I've got a UK STi and I was wondering if anyone out there can give me a simple, yes simple, explanation has to what these Suretrac limited diffs do and when they do it.

My thanks in anticipation of some answers

Leigh

 

Look at the provided link. Not sure what type the AP Suretrac diffs are!.
http://www.howstuffworks.com/differential.htm

 

Cheers Stiler

Leigh

 

They let you go round bends quickly!

 

I would hazard a guess that the AP suretrack works in the same way as the quaife ATB.

it is based on the theory that worm gears can only be driven and cannot apply a reverse torque to drive their drive gear.

They provide a smooth tranisition from slip to lock.

According to pat they require one wheel to have some degree of torque and they can send up to 6 times that amount to the other, so if you are spinning one wheel on sheet ice, then it will be impossible to transmit any torque to the other wheel since the slippling wheel is not transmitting torque.

In such situations, driving with some degree of brake on will allow 6 times whatever braking torque is being applied to the slipping wheel to be trasmitted to the other, enabling the gripping wheel to drive the car out.

 

Thanks for the replies fellas, I'll go with yours STi Man!

Cheers, Leigh

 

Well, you did want a easy explanation....

 

that is damn clever!

nice find!

 

Subaru have obviously forgot to put the bit about the LOW SPEED NSR Knock 'feature' in the suspension section of the PDF file. [img]images/smilies/mad.gif[/img]


I think Phil Harrison needs to show this to the MD of SUK!

 

Torsen Diff is the worm gear one, Torque Sensing.

They all offer similar charactristics, basically more progressive than a plated (Salisbury) diff.

Quaife ATB has lots of gears, can't see from their diagram quite how it works.

The subaru pdf sure is interesting, makes a change from normal car literature!

paul

 

Quaife ATB is also a helical gear device, like the TorSen. Both of these devices will progressively apply lock based on torque differences across the output shafts. Plated (in all cases i can think off) and Viscous coupling differentials apply lock based on speed differences between output shafts.

These diffs differ in operation from plated diffs in that the helical devices are generally more progressive and helical units will never fully lock (plated diffs can be made to fully lock) as they require a minimal torque input from side that torque is transferred away from in order to function, being that they act on torque and not speed differences between outputs.

If you lift one wheel off the ground, the helical device will work like a standard open diff until there is a minimum level of grip returned to the wheel (i.e. touchdown). Plated diffs can be setup to lock the axle in such circumstances, which is nice on loose surfaces, but is less ideal on tarmac.

 

Suretrac doesnt work with worm gears. It uses cams and cam followers. Look here under Transmission for the details:

http://subaru.com.au/downloads/63748.pdf

[Edited by b5m - 1/9/2003 1:43:50 PM]