8 3/4 Sure grip information

[SMCARNUT]

I built a tester to measure the breakaway torque for 8 3/4 rear end center sections. A buddy gave me the old axles out of a C body. I cannot find the exact breakaway torque I thought I had it written down somewhere. Any rear end guru's have the exact breakaway torque spec on clutch and cone style sure grip units?

 

[RustyRatRod]

To my knowledge, the only "accurate" way to measure that would be to measure it at the pinion. Measuring at the axle is "going backwards" from how the sure grips are designed. Since they are torque sensing (clutch type more than cone type) they "ramp up" when torque is applied. So measuring at the axle does not include "that". Some will argue that the cone type does not ramp up and is not torque sensing, but it most certainly is to some extent. All you have to do is look at how it's designed. "I guess" you could get a ballpark idea of how good they are at the axle, but I don't see it getting very accurate.

 

[SMCARNUT]

I can do it both ways at the pinion and axle. I tried it both ways on this old cone style sure grip. It was 25-foot pounds when I tested it both ways. Google said 100-120 foot pounds but it did not say cone versus clutch. Dr Diff website says he tests them to make sure they are 100-120 before he ships but that is a clutch style surge grip. I just was hoping that someone may have had the exact spec's for both units.

 

[RustyRatRod]

I can do it both ways at the pinion and axle. I tried it both ways on this old cone style sure grip. It was 25-foot pounds when I tested it both ways. Google said 100-120 foot pounds but it did not say cone versus clutch. Dr Diff website says he tests them to make sure they are 100-120 before he ships but that is a clutch style surge grip. I just was hoping that someone may have had the exact spec's for both units.

Wow. That seems rather low. I've seen some specs show 800 foot pounds at the axle. That was like form some of the Moroso Brute Strength (clutch type) units. So 100-120 seems low and certainly 25. Does Dr Diff specify whether he tests at the axle or pinion? Regardless, I would certainly respect whatever he comes up with.

 

[SMCARNUT]

This is from DR Diff website I will try and call him tomorrow.


New, reproduction 8 3/4" clutch sure-grip ("powr-lok") includes upgraded EN353 cr-mo 1 piece 30 spline side gears and spider gears.

These are not the same units offered by others. Each unit is bench tested to ensure 100-120 ft lb breakaway torque.

 

[RustyRatRod]

This is from DR Diff website I will try and call him tomorrow.


New, reproduction 8 3/4" clutch sure-grip ("powr-lok") includes upgraded EN353 cr-mo 1 piece 30 spline side gears and spider gears.

These are not the same units offered by others. Each unit is bench tested to ensure 100-120 ft lb breakaway torque.

Ok, clearly he knows what's going, I would think.

 

[4mulas]

I was told and have use 125lbs as a figure for this

 

[john-9]

here is my 50 year experience with these sure grip units --
for the factory cone type sure grip after a rebuild 100-125 lbs/ft rotating torque on the bench ,, i have had pristine cone type sure grips come in and they tend to run at 120lbs/ft rotating torque
for the factory clutch type units with new Mopar Performance MP4529484 clutch pack 180-250 lbs/ft rotating torque on the bench
for the factory clutch type units with the Spicer 22233X clutch pack 120 - 150 lbs/ft rotating torque on the bench
now the new clutch type sure grips you see on e-bay etc. run 100- 150 lbs/ft rotating torque on the bench ,, depending on the supplier.

 

[oldkimmer]

Back in the late 70s I had 2 cone type that were a 1 wheel peel. I only measured the drivers side on both with a torque wrench. Just over 100 foot pounds on both. Not sure what they need to be but 100 isn’t enough. Kim

 

[AJ/FormS]

On the street; For cone-types,
I welded a big nut on the ends of two splined stub-axles, which I insert into just the loose case, down into the clutches. One stub gets chucked in the Bench vise, and the other end gets the beam-type Torque-Wrench.
The cones are pre-oiled with whatever oil-recipe that I am going to use, which includes the whale-oil.
I do not measure Breakaway torque. Instead,
I measure turning torque after the clutch is slipping.
I do all this before the case goes into the chunk, cuz I might be taking it apart several times.
I set my cone-types up at 100>>125; depending on the tires being used.
On the street, I want the thing to slip on tight corners, else it will spin me out under power. To prevent the thing from acting like a spool with skinny tires; 245s get set down on the low end. For 295s , or for drag, I set towards the high end.
Anything less than 90 is not gonna work for me.
Too much more than 120, is gonna end up spool-like.
And so, I have accumulated several cone-types over the years, which are variously set up..

On the street; For clutch-types;
For street, I prefer the clutch-plate type SG which allows a lil slip on corners most of the time, yet dialing the power on, she locks up. and, I can vary the grip around corners with the gas-pedal, perfect for my driving style. But,
I haven't found a scientifically repeatable way of setting mine up; so, for me, it's a hit and miss deal, so; Yeah, it might take two or three tries to get it in the ball-park, after which I use the percentage of whale oil as a fine-tuning tool. Your results may vary.
While I prefer this type, with my manual-trans, it can be tricky, and have a long learning curve, so I set mine up a lil loose. ........ to prevent unexpected spin-outs.



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