Crank pulley

[jimmyybob]

Hi, when fitting the trigger wheel to the pulley is it best to use an aluminium pulley or will the stock steel one be ok,? Iam a bit concerned that the VR sensor will be affected by the steel pulley.
Does there need to be a clearance gap between the steel pulley to avoid any possible interference.

[johnlunt]

VR sensors respond to a magnetic field being interrupted by a ferrous object so aluminium will not work. The gap is not critical at high speeds and 1mm - 2mm should work fine.

Sorry, didn't read your question properly. Aluminium pulley or a big gap would be best

[MartinM]

As long as the steel trigger wheel teeth are reasonable "well-defined" to the sensor, and any other close ferrous material is at a constant distance away (eg the rotating steel pulley) I can't see any great problem

Just to clarify John's statement, the VR sensor creates it's own magnetic field (there is a magnet inside - try it with a screwdriver) and the trigger wheel teeth (ferrous, but [probably] non-magnetic) interrupt that field, causing the output voltage.

[KLAS]

i have my triggerwheel fittet to the original steel pulley as seen here
http://static.flickr.com/74/159364681_c7ee67b103_b.jpg
and here
http://static.flickr.com/55/159876566_47d19458c3_o.jpg
no problems at all

[jimmyybob]

Thanks.

[capri_turbo]

A steel pulley will not cause you any problems at all. I'm using a standard Ford Pinto bottom pulley and a Sierra CVH trigger wheel

<a href="http://photobucket.com/" target="_blank"><img src="http://i105.photobucket.com/albums/m227 ... lj7324.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

as you can see above, the trigger wheel is only just bigger (only 2mm all round) than the pulley, but as the pulley is a constant, it'll only at worst produce a small DC offset to the signal which isn't a problem. I've had absolutely no problems using a sensor gap of between 1 and 2mm.

[jimmyybob]

This is how i have now fitted the trigger wheel i have used an aluminium pulley and machined the outer edge for a nice close look.



This wheel is for a T1 aircooled VW.

[MartinM]

Very, very nice! I'm seriously impressed

[rmaddock]

Do you have something between the two to prevent oxidisation? As a Land Rover owner I'm very concious of what happens over time when you have steel against aluminium......electrolysis and nasty white powder.

[jimmyybob]

HI, the trigger wheel is painted both sides, i to was a little concerned about the effect of cavitiation/corrsion but the pully wheels is quite cheap and so was the trigger wheel so if it lasts a few years its not realy a great loss just to replace them.