Speedo drive

[DamianS3]

Hello got a challenge re the speedo after my engine conversion.

I would like to keep the original speedo if possible but need to find an alternate way to drive it.

Does anyone know of a sensor I could use driven off the prop perhaps?

Also thinking about it I assume I would need the correct number of pulses for a given speed keep the speedo accurate is the original gearbox sensor driven at prop speeds ?

I have a relay coil circuit to drive the rev counter will share if it works.

Help appreciated.

Thanks

Damian S3

[phillpot]

DamianS3 said:

is the original gearbox sensor driven at prop speeds ?

Yes, it's driven from the rear of the gearbox so at prop speed but the actual gearing is probably a reduction (different gearing for different final drive ratios), only bit I can help with.... good luck

[DamianS3]

Thanks good point re the reduction I might have a play with an ATmega to see it I can drive it. If I can do this reliably counting prop rotations will be simple..

Will see if I can find the scope traces someone made a while back.

Damian S3

[glenrobbo]

Hi Damien,
Dunno why, but for me the topic title conjured up an image of hooning in an S , clad only in a pair of budgie smugglers :shudder: ( hence the term "Cossie S"? )

Seriously, Paul Cashman had to sort out a drive gear & cable for his Cossie S1,
but I think the car still had the original Type 9 gearbox and mechanical speedo.

Does your gearbox have any provision for a speedo sensor to be fitted?

[magpies]

I have looked at this too as I will need a new speedo and revcounter.

The easiest way is to purchase a 'programmable' speedo which is set up by driving a set distance and hitting buttons!! I have changed the diff ratio so the original won't be correct. I have an MT75 box with both mechanical and electrical speed out put facilities but cant use either. The speedo's are less than £200

[DamianS3]

Thanks for the replies aftermarket clocks would be too easy although I would love to be able to get a set of stack gauges. I think I have the rev counter sorted will let you know. Re speedo I will see what I can find re drive off gearbox but am also looking at stand alone sensor set up or perhaps gps driven like skybox.

Cheers

Damian

[magpies]

Rev counter needs a device to turn the coilpack signal into a dizzy type signal and can be purchased for about £35 apparently. The speedo would need new innards as final drive is different.