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#1 |
Registered User
Join Date: Nov 2011
Location: Nashville TN
Posts: 3,595
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Speedo fast and jumps at 70mph
So My speedo was crazy jumpy so I replaced the cable and it works great! Now I have tires that are 2 big so the speedo reads about 3 -5 mph faster then I actually go but when I hit 70MPH it starts jumping between 70 - 100mph...
So what could cause this? Is it the speedo gear? If so do I need a smaller or bigger tooth gear to get it closer to the right speed? Currently have a 21 gear speedo gear Thanks
__________________
PLEASE HELP WITH PROJECT UNDERHAULIN http://67-72chevytrucks.com/vboard/showthread.php?t=306320 Gemini - 1978 GMC C15 High Sierra - 305 c/e - Given to Mother Electra - 1967 Mustang Coupe - 302/w 3 speed Build Chyna - 1968 Chevy C20 Long Stepper
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#2 |
Registered User
![]() Join Date: Oct 2011
Location: Wildomar, CA
Posts: 466
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Re: Speedo fast and jumps at 70mph
Found this online awhile back, should help you get pretty close. (drive gear is gear that is on trans output shaft. Pull the speedo gear adapter out, mark one tooth on the drive gear with a marker, jack the rear end up and with the trans in neutral, rotate the driveshaft and count the number of teeth you have.
As for the jumping, might try lubing the speed cable. Disconnect at speedo head and disconnect at trans. Spray lube into the cable at the speedo head connection and let it run out at the trans connection.... |
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#3 |
Registered User
Join Date: Nov 2011
Location: Nashville TN
Posts: 3,595
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Re: Speedo fast and jumps at 70mph
brand new cable shouldnt need lube but thanks
__________________
PLEASE HELP WITH PROJECT UNDERHAULIN http://67-72chevytrucks.com/vboard/showthread.php?t=306320 Gemini - 1978 GMC C15 High Sierra - 305 c/e - Given to Mother Electra - 1967 Mustang Coupe - 302/w 3 speed Build Chyna - 1968 Chevy C20 Long Stepper
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