hi guys, im sure others will have seen the cooper s speedo sticker for a centre speedo.
Im about to buy a pinnion and worm and am wondering what would be the best combination for a 998 cooper engine.
also What would be the standard worm and pinnion combination for a 998 cooper engine?
many thanks in advance!
Ebay Speedo Sticker
Started by
wesson124
, Apr 16 2010 07:45 PM
2 replies to this topic
#2
Midas Mk1
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Crazy About Mini's
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Posted 16 April 2010 - 07:56 PM
The " TPM" of the speedo determines which worm and pinion ratios to use, along with the FD ratio. Look at guessworks calculator Clicky to calculate the ratio you need for your speedo. 
I think with those stickers on ebay, you cannot get the speedo to be accurate, as it will be originally calibrated for 90mp, rather than 120 
I think with those stickers on ebay, you cannot get the speedo to be accurate, as it will be originally calibrated for 90mp, rather than 120
Edited by Midas Mk1, 16 April 2010 - 07:57 PM.
#3
dklawson
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Moved Into The Garage
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Posted 16 April 2010 - 08:13 PM
That is correct. The maker's intent was for people to put these stickers over more common 90 MPH speedos. That said, you can have a speedometer re-calibrated to match the gauge face.
Generally when the odometer portion does not require change, the sweep of the needle is changed by altering the magnetism of the rotating bits inside the speedometer. Usually... with old speedometers, this means increasing the amount of magnetism to restore it to what it once was. It's a bit more tricky if you want to make the speedometer read a bit "slower" which is in effect what is necessary with this decal. What was once 90 MPH on the original face will be closer to 110 on the new face so effectively you have to reduce the magnetism and slow the speedo down. Again, this assumes the odometer is not going to be changed.
For more info and a better explanation for what's involved, see the PDF linked below. It's a good read if you've ever wanted to tinker with speedometers and mechanical tachometers.
http://home.comcast....odes/speedo.pdf
Generally when the odometer portion does not require change, the sweep of the needle is changed by altering the magnetism of the rotating bits inside the speedometer. Usually... with old speedometers, this means increasing the amount of magnetism to restore it to what it once was. It's a bit more tricky if you want to make the speedometer read a bit "slower" which is in effect what is necessary with this decal. What was once 90 MPH on the original face will be closer to 110 on the new face so effectively you have to reduce the magnetism and slow the speedo down. Again, this assumes the odometer is not going to be changed.
For more info and a better explanation for what's involved, see the PDF linked below. It's a good read if you've ever wanted to tinker with speedometers and mechanical tachometers.
http://home.comcast....odes/speedo.pdf
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