calibrating speedometer (C6 trans)
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Posting Guru
Joined: Aug 2002
Posts: 1,493
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From: Great NW
calibrating speedometer (C6 trans)
I just put some new wheels/tires on my rig and need to re-calibrate my speedometer.
How do you do that without tearing your tranny apart?
I'm running a C6 trans, 3.50 rear-end and 31.5" tires...
How do you do that without tearing your tranny apart?
I'm running a C6 trans, 3.50 rear-end and 31.5" tires...
New User
Joined: Jan 2008
Posts: 0
Likes: 24
Once you figure out the right gears, just remove the speedo cable from the trans ...and put the new gear on the end..then re-install cable.
http://www.tciauto.com/Products/Tech...eedo_gears.asp
https://www.ford-trucks.com/calculators/index.php
http://www.tciauto.com/Products/Tech...eedo_gears.asp
https://www.ford-trucks.com/calculators/index.php
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
Use the following to figure your actual speed. I usually time over a measured 10 miles by mile post markers (10X times below) on a flat road holding a set speed.
Seconds to travel a measured mile:
==================================
Time= Actual road speed
50=72
51=71
52=69
53=68
54=67
55=65
56=64
57=63
58=62
59=61
60=60
61=59
62=58
63=57
64=56
65=55.4
66=54.5
67=54
68=53
69=42
Remove your present gear and get the next available size and try again.
Say you were traveling 60MPH by your speedo but it took 572 seconds to go 10 miles. From the chart above you would have actually been traveling 63MPH. Your speedometer is not being driven fast enuf. Get the next lower tooth number gear and try again to see if it is closer. You will probably not be able to get it exact. Get it as close as you can.
Seconds to travel a measured mile:
==================================
Time= Actual road speed
50=72
51=71
52=69
53=68
54=67
55=65
56=64
57=63
58=62
59=61
60=60
61=59
62=58
63=57
64=56
65=55.4
66=54.5
67=54
68=53
69=42
Remove your present gear and get the next available size and try again.
Say you were traveling 60MPH by your speedo but it took 572 seconds to go 10 miles. From the chart above you would have actually been traveling 63MPH. Your speedometer is not being driven fast enuf. Get the next lower tooth number gear and try again to see if it is closer. You will probably not be able to get it exact. Get it as close as you can.
Last edited by Torque1st; Oct 23, 2006 at 10:02 PM.
