Thread: Torque Biasing Diffs

Originally Posted by Roverworks Canberra

Limited Slip Diffs are quite a common fixture for Rovers, but there's a much better option!

Torque Biasing Diffs behave like normal open diffs around town, with no difference to driveability. They also do not drag wheels and wear tyres out. If a wheel slips, they automatically shift torque away from the slipping wheel to the one that is not slipping, without you even knowing it has happened. It’s all in the construction of the diff; there is no electronic wizardry or anything extra to gum up full of mud and fail on you. They still leave about 25% of the torque going to the slipping wheel, so that when it grabs it is ready to grip and move straight away. As soon as the slipping wheel grips, it has 100% of the torque back to pull you out of the situation. These are great for what most people experience in their four-wheel driving adventures – a bit of mud, sand, snow and some loose surfaces on hills etc.

Read more here:
Torque Biasing Differentials

Agree?

Disagree. Something doesn't sound right.
Shouldn't it be 25% of the torque goes to the axle with traction and 75% lost to the slipping wheel? Happy to be corrected...

As has been said by others, LSDs of the friction plate type aren't common in Landies-you might be thinking of Patrols. ATB diffs from Eaton (Trutrac) and Ashcroft have been around for years. I have had two Ashcroft ATBs now, though one now sits forlorn in a box in my parts stash. I'm very happy with the one in my County, when mixed with the Detroit in the rear gives a lot of traction and controllability.
What brand are you installing?

Originally Posted by isuzutoo-eh

Disagree. Something doesn't sound right.
Shouldn't it be 25% of the torque goes to the axle with traction and 75% lost to the slipping wheel? Happy to be corrected...

snip

Mark I think you're on the money. When I looked into these, those sourced via Truetrac were 3:1, and those from Quaife were 4:1. Again I'm happy to be corrected if my hazy memory proves wrong.

And as has been pointed out in an earlier post, lift a wheel and 3 or 4x 0 = 0.

Regards
Max P

Originally Posted by isuzutoo-eh

Disagree. Something doesn't sound right.
Shouldn't it be 25% of the torque goes to the axle with traction and 75% lost to the slipping wheel? Happy to be corrected...

snip

Well it's time to smile. As long as the slipping wheel has some traction, then the slower moving wheel gets biased with more torque.

Have a look at the truetrac video, my understanding of it's operating principle, is that the wheel that's moving faster will push the "idler" shaft ( these are equivalent to the bevel gears mounted on the cross pins of a standard diff) over to the slower turning wheel. It does this because the helical design of the gear sets on the "idler" and sun gears (end of axles) causes a side force when the two axles spin at different rates.
As this happens the idler gear binds up on the side of the "hemisphere" (it's really a cylinder) over on the slower moving wheel. When the idler shaft binds on the side of the hemisphere then torque is biased onto this wheel . The idler shaft stops turning in it's pocket and creates a sort of lock.

"So if it locks then why doesn't it send all of the torque over to that wheel?"
It can only bias a portion of the torque cause it needs the pressure of the faster wheel to keep the idler shaft against the side of the hemisphere, the ratio will depend upon the angle of the helical cut of the sun gears and idler gears.
So if the wheel starts spinning in free air rather than slipping there is not enough pressure on the helical gears of the idler shaft to keep it over on the slower moving wheel and hence form the lock against the side of the hemisphere
That's why ATB's and traction control work so well together. While both wheels are on the ground , the ATB will prevent the wheel with less traction from spinning, yes it will slip but not spin wildly, this will delay TC coming on, and TC will divert power away from the car. When one wheel lifts and starts spinning then TC will kick in but the ATB will start working, this in turn will reduce the torque going to the wheel that the TC is holding meaning that the TC drains less power.

There may be some finer points I have missed but I'm pretty sure that the gutz of it.

Cheers Glen

Ok, Im a newbie and have been wandering if I should go lockers, or ATB. So because I have TC on my TDci the ATB is the best option to compliment my TC??

I thought i read somewhere all you guys were saying TC is bad for the axles or something I can't remember. But TC was BAAAAD!

Cheers.

Originally Posted by voltron

I thought i read somewhere all you guys were saying TC is bad for the axles or something I can't remember. But TC was BAAAAD!

You'll read a lot of things on this site and a lot can be rubbish. Make an effort to sift through all the information and make your own decision.

Originally Posted by voltron

Ok, Im a newbie and have been wandering if I should go lockers, or ATB. So because I have TC on my TDci the ATB is the best option to compliment my TC??

I thought i read somewhere all you guys were saying TC is bad for the axles or something I can't remember. But TC was BAAAAD!

Cheers.

Frankly nothing "compliments" TC if you can afford them and are deciding between ATB and Lockers for me its lockers every time.

This video shows and explains the difference between open diffs, TC and lockers well worth a look.

[ame=http://youtu.be/C2wkW05Pc6c]Air Locker vs LSD vs Traction Control Part 1 - YouTube[/ame]

Originally Posted by chook73

Frankly nothing "compliments" TC if you can afford them and are deciding between ATB and Lockers for me its lockers every time.

This video shows and explains the difference between open diffs, TC and lockers well worth a look.

Air Locker vs LSD vs Traction Control Part 1 - YouTube

Video shows Toyota traction control which is probably the worst out there. The D2 traction control is a little better even thought it's about 10 15 years old but that also makes it a bit less reliable (3 amigos). Video is also sponsored by ARB who are selling, what do you know ARB air lockers.

I drive a 200 series, that is less than 12 months old, at work with Toyota TC and it's rubbish. The brakes grab too hard and lock the spinning wheel, that drives all the power/torque to the opposite wheel which immediately spins because the power transfer isn't smooth. Then as the lifted wheel has just been locked because it has been braked by the TC, TC releases the brakes because the wheel isn't turning then the vehicle lurches backward.

My D2 has none of these traits. One thing it will do, if you go dead slow, there is a pause as the lifting wheel spins maybe a 1/8th of a turn while the TC brakes that wheel. As long as you are going walking pace, the pause isn't enough to loose too much momentum.

What's your experience with TC, Chook 73?

This gnarly hill a lifted 80 series and a lifted Prado with a rear locker couldn't get up.

[ame]https://vimeo.com/105476118[/ame]

Then this hill a 4 inch lifted Patrol with front and rear lockers couldn't get up.

[ame=http://vimeo.com/105515879]Past the Nissan on Vimeo[/ame]

Happy Days