Rear caliper flexing

[mr jamez]

I cleaned up and bled all the brakes on my S4 today, went for a test ride and found I pretty much had no rear brake. I don't think its a hydraulic problem as all I did was flush fluid through, no air. The pin the caliper slides on was seized.

When you push the pedal the piston moves immediatly, then the whole caliper and bracket flexes which also bends the brake disc. I've improved it a little by removing as much grease from the rubber grommet as possible. However the flex gives the brake a really spongy feel. It seems as if rather than sliding it is just twisting.

Any secrets to getting these things to work properly or am I doomed to have a shit rear brake?! It won't even lock the rear.
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NSR 125F > BROS 400 > NC30 > BROS 400 > Trumpet S4 > '97 VFR 750

[lonner]

make sure the pads move on the pins freely use copper grease on the caliper pins and the large sliding pins as it should move easily.

are the pads contaminated with chain grease oil etc as this will also make them crap.
also are you sure they are bled completely


had same problem with my 955st the rear brake on these trumpets is week even in perfect working order .
you will need to change the master cylinder if you wont more power hth

the front brakes are second to none there excellent


i cant remember which one's work (think its a zxr) but i will have a poke around and see what i can find

i never replaced mine as the rear brake is for control only and found it ok for road riding

[mr jamez]

Its all in perfect working order as far as I can tell, just miffs me a little bit that it moves that much. Oh well, I don't think rear brakes are up to much on most modern bikes.

The one on my BROS is really good, even with screwed discs and pads.
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NSR 125F > BROS 400 > NC30 > BROS 400 > Trumpet S4 > '97 VFR 750