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

Originally Posted by twr7cx

When I purchased my front and rear ATBs in 2013 direct from Ashcroft Transmissions in the UK, the Quaifes were more than twice the price and the TT were still significantly more than the ATBs.




The TT are speced differently front and rear - different part numbers. Is there bias the same for both?

AFAIK, its just the different rotation when driving.

The gears are placed in the opposite direction when in front or rear.

You are supposed to dismantle the gears and flip them if changing from front to rear or vice versa.
Regards PhilipA

Originally Posted by PhilipA

The gears are placed in the opposite direction when in front or rear.

You are supposed to dismantle the gears and flip them if changing from front to rear or vice versa.
Regards PhilipA

But the Quaif and Ashcroft Transmissions ATB product down require this.

Just found an old e-mail from Dave Ashcroft, when I asked him about the difference while purchasing my ATBs. For those unaware, Ashcroft Transmissions sells both their own home brand ATB and the Eaton Truetrac product.

Hi,

I think the difference between front and rear on the Truetracs is due to the rear having more preload than the front,

Dave

I am surprised by the use of 'I think' given he sells them and designed their own ATB which probably involved some inspection of how the Truetrac worked...

Sort of, I'm pretty sure its a combination of both. ATBs have different bias ratios depending on if you're going forwards or backwards, with reduced bias ratio in reverse. I was also under the impression the gear set was reversed for the front TT compared to the rear which was why the different part numbers.

But interestingly, that conversation also tells you that Ashcroft are not altering their front ATB's to suit the direction change which Detroit (Eaton??) are with the Truetrac.

Originally Posted by Slunnie

But interestingly, that conversation also tells you that Ashcroft are not altering their front ATB's to suit the direction change which Detroit (Eaton??) are with the Truetrac.

I can confirm from my experience purchasing the ATB direct from Ashcroft Transmissions that they are the same part number supplier and not marked for front of rear application. According to them, either can be fitted to either with no change required.

The true tracs are designed with a a proper thrust bearing on the inside for the side gears. When driving forward the thrust is towards them. That is the reason for flipping the gears. So that the normal thrust force is to the bearings and also to the springs to absorb some shock loading.

The Ashcroft units don’t have proper thrust bearings and use hardened steel washer for the thrust. There have been reports of their springs losing pressure and the preload disappearing over time.

Originally Posted by Red90

The Ashcroft units don’t have proper thrust bearings and use hardened steel washer for the thrust. There have been reports of their springs losing pressure and the preload disappearing over time.

Any more details on this please? Links to discussion threads etc?

Originally Posted by twr7cx

Any more details on this please? Links to discussion threads etc?

From this thread.
Land Rover Series 1 80" 1952

This thread shows the internals fairly well. This diff had been abused but it still does seem like they are using poor quality or improperly sized belleville spring washers. I've quite a bit of experience specing and using bellevilles and they really should last forever.
Open/clean/rebuild Ashcroft ATB: experiences? - Defender Forum - LR4x4 - The Land Rover Forum

You can see a Rover TT apart here:
Flipping Truetrac Gears