Craig-
Yep, this happens a lot w/ aftermarket stuff. It does not take
much in the way of a variance to have these things read just as yours
does. There are differences in the amount of teeth, and diameters, as
well as the colors. The colors are supposed to be the way to tell, but
stuff made in Carjackistan, or somewhere, is not as it should be. To
answer your questions:
a. Yes, the speedo head is different but not internally. The
number is different to denote an OD transmission and pinion gear.
b. Nisonger, in New York, told me how it is done. I am doing a V8
project w/ a Ford 3.08 differential, so I need to do it as well.
Basically is amounts to exposing your speedo cable at the dash. In the
course of your kids pushing you 52' 9.6", or something, (1/100 of a mile)
you count the times, to the nearest 1/8 revolution, that your speedo
cable goes around. It will be between 9 and 11, I think. Anyhow, you
send in that number and your speedo, and some large amount of money, and
they will calibrate it for you. Incidentally, that little number at the
bottom of a Smiths speedo after the "/" is the number you wish your
speedo cable actually did do rather than what it does now. You need to
confirm all of this w/ Nisonger people as I'm operating from memory.
c. If the new speedo pinion were correct, then all would be well in
MG B land. There is no calibration, per se, in the transmission, other
than the pinion.
Sometimes, it might be better to actually put 8 or 10 per cent
less miles on the odometer.
Larry Dickstein
bugide@juno.com
Remember, Paul Revere was a snitch
On Sat, 12 Apr 1997 17:46:43 -0700 Craig Wiper <craigw@sonic.net> writes:
>Hi. In October I dropped an overdrive transmission into my early '74
>B. I
>found that the speedometer was not working. It had been before that
>and I
>did get a new longer cable. I deduced the problem to be a faulty
>speedodrive gear. Upon removing the gear, sure enough the teeth had
>been
>stripped. I found a new one at Moss. It's the white gear made for the
>overdrive unit I've got. It's identical to the gear I pulled out of
>the unit.
>My speedometer now works; only it is about 5 mph slower than it was at
>about 40mph (reads 35mph when it should be doing 40mph according to
>the
>tach). When I'm up to speed on the freeway, in 5th gear, it reads
>about
>55mph (I'm really doing 65mph!). I've loosely calculated that I'm
>losing
>about 3 miles for every 15 I drive. So when my odometer reads 200,
>I've
>really driven about 240 miles.
>My questions are these:
>
> Is there a different speedometer used with overdrive
>transmissions?
> Is there a way to calibrate my speedometer to get the correct
>readings?
> Is there a way to calibrate the transmission?
>
>The gear does match the gear I pulled out of the unit and it is the
>color
>recommended by all I've spoken with and correct according to the
>catalogs
>I've seen these parts mentioned in.
>
>Thank you for your time,
>
>Craig Wiper
>craigw@sonic.net
>http://www.sonic.net/~craigw
>
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