Sure Grip Project

[detmatt]

I had a ‘97 Dodge 1500 pickup that I bought in ‘99 with over 60k on the odometer and it had a rear end that growled but that was the only symptom. I sold that truck 12 years later with over 230k(iirc) on the clock and the same growl.

 

[68PK21 440.6bbl]

Yea I've heard that sawdust in the oil works wonders in taking that growl away, also good to quiet out a manual transmission.

After I bought my first 1968 PK21 the friend that I bought it from informed me that 1 cap of brake fluid put into a leaking automatic transmission will seal it up real gud!
But then this was the same person that threw a clutch disc in his 4x4 Chevy Blazer (plow vehicle) without replacing the throwout bearing (cheap bas'tad)...
Don't need a crystal ball to know what the outcome of that one was.

 

[thrashingcows]

This may help.

How To Recondition a Sure Grip Cone

I can confirm that this works well, I have rebuilt one of my old worn sure grips this way and have been running it in the wagon for many years.

Only thing I would add is to make your shim out of stainless if possible since a regular washer, even a hardened one will wear down more easily then the stainless and the hardened regular washers are generally quite thick. Stainless "work hardens" with heat so it will get very tough after a bit of running. I have several small sheets of stainless around I have scavenged and saved over the years and cut my shims out of one of those then measured the thickness and had that removed from the bottom of the cones.....think it was .050?

 

[furious70]

So, I sold it to him, didn't clean it up to see the pitting,but here's my thoughts

I'd be surprised if you'll hear anything. Think about how many cars spend years off the road and then get put back into service without the gear lube being replaced let alone pig removed to check for rust on the gear that was sticking out of the oil.

If you run it and it's junk I'll make it right with you.

 

[detmatt]

It’s going to be fine.

 

[73Coupe]

So, I sold it to him, didn't clean it up to see the pitting,but here's my thoughts

I'd be surprised if you'll hear anything. Think about how many cars spend years off the road and then get put back into service without the gear lube being replaced let alone pig removed to check for rust on the gear that was sticking out of the oil.

If you run it and it's junk I'll make it right with you.

Thanks man. I wasn't going to call you out or even complain privately, because no wrong was done on your part, despite some frustration that might have been conveyed in my earlier thread posts. The pitting was hard to see for sure and it took some cleaning for me to even notice it.
I know it'll be fine and even if not, no worries. This was sold "as is" and it was evident that you were selling as an extra part that been removed for some time.

 

[73Coupe]

So I rigged this up in the vise with the axles in it. I had a friend at one end and me at the other with short pry bars - 12". With a little force, we were able to rotate the side gears opposite directions. There was definitely some limited slip action....the question is how much slip should be limited.

I wonder if the "grip" if the cones is increased with torque from the drive pinion or if it's constant....

 

[ski]

I made this rig to check the breakout force of suregrips many years ago. I put the pig onto the axel shaft in the vice and stick the other one in the other side. If memory serves me right I believe conventional wisdom said it should take approx. 125 ft/lbs of torque to break the diff. loose. I used them as is if it was 100 ft/lbs or better. You can do the same thing with the rig you set up with a little injenuity.

 

[68PK21 440.6bbl]

And Geeee I thought left foot on the brake and right foot too the floor ann'a when the speedometer needle points straight up a 60 mph'ish, lift left foot off brake and go back to check if you have 2 black lines was the proper way to test your suregrip!

 

[furious70]

And Geeee I thought left foot on the brake and right foot too the floor ann'a when the speedometer needle points straight up a 60 mph'ish, lift left foot off brake and go back to check if you have 2 black lines was the proper way to test your suregrip!

Yes...but an open diff can actually leave 2 marks in that case if the traction is equal on each tire. Over the years we had a few opens that would occasionally lay 2 lines depending on the surface. You need to thoroughly test it a couple different times on different roads

 

[68PK21 440.6bbl]

Yes...but an open diff can actually leave 2 marks in that case

Yes I knew that at a very young age as I taught a older friend of mine with his mothers nice 1967 Ford Fairlane with a 390ci in it how to do a J patch. Don't know how I learned that, maybe my friend with a 1957 Chevy (what is it the Belair with the pointy fins, clapped out wanna be a drag car 4 on the floor, which he bragged that had a 327ci but we young pups all knew it was a 283) taught me.

"Put it in reverse and floor it, then just jam it down into low" I told my friend. 1st results were poor so I had to remind him to keep his foot to the floor on the gas, heh Results!
2 sets of nice long black marks with good 10/15 feet sideways JJ's.

Seem that his parents didn't leave the keys around the house when they went on vacation anymore after that stunt. boooooo.

Fun times thou...

 

[73Coupe]

Well, I finally made some progress...
Cleaned up the teeth with some Scotchbrite discs; they actually turned out very nice. The gears are good.
I washed the entire unit, then decided to pull it apart because I figured I wouldn't be able to get all of the water out of the innards, no matter how much I blasted it with the air gun. It's a good thing I did....the cones are worn as expected, and one side looks like it snapped the axle due to evidence of the cone and side gear spinning against each other. The bearings have minor rust pits on them too.

 

[73Coupe]

Detail shots of cone and side gear mating surface
side bearing outer race
cone and cone seat in the case

 

[Ripinator]

Detail shots of cone and side gear mating surface
side bearing outer race
cone and cone seat in the case

View attachment 312724

View attachment 312725

View attachment 312726

View attachment 312727

Dayum! You are one brave and talented lad!

 

[68PK21 440.6bbl]

Detail shots of cone and side gear mating surface
side bearing outer race
cone and cone seat in the case

View attachment 312724

View attachment 312725

View attachment 312726

View attachment 312727

Glad to see you took my advice. That one is pretty much junk/core.

Do it right and you can drive around with good confidence on a job done right!

 

[JimmyG]

I once tried to use a gear with those pits in them, to save a few bucks. Turned out to be a false economy. The noise level was terrible and sounded like it was eating bearings!

 

[73Coupe]

Unfortunately I don't have any other options, they do not make new 2.76 gears. And I would like to keep this ratio...

Some good news though, I talked to Dr. Difff this week. They make shims for rebuilding the cone case. You have to machine the ends of the cones .040" and the shims make up the difference for proper differential gear mesh....

 

[65sporty]

I am not too worried about the little pitting on the gears, I would put new bearings in it though.
Are you going to try the sure grip rebuild in the link that Big John listed?

 

[70bigblockdodge]

I once tried to use a gear with those pits in them, to save a few bucks. Turned out to be a false economy. The noise level was terrible and sounded like it was eating bearings!

It was not the pits.

 

[68PK21 440.6bbl]

Unfortunately I don't have any other options, they do not make new 2.76 gears. And I would like to keep this ratio...

I just came across a set of used 2.76's on CL, 489 case 10 spline pinion, been listed for almost a month on Minneapolis CL, picture ain't very good, but he says good used.