On Aug 12, 2004, at 22:10, DAKSY wrote:
>
> Hey, Mike
>
> <snip> one of the caliper key bolt holes has a tap broken off in it.
> it's about an inch long, quite rusted, in a cast caliper bracket...
> I'm going to let that tap soak in PB for quite a while<snip>
>
> If you have drift or a pin punch laying around in the hangar, you may
> be
> able to rap on the remains of the tap & shatter it.
I was thinking that might be my best bet. I need a smaller, harder
punch. both of mine dulled in a couple smacks, but were taking bits of
the tap out with them.
> Most of them are one
> form of HSS or another & HSS is verrrry brittle & doesn't take to
> impact
> well.
> The down side to this method is that castings are also brittle & can
> shatter
> 8-(
I'm looking at a 5/16-18 hole with a minimum wall thickness of about
1/4". If the casting isn't notably brittle, I don't think it'll budge.
And if it does, I can deal with a bit of loss in the area - it's
relatively lightly loaded (trailing end of the caliper, about 3/8" from
where the key rides) and worst case scenario is about 1/2" loss out of
2-1/2" surface. Probably worth the risk - but that assumes I can make
headway in breaking it apart.
At least here I've got some void in the hole (the flutes of the tap),
as opposed to when I was trying to get HSS bits out of my broken shock
bolt and it was packed solid.
> If the PB gets it somewhat freed up, a local industrial supply store
> may
> have an "E-Z-Out" tap remover...I've used them with moderate
> success...the
> smaller ones (1/4-20 or M6) tend to trash themselves before they do any
> good, but the larger ones work fairly well...
and I'm on the smaller end of things. I was thinking something like a
very strong 4-way spanner bit. is that what these are?
> Either way, I'd get a helicoil set & re-tap & insert the hole before
> reassembly...
probably not a bad idea unless I can somehow convince it to just back
right out. Like I said, this is an extremely low load application -
it's just retaining a caliper key in shear loading - so that's in my
favor if I end up damaging something.
I'll let you know if I manage to do anything with it tomorrow.
-- Mike Maskalans <http://mike.tepidcola.com/dodge/> '84 RamCharger Daily Driver '98 Dakota under the knife mobile.612.618.4652 home.585.935.7129 fax.360.364.3930
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