The Stovebolt Site Forums The Shop Area General Truck Talk '46 Speedo Question

I'm working on a '46 1/2 ton driver. The speedo and odometer were not working. I removed the speedo/odometer and checked the unit. Very dirty and sticky when I spun the back. Sent this off for a rebuild. I drove the truck today and the cable is not spinning as I drove. I could not move the inner shaft on the cable so removed the cable from the tranny. Looks OK so I cannot see why the cable shaft won't spin. Is this a gear in the tranny (original 4-speed) or am I looking at something else? I searched the threads but could not find anything. Thanks.

Yes the cable is driven by a set of gears in the transmission. If yours is the same as my ’41 unsynchronized 4 speed I may be able to help with some photos as I will be removing and disassembling the transmission this week (I hope)

It is possible for those inner cables to brake over the corse of 60 years or so. I would test the cable by pulling it from the transmission and chucking it in a cordless drill to verify it is still intact.

OK after 4 months of delay I got the speedo rebuilt and back in tonight. Hooked the drill up to the tranny end of the speedo cable and speedometer & odometer work great. Sounds like a tranny issue to me.

Anybody know what's bad in the tranny and how much trouble it is to fix?

Kip's'41: Did you find a problem on yours? Thanks.

I don't remember specifically what your '46 transmission has for speedometer gears, but typically the driven gear, where the cable attaches, is held to the transmission case by bolt and clamp arrangement. Remove the bolt and clamp and pull the gear assembly out or the transmission case. The gear usually slides out, but it may be stuck. Depending on where the gear is located in the case, be ready to plug the opening or you may drain the oil from the transmission- all over you. If the cable attachment is above the transmission fill plug, you shouldn't lose any oil.

You should be able to find a replacement gear, but the speedometer gears are matched to tire size and final drive gear ratio, so make sure you get the proper replacement gear. If I remember correctly, the driven gear will have an identifying number stamped on the end, that is if the gear hasn't been destroyed. Or is at the bottom of the transmission.

The drive gear is located on the transmission output shaft, and is only accessable after disassembling the transmission. Of the two speedometer gears, the driven gear is usually the one that fails.

Harvester

Which speedo are you working on the 46 1/2 ton, or another?
is it a 3 speed or a 4 speed ??

Is the speedo driven gear part of the yoke assembly in the torque tube, or part of the transmission?

https://www.stovebolt.com/ubbthreads/ubbthreads.php/ubb/showflat/Number/385548#Post385548

Found this recent post that I missed and sounds like someone else has the same problem as me. My tranny is a 4-speed all original. I tried to remove the speedo gear. Pulled plugs out on both sides of the tranny but I cannot remove the gear. The shaft will turn until it's shifted about 3/4 of the way out of the tranny. Then it's stuck. With some effort I was able to nearly remove the shaft but found the gear is shifting on the shaft. Pulling the shaft back toward the passenger side revealed a severely chewed up gear. I'm assuming that this means I'm looking at dropping the driveshaft and removing the tranny tailstock.

Sounds like the speedo gear is a bit tough to find, how about the inside gear? Anybody know what to expect on this repair or what parts are needed? Would the procedure for dropping the drive shaft be like dropping one on a '50 1/2 ton? The '46 shop manual is a bit vague. Thanks.

The speedometer drive and driven gears are part of the transmission, and are matched. The drive gear is on the output shaft, the driven gear mates with that gear, but should be easily removable without disassembling the transmission- or removing it from the vehicle.

Jss1956, if you are trying to remove the speedometer drive gear, yes, you have to drop the drive shaft and remove the transmission tail housing- after you drain the oil from the case. Then you need a new gasket and seal for the tail housing.

I don't remember if the drive gear is a press-fit on the shaft or not. I can probably find out, but maybe someone else can answer that.

Harvester

Thanks for the info guys.

I was able to finally remove the gear and shaft. Pulled the 2 out separate. I cannot tell the condition of the gear inside but the mating gear is severely chewed up. The shaft is bent, probably due to the 2 gears clashing. I can't see inside the tranny so for now I'm going to close everything back up and drive her until I can find the parts.

Anyone know where I can find a speedo gear and mating tranny gear? Thanks!