Is the H1 differential a Detroit True Trac? I know the True Tracs require slight resistance to lock up and I used to ride/pump the brake a little to lock up the differentials on my HMMWV to get all four wheels to turn when stuck. The H1 are/were Eaton and the True Tracs are supposed to also be Eaton just renamed.

Are they one and the same or at least an improved version of the H1 Eaton diffs?

Do you mean as stock? My 95 did not have any kind of axle diff lock. The brake gas modulation thing (BTM?) is a way for the center diff to equalize.

When you go in reverse on dry pavement, do you hear a clicking from the diffs? If so, then you have a Tru-Track.

Eaton still makes the pinion type differential, I see them a lot at work.
They do not perform in light weight vehicles, because as you stated, they need some binding force to work. (read: heavy ass F-550 or bigger) .They are extremely expensive also.
They also do not 'click' when functioning in forward or reverse.
ETA: Derp, I was thinking H3 body for some reason.  Yeah, the H1 bodies do use trutracs in the rear that I've seen.



 

I know they are both Torsen type LSD's, but I don't think they are the same.  I had a Truetrac in my Nissan Titan and thought it was outstanding, but it never truely "locks".  It sends more torque to the wheel with traction (up to a 3:1 ratio IIRC), but if one tire has zero traction (example: off the ground) you may end up with no power being sent to the wheel on the ground.  The Truetrac can be "fooled" by lightly applying the brakes in this situation.

I heard the H1 used that type of limited slip.  Also that the drivers are trained to use the brake technique to get through low traction situations.  

The detroit truetrac has no clutches to wear out.  It operates very smoothly, and works extremely well in nearly every situation I encountered.  Riding the brake slightly is all I ever needed to do even on ice.  

I had also heard that the camaro used this type of differential.  Don't know, and I'm too lazy to google it.

From 1992 to 1998 they used a Torsen 1, from 1999 and up to and including 2004 they used the Torsen 2.  Electronic lockers (Eaton) were available as an option for the rear starting in 2003, and then in both front and rear as an option for 2004.  They used the Torsen 3 in 2006 (final year of production), and the E lockers in front and rear were an option as well.

None produced in 2005.

http://www.flashoffroad.com/features/Torsen/torsen_differential.htm

The True Trac is a torque-sensing differential, similar in principle to a Torsen branded differential. The HMMWV uses Torsen differentials, not the Detroit/Eaton branded TrueTrac. There's a Torsen T2-R that also uses clutches to help out.





I did run a True Trac in my Crown Vic and blew out the side cap bolts on the differential causing some issues. They supposed fixed it in the 3 pinion units for the Ford 8.8", but I didn't appreciate the fact I was out $400 due to a design defect. This was apparently known on Corner Carvers since 1999 and I blew up the diff around 2004. The 3 pinion units came out maybe 2005? and you can tell the difference in the # of side cap bolts.

I drove a military H1 for years up to and including when I was a PLT SGT and no assigned driver. I stumbled across a training video for a drivers course the SF guys attend and the civilian instructor was talking about the brake application to lock all 4 wheels during off roading. Tried it myself it works great.

I asked my original question as I read an article in a 4x4l magazine talking about the True Trac being the same as the old Eaton. I know the early/mid 80's model military H1s had Eaton differentials front and rear as they were interchangeable. I ask as I am working on a M715 build with a Dana 60 upfront and a 14 bolt in the rear and was contemplating a True Trac for the front. I'm not a big fan of electric or air lockers. Too many extra parts and you won't know if/when they failed until you're stuck.

Swapping the pickup body for a Wagoneer body shortened to look like a crew cab body and a severly shortened bed. Going to run 38-40 tires and maybe beadlocks. Big block Chevy and tranny TBD. I am going to put some kind of overdrive in it as I plan on 4.56 - 4.88s depending on final tire selection.

Like I said in my prior post, I had and really like the Truetrac.  However, IIRC, Eaton recommended not running 35" or greater tires with it.  I'm not sure why or even if they still make this recommendation, but if you're running 38+, you might want to check with them first.  

Go full Detroit and be done with it.

The True Trac jams the internal pinion gears against the side plates. That's why the 3 pinion True Trac units have pairs of bolts for each contact point. The 2 pinion True Tracs only had 4 Grade 8 bolts and I snapped 3 of them clean off with my puny Crown Vic. I wonder if the taller tires would make the True Trac units fail prematurely?

I have to chuckle when I read the advertising describe some of these diffs.  The Zexel Gleason Torsen diff as used in the original HMMVs doesn't "sense" anything.   There is a torque bias depending on the traction available with both wheels.  The worm gears essentially bind and allow power to be sent to the wheel with the most amount of traction.  The problem is that when one wheel has zero resistance as in a wheel in the air, it can not function properly and no torque is applied to the wheel with traction.   There was no internal preload with this design.   There was also a tendency for the diff to chew itself up.  We (I) replaced pallet fulls of the original Torsen diffs in the Marine Corps.  We were not allowed to order the updated diffs until we exhausted the considerable supply of the inferior ones which were half the price of the updated ones in the system.  The busted units would come in and we would order replacement parts and service them.

No...  There are no additional stresses placed on the diff with taller tires on a car.   You would have to jack a
Crown Vic up crazy high in order to get truck sized tires under it .

I'm running BFG All-Terrain T/A KO truck tires (Load Range D) on my Crown Vic. They're a few inches taller than the stock tires. It has stock suspension settings, but I am running the OEM clutch based limited slip differential. No problems to report because the differential doesn't really see anything different versus the OEM shorter tires.



The Torsen brand differential went through a few name changes:






 

The 8.8 Track Lok is not preloaded all that much so there is not alot of stress on it.

Funny considering HMMWVs have 37" tires. I saw my share of Broken half shafts but very few chewed up differentials. I am looking at a True Trac for the front. I am not putting a Detroit locker in the front. It will get driven on the road some and need a little less wear and tear on parts when possible without degrading offroad abiltiy too much.

IMHO the TT is an ideal front diff, but it's also a good rear diff for many applications.

I think the H1's use a Truetrac type worm gear diff........but it's not a Truetrac.

I've seen Truetracs eat themselfs in Mustangs and Jeeps.   They're not the most durable diff in the world.   I'd rather have a full Detroit rear and an open or Ox selectable front.  

I love Detroits in the rear.  Automatic operation that is allways there when I need it and it deosn't need switched off in turns.  If you never use 4wd when on the road, and have manual hubs or can add manual hubs, in snow conditions for example, then a Detroit is great up front as well.    But if you use 4wd for winter driveing, never put an auto locker up front.