Speedo Problems 67 C10 3 speed - The 1947 - Present Chevrolet & GMC Truck Message Board Network

captainwillie · 03-28-2009, 08:09 PM

OK, my barn-find 67 C10's speedometer isn't working. Cables fine, seems to be the driven gear isn't turning. Removed driven gear. Seemed ok, with some beveling onthe outside edge of the gear. Perhaps it wasn't seated far enough in to make good contact with the shaft's drive gear. Or maybe it was the wrong gear inserted by some past owner. Maybe there were ment to be spaces on it to make it extend more from the adapter. I don't know.

Found another speedo driven gear in the glove box, apparently a take off from some other relic. Looks the same, but in better shape, but is black instead of the nylon white color of the gear i removed. Tried installing it, if fit, but still didn't turn the cable.

Perhaps the driven gear on the shaft is worn, or perhaps i have the wrong adapter or gear(s). Can I just pull the tail shaft off to inspect the driven gear? Can I easily replace it, or am i going to need special tools?

Any speedo shops that have both the drive and driven gears specifically out there for this old girl?

Does anyone out there have a gear/adapter for the original 67 three on a tree behind a 250 six?

Is there really anyone out there at all?

Ha!

**LockDoc** · 03-28-2009, 08:45 PM

-
This is the best place I have found for speedo info. I have it bookmarked.

http://www.transmissioncenter.net/sp...n_______va.htm

LockDoc

**Green Machine** · 03-28-2009, 09:38 PM

Had similar problem on our 68 3 speed, drive gear was worn on the tranny output shaft, sorry trans has to come apart to change it, its not too hard to do and that is what we did, but it is hard to resist rebuilding it while apart. A temporary fix was to get a driven gear with one or two more teeth on it, little larger diameter seemed to catch the teeth. Of couse the speedo was off but it worked so you had some idea of the speed.

willyCJ · 03-28-2009, 09:49 PM

Have you confirmed that the speedo works? I would drive the truck with the speedo line disconnected from the speedometer and see if the cable turns. The line should be long enough to have a passenger observe it while you drive.

Each gear is color coded to get the right rpm to the speedo for rear gearing/tire size. (Mine says I'm going 50% too fast)

captainwillie · 03-28-2009, 09:51 PM

Thanks for the info. I visited that site, but didn't see any contact info. Also didn't see any model specific info for 'my' truck.

Again, can you just remove the tail shaft housing to change the driven gear, or is it more involved with that......Thanks, Bill

**Green Machine** · 03-28-2009, 10:00 PM

Trans has to come apart, can't just pull the tail off, things will come apart inside causing swearing and trans removal anyway. Those 3 speeds just hang on the bellhousing, easy to get in and out and really no big deal to take apart and fix.

captainwillie · 03-28-2009, 10:05 PM

Thanks for the info.....Bill

03-28-2009, 08:09 PM	#1
captainwillie Registered User Join Date: Jan 2009 Location: Delta, Ohio Posts: 27	Speedo Problems 67 C10 3 speed OK, my barn-find 67 C10's speedometer isn't working. Cables fine, seems to be the driven gear isn't turning. Removed driven gear. Seemed ok, with some beveling onthe outside edge of the gear. Perhaps it wasn't seated far enough in to make good contact with the shaft's drive gear. Or maybe it was the wrong gear inserted by some past owner. Maybe there were ment to be spaces on it to make it extend more from the adapter. I don't know. Found another speedo driven gear in the glove box, apparently a take off from some other relic. Looks the same, but in better shape, but is black instead of the nylon white color of the gear i removed. Tried installing it, if fit, but still didn't turn the cable. Perhaps the driven gear on the shaft is worn, or perhaps i have the wrong adapter or gear(s). Can I just pull the tail shaft off to inspect the driven gear? Can I easily replace it, or am i going to need special tools? Any speedo shops that have both the drive and driven gears specifically out there for this old girl? Does anyone out there have a gear/adapter for the original 67 three on a tree behind a 250 six? Is there really anyone out there at all? Ha!

03-28-2009, 08:45 PM	#2
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,425	Re: Speedo Problems 67 C10 3 speed - This is the best place I have found for speedo info. I have it bookmarked. http://www.transmissioncenter.net/sp...n_______va.htm LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - Last edited by LockDoc; 03-28-2009 at 08:51 PM.

03-28-2009, 09:38 PM	#3
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Speedo Problems 67 C10 3 speed Had similar problem on our 68 3 speed, drive gear was worn on the tranny output shaft, sorry trans has to come apart to change it, its not too hard to do and that is what we did, but it is hard to resist rebuilding it while apart. A temporary fix was to get a driven gear with one or two more teeth on it, little larger diameter seemed to catch the teeth. Of couse the speedo was off but it worked so you had some idea of the speed. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

03-28-2009, 09:49 PM	#4
willyCJ Registered User Join Date: Mar 2009 Location: Lafayette, IN Posts: 37	Re: Speedo Problems 67 C10 3 speed Have you confirmed that the speedo works? I would drive the truck with the speedo line disconnected from the speedometer and see if the cable turns. The line should be long enough to have a passenger observe it while you drive. Each gear is color coded to get the right rpm to the speedo for rear gearing/tire size. (Mine says I'm going 50% too fast) __________________ 1970 Shortbed C10 Parts I need: Headlight Switch, Headlight retainers, Bezels (found, thanks jc) wiper arms, wiper switch (found, thanks jc) Carpet (blue/black preferred) about half the e-brake cables (for a shortbed truck) Last edited by willyCJ; 03-28-2009 at 09:50 PM. Reason: missing a word

03-28-2009, 09:51 PM	#5
captainwillie Registered User Join Date: Jan 2009 Location: Delta, Ohio Posts: 27	Re: Speedo Problems 67 C10 3 speed Thanks for the info. I visited that site, but didn't see any contact info. Also didn't see any model specific info for 'my' truck. Again, can you just remove the tail shaft housing to change the driven gear, or is it more involved with that......Thanks, Bill

03-28-2009, 10:00 PM	#6
Green Machine Senior Member Join Date: Jul 2004 Location: Estherville, Iowa Posts: 3,371	Re: Speedo Problems 67 C10 3 speed Trans has to come apart, can't just pull the tail off, things will come apart inside causing swearing and trans removal anyway. Those 3 speeds just hang on the bellhousing, easy to get in and out and really no big deal to take apart and fix. __________________ 1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0

03-28-2009, 10:05 PM	#7
captainwillie Registered User Join Date: Jan 2009 Location: Delta, Ohio Posts: 27	Re: Speedo Problems 67 C10 3 speed Thanks for the info.....Bill



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