Cone Style Sure Grip

vdk2010

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Is there a way to figure out if I have to mill down the top surface of the cones in order to shim them due to wear?

I think my cones still look like they have a lot of live in them and I don't want to mill them down if I don't have to.

The car (and diff) have only 43k miles on them.

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CBODY67

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You've got to consider that the vast bulk of those miles were in straight line driving, not turning corners. The flat-plate limited slip units I have have well past 100k miles on them, even past 700K miles on the one in my '77 Camaro, and they all still work just fine. Even the ones I saw disassembled (back then) didn't seem to have any significant wear on the friction plates. Nor did any of my friends undertake the job of replacing the friction plates due to wear, back then.

How far "out of spec" do you suspect yours might be? I realize that the cones were not supposed to be as stout as the flat-plate units might have been, but where's the wear you are concerned about? I suspect it would be obvious if it's there? Or might it be an age-related issue? Just curious.

Enjoy!
CBODY67
 

vdk2010

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I have no experience whatsoever with wear on these parts. I'm just curious if someone experienced with these sure grip units can give me some tips.
I can't see any wear on them, but now its all apart, so I want to service everything that should be serviced while I'm in it.
 

halifaxhops

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Sometimes you have to get them resurfaced then shim it accordingly. Let me see if I can find his thread on it.
 

rd92west

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First I will say that I have very limited experience with cone type sure grip.
Last winter I got on a first name basis with cone type sure grip.
I had never opened one up before.
Same as you, I have seen the posts about milling the cones.
My cones looked good.
You can put the cones in were they go and fit a feeler gauge in thru the hole to determine if its bottoming out. If you have a gap under the cone you should be fine.
I cant remember how much clearance I had, but feel there was enough for lots of use yet.
I havnt had a chance to test it out
 

RustyRatRod

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I'm rustyratrod from FABO. Take some modeling clay and put a piece about the size of a marble into the case half end where the cone fits into the case. Put a little grease on the face of the cone to keep the clay from sticking to it. Now install the cone into the case and press it in as far as it will go. Remove the cone and measure the thickness of the clay. I recommend machining the cone end if clearance is less than about .060". When the face of the cone hits the inside of the case, the unit becomes ineffective.
 

RustyRatRod

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First I will say that I have very limited experience with cone type sure grip.
Last winter I got on a first name basis with cone type sure grip.
I had never opened one up before.
Same as you, I have seen the posts about milling the cones.
My cones looked good.
You can put the cones in were they go and fit a feeler gauge in thru the hole to determine if its bottoming out. If you have a gap under the cone you should be fine.
I cant remember how much clearance I had, but feel there was enough for lots of use yet.
I havnt had a chance to test it out

Remember, where the cones and case wear is on the sides of the cones where the "theads" are and the insides of the case where those threads engage. As those two surfaces wear, the cones fall further into the case sides until they hit the insides of the case. When that happens, the unit is ineffective.

They continue to get weaker and weaker as they wear, because the cones are getting further apart causing the springs to lose tension as the cones fall into the case. So, even if the cones are close to the insides of the case, it may still need to be refurbished.
 
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vdk2010

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I'm rustyratrod from FABO. Take some modeling clay and put a piece about the size of a marble into the case half end where the cone fits into the case. Put a little grease on the face of the cone to keep the clay from sticking to it. Now install the cone into the case and press it in as far as it will go. Remove the cone and measure the thickness of the clay. I recommend machining the cone end if clearance is less than about .060". When the face of the cone hits the inside of the case, the unit becomes ineffective.
Ok, thanks, that's helpfull!

I used Play-doh because that's what I had and it looks like I'm good! I have 2,2mm (0.087") clearance on both case halves.

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rd92west

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I'm a curious need to know guy. Quite often this costs me money.
The cone sure grip caught my curiosity, or mainly how it operates.
In FSM I see
"During torque application to the axle, the initial spring loading of the cones is supplemented by the gear separating forces between the side gears and differential pinions which progressively increases the friction in the differential."
Something about massive horsepower, sticky tires, and separating pinion gears makes me feel woozy.
 

RustyRatRod

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I'm a curious need to know guy. Quite often this costs me money.
The cone sure grip caught my curiosity, or mainly how it operates.
In FSM I see
"During torque application to the axle, the initial spring loading of the cones is supplemented by the gear separating forces between the side gears and differential pinions which progressively increases the friction in the differential."
Something about massive horsepower, sticky tires, and separating pinion gears makes me feel woozy.

That's because it's not made for "massive horsepower". It's a street sure grip carrier that's for lighter duty applications than the clutch type Dana Power Lock. They work extremely well in their element, like anything else.

The trick to making them last is stock or mildly modified horsepower in a street car, or one that sees limited track time. They're not made for a full time racing environment. They also require a friction modifier, same as a clutch unit, to help make their differential action smoother.

As long as you know their limitations and don't ask more of them, they will last. "About" the only time I've seen them "tear up" is when they are worn out and people do a one wheel burnout. Then, the small pinion gears inside the case over heat and weld themselves to the cross shaft, lock to the cross shaft and force the cross shaft to spin in the case, ripping the cross shaft pin out of the case. But not even the Dana Power Lock can withstand that type of abuse.

They are good units. You simply have to know how to treat them.
 
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