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Hello fellow Packard lovers
I have recently fitted my 1954 clipper super with a turbo 700 auto and Im very pleased with the result , the original speedo is the last challenge to be worked out and if I know how many revolutions the cable has to turn to make 1 mile that will complete the formula since I have the tyre size and diff ratio.
Any info would be greatly appreciated .
Regards Chris

The specifications section of the manual and the transmission section of the parts list should hold that info.

Quote:
I don't believe that specific data was ever published as Packard typically only gave the number of teeth in the various drive pinions available for the rear axle options offered.

If no one can provide the actual TPM number for the King-Seeley speedometers Packard used in 54 there is a procedure mentioned by a company dealing with another car and speedometer brand that you might try. I don't remember ever seeing the number printed on the speedo face as the first half of the article mentions but never really looked for it either. The second half with the instructions on calculating the TPM using the gear and helix thread ratios might be helpful if nothing better comes along. Unfortunately it sounds a bit tedious and means removing the speedo from the car. If you do remove the speedo be sure and place a drop or two of oil in the hole in the square part of casting near the cable threads to lubricate the input socket assy and bushing.

guess-works.com/Tech/speedo.htm

In a related brain fart I just remembered another post from awhile back where this was discussed. In that thread the figure of 1000 was mentioned and confirmed as possible by a forum member that is the owner of a speedo shop. The link I gave to an article on various speedo numbers is no longer working but that 1000 number might be a starting point if a verified number is not found. Another possibility might be a reference book available for speedo shop use that could give a more definitive answer. If you have a local instrument shop in Australia that deals with American cars perhaps a phone call could get a better answer.

If you keep the original rear axle ratio and tire diameter, the speedometer should remain accurate.
Otherwise, the speedometer drive gear on the transmission end of the cable may need changed. In most cases, several different drive gears were available. Generally, speedometers were not very accurate. One way to check on the true accuracy is to use a Garmin device that shows speed and mileage and compare what the Garmin shows to what the speedo shows. In the case of my'37 120 with correct size 7.00 X 16 bias tires, the speedo shows about 23 MPH at a true 25 MPH, and it is dead accurate at or near 50 MPH.
I suspect that that error and non-linearity is typical. To check odometer accuracy, I'd want to drive 30 miles or so on the open road at a moderate speed.

In a motor magazine article the 1951 speedos tended to read about 5% high. In 1955, 10% high.

there are companies that make gear boxes to change ratios also make parts to convert electrical signals for cable driven system speedometers

dicksspeedotach.com

I think HH56 is correct: 1,000 rpm per mile is the standard.

Hi Chris, You could always head out to the Hume Motorway and pass everything on the road at a steady pace. The Police will turn up very soon to tell you exactly what speed you are doing, and help to calibrate your speedo. Peter T

Usually go to Jon Stewart's Daily Show, Bill Maher's Real Time, or Jimmy Kimmel Live's opening to laugh out loud, but Peter's above another case of hilarious hard truth.

Chris,

I like Peters suggstion.
An unrelated item to this topic, ie , is your avatar. I see yov've changed it to be your '48 Standard Eight Club Sedan which has undergone a metal transformarion turning it into a Two Door "Woodie". I've beeen "out of the loop" and wondering, how's progress on the Woodie going?