synthetic gear oil!
with these fuel prices,id rather just keep chaining up than swap back to the old sludge in the rear.
wish we had an e-locker solution.perhaps the ones offered in the new super duties can be swapped in......if you can find one from a totaled truck or something.
Ataylor
Full Access Member
I have a Tru-Trac in the rear of my truck. It has been great. I have been stuck on the same grassy hill many times trying to back up a trailer with the stock open diff. With the Tru-trac it was like I had put it in 4wd. I have never noticed any bad driving characteristics with it in the rain or snow as long as I don't stuff my foot in it.
Archie
Archie
Like Jim, I've had synthetic gear oil in my rear axle for years. No issues. Not sure I remember seeing anything about no synthetic gear oil in the literature that came with mine.
Heath
Last edited:
PwrSmoke
Full Access Member
Heath- Yeah, they have it on their website, my instruction manual says it and I've spoken with their engineering people about it. They say it will decrease the bias ratio a little but they are most worried that some syn oils have produced squealing noises. I gather these were some time back, so who knows with today's syns. Also, I think they are just carrying on with the same-old. My personal opinion is that since this unit was developed in the '70s, it was designed around mineral oils and they know the exact performance with those types of oils. They have had a few issues with syn oils over the years and AFAIK, they have not retested with syns to verify compatibility. I doubt they are inclined to undertake a bunch of testing just to change the oil recommendation. There are several types of "synthetic" oils, some that are quite different from each other (i.e. PAO vs Ester) so they could potentially open a can-o-worms and spend hundreds of thousands of dollars to test all the different oil formulas. If I were the boss, I wouldn't bother. I know of many people using or have used synthetics in Truetracs with no issues. Only know of one that had trouble... and he had the squeal (more like a squawk). But that was many years ago and on Mobil 1 gear oil.
