Measuring cone style sure grip?

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newby

newby

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Hey guys,
Bought a 489 with 355's and cone style sure grip at swap meet and was going to rebuild it before installing. Don't want any surprises. Is there any way of measuring the cone to see how worn it is. Rear diff appears to be all original and in remarkable shape as far as wear goes. Thanks in advance.
 
I am not really sure but I have an extra laying around that I need to go thru also.
I know you can machine the small end of the cone off and add a shim to the large end, but I have never been into one yet.........
 
There's no real way to measure it because the ends are not wears down, it's the o.d. area that contacts the sure grip case and it's tapered so you can't measure it. You just visually inspect it and see if the cones are bottomed out in the sure grip case. I've seen them with very little to no wear and others that you can tell the cones were bottomed out for a long time cause their worn a lot. If it's original and still tight it's not worn bad. I have machined the side cones down in a few cone type sure grips which allows the cones to seat instead of bottoming out then according to what it looks like (how much wear is visual) I install shims accordingly. The thickest shims I ever had to install were .050" and it was worn pretty bad. By your description yours is in good shape so what I'd do is cut the ends down .030" so they won't bottom out for a long time and put some .020" shims in each side to regain preload.
 
Thanks fishy,
stuck feeler gauges between cone and where it would bottom out have .030 roughly. Anyone know what that measurement is on a brand new setup,just for comparison.
 
newby said:
Thanks fishy,
stuck feeler gauges between cone and where it would bottom out have .030 roughly. Anyone know what that measurement is on a brand new setup,just for comparison.
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that should work ,as long as its not bottoming out is what counts. About 15 years ago I did my 9 1/4 s/g ., bear with me i'm picking my breain trying to remember....the cones were galled up (metal rubbing) and I remachined the taper on the cones, tried not to remove material but just clean up the gall marks. The cone was bottomed out and rubbing and somewhere I found reference to .060" clearance....I dont think I removed that much from the end of the cone but left it at about .040" or so (measured it with a bent piece of .040 wire or something - i couln't get feelers in the end

dunno... hope this helps?
 
When I was a kid, I had my small ends milled down too. I did not shim it though during assembly. I didnt know about the procedure, just observed them bottoming out from the wear pattern and observed that removing from the small end would allow the sides to grip again.
My sg occasionally would not lock, probably cause of lack of shims. B4 milling the cones, it never locked.
I would give it a fair amount of mill so you can have a long life left on the cones. Eventually the cones bore out the carrier and I have no idea if they make larger cones to compensate for that.
.
 
A method to check how much clearance you have is to use modeling clay I the case and press the cone in the case halves the measure the thinnest portion of the clay. I've reconditioned a lot of cone SG's. Use .030 as a minimum and use .020-.030 shim between the axle gear and the top of each cone.
 
newby said:
but does anyone know what the original spec. was????????
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Glad to help what little I did but sorry I have no idea of an original spec and it'd surprise me if you find someone who does know. The cone type sure grip was never designed to be a rebuildable unit and my guess is that's the reason there is no spec published. I have a 68 and a 70 factory service manual and neither give any specs. They just say it's a non servicable unit. I'd say we got lucky that someone figured out how to get some more miles out of one by shaving the ends down. If yours has .030" clearance I'd say it's in pretty good shape as all but one I've torn apart had the cones bottomed out.
 
fishy68 said:
Glad to help what little I did but sorry I have no idea of an original spec and it'd surprise me if you find someone who does know. The cone type sure grip was never designed to be a rebuildable unit and my guess is that's the reason there is no spec published. I have a 68 and a 70 factory service manual and neither give any specs. They just say it's a non servicable unit. I'd say we got lucky that someone figured out how to get some more miles out of one by shaving the ends down. If yours has .030" clearance I'd say it's in pretty good shape as all but one I've torn apart had the cones bottomed out.
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x2 - .030 should be good, especially for an untouched diff., like I said earlier, i thought I read somewhere that the clearance was .060 but I honestly cant be sure, it was hard info to find when i was machining mine cause likefishy stated they are described as unservicable/replace if worn
 
Run the cones on a belt sander until you knock the small step on the small side,then install .030 shims in between the cone and the side gear,i put a shim on both sides which has worked well for me.
I have done three this way with no problems so far. :burnout:
 
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