Sources for rear differentials-- what you get--

[Omnibot2000]

Originally Posted by cadillackid

Great info. The set I got for mine which whines only in a certain narrow range definitely was polished a bit. The gears still look great and the mesh / preload / lash are good but definitely on the shiny side, I never realized that affected whine

Agreed. I was not aware of that.

[PorchDog]

Originally Posted by Booyah45828

Porchdog, Sorry you had to find the dirty details of the "reman" market the hard way.

There are too many places that consider a reman to be a visual inspection coupled with a fresh coat of paint.

FWIW my bus whined too. I considered it normal on an old bus with mileage. Nothing crazy though as you could only hear it if you were sitting in the back though. Sitting in the middle or up front you heard the engine, or the trans if it wasn't in 4th(at545).

We go with weller for all of the reman stuff we use in the shop. They're top notch and we've had no issues. I'm glad you found a place that made you happy. Keep clean/fresh fluid in it and it should last forever.

I had accidentally become the owner of a free 5 gallon container of 80W-90 full synthetic GL-5, so that is what I put in it. I would have liked to had the 140-- but free was hard to beat.

[PorchDog]

Originally Posted by Tin Roadtube Vagrant

I performed rebuilds for Eaton and Mack transmission/diffs at the dealership. Back when we fixed stuff because the reman market wasn't as competitive. The sound of a used gear is related most often to its tooth polish. Not to say engagement doesn't matter..... but a gear with the oil hatching polished off to a mirror finish will ALWAYS whine, even though it's fit for service. The rule was to replace transmission main shaft gears in the top hole position. That's the one the driver will be sitting in the most, will polish the worst, and costs the least because it will be a tiny gear for overdrive or direct. Diffs are no different. If you buy a rebuild.... be aware...... polished gears ARE service worth, but will whine. A new ring and pinion, set up right, is the only guarantee for resonance issues.

Thanks for posting this-- great information. No substitute for actual hands on experience.
Jeffrey

[Booyah45828]

Oil turns black because of the soot bypassing the rings. Your new oil turns black because there is still old oil present in the engine during a change. Engines that aren't worked as hard, or engines that aren't as worn out, might not dirty oil as quickly. Also, engines that use EGR will also have dirty oil because of the constant consumption of exhaust gases.

[Omnibot2000]

Originally Posted by Booyah45828

Oil turns black because of the soot bypassing the rings. Your new oil turns black because there is still old oil present in the engine during a change. Engines that aren't worked as hard, or engines that aren't as worn out, might not dirty oil as quickly. Also, engines that use EGR will also have dirty oil because of the constant consumption of exhaust gases.

I just remember 20+ years ago changing oil on a series 60 and even with fresh oil it was disgustingly black. Change oil on a N-14, C-15, M11, ISX (when they first came out) and nothing compared to the filth of the series 60's.

[TaliaDPerkins]

. . . is there a safe way to scuff them? Like with crosshatching a cylinder with a bore hone? Does that necessitate a new "run in" period at low power and then a fluid change?