Rearend Whine after rebuild???
 

Just had rear end rebuilt with new everything. Noticed that through all gears, (speed related), there is a extremely high pitched whine. (Sounded like alternator whine on radio) Not real loud but noticeable. Took it back to shop they tore it back apart, replaced all bearings, and still have the whine. They do a 500 mile inspection and told me to go ahead and drive it and will relook at that time.

Used all Yukon parts and an Auburn Posi.

We did not replace wheel bearings as they were just done about 4000 miles ago. Axles are worn. Using Axle saver bearings.

Im almost wondering if it could actually be from 700r4???

Only occurs in gear and is constant while accelerating. Not while coasting. i.e. if you trow into neutral no noise.


Thoughts?

thanks
tt

Re: Rearend Whine after rebuild???
 

Were the gears new or used? it could be a ring gear whine that happens if the pinion depth is WAY off

Re: Rearend Whine after rebuild???
 

I believe pinion depth may be off - did they set backlash? I'd ask them.

Re: Rearend Whine after rebuild???
 

Like Jocko said, pinion depth is most important and has to be set first. Then backlash. If there is a whine, the gears are not meshing in the center of the teeth. It will wear out in a few miles, getting louder and louder.

Re: Rearend Whine after rebuild???
 

Sometimes the pinion depthe is to deep in the ringear which causes a whine when I put mu 3.08 in my 67 mine is slightly to deep mine has a very very slight whine It has for years , some shops will set them like that on porpose because they are stronger that way ,

Re: Rearend Whine after rebuild???
 

If the whine is only on acceleration ad not while coasting /braking it will be the pinion bearing and still last for years ,Constant whine would be ring /pinion gear lash :chevy:

Re: Rearend Whine after rebuild???
 

I do some differential work and a light whine on acceleration at certain speeds might just be the gear set and not really an issue.

Re: Rearend Whine after rebuild???
 

Id say as mentioned driving it 500 miles then taking the cover off and if the gears are cutting a good pattern and no metal in the oil you are good to go

Re: Rearend Whine after rebuild???
 

Your only concern should be if the whine is still there at the end of 500 miles will that shop do anything about it.

Re: Rearend Whine after rebuild???
 

Pulling the cover will cost you some fluid, but looking at the wear pattern and resolving any issues will be worth it. Better to know and find no real problem, than wait and blow it up, while out of warranty.
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Re: Rearend Whine after rebuild???
 

Why did you have the rear end rebuilt in the first place?

If it did not whine before, it should not whine now. I would take it back and make them fix it. I'd say they are just giving you the runaround by telling you to drive it for 500 miles.

But that's just me.

Re: Rearend Whine after rebuild???
 

My experience with aftermarket gears........they whine.

Re: Rearend Whine after rebuild???
 

After HRPT this year, had serious grinding noise, had rearend checked and metal poured out with fluid. Bearing failure.

Re: Rearend Whine after rebuild???
 

Yes, this is what i have learned.

Re: Rearend Whine after rebuild???
 

Most aftermarket gears I have used whine for a few miles until they clean them selves up. No ring and pinion are perfectly synched. They have to establish there own wear pattern. This has always been my experience. Oddly enough, the only gear set I didn't have whine was a $99 no name set I bought off ebay. 3.42 10 bolt, hundreds of burnouts and dozens of hard track launches, it's still going good in the kickin' chicken.

Re: Rearend Whine after rebuild???
 

I called Yukon, and BTW they have fantastic support. Was told they whine, nothing to worry about. Pulled cover, sent pics to Tech Support and was told job was perfect, mesh was where it should be and looked good.

Thanks to all you guys for the input!!!

Re: Rearend Whine after rebuild???
 

Don't want to start an argument but....I think your backlash is set too tight. With new gears and no marking grease it is hard to see the pattern but the wipe pattern is too wide and too deep indicating a backlash that is well below the 0.006 to 0.0010 inch setting called for in the specs. When the wipe pattern is wide and deep as yours is, pinion depth is correct but backlash is too tight and that makes the gears whine. It might be OK and it might not. The first photo is yours with the wipe pattern crudely outlined. The second photo is an 8.875T GM 12 bolt that I recently did with the wipe pattern shown in grease. This diff was set correctly for pinion depth and a backlash of 0.007 inches. You can measure the backlash with a dial indicator right in the truck, which is what I would do if it were mine. Peace of mind is always cheaper than a busted diff. Best of luck.

Re: Rearend Whine after rebuild???
 

Good call, I have very little knowledge about these rearends and appreciate your expertise. I see what your talking about. Taking truck in tomorrow for their final check out. Wish I had have saw your message a few minutes ago, just put cover back on. If backlash is wrong at this point, is it ok to make a change?

Re: Rearend Whine after rebuild???
 

All they need to do is swap a shim. Simple repair and the diff does not need to come out to get it done. It's a bit tough to do without a lift but I've done worse jobs than that lying on my back.

Re: Rearend Whine after rebuild???
 

Update, just when I thought things may be ok. Last night I put a few more miles on the rearend before taking it back in. First time I had taken the speed to 75 to pass, right at 75-80 have a significant "roar", when I slow to 70 it stops.

With the above info, I am assuming this is all related?

Re: Rearend Whine after rebuild???
 

Yes. The loud roar is indicative of a diff set up way too tight. it needs to be re-shimmed to get the backlash between 0.006 to 0.010 inches before it destroys itself. You are in the middle of the reason why I learned how to set up a diff correctly. I hired one out, it failed because it was set up too tight and the shop that did it just gave me the middle finger salute. Then I learned how to do it correctly, repaired mine and now, there are 12 members of the Classic Chevy Club of Tucson driving on one I set up and none has ever had a problem.

Good Luck!

Re: Rearend Whine after rebuild???
 

Awesome! Thank you for the info! I will feel confident telling the shop what they are fixing to find. Was not going to mention I have already looked, unless I have to. Ha!

Kinda wish I had done this on my own to start with, I have done everything else on many a cars/trucks from engines to trannys but never a rearend. With support from you guys on forum I think we are really miles ahead of most shop folks.

Thanks again!!
tt

Re: Rearend Whine after rebuild???
 

Quick update, shop received new gear set from Yukon on Friday. Installing tomorrow.

Maybe this will fix it all........

Re: Rearend Whine after rebuild???
 

Picked up truck. No whine at all until about 10 miles in when things get warm, then only a very faint whine. Have not gone above 50 yet, will try things out a little more this afternoon. Shop replaced all bearings and new gear set. Shop worked with Yukon and was told to loosen settings, alot, go figure..... Not sure what the pinion depth is set at, but BL was set to Ten-Thousandths. No doubt new aftermarket gear set will whine a bit, hopefully better than before.

Good or bad plan to find an OEM gearset and install? Am i asking for more problems? Just curious.

Thanks


Will keep you guys updated.

Re: Rearend Whine after rebuild???
 

Looks like you may have solved your problem. Don't worry about OEM gearsets. They aren't magic and any good wrench can set up an aftermarket gearset so they run quiet after the first 100 miles or so. Spec is 0.006 to 0.010 and yours looked like it was 0.002 or so. That explains why they opened it up A LOT! Look at it this way. Now you know what shop to avoid if you need another diff worked on BUT stay with this one until they make it right.

Good Luck with your truck.