Labor Day Putting down your wrenches or time for
MORE wrenching? 
Plenty of places to share. | | Click on image for the lowdown. 
====
| | | Forums66 Topics128,004 Posts1,055,250 Members48,418 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Mar 2012 Posts: 174 Shop Shark | | Shop Shark Joined: Mar 2012 Posts: 174 | Hey All,
1955, 2nd series, 3100, Napco, 283, 4 speed trans. My speedometer is off by 10 mph. ie-45mph=55mph. I removed the speedometer cable from the gear assembly at the trans, then pulled the assembly out of the trans thinking I could replace the gear. The assembly is a solid unit, all steel.
Do they make a unit (Part that would fit between the gear assembly and speedometer cable) to slow down or speed up the speedometer? I seem to remember an apperatous on my 1983 Chevy pickup and some F%#ds of about the same year that fit between the gear and cable. I am also probably running to large of tire but do not want to purchase new tires. | | | | | Joined: Aug 2004 Posts: 1,417 ODSS Lawman | | ODSS Lawman Joined: Aug 2004 Posts: 1,417 | Is everything stock on the truck? Tire size etc? If yes, do a good inspection of all parts for wear.
If all checks out, you can get an adapter that fits between the speedo cable and the transmission. I purchased mine from Scott's speedometer for about $80 several years ago.
SWEET Sergeant At Arms: Old Dominion Stovebolt Society BUNS?!?!?!Where we're going, we don't need no buns.....1950 GMC 450 1951 Chevy 1/2-TonThe GreenMachineIn the Stovebolt Gallery | | | | | Joined: Sep 2011 Posts: 2,951 'Bolter | | 'Bolter Joined: Sep 2011 Posts: 2,951 | A large tire will make the speedo read too low. I have a speedo adapter that is designed to reduce the speed and would be used if the speedo was reading too high, not too low. You can find different ones on eBay. Mine is by Stuart Warner and stamped 0.73333 so it reduces speedo reading by 26%. I'm not sure, but it sounds like your speedo reads too low. That's what my mini truck does because I'm running larger diameter tires than stock. | | | | | Joined: Jun 2009 Posts: 1,596 'Bolter | | 'Bolter Joined: Jun 2009 Posts: 1,596 | I don't know what the thread on your trans is, but would one of the adapters on THIS PAGE listed under GM DODGE FORD RATIO ADAPTERS work for you? | | | | | Joined: Mar 2012 Posts: 174 Shop Shark | | Shop Shark Joined: Mar 2012 Posts: 174 | Thanks guys!!! I will check out all information and advice!!! | | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | If your speedometer is off by 10 mph at all speeds, you have an offset error. In that case an adapter won't help. If it is off by changing amounts at different speeds than an adapter will help. I would suggest that you graph the two sets of readings, real and displayed on a piece of paper and then you can see what you have. | | | | | Joined: Jul 2010 Posts: 592 Shop Shark | | Shop Shark Joined: Jul 2010 Posts: 592 | I had a similar problem when I changed my rear end gears and went with larger tires, so I bought an adapter from Jim Carter. Works great...easy to install. Here is the link--
http://www.oldchevytrucks.com/cart/product.asp?prodid=SP249&i=9939|||||
| | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | Maybe this is easier to link to. Adapter Jim Carter | | |
|
|
