Broken Quaife Diff

[niccis dad]

So, Quaife ATB fitted in an English axle Pinto engined Fisher Fury. Sat on start line, mucho revs, clutch in smartly..and..bang!
Propshaft revolving, 1/2 shafts intact so problem obviously with the Quaife diff. Going to strip it out next weekend but would be helpful to know if there's a common "break" component on these units. home repairable or send the thing to quaife?

Any help appreciated. Ta.

[stevieturbo]

Problem could be diff or crownwheel or pinion etc.

There are many gears inside an ATB diff, so potentially lots could break. But they are generally very robust items.

I think Quaife offer some sort of lifetime warranty on them ?

[ouninpohja]

I have had a couple in for repair where the bolts that hold them together can come loose and snap, other than that not seen any internal damage on one yet.

[Krikkit]

Would be interesting to hear what's caused this if Quaife ever tell you. Is the crown an OE item pressed on?

[niccis dad]

I'll be removing the diff from the axle next Saturday and will update with what I discover. Thanks.

[niccis dad]

ouninpohja said:

I have had a couple in for repair where the bolts that hold them together can come loose and snap, other than that not seen any internal damage on one yet.

Yes. The bolts securing the Crown wheel to the mounting ring have sheared. Looks like this has been a progressive failure with bolts shearing over a period of time. Anyway, it's not a major job to fix as the threaded remnants were easily pinged out with a centre punch.
Given that it's a shearing process it does mean that there's very little rubbish floating around the system. So a decent wash and blow dry and a new set of bolts should see us back in action at little cost. Just a few hours of oily fingered endevours will see us up and running again.

[Steve_D]

It may be worth spending a little time working out the failure mode.
For the bolts to shear it would require them all to fail at the same time as they are sharing the axial load.
If the break point has a pinched appearance then the failure would be them stretching then failing.
If this is the case then the likely cause is the crown wheel riding up the pinion. This may then need a mod to the diff housing called 'pegging'. In effect a bolt is fitted through the casing with a bronze pad on the end which runs against the back of the crown wheel preventing it trying to bend away from the pinion.

Steve

[niccis dad]

Steve_D said:

It may be worth spending a little time working out the failure mode.
For the bolts to shear it would require them all to fail at the same time as they are sharing the axial load.
If the break point has a pinched appearance then the failure would be them stretching then failing.
If this is the case then the likely cause is the crown wheel riding up the pinion. This may then need a mod to the diff housing called 'pegging'. In effect a bolt is fitted through the casing with a bronze pad on the end which runs against the back of the crown wheel preventing it trying to bend away from the pinion.

Steve

I can't see how the crown wheel can ride up the pinion as everything is torqued down tightly. I would think that it's simply one tyre warming/ racing start too many over 5 years. Wear looks good and even on both gear sets. In the meantime I'm waiting to hear back from Quaife on this.

[Steve_D]

Difficult to explain.
You go for a spirited start off the line and large amounts of torque are trying to turn the pinion.
The crown wheel does not want to turn but its teeth are meshed with the pinion. Because the crown wheel won't turn the pinion tries to climb up the teeth of the crown wheel. The only way this can happen is if the crown wheel were to bend or in your case snap the bolts holding the crown wheel to the diff flange.
A customers diff failed in a similar fashion only in this case the flange of the diff fractured and came off still bolted to the crown wheel.

Steve

[niccis dad]

Damn, but this gets frustrating. Quaife say that they don't supply the bolts, nor can they tell me who would.
I've just tried looking on Ebay without any success. Plenty of gasket sets, bearing sets but..... no Crownwheel fixing bolts.
I also need to know the torque settings of such bolts if / when I find em. Also need to know the torque settings for the four bolts holding down the 2 clamping shells either side of the diff assy.
All and any help gratefully accepted.
Thanks.
Aah. Bloody obvious really. Burton stock them. just ordered them with a new Diff gasket. Still would appreciate torque settins though.

Edited by niccis dad on Tuesday 11th June 21:25