Bob, and Listers,
The helical drive gear looks impressive but it doesn't have that many teeth.
Working the numbers that Jim gave (on wheel turns vs. speedo cable turns,
knowing the rear axle ratio), gives a number like 7.57. We know it has to be an
integer number, but I'm not going be the one to suggest that either Jim or his
wife counted incorrectly :). Based on your own math it could be as high as 9.
Jim has a transmission sitting in the garage (on the scale still?). You may be
able to look past the output shaft seal to see the speedo drive gear; shine a
trouble light in through the speedo drive hole to illuminate it. Otherwise,
clean the grease or oil off of it by spraying carb or brake cleaner onto it
(through the speedo drive hole) and dry it. Then turn the output shaft, counting
and marking each tooth with a magic marker as they come by. I'm guessing it will
be 7, 8, or 9 teeth.
Theo Smit
tsmit@novatel.ca
B382002705
> -----Original Message-----
> From: Bob Palmer [SMTP:rpalmer@ames.ucsd.edu]
> Sent: Friday, March 26, 1999 2:17 PM
> To: James Barrett
> Cc: tigers@autox.team.net
> Subject: Re: 351C
>
> At 02:37 PM 3/26/99 -0500, James Barrett wrote:
> > Bob,
> > The rear end is 2.88. I also came up with fractional
> >number of teeth. This student is brain dead, that is why I asked for
> >help. Do not trust the speedometer 1020 calibration. The speedometer
> >has been apart many times.
> >
> >James Barrett Tiger II 351C and others
> >
> >
> Jim, et Listers,
>
> If I use the number for the mi/rev Laifman quotes for the stock Tiger, and
> invert this to give rev/mi, you get 876.8853. Multiply by your 2.88s to get
> 2525.43 revolutions of the drive shaft per mile. Now, to get your 22 tooth
> gear to turn 1020 revolutions per mile, we need to drive it with
> 1020/2525.43 as many teeth (or the equivalent). This comes out to be 8.88
> teeth; i.e., pretty close to nine, but not quite. I tried to look up the
> Reference on page 23 of Taylor's book; not there, but he I did find the
> speed at 1000 rpm spec (same for both MkI and MkII), which is 23.92 mph @
> 1000 rpm. This means 2508 revolutions of the motor and, in fourth gear
> (1:1), of the drive shaft per mile. Then, (1020/2508)x22 = 8.946, even
> closer to an even number. Steve tells me the helical drive gear has "lots
> of teeth" and is about 2" in diameter, so somehow it must be geared down a
> lot from the rotational speed of the drive shaft. I think it's time to call
> a moratorium on the math exercises and research how the drive gear works.
>
> TTFN,
>
> Bob
> Robert L. Palmer
> Dept. of AMES, Univ. of Calif., San Diego
> rpalmer@ames.ucsd.edu
> rpalmer@cts.com
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