In a message dated 10/25/01 6:32:29 PM Eastern Daylight Time,
pandachadwell@mac.com writes:
<< Why is it, exactly, that tapered shafts which fit into tapered bores
are such a royal pain the a** to disassemble? Cases in point: TR6
rear inner axle shafts/drive flanges, TR6 outer stub axle/hub, TR6
front stub axle/vertical link, upper ball joints, tie rod ends and
the list goes on.>>
For ball joints, tie rod ends and such tapers are the only practical way to
attach parts. The taper eliminates any space between the stud and casting.
On a single straight bolt, single shear attachment, slip fit system the parts
will eventually start to move ( Fretting) causing the nut to work loose or
the hole to become oval. Race cars can get away with straight bolts and
spherical rod ends for a while since time between rebuilds is rather short as
opposed to a road car where it may never be serviced.
For axle shafts, the practice of tapered assembly was abandoned in favor of
one piece forging. I suspect two piece units were used because large enough
forges weren't available or thick sections couldn't be heat treated
sufficiently.
<< Why on Earth are these things so stubborn when there's not even a NUT
holding them together anymore?! Seems like they oughtta just come
right apart once the nut is loosened and removed. >>
As others have said, the wedging action holds them together. Overtightening
will make the parts difficult to remove, use a torque wrench when
reassembling. When you compare the torque requirements to a similar sized
straight bolt, the values will seem low.
To break the parts remove the nut then strike the part with the hole, 90* to
the stud. If the stud is vertical, strike the casting in a horizontal motion.
If the parts don't separate, wind the nut back on leaving a 1/4" gap. Place
a prybar on the nut or body of the tierod to preload the parts. Strike the
casting with a hammer, sometimes a well placed hit on the nut will work.
Removing lower balljoints ( or ones that take the load of the spring )?
Place a jack under the lower controll arm, remove the nut ( this makes sure
the threads are clean ) then reinstall leaving a 1/4" gap. Lower the jack (
leaving a 1" of space) then strike the casting, jack up a bit to relieve
pressure on the nut, then unwind. Don't remove the nut while there is
pressure in the system !! The spring preloads the taper, the nut prevents
the assembly from flying apart and the jack is there just in case.
For axle shafts, some sort of puller is generally needed. If your puller
isn't strong enough on it's own, use it to preload the parts then strike the
puller screw to jar the system.
The balljoint/tierod forks generally shouldn't be used unless the joints are
going to be replaced since the rubber boot gets torn in the process. There
is a nifty short puller that presses the stud out of the casting, these
should work pretty well.
Harold
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