Stude speedometer revs per mile ??

[Blue66]

Anybody know what revolutions per mile the studebaker speedometers are/were??????
I am trying to calculate the speedo gears for the new trans going in, but can't find how many revs per mile the stude speedo's are.....
Should be something like 940, 960 , 1000.....

Thanks, Brian

[StudeRich]

I have never heard a Speedometer rating in revs per mile, they are standard 1960's Stewart Warner though. Speedometer Shops know this stuff, maybe that's how they know them. [^]

Most people set the Speedo driven gear by drive gear teeth, trans type, tire Diameter, and axle ratio. [:0]


StudeRich at Studebakers Northwest -Ferndale,WA

[DEEPNHOCK]

The standard used to be 1000 rpm (cable speed) = 60 mph
Jeff[8D]

quote:Originally posted by Blue66

Anybody know what revolutions per mile the studebaker speedometers are/were??????
I am trying to calculate the speedo gears for the new trans going in, but can't find how many revs per mile the stude speedo's are.....
Should be something like 940, 960 , 1000.....
Thanks, Brian

[Jeff_H]

When building my '53 I had this same question. I needed to know to calculate the trans gear needed given my tire size, rear axle, etc. I ended up sitting down with the speedo and literally counting the number of turns on the cable input to get 1 mile on the odometer [xx(] If you do this, lock yourself in a quiet place so nobody disturbs your tally [}]

I got 1000 turns. This is for a stock '53 speedo. In the end, I discovered the theoretical correct gear for my transmission does not exist. I need a in-line gear box for the cable. In practice, the OD reads about 6% low but the speed reads high. So, the speedometer indicated speed is near right but the mileage is low. If I fixed the OD with said gear box, I expect that the speed will read too high. As a result, I've not been too motivated to fix it since then the speedo needle return spring will need to be messed with. I saw there is a tension adjustment with a locknut for it.

Jeff in ND

'53 Champion Hardtop

[64Avanti]

The standard for many years has been 1000 turns per mile. So if it turns at 1000 RPM it should indicate 60 mph as well as showing 1 mile after one minute.

It is difficult to get the exact gear ratio with a mechanical speedometer.

David L

[Chucks Stude]

I put my GPS in my Stude while driving on the highway, and the speedo was right on the money. I was stunned. I am like David, I thought the thing would be 2-3 mph off. I am running a 3:31, and 205/15 radials.

[mbstude]

I've just gotten used to deducting 10 MPH from what my speedometer reads. It's about 10 MPH too fast.

So does that mean when the car hits 100K miles, it actually only has 90K?

Matthew Burnette
Hazlehurst, GA

[Blue66]

Thanks guys, I ended up using 1000, and I have enuf gears here to go 1 tooth up or down from calculated #'s......I don't mind being being 5 or even 10 off. Just wanted somewhere to start at least as not to be hugely out of the ball park.

I also have a gps.....sure makes it easier than following someone!!

[Blue66]

quote:Originally posted by mbstude

I've just gotten used to deducting 10 MPH from what my speedometer reads. It's about 10 MPH too fast.

So does that mean when the car hits 100K miles, it actually only has 90K?

Matthew Burnette
Hazlehurst, GA

Actually at 55 being 10 off is about 20% so you will only have 80,000 miles on when it reads 100,000.

My wifes Tahoe is off about 2mph at 60 due to larger tires. You would be amazed how quickly the GPS odometer and the vehicle odometer separate.