In a message dated 2/20/03 12:23:48 PM Eastern Standard Time,
ryoung@navcomtech.com writes:
<< I saved a long-ago post from Kas Kastner, where he talked about measuring
flywheel wobble on a TR6 (stock crank and flywheel) : he found the wobble
could reach 5/8" !! >>
I would hope KK was measuring this with a bare crank sitting on a vibration
table. There is little chance the main bearings would survive or even allow
the crank to bend 5/8 of a inch. With the crank in a engine, the trans pilot
bearing and clutch would limit deflection.
<<This was at 5800 rpm, the third resonance point of the
crank, which of course most street motors will never see.>>
For our Formula Ford engines ( 1.6L 4 cyl Kent Ford of England) the resonance
point is 6800 RPM. We are desperately seeking to get flywheel weight
reduced in a effort to prolong crank life as they tend to crack between the #
4 rod and last main bearing. Less weight is always better, a high flywheel
weight will allow the crank to windup on acceleration contributing to the
problem.
<< Curiously enough, his solution was to add weight to the crank, to move the
resonance up above the speed they were trying to turn (which was not
revealed). >>
At the expense of more rotating mass? Sounds like a hack.
<< He also made the point that the flywheel-to-crank bolts get
heavily loaded in tension, in this situation, and that he found the
clutch-to-flywheel bolts would usually let go first.>>
Yikes! This is a major problem just waiting to happen. When flywheel to
crank bolts fail the FW, Crank and possibly clutch are going to receive major
damage.
For more on the flywheel weight problem go to : http://www.ff1600.com/ and
http://pub3.ezboard.com/bformulafordunderground then search for flywheel
weight. There are some people that have put some effort into researching
this problem.
<< Randall >>
Harold
/// triumphs@autox.team.net mailing list
/// or try http://www.team.net/cgi-bin/majorcool
/// Archives at http://www.team.net/archive
|