VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 '38 Speedometer issue

Hey guys, I have a question, my 1938 Chevrolet Master Deluxe Sedan speedometer has never worked since I bought the car. It had set up for about 20 years when I bought it, and it took 4 months + to rehabilitate it ... replaced fuel tank, filter, carburetor, rebuilt all brakes, master cylinder, etc.

The fuel guage doesn't work and the speedometer doesn't work. HOWEVER the odometer does work. I use the odometer to keep up with mileage so I know when to fill up the 14 gallon tank. My calculations how I am getting about 6.5 to 7.5 mpg, which seems low, but maybe that's expected (the car has a '47 216 truck engine with a '41-'48 head, which my friend and I cleaned up, replaced rods, cleaned valves, etc.).

I took off a rubber line behind the speedometer today, and drove down the road with the male end in my hand. I could feel the center spinning, so it seems to be working. Does this mean the speedometer is shot? I have a great shop manual but unfortunately there is nothing in it for the speedometer, curiously enough.

Thanks everyone, all input is appreciated!

Mark

The problem in in the speeometer.
With every day driving you should get 15 MPG. For short trips, cold engine and evaporation it would be less

Thanks Chev Nut. Looks like I can send it to Filling Station and they can send it off to be re-built for about $160 or so. Looks like there are just four bolts / screws that hold it on to the back of the dash? I am nervous about sending it off ... the DC guage and the oil guage and the temperature guage work so well I hate to un-do them. Thanks again.

Dealers did ot repair speedometers and Chevrolet did not generally sell parts for them They sent speedometers out to Authoized AC Speedometer repair shops.

There are instrument repair specialists listed in the classified ads of the VCCA magazine, the G & D.

You can also Google automotive instrument restoration.

Cool. Thanks. My friend and I pulled the speedometer out of the dash and placed a drill on the end and made it spin. The speedometer and odometer turned freely; both worked. It appears my cable is not engaging in the female end in the speedometer fully or adequately. I pulled the cable a little further out of the housing and reconnected it, but it still didn't work.

My friend has a '40 Chev and he pulled his cable off, and it sticks out from his housing about the same length, or a little bit further (millimeters) than mine. So I think we are going to hook up a spare speedometer to my cable and see if the problem is in the housing of the speedometer (the female end).

I went ahead and ordered a new cable from Filling Station anyway, it was really cheap, and I needed a new shift knob anyway. Looks like I have a project for next weekend!

Thanks everyone

Just a quick follow-up ... we pulled out the old speedometer cable out of it's housing, and found out the speedometer end had been grinded to the four-sided shape. It is supposed to have a male end that is four-sided that is crimped on to the cable. We cut the new cable to the correct size and inserted it into the housing, and tested it with the rear wheels in the air and the speedometer hanging under the dash .. and it worked great. Went up to 40 or 50 mph in 3rd gear. Then we mounted the speedometer back in the dash. For some reason ... still investigating ... it drops to zero correctly at a stop, but only gets up to about 10 or 12 mph, no matter what speed I drive. Like I say, we are still troubleshooting....

That sounds like good progress.

This might be a long shot. I wonder if mounting the speedometer did something to distort the housing or cause some type of binding. I would loosen the mounting screws or maybe slightly loosen the knurled nut that holds the cable to the housing. Then see what happens.

That's a good suggestion Rusty. Thanks. Think I will try it this Saturday. I do wonder if there is something binding the speedometer in the housing.