The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: drewboid on April 13, 2009, 07:38:42 AM

Title: Update on dual front disks
Post by: drewboid on April 13, 2009, 07:38:42 AM

Just to update the list - I had continued using the original 12mm master cylinder when I added a second front disk. Worked fine but I could get the lever to touch the grip with a mighty squeeze although my fiancee could not. Eventually the old master cylinder developed a leak and this weekend I replaced it with a 15mm MC. Quite a difference to me - now I can't get the lever to within 1/2 inch of the grip and the brake seems to engage earlier. I was concerned that it would require considerably more effort to stop the bike but it does not seem so.  Bottom line - both master cylinders seem to work - if you have a mighty strong grip then change to the 15mm cylinder. YMMV

Title: Re: Update on dual front disks
Post by: nhmaf on April 13, 2009, 10:36:48 AM

The 15mm is stock on the LS models with dual Brembos up front.
It provides very strong stopping power, especially with stainless steel braided lines, but the relative small distance of lever travel from actuation to full-on lock is pretty small and takes some getting used to.
I may not change mine out, but I have thought about using the 13mm (I think this is available) bore M/C would give more travel and a more progressive "feel".   I know that one is not supposed to ride with just 2 fingers on the front brake, but if I use more than (2) on my LS there is a greater tendency to "over-brake".