From: sfisher@megatest.com (Scott Fisher)
Any thoughts on thread-locker compounds such as the various ones
made by Loctite?
There are a couple of problems with Locktite. If you do not run into
them, the stuff is God-like. The problems are heat and oil.
Most of the common locktite compounds are good to 300 degrees
Fahrenheit or so. Above that the material decomposes quickly.
Fortunately most things in an automobile don't get that hot.
There are a couple of locktite products good to 450 F. Hard to find
though.
The second problem is that locktite must go on clean metal - oil and
dirt are killers. This means that locktiting the parts you just washed
in de-greaser is -completely useless-. I usually use acetone for stuff
I'm going to locktite. Carroll Smith claims brake cleaner works well,
and he's built a hell of a lot of race cars.
Basic locktite #242 is the blue stuff you can get anywhere. Kinda
weak. #271 red locktite is pretty common, and very good for things
that want to vibrate loose. It's holding my TR3's front suspension
together, for example.
There is apparently a stronger variant of red locktite, which I've
never used. There's also the 600 series of "retaining compounds",
designed for keeping non-threaded things - pins, bushings, etc, where
they belong.
~ If the situation is really critical, safety wire the bolts -
~ cheap peace of mind.
Hmmm. No, I don't think my drilling skills are up to making teeny
holes through two adjacent flats on these bolts, which are 3/8"
fine I think (that is, they use 9/16" sockets).
Indeed - hard to do without a precision drillpress or mill. Mil-spec
aircraft bolts are available pre-drilled, as are some industrial
fasteners.
Oh, I should probably mention belleville washers, which are to regular
lock-washers as Jaguars are to Chevettes. You can find these at
industrial fastener supply places. Basically a full washer (no slits,
cuts, etc) of heavy spring steel, slightly conical, so that when you
install them they squish flat while generating enough force on the
bolt to actually do something.
-john
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