Diff (Final Drive) ID

I have had a number of call with regard to final drives in the last few weeks.

To make sure you get the correct replacement Final drive for your bike, here is how to identify it.

Firstly, check the FD gear ratio.  This can be done from the outside, without removing anything.  A mirror may come in handy.

On the underside of the outer leg, the teeth numbers are stamped, like this:



Here we have 32 teeth on the Crownwheel and 11 on the Pinion.

32/11 gives a ratio of 2.91.  This is also etched into the end of the pinion shaft, here.



Then you need to identify whether it is Gen1 or Gen 2.

Gen1 is normally associated with servo assisted ABS bikes.  The ABS sensor hole is 11mm and the strobe plate notches are much closer together.  Here is Gen 1:  You can clearly see how someone has tried to fit this to a Gen 2 bike, where the sensor hole has been filed out.



This is the Gen 2 FD, with a 15mm sensor hole and a much wider strobe plate.



And just to confuse matters a little, the HP 2 is fitted with a Gen 1 sensor (11mm) and a Gen 2 strobe.



Hope this helps.  I have a list of the ratios fitted to the different bikes and will post it when I find it.