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posi units

THEFERMANATOR said:
GM does not require the friction modifier like others since the clutches are not pre loaded. A G80 is only supposed to be active once wheel speed is between 10-25 mph, and there is a 50(don't remember the exact number, but it's quite a bit of difference required to engage the flyweight) rpm difference between the 2 tires. Alot of people let out of the throttle thinking they're broken before the wheel speed ever gets high enough to engage them. Then theres those who hammer them trying to lock it in, and exceed the speed it will work at.

Edit: found this tidbit straight from GM in a tsb regarding G80 operation specifically stating NOT to ever add friction modifier to one.
Important: Installing any friction modifier causes the clutch pack in the locking differential to slip and miss engagement. A fluid flush can often remove debris that is a contributor to clutch chatter. Adding friction modifier additive can cause a loss of locking differential functionality.
Click to expand...
I guess I goofed by adding the information about the friction modifier, AK, I apologize for that.:nailbiting:
sounds like the differential should now be flushed a couple of times then the proper stuff installed.
Thank You THEFERMANATOR for posting the proper information.
 
MrMarty51 said:
I guess I goofed by adding the information about the friction modifier, AK, I apologize for that.:nailbiting:
sounds like the differential should now be flushed a couple of times then the proper stuff installed.
Thank You THEFERMANATOR for posting the proper information.
Click to expand...
GM used a gov loc which is different than what most anybody else used(unless you have a quadrasteer suburban which uses a dana 60, in which case it uses friction modifier). This is why having a filled out signature and all the details on the vehicle in question is so important because of slight changes from year to year, or one axle uses it while the rest don't.
 
The grabby chattering came on kinda suddenly. I think I'll leave it in at least til things slow down Abit for me. Sounds like the worst it would do is make it an open rear end.
 
ak diesel driver said:
The grabby chattering came on kinda suddenly. I think I'll leave it in at least til things slow down Abit for me. Sounds like the worst it would do is make it an open rear end.
Click to expand...
If I was there now, I would just do that for You. Probably will not make it back over there until next summer or fall. Catch Me some more salmons. LOL
 
MrMarty51 said:
I guess I goofed by adding the information about the friction modifier
Click to expand...

when I started reading down through these posts, I was going to make the same suggestion, or add that Mobil 1 can also be used and no additive is necessary. I had no idea a G80 didn't require some special attention to this detail.

Side note - mom's Buick Rainier was growling, when turning, from the rearend. Dad drained and put in Schaeffer's and the growling quit. I'm curious why the growling started and also why it stopped with the synthetic oil.
 
I believe that Schaeffers lubes has Moly in it, so that would also be a friction modifier.
I know I was looking for oil for the 6.5 that had moly added and Schaefers came up in the search. You might want to check it out though.
 
well after looking at pics on the net I think it is, so now my ? is people said to pop the cover and look for pieces in the bottom but I see no place for said pieces to come out
 
The 10.5" gov bomb comes apart when you take the ring gear off. By design all the pieces will be trapped inside of it most likely. You'll have to pop the carrier out, remove the ring gear, and split it apart to see what it looks like.
 
So I discovered my brakes on the driver's side were dragging. Wheel cylinder was seeping but not alot. So new wheel cylinder and also discovered the backing plate had some grooves from the shoes, tigged those up and ground the flat. Rolled alot easier. Went to town and on the way home it pulled for awhile again (on brand new asphalt) so my pulling is still intermittent comes and goes. Anything else I should double check before I order a posi?
 
Drum brakes self energize if the shoes are tacky from basically anything. Even diff oil. Rule them out. Maybe back them off and block them hydraulically to test and make sure?

I've dealt with stuck ebrake junk before.. They'll drag and make the drum brakes real touchy.
 
I cleaned them really well and if anything they were loose on the adjustment. I'm also wondering if the variable steering thingy might be causing the issue. I know Simon had a pretty bad experience
 
Pressure valving on the pump controlled by vehicle speed and a sensor in the column. I read you could unplug it at the pump and it will give you either max or min pressure (don't remember which) but do it the same all the time. So I just unplugged it and we'll see what happens.
 
well so far so good. steering is way tighter now, I thought I was going to have to replace my box in the near future but not now. no more abnormal pulling either
 
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