sierra diff

[garagewidow]

hi all,first post on pistonheads.

i have a sierra diff with lsd in my triumph.now the problem is i have driveline vibration which i feel may be down to the diff itself,the prop has been balanced twice and am told it is ok.so far i have taken the drive shafts off and run the car in top gear to the point where the vibration starts(4-4.5k),it still occurs so i know it's not the drive shafts.when the engine is idling in gear the diff makes a random knocking noise and last time i looked the cwp had all its teeth.i have had the front flange off to replace the seal at some time,what i want to know is how tight should the pinion flange be to turn when the diff is warm?i know they require preload but i can turn it very freely so i'm wondering if there is any undetectable bearing play which may be causing the vibration and should i fit a new collapsible spacer.
i would like to get to the bottom of it myself before resorting to a costly rebuild.

TIA

[DrDeAtH]

sound like you may have overcooked the pinon nut torque. so yes a new collapsible spacer will be required.
the trick is to tighten the pinion nut until you can feel it pull up to the spacer, then add quarter turn, this then sets the preload.

[garagewidow]

ok thanks,i'll get a spacer and try that first,is it just remove flange,pull out bearing, remove old spacer,fit new one?

[DrDeAtH]

not sure it is as simple as that, but give it a go first... i think getting the bearing race out will be a small challenge

[stevieturbo]

on a diff thats been used, the pinion flange should turn quite easily. Unless you have disturbed the pinion, is unlikely to be the problem.

And certainly dont start fking about undoing teh pinion nut, unless you know how to re-install. Simply tightening and going a bit more is not correct. You must measure how hard to flange is to turn in inlbs as you tighten the nut and preload the bearings.

Its a right pain in the hole to do. If you tighten too much, you must undo, fit a new crush washer and start all over again.

Edited by stevieturbo on Friday 26th February 21:47

[garagewidow]

ok,for the record can anyone recommend someone to rebuild it for me in or near essex if it comes to that.

[stevieturbo]

I'd guess he could do it

http://www.gearboxman.co.uk/contact.html