Noise on over-run

[Martin Prior]

I was just going to say "disintegrating fabric coupling"!

[Bob Culver]

Hi Rick

Relevant to another current post, did you find it necessary to remove more or other than the castellated nuts? If refitted with 
Loctite the studs will likely undo next time, an unwanted complication. 
Split pins are a fiddle. I guess there is an optimum direction for the stud holes. Short twisted wires possibly less fiddly. 
I guess the main objective is to not lose a precious castellated nut if it chances to work loose.
The fabric universals somewaht short lived on cars with increased power and given generous throttle  up protracted grades in 1st and 2nd.
(for locals, Tinakori Radio in Wellington and Liverpool St Auck when allowed up it hastened the demise on my car!)

[Tony Press]

As I said earlier-

"Fabric joint and nuts hitting the brake assembly ?"

[David Witton]

Rick the braking effort from the engine on the overrun could be distorting the fabric coupling as in your picture. Hence coasting in neutral removes the load from the knackered coupling.

[Rick F]

Latest findings : loose drive flange on torque-tube. Axle removerd and flange area sorted - axle backlash also reduced.

2mm shim fitted between handbrake lever and adjuster to increase clearance. Replacement fabric disc fitted

[Tony Press]

A loose pinion front flange allows pinion end float - the mesh goes in and out on drive and overrun. The noise from here and the disintegration of the fabric joint would explain your problem. 

Hopefully the crown and pinion weren't damaged  !

[Bob Culver]

Admittedly not based on a large number but most of the diffs I have dismantled have shown evidence of either the driving flange and/or the pinion bearings retaining nut haveing been loose. The first just gets lost in the general backlash but the second leads to wear of the spacer piece and, if excessive, tooth damage. If latter not evident just tightening nut will likely suffice. Significant wear of the spacer triggers mesh adjustment which involves viewing the teeth patterns and can get very involved.

[Rick F]

Pleased to report that we are back on the road with a quiet (well, A7 "quiet") back axle and no noise on over-run.

Thanks for all your advice.