Tiger Folks,
Check out a good speedometer repair shop and you may find that there is
an inline gear box available to change the speed of the speedometer cable
to allow for correct odometer readings. I have such a device on my V6
Alpine conversion. The speedometer cable is in two parts with correct screw
on fittings to match the gearbox. Various gear ratios are available. You can
also have the speedometer calibrated to 1000 cable revolutions = 60 mph.
Sorry, but the gear box on my Alpine is presently under new carpet that
I receantly installed ( glued down) so I can not get the part number off of it
without messing up the carpet. Yes, the cable runs on the floor, not under
the car. There is a C3 automatic transmission in this Alpine.
By the way, if you have more time than money you can calibrate your own
speedometer as I did. After repairing my Tiger speedometer to stop the
erratic movements (adjust clearance to bearing surface by pressing
the shaft through the bearing. Only 1/1000 of inch or so) I found that the
speedometer was reading low.
I used my drill press with the pully belt twisted ( for reverse rotation)
and set up for 1000 RPM. An old speedometer cable was connected from
the drill press chuck to the speedometer.
I then took the bar magnet (with shaft) and and determined
which end was north and south by using another labled bar magnet.
Like poles repel, unlike poles attract etc. I then wrapped several turns
of 14 gauge wire around the magnet. This is hard to do with the two
shim pieces that are attached to the magnet. I used the "Right hand rule"
to determine the needed current polarity to provide additional magnitism
to the speedometer magnet. I shorted the wires across my Tiger battery
about 10 times for about 1/4 of a second each time. The wire gets hot
fast ! I removed the added wire, reassembled the speedometer and using
the same drill press setup I checked the speed. Too high of course.
Then came the easy part. Using a Radio Shack tape degauser held about 4
feet from the driven speedometer I slowly moved closer and the indicated
speed started dropping. At the 60 MPH point I stopped the degauser and
the speedometer was calibrated at 60 MPH per 1000 RPM of the cable.
Using the other speeds of the drill press I computed the required speed
and checked the linearity of the speedometer. Very close to being correct.
500 RPM should read 30 and 2000 rpm should read 120 mph.
It just takes time to disassemble the speedometer several times. Be
real careful in removing the needle because the needle shaft is very
small and connected to a watch spring.
Do not use a tape degauser near the dash of your Tiger or you may
uncalibrate all other magnetic type gauges.
If you replace the speedometer cable with a "Universal replacement
cable and cut it too long the cable will push the shaft holding the magnet
inside the speedometer and the bearing surface will wear. A jurking
speedometer reading is the result of the damage you caused by having
the replacement cable just a little too long.
By the way, other Smith speedometers such as from an MG
can be used in a Tiger by swaping the connector out from the US 5/8"
to the small English connector from an old cable off an MG or Alpine.
Carefully split the crimped tube from the MG cable and pull off.
Remove the US fitting from the Tiger/Ford cable and replace with
the other connector. Use 2 small hose clamps to secure the split
tube. ( or else have a speedometer shop apply a new connector with
the proper crimping tool.)
Note that the speedometer cable in the MG or Alpine is slightly larger
than the US, Tiger/Ford size so the square hole in the MG or Alpine
speedometer is slightly larger that the US Tiger/Ford cable. It does not seem
to be a problem unless the hole is really worn out.
Original Tiger speedometers will not accept the original MG or Alpine cable
square end due to the size difference.
Jim Barrett Tiger II 351C and others
|