Needless to say the instructions from Caerbont are less than useless.
Other than driving on a road for a mile in an unregistered car not planning on going for a pre booked test.
Could anyone advise the ball park number entered for a T5 box with a standard 3.9 MGB diff and 15" wires Blockleys tyres.
I can tweak it at IVA if it's out.
Cheers
Electronic Speedo Calibration
- StewbieC
- T289R Committee
- Posts: 1356
- Joined: Mon Oct 13, 2008 12:50 pm
- Location: out in the sticks, Shropshire
Electronic Speedo Calibration
________________________________________________
Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
Re: Electronic Speedo Calibration
These are my calculations.
1 mile = 1760 yards = 63,360 inches
Tyre circumference = 83"
Speedo drive = 3/4 rev per 1 rev of wheel
63,360" divided by 83" multiplied by 0.75 = (number of speedo revs per mile) = 572.53 revs/mile.
Calibration number = Cable turns / unit distance x no. of pulses / sender turns
572.53 x 16 = 9160
So calibration number from the chart is 1110101010
This gave me the following speedo results as per the SVA test.
speedo reading / Actual Speed
35 mph / 33 mph
40 mph / 39 mph
50 mph / 47 mph
60 mph / 56 mph
70 mph / 70 mph
1 mile = 1760 yards = 63,360 inches
Tyre circumference = 83"
Speedo drive = 3/4 rev per 1 rev of wheel
63,360" divided by 83" multiplied by 0.75 = (number of speedo revs per mile) = 572.53 revs/mile.
Calibration number = Cable turns / unit distance x no. of pulses / sender turns
572.53 x 16 = 9160
So calibration number from the chart is 1110101010
This gave me the following speedo results as per the SVA test.
speedo reading / Actual Speed
35 mph / 33 mph
40 mph / 39 mph
50 mph / 47 mph
60 mph / 56 mph
70 mph / 70 mph
Cheers, Clive.
(If I'm not here I'm in my workshop or on the golf course!)
(If I'm not here I'm in my workshop or on the golf course!)
- StewbieC
- T289R Committee
- Posts: 1356
- Joined: Mon Oct 13, 2008 12:50 pm
- Location: out in the sticks, Shropshire
Re: Electronic Speedo Calibration
Thanks Clive
As a comparison, if you have an electronic speedo (with a small LCD screen at the bottom) you can check the calibration number by holding the trip reset button and turning the ignition from off to on. After a couple of seconds 5 digits should show and you can let go of the reset button (the first digit is probably flashing at this point. If you turn the ignition off before pressing the trip reset button again then the number will not be altered.
As a comparison, if you have an electronic speedo (with a small LCD screen at the bottom) you can check the calibration number by holding the trip reset button and turning the ignition from off to on. After a couple of seconds 5 digits should show and you can let go of the reset button (the first digit is probably flashing at this point. If you turn the ignition off before pressing the trip reset button again then the number will not be altered.
________________________________________________
Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..