rear end whine diagnosis ??'s 8.8 ford.

my rear axle whines under decel and light cruise, but not at all under load. does that eliminate any possible causes?

tried RP 85w 90, Valvoline 85w 140 w/ lsd additive, no impact in noise. ive pulled the cover and there doesnt appear to be any abnormal wear on the ring gear. i dont have the tools to check the backlash and etc. im pretty sure the trac-lock is getting tired.

ive heard a few people suggest pinion bearings. i was gunna reshim everything, replace all the bearings and rebuild the diff with kevlar clutches this winter, just trying to get a head start as to what to look for and where to look first.

any word from the wise? thanks in advance.

edit: i think theyre motive gears… that might be me problem no matter how its set up.

also, what tools are required for reshimming the ring and pinion? dial indicator, marking compound, tq wrench, shim kit obviously. i havnt found any good “how to…” threads online yet.

They did that as soon as the motive gears were installed. Since the bearings were all changed at the time as with the fluid I didn’t worry about it. I drove the car hard and they held up. I’ve heard 3.73’s and steeper from motive can whine so I guess I just hoped P&J set the back lash right.

Hopefully ChallengerMike can chime in here. He recently set up my rear end and had a ton of knowledge that may help you out with your question.

oh man i didnt know there were new bearings. its not even that bad; im just trying to learn about all this new crap i gotta deal with on a new platform.

fyi as far as the shims go always start with same that was previously in there, it is usually where it needs to be or very close. whine usually comes from low fluid, worn / improperly meshed gears, or bad bearings. considering the gears seem fine and the bearings are new and you just checked the fluid i think your fine.