At last I have the windscreen fitted on the Exmo, and have just managed to mount the Sierra wiper mechanism which I have modified as per the build video. I have made shorted arms and blades, so far so good. I put it all together and set the motor going. No bangs or crashes, so the clearences are okay. However, it's obvious that the sweep is not good enough. On the driver's side it is just about 90 degrees, i.e just 45 degrees each side of vertical, this might just be ok to see through on a wet day, but then the park position leaves the wiper well up the screen. I have searched through the forums and unsurprisingly this topic has already come up before. I quote the ones that I found below. It seems that the perceived wisdom is to add 10mm to the short arm that is attached to the motor spindle. Before I do this i am wondering if anyone has anything further to add to the wisdom on this subject, apart from telling me to fit Mini/old BMC type wiper mechanism.
https://www.rhocar.org/index.php?/forums/topic/4337-sierra-wiper-motor/&tab=comments#comment-31292
https://www.rhocar.org/index.php?/forums/topic/5338-sva-with-windscreen/&tab=comments#comment-40054