Antispin differential - spins freely

[07flatbed]

My 07. 5 differential works great, on anything BUT ice and snow. How great is that!

 

[AH64ID]

This is the One I like... I reserved My Judgment until this winter. . The factory Pinion bearing failed so I replaced the entire differential with truetrac. It is more dangerous on level ground in tight spots were if it spins it will slide sideways if not careful, Off-road and Ice/Snow pack roads it out performs the AA in every category. Yes I will never pay for LSD again I will get the open and replace with Eaton Truetrac.





On edit: Current LSD, If AA improves the design I will re-investigate.

Very interesting considering they are both helical gear LSD's. I know AAM advertises you can adjust the pre-bias in their LSD, but I have never seen parts to do so.



The TT is a great unit, I would like one if my front axle.

 

[JAlford]

OK, I have read a lot of post about ones that work. And apparently it should "lock" the sides if there is motion on both wheels, but a difference between the speed of one and the other? How much speed difference? Those that say "it works", how do you know it works? A standard diff will do exactly the same thing, with no lockup. So what are you buying in "Anti Spin"? My definition of anti spin is it prevents spinning. So now I am at a dilemma. Did I buy a $285 "option" for nothing?





When I carried mine in to the dealer the first time, the first answer I got was that is wasn't a limited slip rear axle. When I showed them the window sticker with the option listed, they retracted the statement and "did some research". They told me then that they "fixed" it, but I don't think they did anything at all. It behaved exactly the same way when I left. And as far as rolling is concerned almost every time I have needed it and it got me stuck I was rolling right up until it got stuck! I wasn't starting off from a stop.

We have plenty of snow and ice here during the winter and I will take my '99 limited slip any day over the '06. I have NEVER been stuck on ice or snow with it. It does slide around a bit sometimes if it is empty, but if I am in 4wd, at least 3 tires are all turning at exactly the same speed, which is IMHO a good thing.

I have tried using the brake and it never really does much, or at least not any more than what an open diff would do. I have used the braking technique many times with an open diff to cause the opposite tire to start turning, and it works if you only need a little bit. It would especially work if you have ABS on 4 wheels.

Speaking of ABS, it also means you don't have independent ABS braking on the truck to help you out if a single rear tire looses traction on ice, as the sensor is only on the ring gear. In my '99, since both tires work together, you cant have that happen.

Bottom line is that IMO it doesn't work at all if it doesn't have any benefit. For my driving, it has not helped me at all. It is a serious pain in the rear to have to swap the '06 truck to the '99 to back my trailer up my back drive in the snow because the '06 won't move the trailer once one front and one back start spinning. The '99 has no problem.

When I carried it back the second time and actually jacked it up and made one wheel spin, the service manager just shrugged his shoulders and said "that is what it is suppose to do!" Funny he never mentioned using the brake or explained how it works or anything, just told me there was nothing wrong and walked off. Chrysler's customer service center is completely worthless, they can't give you any info or good information, just tell you to take it to the dealer. The last time I talked with them about it they basically told me there was nothing they could do and have a nice day. Not any explanation or anything. Just really lousy customer service.

 

[SWithrow]

I have tried using the brake and it never really does much, or at least not any more than what an open diff would do. I have used the braking technique many times with an open diff to cause the opposite tire to start turning, and it works if you only need a little bit. It would especially work if you have ABS on 4 wheels.

Applying the parking brake theory has been around for years, I went out today and confirmed that my Anti-Spin dif will kick in when I apply the parking brake and once it locks I release the parking brake.

 

[AH64ID]

They don't lock, they just need to see speed on both wheels to transfer power and the resistance of the brake helps transfer power too.

 

[TCDiesel]

AA calls the Dodge LSD Trac-Rite, Eaton True-Trac actually transmits power more equally then AA. check out this video YouTube - Exploded View - Inside the Eaton TrueTrac Differential The AAM dis-engages easily, The True-trac will transmit or distribute the traction.

 

[JAlford]

Well mine has never locked when I applied the brakes, that I know. I have reduced the spin some on the slipping axle using the brake, but I almost always have to shift into 4wd to actually move enough to get somewhere. If we get more than 1/2" of ice or a few inches of snow, I can forget pulling up my drive in 2wd, sometimes not at all even in 4wd. I have new BFGoodrich all terrain KO's 305/60/17 so they are wide and grippy. My '99 is a dually with BFGoodrich Commercial tractions, with 50k miles, and no problems.

It just gets me that they "improved" it until it didn't work, from '99 to '06.



I guess at this point I either have to tear the carrier apart and try to determine if something wasn't installed properly at the factory, or just replace the carrier with something that does work. Or just do like I have with the other things on this truck that stopped working or never worked to begin with and just live with it. This '06 truck has been a real disappointment since day one. The Cummins is hardly broke in and I still have a few payments left to make!

 

[Cosmo]

Wide tires aren't good on ice. That's part of your problem.

 

[steved]

The one thing that I have noticed is that after I've had it to the dealer for transmission and diff service, I can feel the rear end grabbing when I make turns. The sharper the turn, the more grab I feel. Over time, it goes away until I take it back in for service. Is there some sort of adjustment that they do on these?

Probably LSD chatter... mine did that at 200k when I changed from Royal Purple to Schaeffers... a little LSD additive solved the problem. It sort of feels like two blocks of rubber sliding past one another.



And regardless of what everyone believes, the AAM LSD will chatter, and LSD additive is needed, for some fluids.

 

[steved]

My definition of anti spin is it prevents spinning. So now I am at a dilemma. Did I buy a $285 "option" for nothing?





They told me then that they "fixed" it, but I don't think they did anything at all. It behaved exactly the same way when I left.

Until mine "broke" free, I felt the same way... the AAM LSD was almost useless. It took almost 10k pounds on a trailer and a good jerk to make it work... I actually thought something broke, as it caused a tremendous snap from the rear axle; it has performed quite well since. I want to remember that happened in the fall of 2007 with about 125k on the clock, it currently sits with 238k and still seems to work.



The dealer gave me the same run around... there is nothing they can diagnose. It either supposedly works, or locks both axles together when it fails. . so basically unless the unit fails, they say nothing is wrong.



I still prefer the plate-type LSDs since they are predictable and have more traction differential resistance than this AAM. Plus, both the Power-Loc (D70) and Trac-Loc (D80) can be rebuilt at home in your own garage by the average joe... and the plates can be re-stacked in the Trac-Loc to make it even more aggressive. The AAM LSD is disposable... basically a $285 soda can.

 

[HSpiering]

JAford

I had the same issue years ago. I asked an automotive expert that did a column for a new paper. This is his reply.



To Chip:

I have a Dodge 4X4 with an anti-spin differential (limited slip rear end). Before that I had Ford Bronco with the same. With both vehicles I have had occasion to be off road in mud or gravel and had one rear wheel spin requiring me to engage 4wd to get out. I have heard to apply the brake to change power from one wheel to the next. This did not prove to be effective. So just what advantage am I getting off road? On other occasions (with both vehicles) I have spun out on ice when in 2wd. Could the limited slip rear end contribute to this happening? If this is so could people who have limited slip be at risk and not know it?



Thanks again for your question.

Here is an early copy of my column in reply. Best regards, Chip

According to Isaac Steele, my off-roading enthusiast co-worker, your problem is common: "Most hardcore off-roaders think a factory limited-slip differential isn't much better than a standard differential. Limited-slips are fine when there's not much traction loss, but they're almost worthless when one tire loses traction completely. " The differential splits the torque applied by the drive-shaft and delivers it to the two drive axles. When the vehicle turns a corner, the outside wheel travels farther than the inside wheel, so the differential must also allow the two drive axles to turn at different > speeds. Therein lies a conflict: how does the differential know the difference between a wheel that's turning a corner and one that's losing traction? Dozens of traction-enhancing differential designs address this conflict. Some, such as the Torsen differential used by Hummer and Audi, are factory equipment. Others are made by the aftermarket, and may be retrofitted to most vehicles. Each can be rated on a "torque bias ratio" scale of the differential's ability to transfer torque to the wheel with traction when one wheel slips. The standard "open differential" is at the low end of the scale. It has a torque bias ratio of zero -- it always transmits all the torque to the wheel that's slipping. Limited-slip differentials improve upon this. Those with clutch packs, like the one in your Dodge, transfer some of the torque from the slipping wheel to the one with traction. Those using viscous fluids or helical gear arrangements have more aggressive torque bias ratios. At the top of the scale, a "locker" differential will lock, or "spool," the two axles solidly together, so both wheels always receive an equal amount of torque. A spooled differential won't leave you stuck until both wheels completely lose traction, but it also won't turn a corner without scrubbing the wheels. A vehicle with a spooled differential can be impossible to maneuver on dry pavement, and unsafe to drive at speed on icy roads. In general, the greater the torque bias ratio, the greater the handling difficulty there will be at speed on ice. There are exceptions however; the Torsen differential is stable under icy conditions, and some locker differentials, such as the Toyota locking differential, or the ARB Air Locker (ARB 4x4 Accessories) allow the driver to switch between a locked and a standard differential by pressing a button on the dash. Factory limited-slip differentials don't generally have enough torque bias to create problems in icy conditions. This low torque bias is also why you haven't been helped by the trick of pressing the brake lightly when a wheel spins. The trick works well when the torque bias ratio is high .

 

[KParsons]

locker

i have used lockers on 3 different work trucks for over 30 years. some were pocket lockers [ lock right]etc. i have snow plowed 8to10k driveways,pulled trailers, empty or full i have not noticed any problems. sure it will click now and then. i will be installing a full locker in my 06 soon. slip lockers are just that they slip. k

 

[retirednak]

Mine has worked great since day one. I've never experienced one wheel spinning,even sitting on ice. In fact I have to be careful at drive through windows when its icy or the rear end will smack wall or polls. I guess I'm one of the lucky ones. I wouldn't own a truck without a working limited slip type diff. I did install a Detroit full locker in my old K5 plow truck and hated the thing,it was real noisy and it made it hard to push snow around a curve or corner. Ended up installing an OEM limited slip.

 

[pwerwagn]

A limited slip will never lock. Ever. It will bias torque from one wheel to another, but never lock. A tru-trac for instance (which is more effective than the AAM unit), will for sure transfer power from one tire to the other, but they will not be the same speed. It will not be 100% the same (like a spool or actual locker).

How much power is transferred to the wheel with traction seems to be issue here. Some will transfer more than others. Even when it comes to the clutch styles, some are better than others, even the same exact model.

It just gets me that they "improved" it until it didn't work, from '99 to '06.

They didnt "improve" anything. The axle in your 06 is an AAM unit, the axle in your 99 is a Dana 80. Totally different units.

 

[Harlacher]

My 99 has always worked. When I do a burn out both tires put down rubber and I am gone. I am interested on how it will launch in four wheel drive. I am going to run it in the quarter mile and I understand to get the best time it has to be in four wheel high. I am assuming the anti slick will work then also.

 

[PLohr]

I will take the old clutch and spring style GM posi-traction over this AAM 11. 5" differential any day. The clutches and steels seemed to last about 80K miles if the owner had the fluid changed occasionally. Fine, I will rebuild the differential every 80K miles.

It is the initial transfer of 100% of the torque that sticks the truck in the mud or sand in the first place. Now that the truck is stuck, I am supposed to use the brakes or emergency brake to switch the power to the other tire. On my truck it does not work. Let's assume it did work, now 100% of the torque is going to the other tire and it is not a gradual application of switching the torque - a more complex system would be needed to do this. If the torque was always delivered as 50% to the left rear and 50% to the right rear at all times unless the preload spring is overcome, the chance of the truck getting stuck is lowered significantly.

I have heard some say that both tires will drive once the driver uses the e-brake. That would be better than transferring 100% of the torque to a single wheel in an abrupt manner. My truck has never done this.

 

[macdaddy]

The helical gear style limited slip in your 06 is superior in function than just about all limited slips, UNLESS you are stopped. The helical gear style needs motion to function properly, so if you stop and you need both tires to spen then your screwed. . But when moving the helical gears do a much better job than a clutch style, and they won't send you sideways like a clutch setup. . So its a trade-off. But if you need more offroad traction I suggest the OEM front e-locker.

Not sure about the part you have to be moving!!!



KOA campground on a uphill and on wet grass stopped. When letting the clutch out in first to pull the trailer up on some leveling blocks all four wheels spin from a stop.



05 dually!!!



Mac

 

[AH64ID]

The helical gear style are much more effective if your already moving, when stopped they don't have the ability to transfer the power as easily and if you have different traction surfaces then it will be more noticable.

 

[PLohr]

I think our complaints are finding their way back to AAM.



I sent a note to AAM asking about the pre-load feature on the TracRite 11. 5 differential. This page on AAM's website states that the TracRite can be used with or without a pre-load feature. I assume pre-load refers to the pre-loading of the side gears or helical gears so that both wheels drive from a dead stop.



Someone from AAM responded to my e-mail and explained there is no pre-load feature and that they are working on two ways of getting both tires to drive from a dead stop (for the AAM 11. 5). The first would be a modification of the helical gear style TracRite differential that would still slip the unloaded tire but would transfer power earlier to the loaded tire than the currently available TracRite. The second way would be an e-locker.



AAM even asked which method I would prefer. The e-locker seems to be the way to go but the price is likely to be as much or more as an ARB system (speculation). Thumbs up to AAM for working on the problem and asking for input. Thumbs down for the poor design of the current AAM 11. 5 TracRite.



I was hoping AAM would have told me there is a way to pre-load the AAM 11. 5 and described how to do it.