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Cone Style LSD

Charlie Brown

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Location
Vars, Ontario, Canada
I have a couple of cone style LSD's currently in 741 cases with 3:55 gears. Is it possible to determine on the bench if these will need a rebuild or not. Without actually testing in the car, can I tell if they will function as designed by a visual bench inspection.
 
@RustyRatRod
RRR did a tutorial 9n the A side on reconditioning a cone. If there's a test, he should know.
I suspect it would involve installing a couple axles, locking one axle, and seeing how hard to turn the other axle is.
 
Mine was so wore out you could see where the cone bottomed out against the housing. Dr diff has a repair kit for this. I haven't tried it yet though.

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Upon disassembly, this is what I found. Perhaps someone with experience with these units could comment if this unit is usable without a rebuild or not.
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Usually a skim off the face of the cone in the lathe to restore it's clearance to bottoming in the housing was the zero buck fix.
If the cone is so worn you need to skim the back to get it to grab again you need to shim the spider gears or the backlash will be too loose
The fact the O/P's unit still has .050 clearance left is a good sign... How's the other end?
 
If the cone is so worn you need to skim the back to get it to grab again you need to shim the spider gears or the backlash will be too loose
The fact the O/P's unit still has .050 clearance left is a good sign... How's the other end?
Both sides are about the same. Is there still life in this unit without machining? Another question comes to mind is if I machine off lets say, .060 - do I need to compensate for the wear that has already taken place - that is - does the added shim need to be thicker that .060?
 
Both sides are about the same. Is there still life in this unit without machining? Another question comes to mind is if I machine off lets say, .060 - do I need to compensate for the wear that has already taken place - that is - does the added shim need to be thicker that .060?
How's the backlash on the spider gears? If they are sloppy a shim between the side gear & the cone can reduce the slop... To much lash = clunk when putting the car in gear.... Most associate the clunk with ring & pinion slop but it's also an effect of the spider gears...
 
How's the backlash on the spider gears? If they are sloppy a shim between the side gear & the cone can reduce the slop... To much lash = clunk when putting the car in gear.... Most associate the clunk with ring & pinion slop but it's also an effect of the spider gears...
That's something I haven't checked yet - but I will.
 
Both sides are about the same. Is there still life in this unit without machining? Another question comes to mind is if I machine off lets say, .060 - do I need to compensate for the wear that has already taken place - that is - does the added shim need to be thicker that .060?
I am NOT an expert on cone suregrips (at all! Never had one, clutches lockers, or spools) but it looks to me like you have clearance on both sides, meaning the cones havent bottomed out. Cones bottoming out is what makes them into one-leggers.
I'd check the spiders/side gears for lash, and put it together, and run it.
 
Wow....been a LOT of years since seeing one that nice! And the 'chatter' marks is normal and isn't bad at all. You might take a rough stone and smooth it out some. Just do the side gears and don't worry about the cones. And I'm willing to bet a new unit that your side and spider gears are fine. Got pics of the pattern of on the teeth? I've done bunches of those things over the years and only shimmed one unit and it needed it. @Charlie Brown
 
Wow....been a LOT of years since seeing one that nice! And the 'chatter' marks is normal and isn't bad at all. You might take a rough stone and smooth it out some. Just do the side gears and don't worry about the cones. And I'm willing to bet a new unit that your side and spider gears are fine. Got pics of the pattern of on the teeth? I've done bunches of those things over the years and only shimmed one unit and it needed it. @Charlie Brown
I do have a couple of pics - care to comment?
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They look pretty good to me. Keep in mind that an LSD rear diff side and spider gears don't see the abuse that a 'one wheel peel' diff does. I can only imagine what my 95 Dakota diff looks like! But, is the anti rotation pin still ok? It should slide in and out easily. I'm looking at the last pic on and looking at the left. What's the pin look like on the opposing side of the shaft?
 
They look pretty good to me. Keep in mind that an LSD rear diff side and spider gears don't see the abuse of a 'one wheel peel diff does. I can only imagine what my 95 Dakota diff looks like! But, is the anti rotation pin still ok? It should slide in and out easily. I'm looking at the last pic on and looking at the left. What's the pin look like on the opposing side of the shaft?
The main shaft looks good. The little pin that goes through it (anti rotation pin?) slides smoothly and looks ok.
 
The main shaft looks good. The little pin that goes through it (anti rotation pin?) slides smoothly and looks ok.
How far does the pin stick out on the 'back' side of the shaft? Just trying to make sure it didn't break off and the shaft was allowed to spin. It's kinda common when things don't go right....
 
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