Thread repair suggestions
Mike W.
I'm about to button up one of my KZP's valve covers. It's amazing how
vulnerable the threads up there are. On this bike, it's my first time in it
ever though I've been in/out of the other numerous times. I had to do, I
think 5 helicoil jobs on compromised threads and fortunately those were all
at the outboard parts of the valve cover where I could easily get at them
from above with a drill.
Unfortunately, there is one that, while not in total failure, just looks
like crap. It's positioned such that the backbone of the bike does not let
a conventional drill fit.
Question #1: Any suggestions I should be aware of for drilling out the hole
in this application?
I'm considering just stripping the crap out of that hole with a bolt (it's
not hard!) and putting the helicoil insert into that hole. Is there
anything less primitive?
Question #2: I've heard a time or two about a thread repair system called
Timeserts. Can anyone give me their third-party comparison of the two
solutions? Thanks.
Mike
--
Mike W.
96 XR400
99 KZ1000P
70 CT70
71 KG 100 (Hodaka-powered)
Neil T. Dantam
> It's positioned such that the backbone of the bike does not let a
> conventional drill fit.
>
> Question #1: Any suggestions I should be aware of for drilling out
> the hole in this application?
Would a right angle drill work?
Examples:
http://www.acehardware.com/product/index.jsp?productId=2967892
Kevin
news:7c4ne4lc0b6n1f2r7...@4ax.com:
just get the epoxy thread repair. it is fine for a low stress job like
that. KB
--
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Rob Kleinschmidt
If you don't pull the head you'll be dropping shavings into
the engine. More importantly, you need to worry about the
little hunk of hardened steel that you break off the helicoil
after it's in place. Also, on a long stud, it's real easy to cock
the drill slightly and wind up with a stud where the far end
is cocked enough to not line up quite right with the hole.
There's a thread restore compound (made by J.B. Weld
I think) meant to work on low stress threads. Like J.B.
Weld, it's a hardening putty. Don't know if this would
work on your problem or not.
I've substituted allthread threaded rod in a longer length
for a pulled valve cover stud. On one cover, I found there
was still good thread past where the original stud threaded
in. On the other side, since the hole went through to
an empty space, I was able to use a locknut to hold
the threaded rod.
Timesert is another thread repair similar to helicoil
but bulkier, using a solid threaded cylinder instead
of a thread coil. Usually, they tell you to try a helicoil
and use a timesert if the helicoil fails.
Mark Olson
> On Oct 7, 9:48 am, Mike W. <outof...@emailbiz.com> wrote:
[snip story of stripped cam cover attachment screw holes in KZ1000P
cylinder head]
> If you don't pull the head you'll be dropping shavings into
> the engine. More importantly, you need to worry about the
> little hunk of hardened steel that you break off the helicoil
> after it's in place. Also, on a long stud, it's real easy to cock
> the drill slightly and wind up with a stud where the far end
> is cocked enough to not line up quite right with the hole.
The cam cover is held on by a number of machine screws, not studs, but
the advice about getting the hole tapped square is still good. I wouldn't
worry about the little piece breaking off the Helicoil doing any internal
damage to the engine since the holes in question are blind tapped.
> There's a thread restore compound (made by J.B. Weld
> I think) meant to work on low stress threads. Like J.B.
> Weld, it's a hardening putty. Don't know if this would
> work on your problem or not.
That's probably not a bad idea, there is very little torque on these 6mm
diameter screws.
paul c
Just my opinion but I think a helicoil or timesert is overkill for a
valve cover. If it is just one of a half-dozen or more fasteners that
only have to counteract oil and atmosphere pressure why not just seal up
the bolt-hole with alum weld or somesuch and forget about it (unless
it's a show-bike, which I guess it wouldn't be if it's full of heli-coils!).
paul c
whereas if the diaphragm cover of a cv carb has had one of its typically
four screw holes mangled, it makes sense (at least to me) to tap up to
the next size thread. (now, when I look at twenty-year old bikes or
older for friends who are thinking of buying them for a grand or so, one
of the first things i look at is the screws on the carb tops and bottoms
- if they look like they've never been touched, I tell friends to
examine the rest of the bike, because this test tells me that there's at
least a chance that a hacker hasn't been wanton with the mechanicals!).
when it comes to cover fasteners of various sorts and a friend hands me
a chipped Phillips head, I tell him to throw that screwdriver out and
get me a good one. If it doesn't budge with my (weak) wrist turning it,
I go immediately to the impact driver. If no luck then, I take at least
a few hours off to reconsider the situation! Just my two cents, I'm on
a budget, both bucks and years.
Mike W.
>
>I'm about to button up one of my KZP's valve covers. It's amazing how
>vulnerable the threads up there are. On this bike, it's my first time in it
>ever though I've been in/out of the other numerous times. I had to do, I
>think 5 helicoil jobs on compromised threads and fortunately those were all
>at the outboard parts of the valve cover where I could easily get at them
>from above with a drill.
Gentlemen,
MANY thanks for the excellent suggestions. I'm embarrassed I didn't
consider a bit extension on my own and was unaware of putty-type thread
repair. I know there's not a lot of torque on these bolts but the ability
of them to strip during routine maintenance is still legendary! Now I have
some better weapons in the arsenal. Again, thanks!