Post by createscript on Apr 21, 2024 13:12:50 GMT -5
OK, so I'm still prepping and testing the SR400 for my Sicily trip. I've made it faster, apparently quite a bit faster, more of which anon in another post.
However, one thing that's been bugging me (and quite worrisome if I was to tackle Alpine pass zigzags) was the brakes. At 70 mph (5K revs on my +1 tooth g/box sprocket) the brake bite point would very quickly come in 1.5" towards the 'bar. No apparent loss of braking efficiency, no sponginess but not ergonomic for an emergency halt.
A bit more testing an analysis revealed it was not actually speed related but rev related. Anything above 5K and the braking would change as described. Back off, and very quickly it would return to a solid early bite point. Driving me mad, I was at a loss, and I was about to rebuild the Master cylinder thinking that the vibes were causing some weird cavitation or bypass on the master cylinder seals as that was the closest thing in my experience to what was happening.
I took it down to my local Yam dealer to book in a service and mentioned it to them - they were as baffled as I was. The service manager asked to take it out onto the bypass to experience it and was mystified. Then one of their mechanics came in on his day off to pick up his sandwich box that he'd left there, got talking and had a go.
Bizarre solution: he discovered that, hidden by the rubber boot, the brake adjustment screw was loose. At 5k or more revs it consistently screwed its way out, and the bite point came in. Below 5K it screwed back in and the bite point went back out. It had been doing this consistently for 1200 miles, reg'lar as clockwork.
I swear the best engineer in the world couldn't have designed something like that in.
Weird tale, but, just in case you ever find something similar happening to you, look under the boot.
However, one thing that's been bugging me (and quite worrisome if I was to tackle Alpine pass zigzags) was the brakes. At 70 mph (5K revs on my +1 tooth g/box sprocket) the brake bite point would very quickly come in 1.5" towards the 'bar. No apparent loss of braking efficiency, no sponginess but not ergonomic for an emergency halt.
A bit more testing an analysis revealed it was not actually speed related but rev related. Anything above 5K and the braking would change as described. Back off, and very quickly it would return to a solid early bite point. Driving me mad, I was at a loss, and I was about to rebuild the Master cylinder thinking that the vibes were causing some weird cavitation or bypass on the master cylinder seals as that was the closest thing in my experience to what was happening.
I took it down to my local Yam dealer to book in a service and mentioned it to them - they were as baffled as I was. The service manager asked to take it out onto the bypass to experience it and was mystified. Then one of their mechanics came in on his day off to pick up his sandwich box that he'd left there, got talking and had a go.
Bizarre solution: he discovered that, hidden by the rubber boot, the brake adjustment screw was loose. At 5k or more revs it consistently screwed its way out, and the bite point came in. Below 5K it screwed back in and the bite point went back out. It had been doing this consistently for 1200 miles, reg'lar as clockwork.
I swear the best engineer in the world couldn't have designed something like that in.
Weird tale, but, just in case you ever find something similar happening to you, look under the boot.
