Quick question as looking at buying brembo m4 calipers do you need spacers on a 2008 model or do they just bolt straight on?
It's all down to your existing disc diameters? Assuming it's on ebay etc make sure what you're bidding on are the 108mm spaced mounting holes for use on Jap bikes. There are quite a few listings which quitely state 100mm which is for Europeon Bikes like Dukes, Aprilias etc
The caliper mounting bolt distances you mention has nothing to do with disc sizes! The spacers if required mount between the fork bottoms and the caliper which means a larger disc equipped bike needs the spacers to move the caliper further away from the fork bottom mounting points! But to answer your question SPS no M4 calipers do not require spacers on 08+ models and the silver ones that's currently fitted on for the nissin calipers should be removed when fitting the M4's.
I know! I can't see where I stated they were? My first sentence states it's all down to disc size in answer to the OP's Q. The next paragraph was just a heads up for the OP on mounting bolt spacings.
I bought some dowels from Arthur for my M4's.. they are not spacers, but they tap into the inside of the fork holes and inside of the back of the callipers.. so hold the calliper in the correct position for the bolts..
