Mopar clutch posi? Boom! Not impressed.

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LXguy

LXguy

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So, here's what happened after 5 passes on my new clutch Sure Grip.

gears.jpg


I haven't pulled the hog head apart yet, but I believe these are most of the teeth off of the diff's side gears.

I let go of the brake off of the line, there was a loud bang, and then some grinding sounds. The trunk lid popped open! I was surprised/relieved to not find a puddle of fluid under the car when I hopped out. The car would actually still roll as long as I didn't give it any gas, but wouldn't climb the ramps on to the trailer.

I've got an 8" DOT tire and about 420 hp at the motor. This clutch unit went in to replace the cone posi that lasted in the same car for 50-75 passes last year.

I thought I had shredded the pinion gear until I got it apart. Of course, the ring and pinion is now junk from a couple of spots where the side gear teeth went through and messed it up. If I have it out again, I'm putting a drain bung in the bottom of my 8.75..

These clutch posis are on national backorder right now. I wonder if they're having a hard time finding the Chinese crap side gears...

It looks like Dr DIff sells side gears on Ebay that are supposedly stronger than stock? Anyone have any experience with those?
 
Screw all that. Just order up a tru trac unit and be done with it. However if your just racin, put a spool in it
 
I'm confused, please excuse my ignorance, but don't most people recommend a clutch type over cone, I have an original mopar suregrip in my 8 3/4, and I was under the impression that mine is a cone, what brand do you have that just crapped out??
 
Ive used Randys Ring and Pinion. I had good luck with way more HP. Was yours set up correctly, or was it a little sloppy before?
 
Dertoit Locker. 'nuff said.
 
412 Stroker said:
I'm confused, please excuse my ignorance, but don't most people recommend a clutch type over cone, I have an original mopar suregrip in my 8 3/4, and I was under the impression that mine is a cone, what brand do you have that just crapped out??
Click to expand...

Yes, the conventional wisdom is that a clutch type is better, and it probably is right most of the time. The one that just blew up is a Mopar Performance unit. I've had incredibly bad luck with everything Mopar branded on this car. One of these days I'll learn..

Racingduster said:
Ive used Randys Ring and Pinion. I had good luck with way more HP. Was yours set up correctly, or was it a little sloppy before?
Click to expand...

The differential was new, straight out of the new packaging. Set up on the gear and all that was good.

Steve
 
Probably a good suggestion. I drive it on the street a good bit, so I don't want to go with a spool.

Plus I break it so often that I dont want to push a spool car. LOL

1970Duster said:
Screw all that. Just order up a tru trac unit and be done with it. However if your just racin, put a spool in it
Click to expand...
 
Then order a tru trac unit. Works like a standard suregrip unit but stronger and uses a worm gear vs clutch or cone
 
I don't believe the clutch is stronger in terms of a straight line. They are about the same IMO. But, the clutch is head and shoulders better than the cone fo rdriving around turns and wear. It sounds like you got a bad one, and for me, the only MP products I use now are the mini starters and timing chain tensioners. I vote Tru Trac too...
 
Steve, I run full spools in all my street cars, I had one in my last dart, It isn't bad on the street really, just don't put yourself in a tight position/tight turns, They are alot cheaper then clutch units & alot stronger, They are not hard to push in a straight line, even slight turning isn't bad, IMO its a very good investment.

I try & stay away from anything mopar for my mopars lol. Sad isn't it!!
 
It was the clutch sure grip parts in the cup.

I put the clutch style unit in the last race of last year when I switched to 3.91 gears. It replaced the 4.11 cone type hog head I had been running the entire summer.

The 4.11 cone type is back in the car as of last night. Hopefully it will hold together until I can get something more permanent going.
 
LXguy said:
It was the clutch sure grip parts in the cup.

I put the clutch style unit in the last race of last year when I switched to 3.91 gears. It replaced the 4.11 cone type hog head I had been running the entire summer.

The 4.11 cone type is back in the car as of last night. Hopefully it will hold together until I can get something more permanent going.
Click to expand...
At only 420hp your cone should last a long time unless its bad to begin with, is it burnt and only one wheel getting most of the power? if you want a clutch type look for a oem unit and rebuild it
 
The cone unit is fine, other than the setup being a little noisy. Its been a 1.58 60'.

The only reason I bought the MP unit was because I wanted the strength "upgrade" and rebuildability.

On a side not, the Royal Purple diff oil is worth the price over mineral just for the fact that your garage doesn't end up smelling like Brontosaurus diarrhea when doing a gear swap.
 
"smelling like smelling like Brontosaurus diarrhea when doing a gear swapwhen doing a gear swap."

Love it! LOL
I'll have to try the Royal Purple as I really don't like the Brontosaurus diarrhea fragrance they put in the other stuff!
 
Cone is better on the street, clutch is supposed to be better at the track, but only in the sense that it is rebuildable (cone can be machined too to freshen up) doesnt look like the SG unit was bad, just the side gears. MP is outsourced, everything MP can be found without the MP stamp on it, rockers, valve covers, camshafts, 'bout all that is proprietary Mopar are the W/P heads nowadays. Even MP intakes are cast at Edelbrock. So its not exclusively MP products that are bad, its their choice of manufacturers that are putting out a sub par product. Do you think MP would put their name on a $400 Milodon gear drive and sell it for $500, or rebadge a CAT drive at $55 and SELL it to the masses for $200? I laugh at the MP "hemi" lifters at $18 a pop. What fool buys those? Chi-nomics 101.......sad but true.

And ditto's on the smell of burned/old diff fluid: Barf out, gag me with a spoon!
 
So who is making the current clutch type sure grips? The originals were made by Spicer/DANA and were pretty tough. Looks like poor heat treat on the gears.

Did you make sure the case bolts were torqued correctly, and verify the clutch pre-load with a feeler gauge? I've seen Powr-Lok units in Jeeps fail in a similar manner, but it is usually because they were not set up right, or were really worn. Even then, the teeth smashed flat and didn't break off.
 
Cone is not good for anything where power is applied in a corner. Just a cheap *** way to get out of a warranty period.

Not sure who makes the clutch type now. I'd be looking for an old original and going through it. There was something wrong if that one came apart at 420hp. I've run more than 550 through them before.
 
Hey LXguy,
Nice to have met you out at RT41. Wish it would have been under better conditions. I was the one that came over and talked to you for a while and showed you the picture of my 70 Dart (Brown color). Are you looking to put a 391 back into it?
Ken
 
Hey!

Good to meet you also. Hope you get it on the road soon!

I don't know. It seems like the car breathes better with the new carburetor, so maybe it could use a steeper gear. I'm going to throw my old 4.11 back in it, and see what it does before I build something permanent. Don't want to get a tru-trac or a spool, put it all together and then have to redo it with a different R&P.
 
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