I would guess that the problem is in the drive gear in the transmission. Do you have the original 49 single lever transmission?

Does the odometer work about as it should, or is it slow also? If so, it's possible someone has put a '50 or later tranny in it and not changed out the speedo drive gear, which Dave's mentioned. '49 and earlier require 2000 rpm of the cable to show 60 mph, while '50 and later only require 1000 rpm for 60 mph.

As far as I know, yes. I was told that the transmission is original to that motor. Not sure how that was determined though.

I think you may be on to something as I notice that around 55 it almost read 30 miles per hour. It would appear to just about half. Is it possible to simply change the gear? Or, Should I ask are they even available anymore?

The tranny may be original to the engine, but is the engine and tranny original to the car? You can confirm whether it's the drive gear by checking the odometer behavior. See if it's also reading about 1/2 what it should.

I am pretty sure they are original to the car. I only say that because it still has the Drive Master in it:) But who knows. I will double check the odometer next time I am out. I will let you know.
Appreciate You,
Rob

Park/David,
Finally got a chance to get the '49 out on the road this weekend. Turns out that the odometer DOES only go about have. Thanks to your help it all makes sense now. Something in the car has been changed somewhere along its life. Now my question is, how do I fix it? Can the gear in the tranny be replace with the correct one? Or, is this something where I would need to find a different speedometer that matches the tranny gear?

Appreciate You, Rob

Robert, a few questions. Is there an adapter coming out of the back of the transmission?. This adapter should not be there for your model. Next, you said you replaced the speedometer?, if so, did you replace it with the same number that was on the speedo head ?. If it has the adapter in the trans, this makes the sppedo read about 1/2. next, it could have had the wrong speedo head in it before you replaced it. I would also make sure that the output yoke on the trans is tight. If it is NOT tight, it could allow the gear to slip on the output shaft and cause a low reading. These are just guess's, until more info. ?

Does the speedo cable screw on at both ends, if it does, it is the wrong type.

Hey Doug, Appreciate the input here. To answer your questions. No, I do not see any sort of adapter. It just slips into the yoke with a retaining bracket held with one bolt. Very much like a distributor bracket. I did replace the speedometer with one that had the same number on it. Result was the exact same operation as the old one. Checked the yoke and it is solid plus the speedo needle does not seem to jump at all as I would suspect with a slipping gear. I am really beginning to think someone changed the original speedo head long before I got it with the wrong one. Is there a way to tell by the trans what number speedo head I should have?

One way to correct the problem is to go to a speedometer shop that makes a small transmission to install at the trans take off point. When I installed a 2:73 ratio in my 3:08 rear this is what I did. Have 100,00 miles on it and still works great. Solves all problems. Walt.

Rob, what year is your car again?.

1949 Super Six

Robert, it sounds like someone has changed the speedometer. The next question, does the brown marbled face of the speedo head look like it is all intact ? You can take the later speedo, change the face to the '48-'49, and install it. This probably what someone has done. This would make the speedo off, something like you are talking about. I think the next step would be get a '51 face, which has different increments and registers 120 ,vs 100 ,hold it up to the dash while you are driving, estimate where it reads at say 30MPH, . If it is just about 50% off-slow- then you know what is going on. If it is the case, you can get the speedo cable assembly for a '51, with the adapter-[required], change them, and now the odometer will read correctly, but the speedo will now show incorrectly because of the different face. Using time and distance-mile markers- you can determine how fast you are going accurately. This sounds like alot, but it really isn't. I hope this didn't confuse you.