Rear End Question

RETIDEPXE · Dec 9, 2009

2007 M2 345,000 miles, switched to mobil synth 75-90w rear end grease about 100,000 miles ago and now I believe a pinion bearing is going. Noticed a whine in the rear, checked grease level, looked good, no noticeable metal on the magnet, but the pinion housing is getting too warm to the touch, not hot enough that i can't hold a hand on it but warmer then it should be. Hubs are cool and back of pumpkin is warm.
Being somewhat new to trucking, are these rear ends rebuildable or am I better off with a replacement? Any suggestions of a good rear-end shop?

Any advice appreciated,

Retidepxe

piper1 · Dec 10, 2009

Depending on the brand of rear end it could be a very simple fix, at worst, you could get a re-manufactured rear.

If you look at where the pinion shaft sticks out, and you see a circle of bolts (6 or 8 likely) facing the front of the truck your pinion shaft can very likely be removed separately and re-bearing-ed.

RETIDEPXE · Dec 10, 2009

Thanx Piper. I have determined it is a Meritor R-series 21000# single. It is only serviceable by splitting complete front housing from the pumpkin (16 or so bolts). I am not so sure now if it is a bearing rather then just the unever wear on the tire lugs as the noise seems to dissappear on different pavements, the smoother the pavement the more pronounced. I'm going to wait till I get home and put a steth-a-scope (read long screw driver) to my ear to decide if bearing noise or not. Pinion seal is not leaking so maybe I'm OK. Will post in a couple weeks my findings when home, if it last that long.....knock on wood.

Retidepxe

RETIDEPXE · Dec 27, 2009

Made it another 2500 miles with no probs. Put an electronic steth-a-scope in the pinion bearing area and everything sounds smooth. I did notice the pinion housing area did get almost too hot to hold (almost). Question is now, is this amount of heat normal?

Retidepxe

piper1 · Dec 28, 2009

Meritor likes to see the oil stay under 250 deg F. Operation above 190F is very common though.

Refer Hauler · Dec 29, 2009

Not sure on the warranty on the lighter rear ends, but If you are under warranty get it checked out ASAP by a dealer so there is record of problems/concerns. The 40 k rears are warranted to 500k miles yours may be the same.

moose · Dec 29, 2009

Take an Oil sample , (any grease monkey can do it)
and send it to a lab . (not the Speedco machine and alike)
(you can find a good lab , by calling any of the by pass oil filters company's )
BTW how do you like that Synt. Oil ?
was it a good switch ?

tazgunney · Dec 30, 2009

I found out the hard way two years ago that synthetic oils are good but there was a trade off with heat and noise. Redline suggested I change from thier 75w90 to 85w140 synthetic. took care of all my problems and is still working today.

RETIDEPXE · Dec 31, 2009

All great advice. I do think changeing to 85w140 would be a good idea or slip some Lucas in it. As far as rr end grease goes, it always seemed a little too thin to me when I checked it hot. I do oil analysis for my motor thru OPS so I'll consider sending one in. Sounds like I better check the warranty also but I am fairly certian the whine I was hearing is my tires (Yokohoma 577 lugs wearing farily evenly)......or can a smoother road surface carry the sound forward better, hum??
thanx all,

Retidepxe

greg334 · Jan 1, 2010

Why would you put Lucas in with any synthetic oil?

nightcreacher · Jan 1, 2010

As long as your temps are not over 200 degrees,your ok.If the temps go higher,it could be a pinion bearing.My rears have 835000 miles,oil samples fine,and original synthetic oil.I usually change box oils at 500000 miles with synthetic oil,but this time I'm going with the oil samples.I change engine oil at 20000 miles,even though oil samples were fine at 30000 miles

RETIDEPXE · Jan 2, 2010

Hey Greg, Lucas to thicken it up a bit. And I'll throw this out there because I really am no expert, but, why not Lucas in Synth? From the Lucas web, "It safely blends with synthetic oils." However it does not differentiate between "oil" and "grease". I have heard it can create cavitation bubbles in a motor where the oil is abused a bit more then in gear boxes.

Retidepxe