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[TR250] Vibration under load at speed

To: triumphs@autox.team.net, s6pack@autox.team.net
Subject: [TR250] Vibration under load at speed
From: david brady <dmb993@earthlink.net>
Date: Sun, 09 Nov 2003 20:53:35 -0500
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:0.9.4.1) Gecko/20020508 Netscape6/6.2.3
Folks,

I had the TR250 out today for a pleasant 250 mile
trip! Yahoo what a time. The car is completely restored
with a healthy 175hp motor plus many other upgrades.
I had all the rotating and reciprocating parts of the
motor balanced at rebuild time including the
harmonic balance and the flywheel and clutch
assemblies. I'm running quaif (sp?) hubs in
the rear and nylatron suspension bushings
throughout including the diff mounts.  She
runs perfectly... except for a rather significant
vibration when under load and at high rpm.
At a standstill I can rev the motor to its six
thousand RPM limit and its as smooth silk.
On the road with light throttle application, I can
hit redline in every gear, except 4th for obvious
reasons), and everything is smooth. But, when
I'm up in the RPMs, where the power is, above
4k and with wide open throttle, I get a good
front end vibration that I can feel through my feet.
The vibration gets worse as the revs approach
redline. I'm thinking maybe a bad harmonic
balance, which was replaced as part of the
rebuild; a bad motor mount; or maybe as a long
shot, out of balance front wheels, loose front wheel
bearings, or tires out of round that is exacerbated
by the unloading of the front end which occurs under
heavy accelerations. Remember, my motor is
quite healthy. Another possibility is that this is
simply the crankshaft whipping  torsionally as a
result of twisting due to the power pulses. Any
thoughts are greatly appreciated.

Thanks,
Dave
68 TR250
CD8124L




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