Detroit Locker? Help Identifying this limited slip? 742 3.73 Can it be rebuilt.

[DaveyRocket68]

Hi Guys,
I am a new member but not new to mopars. I have a limited slip differential that I got from an old drag racer a few years ago. I have some questions about what kind of limited slip it is. The guy I got it from said it is a detroit locker. The old kind where you have to back the car up to get it to unlock. It is in a 742 diff with 3.73 to 1 gears. I dont know anything about these except how to pull the pumpkin and stick it in. I have it in a 68 satellite. The axles have the green style bearings. it is running a 400 block stock out of a 74 newport. The car needs some work as you would expect. The trany ran fine in the newport but I am having some trouble with the shift linkages and getting it to shift into 3rd. It has a thermoquad 750 vacuum sec. It has hooker headers and duals. I dont expect it to be a race car but I like to get it out and drive. it sounds great with the dual exxhaust and glasspacks. I put the diff pictured below ( I Hope) in and hooked it all up. the diff spins fereely by hand but when I put it in the car and there is a load on it it makes a sound even when pushed in neutral. I dont know if the diff is bad, needs to be rebuilt, can be rebuilt or just needs to be set up. I dont know how much back play it should have (not sure what thats called) but it seems to have a lot around 1/2 inch. I have looked online and I dont think it is anything like the eaton or other types but again I dont know. I can send addl pics. There are some numbers on the limited slip unit but nothing that looks useful. Any help would sure be appreciated. I really think this 3.73 limited slip would be more fun that the open 3.23 currently in the car. Also is there any way to get all this cat hair off the gears with out completely disassembling the diff. :icon_silent:

 

[Cranky]

Looks like a DL to me....and backlash is the amount of clearance the ring and pinion have. That needs to be checked before installing the unit into the housing but 1/2" rotation sounds a bit much to me but it also depends on how much slop there is in the axle splines too. The older design DL's were more noisy than the newer ones or what's called Detroit Soft Locker. As for having to back up to unlock it.....that's a new one on me...

 

[bigblock]

IF its a Detroit a half inch is normal.

 

[Supershafts]

Looks like that gear is running way off the heel, but it could be the pic.

Lockers have lots of play if you're going by the end yoke feel, depending on the locker and side gear engagement you can either have a 1/4 inch to as much as half a cycle, and more with a soft locker version or the nascar or oval track version and they will make noise as they find there set and lock the side gears or unlock the side gears.
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