Geoff:
A method of isolating the source is fairly easy. At a local lawn mower
supply or tool store, you can get a reed tachometer. It's a little round
disc with metal tangs all the way around, used to measure engine speed of
single cylinder engines. The frequency of the vibration will set off one of
the little tangs, or reeds.
Once you have that, then all you have to do is drive the car to vibration
condition and with the reed tach on some suitable spot, find out the
frequency of the vibration. If your engine is going, say, 3000 rpm and the
reed is vibrating at that speed, then your problem is in the lower half of
the engine. If 1500, then it would be head related. If it is some other
reading, then you have to begin doing some calculations. Working through
the gear ratios you can calculate the speed of the driveshaft, and then the
u joints, tires and so forth.
Good luck
Paul
----- Original Message -----
From: <gameparker@cs.com>
To: "Walter Fogle" <lbc4me@hotmail.com>
Cc: <6pack@autox.team.net>
Sent: Friday, October 26, 2001 6:12 AM
Subject: RE: Re: Vibration @ High RPMs
> Walt,
> thanks for your reply. I think it has to be a function of the engine
because I got everything balanced (driveshaft, wheels and hubs on the car)
to cure a 60mph shake, which I did cure. Also, I can get to and cruise at
105mph without any shake so long as I don't exceed 4500 rpms - in other
words, my shake is dependent on engine rpms, not road speed.
> Thanks and regards
> Geoff
>
>
> "Walter Fogle" <lbc4me@hotmail.com> wrote:
>
> >
> >Geoff:
> >
> >I have a '69 TR6 that I've owned for about two years. For quite some
time a
> >wrassled with different vibrations and wobbles at highway speeds. The
main
> >offenders that I discovered were; a bent front wheel that would not
balance,
> >a bad u-joint at the front of the main driveshaft, and a worn
transmission
> >mount. All the vibrations were basically transmitted through the front
end
> >it felt like everthing up front was loose. After fixing those three
items
> >(I bought a complete set of 8 spoke alloy wheels and new tires!) we motor
> >down the road straight and wobble free.
> >
> >I'd check your wheel balance and u-joints first. I hope this helps and
I'm
> >sure that others will reply with good suggestions.
> >
> >Good luck.
> >
> >Walt Fogle
> >'69 TR6, CC30689L
> >Woodinville, WA
> >
> >Geoff wrote:
> >List,
> >>thanks to all who take the time and interest to answer my (probably)
silly,
> >>but nonetheless "important to me" questions. My engine was rebuilt
about
> >>1000 miles ago, and hopefully fully "run-in". I have a mild cam shaft
in,
> >>Petronix, and an electric fan in addition to the mechanical one (gets
hot
> >>here in South Fla.). When accelerating through the gears, when I get to
> >>about 4500 rpms, I'm forced to change up because of a significant
vibration
> >>that causes the whole front end to perceivably shake. Is this a case of
"I
> >>should have had the engine balanced when being rebuilt" or is there an
> >>easier
> >>answer (solid engine mounts, for example, if they even exist)? I was
> >>really
> >>looking forward to seeing the other side of 5000 rpms....
> >>Thanks and Regards
> >>Geoff
> >
> >
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