Speedo / Tach / Gauges: Adjustment

[mrkstudebaker]

Can anyone explain how to adjust the speedometer on my 51 Champion?
my original one broke a year ago. I found a NOS one, installed it, all works, just reads 6 miles slower. I have been allowing for that since I put it in, but which way do I move the spring?

[yeroldad]

You need to change the gear that goes into the transmission. You can call most any speedo shop, speedo cable shop, give them you tire size, what transmission, and differential gear ratio, and they can tell you what gear you need. Many of them will have one or can get one, or someone on the forum will have one.

[gordr]

First thing to do is to find out what is wrong. Are both the speedometer and odometer out, and by the same amount? If so, messing with the pointer return spring in the speedo won't fix the odometer. Find a nearby stretch of highway with a marked "Speedometer Test Section", or use a GPS to verify the exact mileage between two landmarks about ten miles apart. Make the run at a constant speed, and note odometer readings (to a tenth mile) at start and end of run, and note time (to the second) for the run as well. Do your math. Example: you find a run of of exactly 10.0 miles between landmarks. You drive at an indicated 60 mph between those points. Trip takes 11 minutes. Your true speed for the run was 54.5 mph. Odometer shows 11.0 miles. The speedometer and odometer are in agreement, but both are out by about ten percent high. A change of speedometer pinion in the transmission is in order. Now, imagine the same run, same time, but the odometer reads 10.0 miles, dead on the money. In this case, the speedo itself needs recalibrating, and that is a job best left to a speedometer shop, if you can find one,

It might be that a previous owner tinkered with the speedometer to make it read "right" after an axle ratio change, and never cared about the odometer being off. New factory speedometers are all calibrated to the same standard.

[mrkstudebaker]

This is a NOS , it had .09 miles on it when I installed it. My old one was pretty close to right on. I had a 16 tooth and changed tho a 15th tooth, and it is 6 miles off.

[mrkstudebaker]

If it tightened it clockwise will the speed increase, just not sure which way to turn it

[gordr]

Well, if the old one was right on, and you changed to a 16 tooth gear from a 15, you would expect the speedo to be out by about 6%. Speedometer error is usually a percentage of indicated speed, not a constant. Find a 16 tooth pinion, and try that, before messing with the speedo head. If the wrong pionion is used, the odometer will be wrong, too, and there is no adjustment possible for it.

[mrkstudebaker]

I started with a 16 tooth and Was using that one when my speedometer broke….
sofar I used a 16 , 17 which was worse.
and now have a 15 which is better but still off. ( slow by 6 mph )

[mbstude]

It's likely gummed up from sitting for 70+ years. Did you put oil in it? There's a little brass plug close to where the cable screws on, it has a felt wick under it to keep the internal mechanism oiled. Pull the plug out and add a few drops of light oil while spinning the shaft.

Having it serviced by a gauge repair shop would be a good idea. NOS speedometers for a 51 Champion are a scarce thing.

[mrkstudebaker]

I oiled it when I installed it,
I have put 12,000 miles on it.
The needle doesn’t jump around, it is very smooth, just not right.

[Big Dan]

Are you running it with stock sized tires on the back?

[mrkstudebaker]

Yes, 670 -15 Radials, my old speedometer that broke was so very close to being right on.
Today, I finally got the little brass cup out.
put a few drops of 3 in 1 oil in it. Ran out of time, will check it out tomorrow

[mrkstudebaker]

No change with oiling the wic
still 6 miles slower than the actual speed.

[yeroldad]

Re-read post # 6 again. Check the odometer, on the road, as was stated. If it's right, then there MIGHT be something in the head but I seriously doubt it, as has been stated. If the odometer is off, then you need to change the "pinion", gear, in the trans, as stated. Messing with the head will most likely screw it up, or damage it to the point that it won't work at all and you'll have to send it out for repair.

[mrkstudebaker]

Thank you for the information
I’m going to check out The odometer On the road and see if it’s off even with the 15 tooth.
I originally had a 16 tooth , which is what is supposed to be, I’ll put that in and do the odometer test.

[mrkstudebaker]

Update:
I did the test with the 15 tooth.
I used my GPS on my phone, the odometer is right on. I did it twice.
I have a 16, and a 17 tooth as well but it will make it worse.
i said earlier that my original one was right on, well looking at the original one after the test, I noticed the needle is bent a little. You can see it plane as day when it is out , when it was in, I didn’t notice it.
I don’t know what else to check, other than the speedometer.
I have been told to leave it, and just do the math. Probably what I’m going to do.