Speedo ratio

Puglife · 21-07-09, 01:19 PM

If anybody can help here, i need the speedo cable ratio from a Coupe Quattro type 85. Need to know how many revolutions the cable makes for 1mile. Prob not going to be able to find this info but its necessary for my new speedometer calibration.

regards

Jay

20vcqdriver · 21-07-09, 01:40 PM

How longs a piece of string... Going to be several thousand revolutions...
Better to work out how many per revolution of the wheels and take it from there...

Puglife · 21-07-09, 02:00 PM

Standard modern calibration for the speedometers is 1000/mile so hoping audi is around that otherwise it costs alot for recalibration.

4v6 · 21-07-09, 02:48 PM

Jack the car up, rotate the wheel 1 revolution, count the number of turns out from the speedo drive.

Drop the car back down, mark a line on the ground and a chalk mark on the tyre, roll the car so the wheel goes 1 revolution.
Measure the distance travelled for 1 rev.
Using a bit maths jiggery pokery, you need to divide 5280 feet ( 1mile) by the distance travelled to find out how many turns the wheel makes per mile vs the speedo drive revs.

Did have the exact formula written down someplace but its plenty do-able.

Puglife · 21-07-09, 03:46 PM

Yeh you need circumference of the whole wheel and tyre. I'll prob get round to it this evening but was hoping somebody already had done the math???

Isimmo · 21-07-09, 10:13 PM

Quote:

Originally Posted by Puglife

Yeh you need circumference of the whole wheel and tyre. I'll prob get round to it this evening but was hoping somebody already had done the math???

No you won't get round to it this evening...

As some southerner bloke with the spare parts barge will stand in your barn doorway for hours talking shite...

Puglife · 21-07-09, 10:36 PM

Lol, happens everytime ian! I honestly think if we stand there long enough we could redesign the quattro......

21-07-09, 01:40 PM	#2
20vcqdriver 4 ring whore! Classic Audi Club Member Join Date: Dec 2007 Location: Wirral Posts: 3,910	How longs a piece of string... Going to be several thousand revolutions... Better to work out how many per revolution of the wheels and take it from there... __________________ Coupe quattro 1986:-~450bhp + loooong list of mods! Audi A7 Bi-TDI SLine Black edition 2015 mapped to produce 600lb/ft torque! Audi S4 4.2 V8 cabriolet 2004:-

21-07-09, 02:00 PM	#3
Puglife ==>PUGSPORT!<== Classic Audi Club Member Join Date: Jan 2008 Location: Leyland Posts: 1,544	Standard modern calibration for the speedometers is 1000/mile so hoping audi is around that otherwise it costs alot for recalibration. __________________ 1986 UR Quattro - (1982) Lombard RAC Group 4 recreation - #24 H.Demuth/J.Daniels 1981 VW mk1 golf GTi - now 5cylinder and RWD.

21-07-09, 03:46 PM	#5
Puglife ==>PUGSPORT!<== Classic Audi Club Member Join Date: Jan 2008 Location: Leyland Posts: 1,544	Yeh you need circumference of the whole wheel and tyre. I'll prob get round to it this evening but was hoping somebody already had done the math??? __________________ 1986 UR Quattro - (1982) Lombard RAC Group 4 recreation - #24 H.Demuth/J.Daniels 1981 VW mk1 golf GTi - now 5cylinder and RWD.

21-07-09, 10:36 PM	#7
Puglife ==>PUGSPORT!<== Classic Audi Club Member Join Date: Jan 2008 Location: Leyland Posts: 1,544	Lol, happens everytime ian! I honestly think if we stand there long enough we could redesign the quattro...... __________________ 1986 UR Quattro - (1982) Lombard RAC Group 4 recreation - #24 H.Demuth/J.Daniels 1981 VW mk1 golf GTi - now 5cylinder and RWD.

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21-07-09, 02:48 PM	#4
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	Jack the car up, rotate the wheel 1 revolution, count the number of turns out from the speedo drive. Drop the car back down, mark a line on the ground and a chalk mark on the tyre, roll the car so the wheel goes 1 revolution. Measure the distance travelled for 1 rev. Using a bit maths jiggery pokery, you need to divide 5280 feet ( 1mile) by the distance travelled to find out how many turns the wheel makes per mile vs the speedo drive revs. Did have the exact formula written down someplace but its plenty do-able.