On 9/6/2017 6:04 PM, Jason Ostrowski via Fot wrote:
> Hey.
> Yeah... most of the diffs I have around have at least one thread hole
> screwed up somewhere on the thing.
>
> I'm not sure this will work at the narrow edge area you are working on
> but I figure its on topic enough to mention...
> we have used something called A "Steel cert" or "Time sert" or "big
> sert" recently.
>
> Perhaps many already know about these "better than a heli coil fix"
These are variants on the name brand "KeenSert," which was originally
developed for repairs of stripped internal threads in aluminum and other
metals softer than steel:
http://www.repairengineering.com/keensert.html
The KeenSert uses hardened steel flat pins to positively lock the insert
into the softer metal, preventing it from rotating with the bolt, but I
don't think these can be used with harder materials like steel or cast iron.
The problem I see in using what you've suggested is the need to
accommodate the locating sleeve.? The sleeve doesn't so much resist side
forces as much as it serves to locate the carrier bearing cap, with the
retaining bolts providing the force to resist most of the movement of
the carrier bearing cap.
That said, these fixes probably can be used if the correct cutter can be
found to create the recess for the sleeve.? The setup would be a bit
tricky, but not difficult for an experienced machinist.? It would
require finding a sharp hole saw sort of cutter (a shell mill) that had
an OD the same as the OD of the sleeve, indexing the part so that the
mill and cutter would be concentric and true to the old hole, then
drilling or milling the new recess for the insert, raising the mill bit
sufficiently to tap the hole for the insert, install the insert, and
then without losing the location, use the shell mill to cut the new
recess in the insert for the sleeve.? This wouldn't have to be as deep
as the original so as not to lose too much thread on the insert.? The
sleeve can always be turned down a bit if necessary to ensure it fits in
a shallower recess.
If I couldn't find another good diff case, that's the way I'd do it.?
But, truthfully, that's more time (that you're paying the machine shop
for) than fitting the gears to a replacement diff case, which, with the
right tools, doesn't take more than two or three hours to fit new gears
and set pinion depth and preload. Additionally, I don't think I'd want
to do any machining on an assembled unit, anyway--too many chips flying
around that might be difficult to remove after the fact, and could futz
up the works.
If another diff is available, use that, and have the old case with the
stripped hole repaired at one's leisure.
Cheers.
--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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