My rear end and its gear lube...help.

[Turbo6Smackdown]

I just threw in some new redline synthetic gear lube with no limited slip friction modifier in it(75/90 ns) in my rear diff, to see if it would help with evening traction out on my tires. Well I was told by several people that it took a little less than two full one quart bottles. Well mine swallowed both of them up without leaking any from the diff plug, and i think it could have taken more too. Do our rear diffs (stock) take 1.8 quarts WITHOUT leaking? or does that mean 1.8 qts is full, and any more would leak out of the fill hole. are they not fully 'full' unless theyre leaking out the fill hole?

And I thought the 'no friction modifier' gear lube would make my rear end chatter around the corners. it didnt one bit. is there something wrong with my rear end?

 

[ponykiller]

i'm looking for the same, how much lube does the rear end take?

 

[turbo nasty]

:biggrin: Make sure the car is level and pump till it starts running out the fills plug and cap it I think it is right over 2 qts.
Alot of folks we argue...But I never use synthetic in the rears of the GN's. I believe that Eaton was the original manufacturer of the posi units OEM wise and every replacement I have purchased from Eaton has always had a BRIGHT colored label warning not to use Synthetics as they will hamper the operation of the posi unit.
I have had stellar luck with bottle of Lucas oil Stabilizer (dino), 1 bottle of Valvoline 75/90(dino) and 1 tube/bottle of limited slip additive and the rear end has never made a noise or chatter.
I have even ran it for 2.5 years once w/o changing it and NEVER had the sucker chatter. With just dino and limited slip additive I would get chatter in turns after a year and especially after being on the highway for a while and then turning at low speeds right off the highway. This has been for over 75 k miles in the 87 and 15 k in the 86 so if it was a crap it would have smoked it by now definetly the way I pound em. :biggrin:

 

[Turbo6Smackdown]

i wonder why? i got the NS formula. it has no additive in it. and i didnt put any in when i replaced the gear oil for extra grabbing power.. seems to have made no difference at all.

 

[Ormand]

The friction type posi rears depend on a balance lube, that slips just enough, but no too much. If you use lube that is "too slick", you won't get any chatter, but you might lose some of the lock up capability. You can measure the clutch slip with a big torque wrench, if you want to. It would be a good test to do it with several lube combos.

 

[ponykiller]

i changed the rear end lube last night (2 qts) it has been about 3-4 years since last change, looked good in side also was foammy, is that the lube break down?

 

[Turbo6Smackdown]

mine has NONE of that stuff in it. for maximum grabbing. but, it doesnt chatter... i wonder why...

 

[RT87]

I have had one of these cars since new. I never had any chatter until the first trip down the interstate with the car. After running 200 miles or so and then pulling off of the highway, everything was normal. When I backed out of the parking space, I got the thunk, thunk, thunk chattering noise that you are referring to. It would not go away until I added GM limited slip additive later in the trip and did the basic S turn maneuver to work in the additive.

It seemed that I never had problems around town, even after thousands of miles, but after a lengthy drive on the highway, the posi lube would break down and chattering would start. I learned to take a tube of the additive along on trips, just in case.

Just my 2 Cents.