Holy smokes, I knew the Brits were totally nuts. This reply proves it.
I would:
Replace all three engine mounts (pretty quick job, and it always seems to
help)
Have the driveshaft balanced by a really, really good shop
Check the centering of the diff shaft and the output shaft of the trans.
Offset is not so bad, but the shaft centerlines have to be parallel in both
the vertical and horizontal planes. A little tweak in the frame or a frozen
rear spring shackle can make a nasty vibration. I learned a lot about
driveshafts and vibration when I stuck a Toyota 2TC motor in my TR3 for a
couple of years (yes, I eventually put the stock motor back in). I
originally mounted the motor so the transmission output shaft pointed at the
differential (and was therefore NOT parallel to the centerline of the
differential input shaft in the vertical plane). Great for mixing martinis,
but not much for keeping your fillings in place.
-----Original Message-----
From: Paul Richardson [mailto:Paul-Richardson@cyberware.co.uk]
Sent: Wednesday, April 07, 2094 12:20 AM
To: fot@autox.team.net
Subject: Memories of transmission vibration (Very high-tech!!)
When the Herald came out it had many a problem including tranny vibration
that could nearly shake the car to bits and open doors etc..
The ' official factory cure,' if all else failed, involved the good old
'jubilee clip'.
The rear of the car was jacked up and mounted on axle stands under the
shocker mounts (for this procedure the suspension had to be loaded with the
wheels and brake drums removed). A jubilee clip was then fitted to the rear
of the prop shaft and by the following procedure adopted.
The engine was run up by a 'driver' to about 50MPH on the speedo with the
car in top gear - and dozens of stop start sequences were then needed to
achieve prop balance. The jubilee clip was moved round the prop shaft so as
to achieve the least prop vibration (it was very rarely cured at this
stage). Then a chalk mark was made on the prop shaft opposite the jubilee
clip screw case. The clip was then moved round the prop shaft so the screw
case was 90 degrees from the chalk mark. A second J clip was then fitted to
the prop shaft next to the first so that the screw cases were 180 degrees
apart. Then, often with dozens of starts and stops, both the J clips were
moved by equal amounts towards the chalk mark to achieve perfect balance (
this was judged by diminishing body vibration).
If vibration was still outside acceptable limits - the same damned
procedure had to be carried out on the front end of the prop shaft.
Sometimes this could be a damned dangerous opperation because the
vibrations were sometimes so bad the axle stands would chatter about on the
workshop floor!!
Another method we used involved a stroboscopic 'wheel balancing machine'.
The car was put on a four poster ramp with the rear wheels jacked up etc.
The balancing machine was positioned at the rear of the car so the strobe
flash beam pointed to the front and aimed at the rear prop shaft uj. The
flash pick-up (which was normally positioned under the front lower trunion
etc. for wheel balancing) was positioned to locate on the differential case
mounting bracket. The usual palaver with chalk marks and j clips then
followed. Strobe observation of the chalk mark positions on the prop when
the speedo registered 50 dictated jubilee clip positions - in conjunction
with the 'in balance' needle reading on the strobe machine. Does this help
Joe???
Paul
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