Trying to work out required speedo switch settings. HELP !!!

[w7rren]

OK trying to check dip switches on the back of my speedo as it seems to be reading far too high.

I have 10 dip switches.

2 , 7 & 9 are ON.

I have measured the rolling circumference (15" CR500) & get 1690mm.

I have a 3.92 diff.

I have seen the Caerbont site & it seems that to use their formulae I need to know where the sensor situated. The de-dion kit was supplied in late 2004 .

 

Any help will be Sooooo welcome

I don't mind if you work it out for me 😬

Cheers,

Mark.

 

 

Born again sevener

[Bob Simon]

 

Look here.

 

 

 

-Bob

94 HPC VX Evo III

 

[w7rren]

Hi Bob, yep I've seen that but how do I get to that figure given the info I have given ? As my text says I think I need to know where / what type of sensing system is used on my car details above

 

Born again sevener

[PAC]

Yes! This is the technical bit:

Calculate you calibration number: - N.B. For most of the following calculations you will need to know the number of times that your tyre revolves per mile or kilometre. If you do need this information for your installation then stand the vehicle on a flat surface and make a mark on a tyre, mark the floor at the same point. Move the vehicle forward for one revolution of the tyre and measure the distance covered. You can then figure out how many times the tyre would revolve in covering a mile or a kilometre.

Magnetic Sensor - using a reed switch using prop shaft revolutions, Number of magnets x differential ratio x tyre revs per mile or per kilometre = calibration number

Magnetic Sensor - using a reed switch, using half shaft or wheel revolutions, Number of magnets x half shaft or wheel revolutions per mile or per kilometre = calibration number

Magnetic Proximity Sensor - using prop shaft revolutions, Number of bolts at the universal joint x differential ratio x tyre revs per mile or kilometre = calibration number

Magnetic Proximity sensor - counting brake disk slots or wheel nuts, Number of wheel nuts or slots x tyre revs per mile or kilometre = calibration number.

Hall effect sensor, Number of poles on sensor x cable drive revs per mile or kilometre = calibration number.

Electronic Control Unit, number of pulses per mile or per kilometre as declared by the engine manufacturer = calibration number.

---

Paul

[w7rren]

Hi Paul, seen that too , but which scenario exists on my 7 ... which sensor set up 🤔

Cheers, Mark

[Andy Best]

using your settings an calculating back will help work out what settings you need. ie if you're 10% out change the existing pulse count by 10%. I think the caterham uses 4 pulses per revolution of the prop shaft.

[w7rren]

Thanks Andy ( & others ) ,

Using 4 pulses per prop shaft rev would now seem to make sense...... I think .

I'll try the new switch setting after work to-morrow afternoon if the weather brightens up .

I'll sleep well to-night , not thinking of revs / pulses etc.

 

Cheers,

Mark.

 

Born again sevener