Posi issues, how much friction additive?
Thread Starter
Racer
Joined: Apr 2008
Posts: 447
Likes: 6
From: Dublin CA
Posi issues, how much friction additive?
I replaced my rear end fluid recently and my posi isn't working very well. I did not add any friction additive, i'm not sure how much to start with. Can anyone help?
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
easy way is just to use redline 75-90, it has a great additive pack for our LSD's
not the stuff that says NS or no slip
or you could buy a bottle of gm additive and add an ounce at a time until you get the feel that you're after with what you have
if you used regular 75-90 dino oil it's probably chattering like mad
not the stuff that says NS or no slip
or you could buy a bottle of gm additive and add an ounce at a time until you get the feel that you're after with what you have
if you used regular 75-90 dino oil it's probably chattering like mad
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
if you used the gm oil there is probably a service bulletin for our cars that says how much to add
or
what you said above would work too. just may take some experimenting. you don't want to use too much, doing so starts bringing you closer to an open diff
or
what you said above would work too. just may take some experimenting. you don't want to use too much, doing so starts bringing you closer to an open diff
Safety Car
Joined: Aug 2011
Posts: 4,449
Likes: 409
From: Portland OR
You may have broken bellvile springs. It's common for one or both to fail.
How many miles?
Something to consider if the GM "moose juice" doesn't help.
BTW, the stuff is usually used to cure posi chatter.
Ron
How many miles?
Something to consider if the GM "moose juice" doesn't help.
BTW, the stuff is usually used to cure posi chatter.
Ron
Burning Brakes
Joined: Nov 2006
Posts: 989
Likes: 8
From: Chino Ca.
Depending on what fluid you used you may need friction additive.
If you used part number 12378261 changed to 89021677 you need two 4 oz. bottles of friction modifier 1052358.
GM's new differential fluid for the C6, 88862624 needs no modifier. I use this in my differentials, but I always use C6 clutch packs.
OP, what do you mean when you stated "My posi isn't working very well"?
If you used part number 12378261 changed to 89021677 you need two 4 oz. bottles of friction modifier 1052358.
GM's new differential fluid for the C6, 88862624 needs no modifier. I use this in my differentials, but I always use C6 clutch packs.
OP, what do you mean when you stated "My posi isn't working very well"?
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
actually that's a good point. the op never defined what not working very well was. the additive increases slip and reduces chatter. if that's your problem that's the solution. if that's not the problem, it's likely not the solution
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Thread Starter
Racer
Joined: Apr 2008
Posts: 447
Likes: 6
From: Dublin CA
Im only getting one tire to spin most of the time......
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
additive won't help this, additive actually makes it more likely to happen, increases slip
you may well have something wrong with the lsd
either that or the oil you used had too much additive in it. did you have issues before the oil change?
you may well have something wrong with the lsd
either that or the oil you used had too much additive in it. did you have issues before the oil change?
Safety Car
Joined: Aug 2011
Posts: 4,449
Likes: 409
From: Portland OR
When the belville springs break, you lose the preload on the clutch pack. And the clutches wear out.
When I went through my diff to beef it for racing, one spring was busted and the clutch pack on that side was toast.
The C6 clutches along with DTE springs is a really good upgrade. And not all that spendy.
When I went through my diff to beef it for racing, one spring was busted and the clutch pack on that side was toast.
The C6 clutches along with DTE springs is a really good upgrade. And not all that spendy.