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    speedometer off by 10 mph

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    delraydoug

    Number of posts: 120
    Location: buffalo, new york
    Age: 53
    Registration date: 2010-07-01

    speedometer off by 10 mph

    Post by delraydoug on Sun Sep 18, 2011 6:25 pm

    have a 1966 with a 170 6cyl / 3spd. with 14inch wheels. i used my gps and found out im going 10 mph slower than my speedometer is reading how can it be so far off ? far as i know everything is orginal. how many teeth sould i have on my speedometer gear Question

    Barnabas

    Number of posts: 563
    Location: Raleigh, NC
    Age: 54
    Registration date: 2011-01-16

    Re: speedometer off by 10 mph

    Post by Barnabas on Sun Sep 18, 2011 7:10 pm

    Is it 10 MPH slower at all speeds? Or is it 10 MPH slow while driving 60, and 5 MPH slow while driving 30 MPH?

    delraydoug

    Number of posts: 120
    Location: buffalo, new york
    Age: 53
    Registration date: 2010-07-01

    speedometer off by 10 mph

    Post by delraydoug on Mon Sep 19, 2011 5:29 am

    only tested it at 50 & 60. 50 it ran 40 at 60 it was showing 50

    gh0st

    Number of posts: 49
    Location: virginia
    Registration date: 2011-07-25

    Re: speedometer off by 10 mph

    Post by gh0st on Mon Sep 19, 2011 6:17 am

    i'm waiting for an answer on this as well. my van does the progressive misreading, the faster i go, the more it's off.

    Barnabas

    Number of posts: 563
    Location: Raleigh, NC
    Age: 54
    Registration date: 2011-01-16

    Re: speedometer off by 10 mph

    Post by Barnabas on Mon Sep 19, 2011 5:23 pm

    If you have the wrong gears somewhere, it should be off by a percentage. My not-so-old Econoline reads one MPH faster for every 30 miles. It reads 31 when I'm going 30, and it reads 62 when it's really doing 60. If I was to go 120, the speedometer should read 124, but if I was going 120, I wouldn't be looking at the speedometer!

    If it is always off by 10, then you might have a problem with the speedometer. Is it at 0 when you are stopped?

    Barnabas

    Number of posts: 563
    Location: Raleigh, NC
    Age: 54
    Registration date: 2011-01-16

    Re: speedometer off by 10 mph

    Post by Barnabas on Mon Sep 19, 2011 5:26 pm

    gh0st wrote:i'm waiting for an answer on this as well. my van does the progressive misreading, the faster i go, the more it's off.

    There is a small gear where the speedometer cable goes into the transmission that can be changed. I remember reading about the different gears and how to identify them on one of these forums. Try searching for speedometer gear.

    chester42

    Number of posts: 1365
    Location: Homosassa,FLA
    Age: 71
    Registration date: 2009-04-06

    Re: speedometer off by 10 mph

    Post by chester42 on Mon Sep 19, 2011 5:50 pm

    On GM tranies, ! tooth less wil increase speed 5 mph at 50mph. don't know on Ford set up.

    fmc56

    Number of posts: 519
    Location: Warwick, RI/Ellsworth, Maine
    Registration date: 2008-05-20

    Re: speedometer off by 10 mph

    Post by fmc56 on Tue Sep 20, 2011 1:48 am

    There are sevral different gear available for the end of the spedometer cable. If yours is off by a percentage then you need to change the gear. IO have a formula somewhere that calculates it for you.
    Fred

    delraydoug

    Number of posts: 120
    Location: buffalo, new york
    Age: 53
    Registration date: 2010-07-01

    im thinking now i have some really low gears in the rear end

    Post by delraydoug on Tue Sep 20, 2011 7:07 am

    i was told this van was orginaly from a air force base. most military veh. are governed at 55-60 mph any way i will take it for a slower ride and see if its stil off by 10 mph


    Last edited by delraydoug on Tue Sep 20, 2011 7:10 am; edited 1 time in total (Reason for editing : added to)

    Twinpilot001

    Number of posts: 4512
    Location: spokane ,Wa.
    Age: 65
    Registration date: 2009-09-28

    Re: speedometer off by 10 mph

    Post by Twinpilot001 on Tue Sep 20, 2011 8:55 am

    Possibly spedo gear change is warranted?? Also consider wheel size=?/ and Tire sizes also =ive seen everything from 13-15 inch wheels on the older econos= you can also consider a spedo compensator -goes inline on cable & spedo gear-where cable goes into-Happy Vannini]

    EconoCarl

    Number of posts: 1102
    Location: Beaumont, TX
    Age: 56
    Registration date: 2008-05-19

    Re: speedometer off by 10 mph

    Post by EconoCarl on Tue Sep 20, 2011 11:32 am

    delraydoug wrote:i was told this van was orginaly from a air force base. most military veh. are governed at 55-60 mph any way i will take it for a slower ride and see if its stil off by 10 mph

    If I had to guess and since you said it was an Air Force van it might have had a 4.56 rear end ratio and it was probably changed out by a previous owner. Like Fred said, you probably need a different gear for the speedometer (at the transmission end). Pretty simple fix once you find out which gear you need.

    delraydoug

    Number of posts: 120
    Location: buffalo, new york
    Age: 53
    Registration date: 2010-07-01

    found out now i have 3.50 gears in the rear end

    Post by delraydoug on Sun Oct 02, 2011 5:06 pm

    yes i do think it orginally had 4.56 and was changed out to a 3.50 and they never changed speedo gear in tranny. thats why its off so much. what color gear or how many tooth should i have running 3.50's ?

    gh0st

    Number of posts: 49
    Location: virginia
    Registration date: 2011-07-25

    Re: speedometer off by 10 mph

    Post by gh0st on Mon Oct 24, 2011 11:56 am

    so can anyone comment on what tooth speedo gear was stock for the 3.03 manual econolines?

    RodStRace

    Number of posts: 2858
    Location: Chino Valley
    Registration date: 2010-01-21

    Re: speedometer off by 10 mph

    Post by RodStRace on Mon Oct 24, 2011 1:26 pm

    The info is out there if you look.

    http://www.transmissioncenter.net/speedometer_calibration_______va.htm

    There isn't an exact speedo gear for a rear axle ratio, the tire diameter also affects the final drive ratio.

    gh0st

    Number of posts: 49
    Location: virginia
    Registration date: 2011-07-25

    Re: speedometer off by 10 mph

    Post by gh0st on Tue Oct 25, 2011 5:04 am

    RodStRace wrote:The info is out there if you look.

    true, but the info is also in here if i ask.

    anyone with a 61-67 econoline van or truck, with a 3 spd 3.03 manual transmission, with driver's side speedo cable drive gear hole, with a 3:50 rear end, and your speedometer is accurate:

    what is the tooth count of your speedo cable drive gear?

      Current date/time is Thu Apr 24, 2014 8:18 am