Dull scraping,grinding kinda noise

[HellfisH]

A couple of months ago I had the 4.1 diff gearing change to 4.6, and ever since, when I get up over 60 I get a dull scraping, grinding kinda noise, not all the time, mainly when I back off the accelarator or just coasting down a hill. Its hard to pick where the noise is coming from, sometimes sounds like its coming from the front left and sometimes sounds like its coming from the middle of the car. Any help to figure this problem out would be greatly appreciated.

[rollin]

i no it sounds weird but check the tail shaft uni my old ute hade a similar noise. to check them just park on level ground apply the hand brake end leave in neutral then just get under the car and shake the tail shaft up and down and side to side and look for play in the unis. good luck

[gqroo]

Mmm i have wat sounds like same prob, tryed changing uni joints still does it,(not saying yours isnt uni's)thought it could be bearing noise to, im sure there are some people that know answers to this problem(mines still got standard gearing,think its only done it since lift.

[raptorthumper]

I believe i know what it is. Either the diff carrier bearings or pinion bearings were setup without enough preload. This allows the pinion or crown wheel gears to move around significantly and then the bearings carry no load but the gear teeth do, when you back off. Stop now or else the pinion gear will break a tooth of soon. Ive seen it before.

[gqroo]

Is it normal for the noise to come from the gearbox area if this is the case?

[badger]

im with raptor thumpor. but if that fails try the drum handbrake cover. if you have manages to slightly dint it they make that noise aswell, tho it seems strange that would happen after chaing diffs

[HellfisH]

Thanks for the feedback guys, will take it all under advisement, looks like I'm in for a long weekend.
Thanks again.

[YankeeDave]

if it is the front diff and not the back, surely then this wont be it as i imagine you have your hubs unlocked on the road and 4wd not engaged. So the front diff shouldnt be turning. so no probs from the diff.

I"m thinking wheel bearings.

[HellfisH]

if it is the front diff and not the back, surely then this wont be it as i imagine you have your hubs unlocked on the road and 4wd not engaged. So the front diff shouldnt be turning. so no probs from the diff.

I"m thinking wheel bearings.

Yeah, I think it will be a case of starting at the front and working my way back.

[embryo]

check your brakes all round. could be bent backing plates, mud between backing plate and disc, mud in caliper, or you disc pads could be getting low.