TwinPlenum3500S
New Member
Can anybody recommend a firm to do the above. Have a new speedo in box, which I need recalibrating due to the modifications I have made to my car.
Many thanks.
Many thanks.
Speedo recalibration
- Thread starter TwinPlenum3500S
- Start date
Speedy Cables in Neath (IIRC) south Wales. They did mine when they were in Islington, before moving to Hertford, and then Wales. I think they have a website that will show you the info they need to recalibrate, which is the distance between the centre of the driven wheel to the ground, then push the car forward through 6 rotations of the wheel and count the number of turns the inner cable makes. Then send the head to them and they'll do the recalibration.
TwinPlenum3500S
New Member
Is it not size of wheel and gearbox & diff ratio? How on earth can you accurately calculate the amount of turns in the speedo cable?
Hello TP,
Just a question if I may on your tyre size. I note that you are running 195/70 R14, which if you don't mind me saying are somwhat smaller in rolling diameter than the original tyre sizing. To be much closer to the mark, you could either run 195/75 or 205/70.
The original sizing was 185 R14 which had an 80% aspect ratio. The rolling diameter is 652mm. 195/75 yields 648mm while with 205/70 you will see 643mm. With the 195/70 sizing that you currently have, the rolling diameter is 628mm, which as you can see is quite a bit smaller.
Seeing you will be having your speedo calibrated to suit, I wondered if you wanted to keep the smaller sizing or revert to a size closer to the originals?
Ron.
Just a question if I may on your tyre size. I note that you are running 195/70 R14, which if you don't mind me saying are somwhat smaller in rolling diameter than the original tyre sizing. To be much closer to the mark, you could either run 195/75 or 205/70.
The original sizing was 185 R14 which had an 80% aspect ratio. The rolling diameter is 652mm. 195/75 yields 648mm while with 205/70 you will see 643mm. With the 195/70 sizing that you currently have, the rolling diameter is 628mm, which as you can see is quite a bit smaller.
Seeing you will be having your speedo calibrated to suit, I wondered if you wanted to keep the smaller sizing or revert to a size closer to the originals?
Ron.
TwinPlenum3500S said:
You remove the speedo head, which you need to do to change it or send it off, then stick a tag of masking tape on the inner cable as a marker, then as you push the car forward count the number of times the inner cable turns for 6(?) rotations of the driven wheel. Be as accurate as possible with the number of turns, including fractions. Gearbox and diff ratios have nothing to do with the calculation, whatever they may be, doing it this way calibrates the head, the different ratios are only the reason why you're doing it in the first place........