Difference between a Sure Grip and a Dana Power-Lok

[Cranky]

My 64 Savoy with a stock 74 440 auto big tires shucked all the ring gear teeth (42 case) in 20 runs, spool and 35 spline axels

Dang. Who set up the gears?? Do you know what the back lash was?

 

[Ceedawg]

Dang. Who set up the gears?? Do you know what the back lash was?

There when I bought the car, did have a Max Wedge but the previous owner bought it for engine then stuck the 440 in it. After rear broke in went the Dana and still there to this day, that was 1992. There’s ways I would build the 8-3/4 that I think would make it stronger. One is heating up the gears to 450 for 5 hours then cool slowly. 95% of gears are street gears and HARD-BRITTLE. Heating make them a tad softer, an old guy told me this in the 1970s, nascar thing he said.

 

[Cranky]

There when I bought the car, did have a Max Wedge but the previous owner bought it for engine then stuck the 440 in it. After rear broke in went the Dana and still there to this day, that was 1992. There’s ways I would build the 8-3/4 that I think would make it stronger. One is heating up the gears to 450 for 5 hours then cool slowly. 95% of gears are street gears and HARD-BRITTLE. Heating make them a tad softer, an old guy told me this in the 1970s, nascar thing he said.

Used to be able to get the "pro" gears for the 8 3/4 but as the 9" became the chosen one everybody (aftermarket) gave up on the 8 3/4. Setting them up with a little bit tighter backlash seemed to help a little....and using just a little bit of clutch to help preload the drivetrain did too but going to the Dana was the best thing we did for all the parts concerned.

 

[old guys rule]

The term "Sure Grip" is a brand name that the Chrysler Corporation used to describe their limited slip differential. General Motors had brand names for theirs, Ford and AMC did too.
You could have a clutch or cone type and the term Sure Grip would still apply.
My experience.....Many called the 8 3/4" cone type limited slip the "Auburn" unit since they were known for producing those. The Dana Power Lock uses replaceable clutch discs to facilitate the limited slip action and is often preferred since it is rebuildable.

Aren't sure grip clutches replaceable also?

 

[Cranky]

Now I have to make a weak point in the drive train thinking front u joint whats your thoughts? Remember I do stupid strong.

Use the better U-joints and don't use stock axles.....

 

[old guys rule]

Use the better U-joints and don't use stock axles.....

Aren't sure grip clutches replaceable?

 

[Cranky]

Aren't sure grip clutches replaceable?

Yup but the cone unit can be machined to work again if the guts are not a total waste....

 

[1KoolBee]

The term "Sure Grip" is a brand name that the Chrysler Corporation used to describe their limited slip differential. General Motors had brand names for theirs, Ford and AMC did too.
You could have a clutch or cone type and the term Sure Grip would still apply.
My experience.....Many called the 8 3/4" cone type limited slip the "Auburn" unit since they were known for producing those. The Dana Power Lock uses replaceable clutch discs to facilitate the limited slip action and is often preferred since it is rebuildable.

What KD said. 8.75 Dana Power-Lock will fit in 741, 742, and 489 cases with proper bearings. In fact I’ve pirated one from a 741 case and put it in a 489. It’s the baby bro of the 9.75 D60 power-lock. “anti spin” cone type is ok until it wears out, then it’s junk. You can “tune “ the preload of a power lock by varying the number of concave clutch plates in each side.

 

[1KoolBee]

Yup but the cone unit can be machined to work again if the guts are not a total waste....

How do you correct the lash of the spider gears if you machine the cones? Shim the spiders?

 

[33 IMP]

How do you correct the lash of the spider gears if you machine the cones? Shim the spiders?

Pretty sure there are tutorials both here and A-bodies. I even think Cranky might have wrote one.

 

[Cranky]

How do you correct the lash of the spider gears if you machine the cones? Shim the spiders?

If it's the first time to machine the cones, I don't worry about them but anything after, I'll shim them. Used to get my shims from the Ferd dealership. Also, don't machine more then .025" from the cone's faces.....no need to go more than that and will last for many years. Years back someone said to machine them .100" but all that does is makes them .100" thinner.

 

[old guys rule]

How do you correct the lash of the spider gears if you machine the cones? Shim the spiders?

Use a spacer metal of course to realign things. I've had it done before.

 

[old guys rule]

Use a spacer metal of course to realign things. I've had it done before.

You use a spacer on the cone

 

[Kern Dog]

If it's the first time to machine the cones, I don't worry about them but anything after, I'll shim them. Used to get my shims from the Ferd dealership. Also, don't machine more then .025" from the cone's faces.....no need to go more than that and will last for many years. Years back someone said to machine them .100" but all that does is makes them .100" thinner.

I have heard conflicting opinions on the re-buildability of the CONE differentials.
For the most part, the ones that are against it are Rick Ehrenberg and people repeating the opinion of Rick Ehrenberg.
I like the guy's work and trust most of what he has written but this is one of the few things from him that I don't trust. It seems like if the cones are machined to ride on a fresh surface AND a spacer is used to make up for the amount of material that is machined OFF, you'd eliminate excessive clearance and basically be where you'd be when it was new.

 

[Cranky]

I have heard conflicting opinions on the re-buildability of the CONE differentials.
For the most part, the ones that are against it are Rick Ehrenberg and people repeating the opinion of Rick Ehrenberg.
I like the guy's work and trust most of what he has written but this is one of the few things from him that I don't trust. It seems like if the cones are machined to ride on a fresh surface AND a spacer is used to make up for the amount of material that is machined OFF, you'd eliminate excessive clearance and basically be where you'd be when it was new.

Well, imo, the spiders have slowly moved slightly to a new pattern over the years and there's not enough slack or excessive clearance to hurt things. I've done a bunch of these things since the 80's and even maintained one for a buddy that was racing a fully optioned out 70 Challenger RT that was running low 11's plus I've done several for myself that also saw drag strip action. Also, the cones to not operate on a 'fresh surface' The part that 'bites' or locks isn't machined.....the faces are. When the faces end up with '0' clearance, that's when the OD of the cones do not bite the 'cups' anymore. Also....I thought the same thing the first time to machine one and added .010" shims to both sides and it turned into a locker and had to take the shims out. Many years later I machined the cones again and THEN added the .010" shims and it was fine. Ran that one for several years too. Rick has some pretty good thoughts on how to do things but even Rick isn't always 100% right on 100% of the things we do.