Sensor Brackets

The VR sensor needs to be mounted on a rigid mounting as any vibration may cause the gap between sensor and wheel to change, thereby altering the signal from the sensor. It is very helpful if the bracket can have some adjustment as no matter how many times you measure up you won't be able to get the sub-millimeter accuracy that is required.

In order to provide adjustment for the sensor I like to use mounting slots rather than mounting holes in the bracket. The pictures below show the bracket that I made for the CV-joint mounted wheel for the mini. This bracket was constructed from some 3mm wall thickness 25mm L-section mild steel which was painted once the fitting had been fine tuned. In the first image you can see how the sensor mounts to the bracket, in this case with an M6 bolt in a 7.5mm hole, thereby providing 3mm of adjustment in that plane. That hole was first drilled with a 6mm drill and was tested to confirm that the hole was correctly positioned. Had it not been I would have had the opportunity to either re-drill or file out the hole in the required direction rather than simply drilling with the 7.5mm drill bit.

In the second picture you can see the right hand slot, which provides adjustment in a second plane. Additionally washers could be added between the bracket and the sensor to space the sensor away from the wheel.


Bare sensor bracket	Here you can see the right hand slot, which provides adjustment in a second plane. Additionally washers could be added between the bracket and the sensor to space the sensor away from the wheel.

Sensor mounted on the bracket

This next example is far simpler than the last one, constructed solely from a piece of aluminium L-section. Fastening the bracket to the block is accomplished using pre-existing bolts in the block, in this case by replacing the bottom two bolts in the timing chain cover of this mini. The holes for these bolts are slotted to allow adjustment of the sensor to ensure that it is perpendicular to the teeth, the sensor is packed out with washers to adjust the sensor spacing.

A useful trick to allow fine tuning of the sensor gap is to design the bracket to position the sensor slightly too close to the teeth. This allows the use of a mixture of standard and heavy washers to be used - if you need to narrow the gap replace one heavy washer with a standard one or two standard ones with a heavy one. To expand the gap, well you get the idea.


Aluminium bracket mounted to A-series	Washers and adjustment slots just visible

Since fabricating the bracket above for that particular mini engine we have developed a bolt-on mounting for the A-series. The picture below shows the bracket and spacer fitted, ready for the sensor to be installed. Other than a slightly different profile the design is very similar to the prototype above, the big difference is that it is formed from steel rather than aluminium to improve rigidity.

For more details of the a-series bolt-on kit see our A-series fitting guide and our bolt-on trigger wheels pages.