broke another 8 3/4 sure grip?

[cageman]

I have an 8 3/4 in my Valiant, it is 273 powered and has a 5 speed. Last september I was drag racing it and I did the burnout in the water box fine and rolled out, did a quick chirp and staged, when I let out the clutch, bang, no more rear. It was a 391 sure grip, the clutch style.
So fast forward to yesterday. I decide to pull it in and swap out the broken gear for a set of 323 sure grips. I put it in and examined the best I could the broken chunk. I couldnt see any visual signs of something bad. Must be the clutches are shot. So in goes the 323's and I drove it 100 miles to work and back today. Went over to some gravel across the street from my shop to verify that both wheels were spinning equally, and they indeed were. Went out to the street, and let out the clutch, bang, no more drive. Same exact thing.
Am I just this unlucky, or am I doing something wrong. I have green bearings on the yukon big bolt pattern axles. I have killed a few sets of these sure grips in my day, but I just sold them as needing rebuilds, never have rebuilt one. is it just a crappy design? I have one set in my 70 short box and it will spin the drive shaft a 1/4 turn before it goes, and if I put it into reverse, it will spin that 1/4 turn again till it goes, is this one about to go. None of the two in my valiant did that tho. I have killed a couple dana 60's too, so either Im hard on stuff, or these chrysler sure grips are junk.
What do you guys think?

[dodger1]

I'm thinkin' that anyone who can break an 8 3/4" with a 273 should be on my list to build my next A engine! Otherwise I can't help.

[nhdriver]

The later 8 3/4 sure grips with the cone type clutch are not very strong. The early "Dana" Style are pretty strong. If you want the ultimate strength get a Dana 60. Their pretty hard to break.

[Cudadrag]

Hell, you can get aftermarket gear and axle sets for the 8 3/4 (I use Mosier. 35 spline axle, 4.56:1 gear set with spool) that are very hard to break. Mine has about 200 runs at 500-600 horse. The rear has broke 1 yoke and 2 driveshafts and still going strong. But it is possible to just be having bad luck. I have seen stranger things.

If you have indeed broke Dana's (Which I personally have never seen) then you may have an angle problem. Are you sheering the ring gear at the pinion? If so you may have too steep of a pinion angle. Adjust angle to about 3 degrees. (The closer you get to 0 degrees the less stress on the gear but the more "harmonic" type wobble you will feel thus wearing on bearings and other components) Balancing everything from the flywheel back will help allot with shallower angle setup. No more than 7 degrees and no less than 3. (I believe is the correct mine set) for a street/strip setup.

[aarracer]

cageman

Are you adding the "Suregrip" friction modifier additive to the oil?

If not, this is "Surely" your issue!

[John Kunkel]

Before making a judgement I'd like to see exactly what broke in both units. Clutches don't usually fail with a "bang", they just slip.

[John Van]

Originally Posted by dodger1

I'm thinkin' that anyone who can break an 8 3/4" with a 273 should be on my list to build my next A engine! Otherwise I can't help.

Damn, a 273? Tell us about that motor! What are you doing? Dumping the clutch at 7grand? I have a 440 stroked to 499 in a heavier car with a 8 3/4 rear,with drag radials,made about 150 passes last year without a problem.

[cageman]

No, it wont turn over 5500, the magnum heads still have stock springs in them.

I havnt disasembled the gears yet, and the one set is in the car yet.

[DartGT66]

I have never broken a sure grip in a 8 3/4. I have had some tooth losses, but the sure grips, either cone or Dana style have worked great. In my 3310 lbs 9.6 second car, the rear lasted eight years, hundreds of launches and maybe 20 000miles of hard streett driving until it was so worn out that I rebuilt it. Th other car was similar weight and run 9.5's. Changed in to a spool because veryone told me it would be worthwhile, byt nothing really changed. Both were cone style. I would like to know too what exactly broke in those things.
The one you described having slack is propably a non sure grip rear, the shaft of the spider gears has started moving in the housing and gorund a groove in to it. When this happens, it usually also locks the spider gears at some point making it act somewhat like a sure grip.

[John Van]

Cageman, When you tear it down,take some pics,I got to know! I have destroyed side gears and snapped axles,but that was in a heavy '70 fury doing those neutral,rev it up,drop it in gear jobs.
They now make Detroit Lockers for the 8 3/4 rear which is more street friendly than a spool.

[cageman]

The one sure grip that turns part way each direction looks like a locker, and after doing some reading on them, that is what they do, so maybe that is normal, IDK.
I was looking at the 3.91 I broke, and it appears to have scrapes on the carrier that look like the pinion was gouging it, but it all appears tight and it has the proper back lash. Im not sure if it was from before or now. I got the sure grip in a box of parts ten years ago, dont remember if they were there then or not. Im running mobil one sythetic gear lube, and I had friction crap in the last one as it chirpped going around corners, so I added it, I only put 120 miles on the 323, but it apperaed to work fine till it let loose. It tries to move if I put it in gear and let out the clutch, but nothing in reverse.
To clarify for speed readers, I am breaking the sure grips, not gears or axles, same thing with the dana 60's, the sure grips are what I have broken twice. I have never taken one apart, so I have no clue what has gone bad, i just sold them as being in need of a rebuild, and they sell right away. Finding sure grips any more is tough, so I plan on holding on to these three. I was talking to a local, and he says the hardest part of rebuilding them is getting all the stuff in line, so you have to use an axle in each side, which is awkward.

[bbaspense]

I had over 200 runs on a 1958 Sure Grip with 3.91.. running 12's.. never had an issue...

Something is REALLY wrong if you keep busting them...

[JVMopar]

But you should still be able to drive it even if the cones or clutches are worn out. Unless your breaking the spider gears. I know when they break the go bang and you loose your drive.

[Ray Bell]

Originally posted by cageman
The one sure grip that turns part way each direction looks like a locker, and after doing some reading on them, that is what they do, so maybe that is normal, IDK.

I was looking at the 3.91 I broke, and it appears to have scrapes on the carrier that look like the pinion was gouging it, but it all appears tight and it has the proper back lash. Im not sure if it was from before or now. I got the sure grip in a box of parts ten years ago, don't remember if they were there then or not.

I'm running Mobil 1 synthetic gear lube, and I had friction crap in the last one as it chirped going around corners, so I added it, I only put 120 miles on the 323, but it appeared to work fine till it let loose. It tries to move if I put it in gear and let out the clutch, but nothing in reverse.

To clarify for speed readers, I am breaking the sure grips, not gears or axles, same thing with the Dana 60s, the sure grips are what I have broken twice. I have never taken one apart, so I have no clue what has gone bad, i just sold them as being in need of a rebuild, and they sell right away.

Finding sure grips these days is tough, so I plan on holding on to these three. I was talking to a local, and he says the hardest part of rebuilding them is getting all the stuff in line, so you have to use an axle in each side, which is awkward.

cageman, I seem to recall you're pretty knowledgeable about a number of things, so it surprises me that you've never investigated this problem.

I have never read anywhere about any unreliability problems with the clutch-type (Power-Lok by Dana) Sure Grips, while the only issue I've heard of with the Borg-Warner/Auburn units is that they wear and you need to do some careful machining to restore them. Not that it's ever impossibly to break anything.

So for this reason, I'm really keen to see what you find inside. I've got a big investment in both a couple of Power-Loks and a Borg-Warner and I'd like to know what problems I should look for.

Also, the 'speed reading' award I think is perhaps yours... I don't think anyone is suggesting you've broken axles or sun gears or anything, they are just saying that they only ever hear of this problem, not of the Dana bits breaking.

[John Van]

Cageman,There is a guy in Montana who specializes in differentials,I would get a hold of him and see what he says.
http://www.doctordiff.com/

[Dart 360]

You said you are running Mobil 1, have you tried 80/90 LSD oil. The clutches don't usually like synthetic oils.

[cageman]

My 70 power wagon was an 8 3/4 truck when I first got it. I broke every sure grip it ever had in it, and it would not move, I would just put it in four wheel drive and go home. Now it seems these are doing the same things. I have done this same thing to the dana 60 sure grips that it now has. I have detuned the engine, and now I shear off the front lockout bolts all the time when hard wheeling. Those 35 14.50 boggers are sure hard on stuff, and the four speed doesnt help either.
Since these sure grips are hard to find now, It apperas I will have to rebuild them somehow and try it again. Im thinking it is just due to 1960's parts just plain ol wearing out. Plus Im hard on stuff. I would have thought I would have broke the s10 5 speed before the rear end, but it is still going strong.

[Ray Bell]

I find it hard to understand why you break every one you touch and nobody else ever mentions breaking one!

Could this relate to shock absorbers?

[aarracer]

I have seen this happen on other brands from bent axle housings.

[bulldog426]

Originally Posted by nhdriver

The later 8 3/4 sure grips with the cone type clutch are not very strong. The early "Dana" Style are pretty strong. If you want the ultimate strength get a Dana 60. Their pretty hard to break.

can anybody come up with pics to show the difference?

[Ray Bell]

There's a previous thread with comparative pictures...

Use search with 'Borg', 'clutch' and 'open' as your key words.

[cageman]

Hmm, bent axles, no, I think my combination of right foot and a clutch seem to be the problem, or maybe I actually drive my stuff.
The 9 14 I have in my 95 has a burned out posi, and it still drives. Just is now a one wheel wonder. I think the 60's stuff, when it goes, it goes. No more drive.
I appear to be missing a 1/4 inch of splines off of the driver side axle, so I was actually thinking of calling dr diff and seeing what he thinks might have happened, and possibly ordering a new axle. Im not sure if yukon has a warranty or not. He will know. Im sure Im going to eat it. Ill get the rebuild kit from him too. I met him down in Vegas a couple years ago and we picked each others brain a bit.

[Ray Bell]

It's over a week now since it was requested that you let us know what had broken...

Will you get to that stage, or are you afraid to take the pumpkin out?

[cageman]

Nope, this isnt my full time driver, I drive a neon every day to work, and then friday through sunday is my circle track race time. Then it is back to work again. Race car is priority, things I cruise in once a month isnt a priority. I also have ten vehicles to choose from, so until 9 of them break, this one can sit. But if I did need it, i like to have my research done and bases covered, cuase this sint the first time I have done this now, and im kind of sick of it, and short of putting an auto in it, Im wanting to pick some brains so i have a third and 8th opinion, lol I am also in the middle of building two race engines, putting gas in my car, paying shop rent among other things.
So be patient, when I know, youll know.

[John Kunkel]

can anybody come up with pics to show the difference?

See the pics below, the cone type has an open window with coil springs vivible inside.

[cageman]

all of mine have been sure grip style.

[dodger1]

Originally Posted by cageman

all of mine have been sure grip style.

Which suregrip style? Chrysler used both, Suregrip was just their brand name for a ltd. slip diff.

[cageman]

Mine are clutch type.
After looking at John kunkels photo, I remembered I had a tsm for a 60's era dodge truck, so i opened it up to the rear end section and low and behold all the info i needed was there. After looking at the diagrams, I find that the end of the axle is engaging into the differential side gear only part way, that is why the one axle stripped off. I think I need longer axles. This is why the clutches burn out, as it is only putting power to one axle and it burns that axles clutch right out. The other axle that is stripped, has its splines in the side gear retainer which does nothing, due to the side gear isnt contacting the axle, so it thinks it is a one wheel wonder.
So it looks like I need two clutch rebuilds, two axles that are a 1/4 inch longer or so, and Ill be good to go. I wonder why they only offer one size for a body axles. It lists in the tsm I have that only the full floating dana can use the same axle for antispin or standard differential. The ra36 needs different axles for each. WTF.
Oh well, looks pretty straight forward to rebuild. Maybe I will just narrow the rear end in it instead of buying new axles. plenty of splines on it.

[Ray Bell]

Progress...

Has this happened in every case?

[dodger1]

Originally Posted by cageman

Mine are clutch type.
After looking at John kunkels photo, I remembered I had a tsm for a 60's era dodge truck, so i opened it up to the rear end section and low and behold all the info i needed was there.
Oh well, looks pretty straight forward to rebuild. Maybe I will just narrow the rear end in it instead of buying new axles. plenty of splines on it.

Interesting info for sure. Keep us posted.