Eaton Truetrac are designed for medium duty 2WD and 4WD applications. They work well in the front and rear, and are so smooth that there is little or no hint of resistance in the steering wheel when used in front drive steering axles. Like the Gleason Torsen, the Eaton Truetrac does not bang or clunk, has no clutch chatter, does not wear out like clutch type positractions, does not need limited slip additive, and needs no preload or clearance adjustments.
They use worm wheel gears that work on the same principle as a worm gear. When the unit is loaded, the worm wheels are forced away from each other and against the case. They develop locking torque by the light friction between the worm wheels and the case. This light friction is multiplied by the ratio of the worm wheel which depends on the size of the worm wheel relative to the size of the side gear.
When I had my 01 2wd Yukon with this installed I could drive through most things. Control was superb, would even drive in deep mud. Could get out at idle speeds and both tires would spin in place, hop back in and give throttle. Would push right right out of low traction situations. Also handled the abuse of drifting with ease.
Funny, in a very good way, how the comments posted here by whoever it is at SUMMIT seem to explain the Truetrac's operation, application, limitations and performance within those limitations better than anything I have seen on RU-vid so far. Within these comments are nuggets of wisdom, experience and knowledge posted by those folks handling this YT Channel for Summit Racing. Bravo, fellers! Bravo.
Just replaced the stock clutch based LSD in my Jeep with this unit. What a difference in traction. Instant lockup, feels like there's a locker back there and it handles the rain with no weird handling. Tested it out by putting one wheel on pavement and the other in dirt and stomped on it. Jeep took off like I was on pavement with nearly no slip on the dirt side wheel. Amazing unit, quiet too.
I put one of these in the Suburban we take camping and tow our old bass boat with, I absolutely love it. This differential really helps with GREAT traction in the rain and on slippery boat ramps.
When used in situations like rocky trails where one wheel gets off the ground, the unit will not lock up 100%. Light application of the brakes will help the differential engage more transferring power to the tire that is still on the ground. For extreme situations where the vehicle will have one wheel in the air often a locking differential provides better power transfer to the wheel on the ground.
So for off road applications it’s better to go with a Detroit locker that will just ratchet around corners cause you don’t need the power transfer so this would be better for race car applications where you want as much power to the ground as possible
To my understanding, new vehicles such as the 2024 Sierra, automatically actively engage the brakes in stock form to provide traction to the opposing wheel. Are these True-tracs suitable for newer vehicles that have this feature? Are there any downsides to applying this the the rear of my Sierra?
@@christophermoore3785 YES. In fact, with E-limited-slip equipped vehicles (mechanically, this is an open diff but with the aid of the vehicle's ABS hardware), the Traction Control software will add a little brake to the spinning wheel, effectively engaging the Truetrac operation. It is perhaps an unforeseen advantage making the Truetrac a perfect candidate for vehicles with such systems.
I had one of these(GM 10 bolt, 8 1/2" 3.23), put in my '79 Buick a few years ago. It works great, I went through some deep friggin' snow/ice over Donner Pass with chains on and it handled well, not scary at all. I'm going to put another one in my kids car, maybe a 3.08 : ) Only thing they say is to keep equal tire pressure/diameter and even wear on the back tires.
The manufacturer can change the amount of torque biasing or lockup by simply changing the diameter of the gears, or the pitch and spiral of the teeth. A larger difference in the size for the worm wheels and side gears (smaller worm wheels and larger side gears) will increase the lockup force. Increasing the pitch and spiral of the teeth will also increase the lockup forces.
Just got this installed in my gmt800 after the original diff gave out at 230k. It's only in the rear as my truck is only 2wd, but coupled with 4.10 gears, she hooks up nice and inspires confidence at speed. Even just today in the rain, nice and composed when it needs to be, wild and fun when it wants to be. Well worth it imo.
Yes that’s correct, when a wheel slips it engages. Under normal driving & road conditions, this unit will last the life of the vehicle. It is not designed for huge tires, extreme off road or ultra high horsepower. It is designed mainly as an upgraded replacement for factory limited slip differentials.
@@nemesis851_ Tire weight being a factor. Imho, 37s may be a practical limit for such a simple device like the TrueTrac. If one is running 40"+ tires, they're usually also upgraded to 1-ton axles or at the very least 3/4-ton components for which there are some outstanding, very beefy, air- or electric-lockers with greater strength.
Like everything, there is a limit as to how much lockup force is reasonable. Making the unit too "aggressive" will cause tire scrub during everyday driving and will cause the unit to wear out too quickly. All of the feedback that I have received from customers indicates that the unit works very well for mud and snow, while going unnoticed during every day driving.
I’ve read that these are great for front differential applications in non-hardcore applications. I had Auburns in both ends of an F150, and it would get a little twitchy turning in snow with the hubs locked.
I have a detroit tt in my 95 z28 camaro from moser who built a 12 bolt for me to get rid of the 10 bolt that i had rebuilt for me 3 times. After the 3rd time breaking the 10 bolt i said screw it and paid the 3 grand. All i said was i wanted the latest and greatest and they suggested and True Trac instead of a clutch pack limited slip differential. I love it. It even has a slight hum to let you know it's tough and ready for abuse. The only problem ive had with my 12 bolt is a right side axle seal leak. So i give a Tru Trac a 10 out of 10.
had one of these units installed in my 02 silverado z71....best thing money i ever spent on it...well besides my vigilante and trans upgrade haha..honestly though, huge difference, posi burnouts, great handling in inclimate weather, good stuff
@gasripper2 That is when you press the brakes to get some traction on both wheels. I know it sounds weird but that's what they teach you in the army to do and it works. The explanation is simple when you brake the light wheel slows down and it forces the locked one to go.
Only then will the torque transfer occur - when it is needed. As with an open differential, the TrueTrac side (or spider) gears are interconnected by pinion gears, which allow one wheel to slow down or speed up as required. TrueTrac gears have spiral teeth and the pinions are mounted in pockets in the case.
@deezynar it's on the older Hummer and military HUMVEE driving manuals somewhere that if you apply the brakes to the spinning tire, it will force some of the torque to transfer to the other side. This is the same thing a limited slip will do, take some of that wasted torque and transfer it to the tire with more grip by providing a certain amount of built-in "braking" action for each axle that simulates traction.
From looking at diagrams and pictures of this differential, I have concluded that the torque-biasing works due to the helical nature of the gears. As the input torque increases, the "sun and planetary" gears are forced into the walls of the unit, creating friction and turning the wheel. Whatever wheel has more resistance to movement (taction), therfore receives more horizontal force, resulting in increased friction on the gears, thus the torque bias functions.
Hello Summit i have this Exact one in my 85 chevy Caprice and its been in my car for 2 yrs now and it works really well. i have 3:73 gears also Love it
I put one of these in my Jeep and my Bronco. After that, I rarely need to go into 4WD even in snow, sand, mud, etc. at least on level ground. Still need the front wheels for uphill slippery slopes.
Truetrac differentials are unique in that they increase traction but do not affect steering or wear out prematurely; these problems are common with limited-slip differentials that use clutch plates and springs. A TrueTrac performs like a conventional (open) differential, until there is a loss of traction.
The one in my 2010 Chevy Camaro SS manual coupe, came with a super noisy rear diff at around ~19k miles, despite me changing the gear oil and seeing that it appeared to be decently clean and barely having metallic particles. Maybe the prior owner did the rear diff gear oil change and didn’t use the right weight of gear oil, or maybe forgot to get a formula that included limited slip additive? Cold starts when I first got the car, would have my car turning more than a 1/4 way, to start groaning and clunking. It scared me so much, I’m an idiot for even getting the car. I did my first gear oil change (simple drain and fill) with a semi-synthetic (?) Lucas GL-5 80w-90 gear oil. It supposedly contained “additives”, but nothing that suggested LIMITED SLIP specific additives. It probably meant friction modifiers or some other stuff. Either way, it surprisingly cleared up most of the noise, but was still groaning half as bad during cold starts. The diff would be fine and quiet after reaching optimal temps, which it didn’t before, which also prompted me to believe that someone may have also used a super heavy weight, such as 75w-140. But weren’t these things able to warm up decently? On the dealership test drive, I drove on the freeway for a solid 15-20 minutes, and was also doing a lot of turns and full steering locks around the dealership area during the test drive. Regardless, I stuck to 75w-90 gear oil, but decided to go for a Mobil1 semi-synthetic(?) GL-5 gear oil that contained LS additive already added(‘High Performance’ was the model of the gear oil, I believe). This was my 2nd gear oil change since getting the car and I still didn’t see much metal particles on the magnetic drain and fill plugs for the rear axle differential, but flushing the gear oil probably helped some, as it got to maybe 30-35% as loud as when I got the car. I finally decided to flush it for the final time until this day, which I used the infamous Royal Purple Max Gear 75w-90 that everyone in the Camaro5 community recommends. It comes with LS additive, as well as being a ‘Synchromesh’ specific GL-4+ (GL-4/5) rating, which was safe for yellow metals, such as brass (used for most gearbox synchronizers). Now, this finally got the rear diff to shut up and stay quiet up to a good 10-15% as loud as when I first got the car. However, really cold days (50 F or lower), will have the rear diff groaning just a bit longer (takes longer to warm up probably), but not any more louder! I’m pretty okay now, and dodged a bullet with trying to hassle Chevy to go through the process of trying to work with my rear diff issues, which they did NOT try to address AT ALL whatsoever (that’s a WHOLE other crock of beans…). I may or may not actually try some of the OEM AC Delco gear oil and separate LS additive formula, to see how well it stands up to the aftermarket support products. But as of right now, I don’t plan on adding EXTRA LS additive, like most ppl do to quiet their diffs down, bc I fear of adding too much and having excessive slip that might cause ‘one-wheelers’ with literal straight line driving!!
@MudBarf I think, basically, that the pinion gears get "locked" in their cups in the carrier, until in a turn the outside wheel over-runs the inner, causing its associated pinion gears to become unloaded and allowed to turn. Probably I'm wrong, but it seems similar to a standard open differential except that under load both axles are locked together unless in a turn.
@alcram Thanks, that's interesting. Did you have a lot of traction problems with these units. Theoretically, you should be able to take one drive wheel off the vehicle and support the axle on a wheeled dolly and the remaining drive wheel should push you down the road.
This type of differential is designed primarily for street and light Off Road operation. It is not designed for continuously abusive situations such as Drag Racing, Truck Pulling or Rock Climbing. Please let us know if you have any additional questions. Thanks for watching!
I have one in a 2007 Mustang GT with a Roush supercharger and 5 speed. Killed the plate posi 1000 miles after installing the supercharger. TrueTrac is the way to go for street use.
If one wheel begins to lose traction , the pinions separate slightly from the side gear and wedge in the pockets. As torque increases, the separating force increases, thus slowing or stopping the spin-out. This allows torque to be distributed to the wheel with the best traction.
gasripper2 sounds like a Ford problem I get 2 tires spinning even if I have one in the air 99.9% of the time I've had one spin a couple times but a little more throttle or stopping and starting again kicked the other one in. I'd have to say they are pretty strong. In my 98 k1500 I blew up 2 factory differentials so I decided to try the trutrac I liked the idea of no clutches or springs and no center pin to break. About 100k miles sense install not one problem and sense then the truck has seen allot of upgrades. Vortec 454 swap 5 speed manual swap and I abuse the hell out of the thing without a single complaint.
Oh...I think i thought about it backwards... Instead of thinking about it from the perspective of the tire that slips, if you look at it from the perspective of the tire with traction: The traction wheel applies resistance to the slip wheel to make it refrain from spinning..that is to say the system as a whole attempts to keep the slipping wheel going the same speed as the traction wheel...that makes a lot more sense...but I feel like you're losing drivetrain power in the resistance force.
This is a *TORSEN DIFFERENTIAL*. They're basically an *OPEN DIFF* when one wheel has 0% traction (off the ground, slipping on ice, or doing a "burnout" with one tire), so they aren't all that good for OFFROAD or RACING (because you'll lose power to BOTH wheels if one completely slips), but they're awesome for bigger vehicles that know you'll always have SOME grip at least. *Plus they're smooth, bulletproof, and quiet.*
Vladimirization Quaife isn't a brand? Quaife makes Metal Plates LSD, no? They also make Helical one? I know for sure Mfactory produces nice Helical LSDs.
Kind of but with the work gears rotated 90* and interfacing directly with each other side to side instead of through additional ring gears. This is simpler and lighter and probably has less parasitic loss than a Torsen.
@@flacjacket What do mean by "parasitic loss?" I don't have a lot of experience with differentials. Remove fill plug, remove cover bolts, pop cover/empty lubricant, clean internals with suitable solvent, clean gasket mating surfaces, check for damage, replace old gasket with new, line up cover to gasket to diff. housing, torque cover bolts in pattern to specs. fill with new (and very pungent) 80w 90 gearbox oil, replace fill plug, check for leaks. I've done that twice to open diffs.
Do you have to time the gears för this type of unit. I have seen the other type (torsen--1 or A) where the gears have markings and installs in a specific way. If yes on timing torsen type 2. Could you explain why, cause I can't see how it would make a difference :)
I have this unit on my 4X4 F150 and on the really rough stuff I have to apply a little brake to get it to work correctly. I am not sure if I would go with this unit again. I may go with the ARB
are these units going to perform as well for initial straight line grip as a conventional cone type lsd? (i understand neither will outperform a locker), or will it send the torque to the drive wheel and then bias once it loses traction? also with the friction created from the pinion gears while unit is 'locked', generate excess heat?
The old school cluthc type diffs take more abuse racing than any other. What happens with hard shock loads. The clutch types slip for nano seconds & still live. These others blow into peices.
@kingkruel123 Actual opposite rotation wouldn't happen in a car, the video is exagerated. This diff won't allow the 2 wheels to rotate at different rates without both of them having traction with the ground. If one wheel loses traction, the slipping wheel will rotate at the same rate as the wheel w/ traction because w/ out traction, it can't rotate its worm gear to let the worm wheel rotate, thereby keeping both axles "locked".
Is this designed to work trough continuous track day usage trough years? Also, it's the exact same principle as Quaife Helical ATBs right? Any major differences?
Ok, this is really bothering me. I've watched this 3 times. I understand the gear meshes, I understand how it allows differentiation through the gear movement, and I even understand (pretty sure) what they're trying to explain with the force diagram. What I still don't understand is how any of that gear meshing provides any resistance to the differentiation process. Is it basically by utilizing the friction created by jamming the pinion gears into the side of the pockets? (Fc) in the diagram?
damn. I'm putting one in my 2000 Z71 in a few weeks with new 4.10 yukon gears. Old open diff is making whining/howling noise when accelerating but quiets up when coasting. Shop is going to put in new bearings, gears, and I asked to upgrade to the truetrac. I'm on stock diameter 32" tires. Might get aftermarket wheels and 33's but that's all the bigger I'll go. I pull a boat, a car trailer, and getting a 6000 lb camper this summer.
When the spiral gears push apart, left to right, they push against themselves, the side gears, and the carrier housing. Notice the carrier has round holes where The spirals are, THIS allows the spirals to pass through and touch the case. The friction builds until it almost kind of locks and now you have traction to both sides. It's not perfect. You may have to hold the brakes a bit to induce that friction. Once you have, the power will transfer to the wheel with traction. U.S. Army vehicles runs this system.
When the spiral gears push apart, left to right, they push against themselves, the side gears, and the carrier housing. Notice the carrier has round holes where The spirals are, THIS allows the spirals to pass through and touch the case. The friction builds until it almost kind of locks and now you have traction to both sides. It's not perfect. You may have to hold the brakes a bit to induce that friction. Once you have, the power will transfer to the wheel with traction. U.S. Army vehicles runs this system.
@@xmo552 The TrueTrac employs a worm gear & worm wheel system and operates under the principal that a worm wheel can turn a worm gear, however, a worm gear cannot turn a worm wheel. When one tire starts to slip its corresponding worm gear is engaged with the corresponding worm wheel. Since the gear cannot turn the wheel it is locked and the torque is then transferred to the opposing worm wheel which turns the worm gear attached to the opposite axle. Thus locking the differential.
I just had one installed and it’s doing a lot of clicking on hard turns. Do ya think something may be wrong with the unit or the gear setup? I also just put a cheap STP 80-90 gear oil for the break in, should I put something different?
@@Long-nd8bq yes, I figured it out. It’s not the Detroit true track. It was the cheap gear oil. All I did was change to Lucas 7590 gear oil and it solve that problem. It was so weird but when I drained the cheap STP fluid it came out like water. It was so thin. I think the clutches/worm gears were binding because of lack of lubrication.
I currently have this unit in my '05 Mustang GT. My engine puts out 392rwhp (460hp flywheel). I'm thinking of supercharging my setup and will have around 680-700rwhp. Am I going to grenade the Truetrac? I use the car 70% street use and 30% road course. No drag racing in my future, which is where I understand they are most likely to explode.
Hi Danny Eddy, You’re correct, usage of slicks at the drag strip and dumping the clutch (shock loading) is where these units get into trouble. With your usage, you’ll be fine!
I have a Detroit truetrac and I’m having a clunking sound from starting off till like 10 mph and a loud roar while accelerating until I left off. I was wondering if there is a rebuild kit for the locker it self
HI Justin, Rebuild parts are available for the Truetrac. We would need to know the exact model number or application your unit is to offer the correct parts.
i have the same issue it slips horribly until it binds up its barely a year old less than 1k miles on it. they are made overseas so im not surprised im pulling it this weekend and putting in a clutched lsd
so the side gears jam the pinion gears into the pockets and the friction of the pinion gears cutting into the case make this thing work.. this thing would wear out pretty fast
Awesome design Summit! It's essentially a Torsen-type differential but arranged to be more bulletproof right? Having those worm wheel's horizontal probably gets more surface area strength.
Finally, I think I have a basic understanding of how these work. Has anyone ever used one of these in a drag race application? What kind of shock loads will it accept before destruction?
is this locker puting in a front differential and is it worth buying for hardcore off roading how about if your going up a hill or in the mud and turning the front wheels would it still have a both tires spining at the same time ???
So how does this get any posi action? By cranking the planets into the housing walls? Seems like it's going to rip itself up quick. It's an open diff as far as I can tell unless the friction of the planets into the housing is enough to stop them from turning.
I know entirely that im nitpicking, but shouldnt the answer be more concerned with torque, than power? 400 hp from an na v8 is a different ball game than 400 hp from a turbo charged diesel engine. Just saying. Great product, LOVE this video. Its fascinating to see whats actually going on inside.
There idea is probably off of power band of engine. Diesels make horse power low to high steady. But torque is made low to mid because they are low rpm naturally. I would have the same question.
the Nismo Wavetrac and True Track are much alike, but the Nismo Wavetrac has 12 pinion gears while the True Track has only 6, it seems to me that the Wavetrac would be much stronger
does anyone know where to get this type or style of diff for a 1987 Suzuki samurai (sj413) . I can't find any models for a samurai on the eaton website, and I hear rumors about the Russian made ones but I only see listings for like new trackers and vitaras, I found a brazil made torsen diff but the website doesn't work right and I can't see how to buy one, or anything.
this device connects inside your pumpkin case to your ring gear which is driven by a smaller gear which connects to the drive shaft outside of the differential housing unit the pumpkin
What would happen if i use a brake bias n lock one of the rear wheels to do a drift u turn on a mud? Scared it still apply for to those jammed wheel and break the shaft...
Apology acepted. The spelling error is intentional so you dont feel bad. But to answer your question, you would replace your "open diff" with one of these, and yes it will be an LSD now. More "torque sensing" than LSD though.
I have this unit on my F150 and when I get into some steep stuff only the wheel with the lightest load spins. I have tried applying some brake but it does nothing. I am not really happy with this unit.
