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Differential sanity check

Potshot

Potshot

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Bear with me, I work on cars for for fun, not for other people so my experience level is pretty lean on things quite often.

I have a 67 charger I'm waking up, and it has an open diff, i.e.; spin one wheel, the opposite side spins the other way. Among the parts I have are this diff that I'm told is a cone style sure grip. Given it's appearance, what's the consensus as to whether I can use this or not? Any advice on what kind of clean up I should do, or should I just move on to another unit?

Thanks!
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That looks rough. I'm not even sure the gears would clean up, I doubt it. For sure it would need to be taken apart, cleaned and new bearings. Then you're stuck with an old cone style sure grip that is likely worn out. 742 is the best case to start with but this is a project diff.
 
At the very least, it needs to come apart and be cleaned. Look at the ring gear bolts.
 
Got it, thank you. I'm not about rebuilding, I'll move on from this one.
 
You own it, or thinking about purchasing?
 
I own it. I have another rear axle that may have something better in it, I'll be checking that one after work.
 
Potshot said:
I own it. I have another rear axle that may have something better in it, I'll be checking that one after work.
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If I were going to have to build a rearend, the 742 case would be my choice.
 
There's a way to test cone sure-grips. @Cranky he can tell you how to. 3.23's aren't going to "wake up" your Charger much. 3.55 if you do highway driving or 3.73's if you drive less than 50 to 75 miles in any direction. If you have a stock 318 3.73's would be to much. MO
 
Potshot said:
Got it, thank you. I'm not about rebuilding, I'll move on from this one.
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Looks pretty rough on the outside. Go ahead and pull it apart. Is there a lot of back lash in the gears? If you don't have any experience in rear ends leave the pinion alone for now and just pull off the bearing caps and roll out the diff. Looks like there are some ring gear bolts backing out. If you have an impact, that will be a big help. Do you have a vise? If so, clamp an axle into it and then you can mount the diff on it. If you have a junk axle and don't plan on using it, don't worry about using something to protect it from the vise jaws. I've seen several that looked like hello on the outside but were nice on the inside. And years ago I made a couple of 'T' handle tools made from 2 shortened axles. Plug them into the diff, stand on one T and grunt on the other. If there's a lot of resistance, that's usually a good sign. If kinda easy to turn, the clutch cones can be machined and they work great doing that. First time I did one was in the 80's and that thing got a lot of miles put on it. Lost count how many I've done over the years....

Fran Blacker said:
There's a way to test cone sure-grips. @Cranky he can tell you how to. 3.23's aren't going to "wake up" your Charger much. 3.55 if you do highway driving or 3.73's if you drive less than 50 to 75 miles in any direction. If you have a stock 318 3.73's would be to much. MO
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Naw....small blocks don't mind some rpm and they wake up petty good to 3.73's and a lot of times the MPG goes up in town.
 
By waking up the 67 I meant it had been parked for 27 years. It's got the 440 it came with and I hadn't planned on doing too much more than wheels, tires, brakes and fuel system. All mostly done.
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I'm going to try to avoid trans or diff rebuilds for now, both are things I'm not much ready for. Just seeing what I'm in for later and what a good course might be later.
 
Potshot said:
By waking up the 67 I meant it had been parked for 27 years. It's got the 440 it came with and I hadn't planned on doing too much more than wheels, tires, brakes and fuel system. All mostly done.View attachment 1188674

I'm going to try to avoid trans or diff rebuilds for now, both are things I'm not much ready for. Just seeing what I'm in for later and what a good course might be later.
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I would also change ALL the fluids too. 27 years is a long sleep. Was everything working ok when parked?
 
Cranky said:
I would also change ALL the fluids too. 27 years is a long sleep. Was everything working ok when parked?
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Well understood, and yes; cylinders were lubed before cranking, oil has been changed, coolant flushed, yada yada. It was a ran-when-parked situation by the PO, a friend I'm still in contact with though a couple thousand miles distant.

This was the first time I've dealt with a car in this condition, so I researched it pretty heavily. On the upside it's in pretty darn good condition other than having sat for so long.
 
That car looks great. If you have to change diff fluid anyway you could try that cone style suregrip on the current gearset that is in the car. I would recommend new side bearings though. It's a pretty easy changeover, but you need a dial indicator to check backlash before and after the sure grip install.
 
Good tips and info, thanks!
 
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