1966 c10 speedo help

[Zcle91]

this is my first time posting so if im doing anything let me know. i have a 1966 c 10 as the title says my speedo is not working i tried the "drill" test on the cable and it works then. i looked at the gear that the cable attached to and it is in good condition the gears look sharp. when i connect the cable to the gear through the metal "plug" and spin the gear you can feel tension so i know the gear is connected to the cable. i put my finger in the whole where the plug goes and i can feel the gear around the transmission. but when i drive nothing happens. so im guessing my next step is taking off the end of the transmission to see if that gear is free spinning on the trans?to do that i have read that you need to remove the drive shaft? i will do that but my driveshaft center support is riveted to the frame. so before i start grinding rivets off next weekend i was wondering if anyone knows a different way to take off that back case or a step i am missing through the whole process. im very welcome to any help at all thank you all

[Lugnutz65]

Originally Posted by Zcle91

this is my first time posting so if im doing anything let me know. i have a 1966 c 10 as the title says my speedo is not working i tried the "drill" test on the cable and it works then. i looked at the gear that the cable attached to and it is in good condition the gears look sharp. when i connect the cable to the gear through the metal "plug" and spin the gear you can feel tension so i know the gear is connected to the cable. i put my finger in the whole where the plug goes and i can feel the gear around the transmission. but when i drive nothing happens. so im guessing my next step is taking off the end of the transmission to see if that gear is free spinning on the trans?to do that i have read that you need to remove the drive shaft? i will do that but my driveshaft center support is riveted to the frame. so before i start grinding rivets off next weekend i was wondering if anyone knows a different way to take off that back case or a step i am missing through the whole process. im very welcome to any help at all thank you all

After reading the above I need some clarity.
Sounds like you disconnected the cable where it connects to the transmission. Right?

Connecting a drill to the end made the speedo in the cab work. Right?

If the above is correct, then it sounds like you have a broken or missing connection in the transmission. You need to tell us what transmission you have. Then we can make some progress towards fixing it. No need to take things apart if it's a simple fix.

Also, it sounds like you have a long bed tuck with a carrier bearing and a 2 piece drive shaft. You do NOT need to remove the cross member for the carrier bearing to get the drive shaft out.

[Zcle91]

the speedo in the cab works when i hook up the cable to a drill. its a 1966 c10 with a 292 engine and three on the tree. and it is a long bed as for a specific transmission i do not know. it looks like the stock one i see in a lot of threads.

[Lugnutz65]

Maybe you are missing the DRIVEN gear. The end of the cable fits into a thing called a DRIVEN gear. Do you have any pics showing the place on the tranny where the cable screws into?

[Zcle91]

the driven gear is there and i can feel the drive gear through the hole in the trans. maybe my gears are worn out? they feel good but i have never dealt with them before. and when i connect the cable to the metal piece and spin the gear you feel tension of the cable spinning? i have been searching these forums for an answer and im clueless.

[Lugnutz65]

Originally Posted by Zcle91

the driven gear is there and i can feel the drive gear through the hole in the trans. maybe my gears are worn out? they feel good but i have never dealt with them before. and when i connect the cable to the metal piece and spin the gear you feel tension of the cable spinning? i have been searching these forums for an answer and im clueless.

OK, thanks for the pictures. Yes, that's the driven gear in your hand. If the drive gear is worn, then it won't turn the driven gear.

What you can do to check is put the driven gear back in but leave the cable disconnected. Put the rear axle on jack stands. Start the truck and put it in gear so the rear wheels turn. Have someone with a flashlight look to see if the driven gear is spinning. Make sure you take all the safety precautions. Your helper should be able to see the end of the driven gear without needing to get under the truck. No need to get the wheels spinning very fast. It should be obvious.

[Zcle91]

Ok thank you a ton. I'll do that this weekend. Maybe sooner depending on when I can get a helper. Which would be better the driven gear spinning or not spinning? And what are the actions after that?
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[Lugnutz65]

The drive gear turns whenever the drive shaft turns. The drive gear makes the driven gear turn. So, your driven gear should turn whenever the drive shaft turns. Make sure you have the driven gear pushed all the way into place.

[PGSigns]

No need to run the trick on the stands. Just put it in neutral while on the stands and spin a wheel by hand to turn the drive shaft. Also take that driven gear and clean it up good and look where the cable goes in it. The end of the cable should be a nice square shape and so should the end of the gear. I have had them wear out and the driven gear was nice and round inside.
Jimmy

[Lugnutz65]

Originally Posted by PGSigns

No need to run the trick on the stands. Just put it in neutral while on the stands and spin a wheel by hand to turn the drive shaft. Also take that driven gear and clean it up good and look where the cable goes in it. The end of the cable should be a nice square shape and so should the end of the gear. I have had them wear out and the driven gear was nice and round inside.
Jimmy

^^^^^ all good advice. ^^^^^
No need for jack stands if you just spin the rear tires by hand.

[Zcle91]

Sorry for taking so long. Work can be rough. But while spinning the tires the driven gear does not spin. So does that mean my drive gear is bad?
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[Lugnutz65]

Originally Posted by Zcle91

Sorry for taking so long. Work can be rough. But while spinning the tires the driven gear does not spin. So does that mean my drive gear is bad?
Posted via Mobile Device

Yes, probably a bad drive gear.

[Zcle91]

Ok thank you. Will I have to remove the drive shaft to take that back casing off
Posted via Mobile Device

[Lugnutz65]

Originally Posted by Zcle91

Ok thank you. Will I have to remove the drive shaft to take that back casing off
Posted via Mobile Device

Yes. Sounds like you should have someone familiar with transmissions help you.

[slorio]

Zcle91:
A couple of other ideas. When you have that bullet holder out, you can use a flashlight to peak inside the tranny and see the drive gear. Before I pulled out the tailshaft, I would take a look at it and run my finger across it inside the transmission to see if you see/feel any damage and whether it was plastic or steel. If you have the steel gear, it is unlikely it is damaged.

One other thought. I would measure the diameter of the driven gear that you have in your hand with a caliper. Those came in two sizes. A larger 7/8" and a smaller 13/16". They are very close in size, so a caliper is necessary to tell the difference. If someone changed the gear before you got the truck you could have a mismatch. The 13/16" is way more common and available. The larger 7/8" is only available in 22 teeth (green in color). If someone put a 13/16" gear in a truck that needed the larger 7/8" gear you would have the problems you describe.

Hope that helps.
Regards,
Steve
New Orleans