Diff oil for 84 Toyota PU

[expat]

I have an 84 2wd Toyota Pickup, it has 64k from new. I do not know the service history other than I have a bunch of receipts from oil change specials from 'Les Schwab' (a Washington Tire dealer)
There seems to be a whine coming from the rear end, and I want to change the rear Axel oil.
What do you suggest I use?

 

[4x4taco]

80/90 cheap stuff. If you have a wine, good chance you'll need a rebuild, so you'll be dumping that oil soon.

 

[expat]

I don't think there is much chance I will be rebuilding it soon.
Does this Axel require Yellow metal friendly gear lube?

 

[Falcon_LS]

When do you hear the whine? Do you hear it continuously, or does it happen when you release the gas, etc? Get your hands on the cheapest GL-5 rated, mineral 80W-90 you can find, and add 60 ml of Auto-Rx per litre of oil (e.g. if the unit takes 2.5 litres of oil, add 150 ml). Drive 2,000 km and drain/refill. See if it helps with the whine.

 

[expat]

The whine seems constant and increases with speed, there is little, or NO change on left or right bends.
There is some slack when the drive shaft is turned.
Does (did) this Axel use yellow metal thrust washers?

 

[Steve S]

First of all change the oil and see what happens. The diff gears are setup with some clearance between the gears cause they expand when hot and for the oil, so some "slack" is needed. So there will be some play. .Yellow metals ???? the required oil is a GL 5. Could be tire noise.

 

[4x4taco]

Lil slack is normal. that diff needs about .006" of gear slack. which yields about 1/4 turn in the driveshaft.

 

[expat]

I think my plan will be to get the rear on Jack Stands and run the truck to establish that the noise IS coming from the Diff. I will then change the oil, (and see what comes out) then see if things improve.
I really can't see how Arx could help here? (Unless I had a seal leak or something)

 

[KilgoreBass]

U-joints can whine and/or screech if a needle bearing is failing.....check for slop in a u-joint by holding the front yoke and trying to move the drive shaft, then do the same to the rear pinion flange. Also, a center bearing support going bad on a 2 piece drive-shaft, if you have that (extended beds/cabs sometimes do)....

 

[KilgoreBass]

Originally Posted By: 4x4taco
Lil slack is normal. that diff needs about .006" of gear slack. which yields about 1/4 turn in the driveshaft.


1/4 turn??? That sounds very excessive for 6 mil of backlash, no????

 

[Falcon_LS]

Originally Posted By: expat
I really can't see how Arx could help here? (Unless I had a seal leak or something)


If the cause of the whining is friction, ARX can help.

 

[expat]

Originally Posted By: Falcon_LS
Originally Posted By: expat
I really can't see how Arx could help here? (Unless I had a seal leak or something)


If the cause of the whining is friction, ARX can help.



As I understand it Arx is a cleaning product, not an EP additive.
Also I believe gear whine to be a result of incorrect tolerances in the gear arrangement (perhaps due to gear, or bearing wear)
I have some Arx on hand, but I can't understand how it could help in my rear Axel? Contaminant build-up is unlikely here!

 

[4x4taco]

.006 of backlash gave me about 1/4 turn. Then again I had a full blown Detroit Locking Diff. That might of altered that. I know my diff was right, b/c I had the gears built by a "special someone" in the 4x4 world and they survived things I've never seen.

 

[unDummy]

If the end is whining, your fluid is shot. A simple solution is to step up a weight. If the whining subsides, you know the problem.

Use a 140wt gear oil, or a 50:50 blend of 90wt with 140wt. Thats it. No additives, no cleaners, no nothing but the cheapest 'new' gear oil you can get.

BTW, prior to your gear oil change, pull all the fill plugs cold and measure how much it takes to top off.

 

[expat]

Changed the oil, it came out very clean, and there was minimal 'paste' on the magnetic drain plug.
I ran the truck while on Jack Stands and the Diff was quite. (perhaps I should have put some load on by pulling the Hand brake?)
I have re-filled with Super tech 85w-140, I'll see how it sounds on the road tomorrow.