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Toothed Pulley Material
ashg - 15/9/09 at 09:33 PM

just a quick one.

i purchased a megajolt and all the necessary bits off a fellow forum member.

today i was having a good look at how i could fit it to crank pully on the engine.

i decided welding would be best. i got the pully out trigger wheel out to mock it up only to discover its made out of auminium.

now im no expert but i thought they had to be made out of a ferrous (magnetic) material to have an effect on the sensor?

so the question is. will the ali one work or do i bin it and buy a steel one?

[Edited on 15/9/09 by ashg]

mediabloke - 15/9/09 at 09:51 PM

Hi Ash. My immediate reaction was "nope, it won't work, scrap it and get a genuine one." But in theory, movement of the teeth could generate eddy currents in a sensor ciruit. Not sure that this would work with Megajolt though - I can't see that the pulses generated in a std sensor would be large enough to feed EDIS.

Francis.

mangogrooveworkshop - 15/9/09 at 10:01 PM

http://trigger-wheels.com/store/index1.html

flak monkey - 16/9/09 at 07:01 AM

Nope, needs to be a steel toothed wheel.

VR sensors require a ferrous maeterial to pass within 1-2mm of the end in order to generate the pulses.

Cheers,
David

02GF74 - 16/9/09 at 07:06 AM

I'm with the monkey on this one.

seach my post about trigger wheels - I post contact details of geezer who would make a trigger wheel at 1/2 price of the one above - and he can make it to your size. good kwaleetee too.

ashg - 16/9/09 at 07:51 AM

didnt think it would work. cant understand why someone would go to all the trouble of water cutting one in aluminium.

blakep82 - 16/9/09 at 10:49 AM

cutting from ali would be the same trouble as cutting from steel. plus everyones on the mission for ultimate lightness. if ali worked then it does make sense really

steel is the way. ali won't work.

[Edited on 16/9/09 by blakep82]

mediabloke - 16/9/09 at 08:56 PM

Yep - the only ali sensor applications appear to be proximity-related rather than speed measurement. Plus, since most modern engines use ali for lightness, you'd have a ready source of noise, even if VR was possible!

MikeRJ - 16/9/09 at 09:23 PM

quote:
Originally posted by ashg
didnt think it would work. cant understand why someone would go to all the trouble of water cutting one in aluminium.


I agree with mediabloke, it will almost certainly give some signal since the sensor itself generates the magnetic field which will induce eddy currents into the wheel, whose own magnetic field opposes the one in the sensor. However, this isn't how a variable reluctance sensor is designed to operate, and the signal level will likely be far too low to be useful.

I suspect whoever had it made simply did not understand how the VR sensor operates.