Everything has a natural resonate point. The Triumph TR-3/4 engine has a
resonate point of 2800 to 3000 RPM. IT"S NATURAL. The same vibration will
again be felt at 5800 (approx). The third sequence of the vibration is off
the scale. Anything loose, hitting the chassis, out of balance etc is going
to be just that much worse at this point of natural resonance. As I
remember the rear weight on the transmission ( we called it the "dong") was
fitted while waiting for the new gearbox casting to be introduced to
production. The idea was to reduce the vibration in the bellhousing and
thus to stop the case from breaking right around just in front of the
transmission casting and the beginning of the bellhousing. We broke a ton of
gearbox bellhousings. For while with the first TR-4' cars we would need to
change the gearbox after any session lasting more that thirty minutes. It
was nuts to have to change the box every Saturday night so that you could
get through the race event the next day but at that time very necessary.
The new casting has very heavy ribs down each side of the case and actually
I think there were two ribs on each side and this fixed the problem. The
bell housing case was also thicker. To keep the problem within bounds I
wound up welding long pieces of thick aluminum down each side of the case
and onto the bellhousing portion. This stopped the deal. Ultimatly the new
stock version was much like my welded up part.
----- Original Message -----
From: <KHoward515@aol.com>
To: <N197TR4@cs.com>
Cc: <fot@autox.team.net>
Sent: Friday, April 07, 2000 10:26 AM
Subject: Re: Pile-o-Parts...Plus driveline vibration inquiry
> Hi Joe,
>
> What's the problem? Is your butt still vibrating from those 10 hours
nonstop
> in my TR4A last week?
>
> In any case, thanks for the online inquiry into my problem. In my mind it
> definitely is forward of the transmission because the vibration occurs
> between 3100 - 3300 rpm not matter what gear I'm in. It even vibrates in
> neutral!
>
> I'll pass all the suggestions on to Bob Dempsey. Hopefully we can find
the
> problem before our next multi-country trip.
>
> And now, how do I get rid of the whining coming from the rear end.
> Differential or what?
>
> Kent
>
> PS: I'm picking up some TR6 seat parts on Monday from Chris Mills and hope
to
> adapt them to the 4A so the passenger seat will recline. That way Carole
can
> tilt back and sleep on our May trip and you can doze off on our trip next
> fall.
>
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