Brian :
I'm a real believer in Helicoils (although I buy a different brand 'cause
it's cheaper <g>).
Generally, with stripped threads, there is no need to use the drill that
(usually) comes in the kit. Just run in the special tap, using the usual
"forward 1/2, back 1/4" motion, until it bottoms (lightly) in the hole.
Then clean the hole thoroughly with solvent (I like to use Gumout), thread
the insert on the tool, coat the insert with Loctite, and thread it into
the hole. You need to leave some space (about 1/4") between the bottom of
the hole and the bottom of the insert, since the threads at the bottom are
not cut full depth. If the insert is too long, you can use a Dremel or
similar to cut it off flush with the surface, later. (A three cornered
file would probably also work, used carefully.)
Give the Loctite plenty of time to set up, then assemble everything as
usual. The inserts are stainless, so corrosion shouldn't be a problem, but
I always like to put some anti-seize on the bolts anyway. Anti-seize is a
good idea any time you have a steel bolt in an aluminum part anyway.
The result will be stronger than even a 3/8" bolt running in aluminum !
Plus, you have the advantage that all the bolts are still the same size,
the repair is invisible, and you don't have to worry about weakening the
cover or case by drilling oversize.
BTW, Enco is a good source of inserts and kits. They carry a wide range of
UNC and UNF sizes (no Whitworth or BSF unfortunately <g>).
Randall
On Wednesday, February 24, 1999 7:40 AM, sanborn@net1plus.com
[SMTP:sanborn@net1plus.com] wrote:
>
>
> Listers,
>
> Need some Help!!
>
> I noticed when I took apart my gearbox that the bolts were
> very tight... I now think maybe too tight.
>
> While in final reassemnle of the box one of the threads for
> the input shaft front cover stripped while torqing to 15
> ft/lbs. I have no experience with cutting threads in
> aluminium, but am very familiar with tap & die use. I
> picked up a 5/16th Helicoil kit this morning thinking that
> is the best path... or I could try to drill out to 3/8th
> and cut new threads.... but that means drilling out the
> cover flange as well.
>
> Anyone that can share some experience and/or knowledge
> would be appreciated
>
>
>
> Brian Sanborn
> 62 TR4 CT16260L Groton,MA
> sanborn@net1plus.com
>
> ------------------------
>
>
>
>
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