Thread: Why isn't Eaton torque biassing diff more popular

Was the TrueTrac before the Quaife? The TT is the most positive of the 3 options also, you would use one of those before the Ashcroft or Quaife if you wanted the most positive ATB

Probably because the type of person that upgrades the diff wants all of the postive drive that they can get, which really comes with a locking diff.

Does the TT have the better bias ratio?

Both ATB's should be quite a bit stronger than the TT as they use more gears (6 vs 3) which is why I've always had a preference for the ATB.

The Torsen 1&2 predate both, the TT was a copy of the T2 as far as I understand.

The original Torsen design goes back a very long way but how it generates bias is very different to the T2, TT and ATB.
It's a lot more complicated, uses cross axis worm gears and can go boom much more easily in very high HP/torque situations.

Back in the 70's it was advertised as the Dual Drive diff in the US 4wd magazines.

And that's the first time I've seen a TT cheaper than the ATB here.
LRA have the ATB for $855 including ATM.

I bought an ashcroft over a trutrac because it was much cheaper at the time.

But after dealing with eatons in regards to an issue with my detroit nospin, i don't think i will deal with them again, they have no idea about their own products.

Originally Posted by rick130

Does the TT have the better bias ratio?

Bias ratios are:

TT is 3.5:1
Ashcroft is 3:1
Quaife I think is either 2:1 or 4:1, but I'm thinking it's 2:1 for the spec in the 4WD.

Ashcrofts website insinuates that the Ashcroft ATB has the most positive bias ratio and that the TT is 2:1, but thats not the case for both of those points.

Torsen designed and patented these.

Bias ratio is whatever you want to make it based on the thrust angles. There are reasons that you do not want too much.

All of the ones currently available for LR diffs use the T-2 design. Torsen(R) Traction Each of the companies has variations on how they set things up, but the general principle is the same. TBR is adjusted by setting the helix angle. Too much TBR and the inner wheel will break traction when turning a corner. The outside (faster) wheel can only move faster than the inner wheel after the inner wheel receives torque higher than the outer wheel at the TBR ratio. This means the inner wheel always gets more torque.

Gleasman applied for the first patent in 1955 and had it granted in 1958. US2859641A - Differential gear mechanism
- Google Patents