Need help selecting speedometer gear
Need help selecting speedometer gear
We are finishing work on a bumpside f 100 project , the speedometer is reading way too slow, it's got 3:50 gears in the rear end and a 302 with 3 speed manual transmission with no overdrive. We have a 17 tooth gear on the tranny end of the speedo cable and it all works but reads about 15 mph at 40+ mph Road speed. Does anyone have an idea what gear we will need to make it read closer to actual?? LMC offers gears from 16 to 21 teeth. The rear rims have 15" tires a little fatter and taller than stock, about 29 1/2" tall. Thanks for any help!
Re: Need help selecting speedometer gear
I've never seen one that far off
I'm wondering if the speedometer itself has some issues
Or something like cable ends slipping
I'm wondering if the speedometer itself has some issues
Or something like cable ends slipping
.
.
.
'' I think what scares me the most about you guys is that I understand you '' ..... KID
'' lookin good, a little paint adds at least 100hp!'' ....... COOTER
'' well an old guy can dream cant he? ''............ICEMAN
''I would donate organs before selling my slick''........ HOOFBEAT RACER
.
.
'' I think what scares me the most about you guys is that I understand you '' ..... KID
'' lookin good, a little paint adds at least 100hp!'' ....... COOTER
'' well an old guy can dream cant he? ''............ICEMAN
''I would donate organs before selling my slick''........ HOOFBEAT RACER
Re: Need help selecting speedometer gear
Try this link to formulas and a calculator.
Scroll to the top of the page at link below for formulas and calculator.
http://www.tciauto.com/tc/speedometer-g ... ator/#FORD
Scroll to the top of the page at link below for formulas and calculator.
http://www.tciauto.com/tc/speedometer-g ... ator/#FORD
Always know where you will be, when you get where you're going - Jerry Clower
Re: Need help selecting speedometer gear
You may have an automatic transmission shop in your own town that can help. They may have gears on hand to help you go up or down. It won't hurt to check.
- charliemccraney
- Posts: 1743
- Joined: July 9, 2008, 10:02 pm
- Location: Lawrenceville, GA
Re: Need help selecting speedometer gear
I agree that something isn't working right. In order to speed up the speedometer, the gear must have fewer teeth. Since the difference is almost 3x, you would need about a 7 tooth gear on the cable, which does not exist.
Depending on the output shaft gear, your combo should require a 17-21 tooth cable gear.
Depending on the output shaft gear, your combo should require a 17-21 tooth cable gear.
Lawrenceville, Ga
1961 F100 Unibody
318 Y-block (292 +.070 bore, +.170 stroke), FMS T5-Z w/Mustang 10.5" diaphragm clutch.
1961 F100 Unibody
318 Y-block (292 +.070 bore, +.170 stroke), FMS T5-Z w/Mustang 10.5" diaphragm clutch.
- bobenhotep
- Posts: 911
- Joined: January 9, 2007, 4:15 am
- Location: Las Cruces, NM
- Contact:
Re: Need help selecting speedometer gear
Something is wrong in the speedometer head or the cable is slipping. I have never seen one that far off.
Dan
Dan
For every person with a spark of genius, there are a hundred with ignition trouble
My '63 short wrongbed
"The Iron Rhino"
300 I6, 3 spd manual, DS II/ HEI ignition.
Stuff I added to Hints and tricks
-300-6 choke tube repair
-duraspark II/ HEI
-Horn ring contact tube repair
-turn signal indicator fix
Mikhail Kalashnikov and Nikola Tesla are the guys i think of when i build things.
My '63 short wrongbed
"The Iron Rhino"
300 I6, 3 spd manual, DS II/ HEI ignition.
Stuff I added to Hints and tricks
-300-6 choke tube repair
-duraspark II/ HEI
-Horn ring contact tube repair
-turn signal indicator fix
Mikhail Kalashnikov and Nikola Tesla are the guys i think of when i build things.