AAM Tracrite GTL - NEAT

"HammerheadFistpunch" (hammerheadfistpunch) 03/06/2020 at 15:34 • Filed to: neat, diffs, don't judge my sickness

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You may have heard I like differentials... !!!error: Indecipherable SUB-paragraph formatting!!! ? Well I do! Anyway I was having a chat with a fellow Land Cruiser nerd this morning and he was telling me about his new Power Wagon 4 wheel camper. He mentioned something I did not know about the Power Wagon and now I’m kinda geeking out on it: The locker in the back, it turns out, is really neat.

This is a Tracrite GL, but not the cooler GTL in the Power Wagon. True to AAM form there is zero information and zero good pictures of any of the products I happen to be actually looking for. They are either intentionally cagey or the absolute worst marketers in the world.

Here is the best version of this diff I could find and then I cleaned it up a little.

Anyway, if you know diffs you probably know you are looking at a helical or Torsen type diff, which is an LSD...and a really good one.

“But an LSD isn’t a locker HHFP and the Power Wagon has a locker dum dum.”

Well...yeah...hurtful but true. Thats the difference between the GL (top) and the GTL (bellow). The GTL takes a the standard Torsen and adds an electromagnet and pins that allow for true locking. Im only guessing here, but what I would assume is that its a ball ramp mechanism. i.e. the current is applied to the magnet, which stops a plate from rotating freely with the carrier and thus forces ball bearings up a ramp and forcing a top plate, or pins up and into the side gear, locking it to the carrier and thus bypassing the differential gears.

At least thats how I think it works. It could lock the side gear without ball ramps which would be ideal since ball ramps require rotation to apply their force. T hus the diff isn’t locked until you move forwards and it temporarily unlocks if you change directions as the balls ramp down and then back up in the opposite direction.

Anyway, I think it’s really neat. It gives you the total control of a Torsen diff in 2wd and 4hi which aids traction everywhere up to a total wheel lift, and then lock the sucker in 4lo in the event you plan to lift a wheel. Plus because it’s electric (boogy woogy woogy) it doesn’t require an internal or external solenoid or air lines. I wish my lockers were also Torsen’s...but Im a choosy begger so...

As a bonus it works and is available aftermarket, for ANY AAM 11.5 or 10.5 rear differential, and actually 9.25 front diffs. This means Chevy too, in fact the 9.25 fits the front IFS diffs in some chevy trucks and because all you need is 12v you can just pop it in and go.

The downside is that I hear they can be very slow to engage or disengage but I feel like people who complain about that have either never used electrically switched lockers before or are just habitual complainers.

Arch Duke Maxyenko, Shit Talk Extraordinaire > HammerheadFistpunch 03/06/2020 at 15:40

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Is it like a Wavt rac?

http://www.wavetrac.net/different/

HammerheadFistpunch > Arch Duke Maxyenko, Shit Talk Extraordinaire 03/06/2020 at 15:43

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kinda sorta.  They are both torsen diffs at heart.  While the wavetrac tries to lock automatically via ramping the AAM one will only lock with a signal. 

If only EssExTee could be so grossly incandescent > HammerheadFistpunch 03/06/2020 at 15:43

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It looks like the inside of a pencil sharpener

HammerheadFistpunch > If only EssExTee could be so grossly incandescent 03/06/2020 at 15:46

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Pencil sharpener tech is too expensive for automotive use...

Jim Spanfeller > HammerheadFistpunch 03/06/2020 at 15:47

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I still don’t understand how a T orsen diff works. They baffle me. I feel like at some point I need to get one JUST so I can finally see in person how it actually works.

wafflesnfalafel > HammerheadFistpunch 03/06/2020 at 15:55

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and “leaded” fuel is no longer allowed

Rusty Vandura - www.tinyurl.com/keepoppo > If only EssExTee could be so grossly incandescent 03/06/2020 at 15:57

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My students struggle at operating these. Srsly.

HammerheadFistpunch > Jim Spanfeller 03/06/2020 at 15:58

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They took me a long time to wrap my head around. The easiest way would be that the diff can turn the half shafts but the half shafts can’t turn the diff but they try because of the special cut of the gears.  that resistance is applied as friction into the case and acts as a clutch to bind up both sides with a limited locking effect.

For Sweden > HammerheadFistpunch 03/06/2020 at 15:59

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I’m just deferential to differentials

Snuze: Needs another Swede > HammerheadFistpunch 03/06/2020 at 16:03

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I’ve been reading about Torsens a lot recently. I am in the planning stages for a potential project and was looking for a rear to use. Turns out from 2002 to 2009 you could get a Ford Ranger FX4 with an 8.8" rear that was filled with 4.10 gears, heavy duty 31 spline axles, a Torsen, and disc brakes! Not super heavy duty for an overland rig, but maybe good for a smaller crawler?

Also, when I was in Formula SAE we ran a custom Torsen style rear. The car was chain drive, so the differential was fully sealed with the ring gear and carrier bearings external to it. W e filled it with a high viscosity silicone fluid and had pre-load b ellvue washers in it. That thing would lock up tighter than... I dunno... something really tight!

RamblinRover Luxury-Yacht > Jim Spanfeller 03/06/2020 at 16:34

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If gear trains were lossless, Torsens wouldn’t work. Because real life gears push each other around in strange ways, the Torsen deliberately does what would be Dumb Things in designing a gear train to make sure the whole thing binds up when you want it to.

Imagine if you put a series of Lego TECHNIC gears together with a big gear either side and a little gear in the middle.

It would be really easy to turn both big gears together from the middle, but if you try to turn one big gear from the other big gear, the whole thing binds up a lot - at least you’d know that if you’ve ever done this. Due to the torque required at mechanical disadvantage to turn the little gear and make the little gear spin faster, and it thrusting off the other gear in the process - the whole thing is much, much harder than if the two big gears meshed directly with each other.

Torsens are basically that, but much worse. On purpose.

RamblinRover Luxury-Yacht > For Sweden 03/06/2020 at 16:35

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There are some people who are deferential only because they’re indifferent. It’s the people who are deferential but differ about differentials who make a difference.

TheRealBicycleBuck > If only EssExTee could be so grossly incandescent 03/06/2020 at 16:57

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The first time I saw that, I was in 2nd grade. Right as I put my thumb on it to feel the gears (kids are stupid), another kid cranked the handle. My thumb had a neat row of slices which bled like crazy. The teacher was not amused.

Snuze: Needs another Swede > Jim Spanfeller 03/06/2020 at 17:15

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HFV has no HFV. But somehow has 2 motorcycles > HammerheadFistpunch 03/06/2020 at 19:06

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So that’s not a pencil sharpener

Longtime Lurker > HammerheadFistpunch 03/08/2020 at 01:30

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Interesting. Side note we had a F150 in the shop recently for a diff inspection. It had the factory Ford locking diff, the mechanics noticed that it also had clutch discs in the diff as well.