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Speedo sensor help needed
Hammerhead - 12/10/07 at 10:29 AM

I have some Stack clocks from a Lotus elise I'd like to fit. The main problem is that I have no idea how to make the speedo work.

I know you can get a sensor like this:
http://www.gprdirect.com/epages/GPRDirect.storefront/470f47270023d7be2719d9c7b805064e/Product/View/TERT005

that can read wheel studs or driveshaft bolts. But how would this calibrate to work the speedo?

The elise uses a trigger wheel bolted to the drveshafts, but I cannot find this available to buy.

Does anyone know how to tackle the problem? Help appreciated

gingerprince - 12/10/07 at 10:38 AM

Isn't that what the Speedo Healer does? IIRC it lets you convert electronic blips at one rate to a different rate to suit your clocks. Might be trial and error if you don't know the actual ratio but it should do what you want, I think.

Hammerhead - 12/10/07 at 10:51 AM

is that what everyone tends to use? great, saves me another headache.

dan__wright - 12/10/07 at 11:05 AM

quote:
Originally posted by gingerprince
Might be trial and error if you don't know the actual ratio


there is a calculator on the speedohealer website, put in speed the clocks read and your actual speed and it tells you settings.

Schrodinger - 12/10/07 at 11:06 AM

ETB uses a trigger wheel for it's electronic speedo, I had it clamped between the prop and the dif on my Tiger Cat.

BenB - 12/10/07 at 11:09 AM

If you need a trigger wheel that bolts to a Standard Lobro driveshaft let me know I've got a few spare from when I had some laser cut

Hammerhead - 12/10/07 at 11:12 AM

quote:
Originally posted by Schrodinger
ETB uses a trigger wheel for it's electronic speedo, I had it clamped between the prop and the dif on my Tiger Cat.


but if the trigger wheel isn't exactly the same as a lotus one, wont I still need a speedo healer?

nib1980 - 12/10/07 at 11:18 AM

yep but most people use 36-1 tooth, and if not norbert at speedo healer will be able to help you, over 6 nightsd of emails and he got mine working no bother!

paulmw - 12/10/07 at 11:19 AM

Sorry to High Jack your thread.

I have a BEC with a 07 ZX10R, how does the speedo work on the bike and how can you adapt it to the car.

Thanks Paul

Hammerhead - 12/10/07 at 11:29 AM

quote:
Originally posted by nib1980
yep but most people use 36-1 tooth, and if not norbert at speedo healer will be able to help you, over 6 nightsd of emails and he got mine working no bother!


so you recommend a 36-1 trigger wheel, a speedo sensor like the one I posted a link to, and a speedo healer.....and that should do the job? Cool.

BenB - 12/10/07 at 11:47 AM

quote:
Originally posted by Hammerhead
quote:
Originally posted by nib1980
yep but most people use 36-1 tooth, and if not norbert at speedo healer will be able to help you, over 6 nightsd of emails and he got mine working no bother!


so you recommend a 36-1 trigger wheel, a speedo sensor like the one I posted a link to, and a speedo healer.....and that should do the job? Cool.


Bascially yes
Unless you can find the number of teeth that was originally on the lotus. Then you could work out from the tyre size the number of revs per minute to work out the number of teeth needed at a certain mph then work backwards for your setup (obviously unless you've got the same wheel and tyre choice as the Lotus you're rolling circumference will be different) and get some laser cut like what I did

Hammerhead - 12/10/07 at 11:52 AM

quote:
Originally posted by BenB
quote:
Originally posted by Hammerhead
quote:
Originally posted by nib1980
yep but most people use 36-1 tooth, and if not norbert at speedo healer will be able to help you, over 6 nightsd of emails and he got mine working no bother!


so you recommend a 36-1 trigger wheel, a speedo sensor like the one I posted a link to, and a speedo healer.....and that should do the job? Cool.


Bascially yes
Unless you can find the number of teeth that was originally on the lotus. Then you could work out from the tyre size the number of revs per minute to work out the number of teeth needed at a certain mph then work backwards for your setup (obviously unless you've got the same wheel and tyre choice as the Lotus you're rolling circumference will be different) and get some laser cut like what I did


Is there a online calculator for this or a formula I could use? I know the tyre is 225/45/16 and could get the revs/mph from my lotus maintenance cd. I guess i'd need the radius of the wheel to be correct too.

Thanks for th eoffer on your trigger wheel by the way. I'll let you know if I need one.

BenB - 12/10/07 at 12:06 PM

http://www.carbibles.com/tyre_bible_pg2.html

gives a rolling circumference calculator for various tyre types.

This is how I got my speedo to work anyway- my speedo needed 833Hz @ 100mph. I worked out the rolling circ of my tyres, worked out revolutions per second etc etc, got to 34 blips per second (hence the number of teeth on the split wheel).

Let me know if you want one I've got 'em stashed away somewhere.

dan__wright - 12/10/07 at 12:08 PM

quote:
Originally posted by paulmw
Sorry to High Jack your thread.

I have a BEC with a 07 ZX10R, how does the speedo work on the bike and how can you adapt it to the car.

Thanks Paul


is a sensor in the engine, it over read by a very large amount (70 will be about 170 lol) so you need to get a speedo healer to correct it.

andrew.carwithen - 12/10/07 at 12:30 PM

BenB,

If you've got several available, I'm interested in one of your trigger wheels. (I've sent U2U.)

Cheers,
Andy.

On another note:
I'm a little confused.
Why is it recommended that a 36 - 1 toothed wheel is used for speedo sensing?
I understand the need when used in an application such as a megajolt ignition system where crankshaft position is required but why is a position sensing capability req'd for speedo use?

Andy.

BenB - 12/10/07 at 12:36 PM

You don't need a 36-1 wheel for speedo sensing. Infact, the missing tooth might confuse it!!!!!

Edited to say: if your speedo is adjustable you could use pretty much any trigger frequency (with reason). My Racetech speedo had to have exactly 833Hz @ 100mph(!)....

[Edited on 12/10/07 by BenB]