Brakes - Is This Normal?

I’m using stock calipers, discs, wheel spacers, etc. On one side the disc is perfectly centered in the caliper, but the other apparently isn’t. You can see that the pistons are compensating for it. Bike has never been crashed. Thoughts?

 

The smaller slave cylinder will see a lower net force than the larger cylinder. That is the hydraulic pressure will be the same but since the larger piston has a bigger net area it will apply more net force. The affect is the smaller cylinder will move more. As long as there is no binding that looks OK to me.

 

looks like the caliper is missing a dowel??
Does the wheel spin a couple revolutions when assembled and on a fotk stand?

 

Both dowels are there. No, the wheel doesn’t spin freely at all. Maybe half of a revolution.

 

Unless you have fully floating rotors the pads will sit where the rotor "forces" them to.

But you should get more rotation than that, you have too much drag for sure.

 

You can see dirt on the pistons, I'd pop them apart and give them a good cleaning. May be time for new seals too.

 

wasnt able to see on my phone. I agree... clean & rotate the pistons in the bores then push them back. Then pump the lever and see how they act. Also clean and polish the slide pins. You should get at least 2 full revolutions when cold.

 

Remove the pads and use a light lube (WD-40) and liberally spray the pistons on both calipers. The light lube will act as a solvent and allow the brake dust to be cleaned off the pistons with an tooth brush.
Seat the pistons and then spray with contact cleaner, and reassembles they pads/ calipers.
PUMP THE BRAKES to get the pads seating before you ride it.

 

Mount the wheel w/ the axle torqued properly. Leave the calipers off. Spin the wheel - it should rotate freely, very freely, and not stop for a while.

If true, spin it again, this time holding a pointer horizontally against each rotor. See if there is any wavering - you might have a bent rotor.

 

Thanks for all of the tips. I have some HEL billet calipers ready to go on so I’m mostly concerned about the alignment.

 

Is that an optical illusion? Why the hell would the put opposing pistons of different diameters? I haven't seen tons of fixed calipers but of all the ones i have all the pistons were the same OR just smaller ones at the leading edge, but again opposing were still the same.

 

The only thing that pulls the piston back away from the pads when you release the lever, is the tiny little lip on the seal. That, and the rotor spinning knocks the pads back a bit.

On my 848 I spent alot of time making sure the pistons were clean and the pins cleaned and polished a little. tiny bit of high temp grease on the pin helps, too. Remove one pad and pump the lever, that extends the piston a bit and allows you to clean it up better. Toothbrush handles melt with brake kleen, so I use those little metal handle brushes for epoxy work. Once all that is done, bleed the brakes.

Then make sure the axle lines up and if you follow your little procedure outlined above, bolt up calipers, put axle and pinch bolts finger tight, bounce up and down the front end, then tighten the axle and repeat, then finally the pinch bolts. The axle needs to find it's little home in there.

This is one reason I wash my bikes after every weekend. Less buildup to remove when you do a pad change.

It's tedious and not very glamorous, but this is the difference between a racebike that rolls around the pits with one finger and one that needs to be ridden into the trailer.

Or, just put your new billet calipers on and enjoy.

 

Do those pistons that are retracted even move? There is a ring of dirt where they sit looks like they have not moved in awhile - but the others have based on the same ring of dirt.. like others recommend time to pull apart calipers and clean while you are there anyway.

 

Not normal something is not lined up.

 

These are Tokico monoblock calipers off a CBR, right?

I fitted them on my GSX-R and I have noticed the pistons position is just like yours. Not a problem as long as the edges of the pads are within their race(?) (might not be the right term)

 

Make sure that your wheel is mounted correctly, that the right spacers are on the right side. How is the other side? Did you recently change anything about the wheel and or rotors?
And then push all the pistons back in, mount caliper and rotate the wheel(keep it spinning) as you slowly pump the brakes. You can probably watch the pads come out as your pumping.

 

installing the axle incorrectly will cause that, as it pulls the sliding fork out of alignment. the axle nut is always tightened before the pinch bolts or the calipers are installed. you may also want to bounce the front end with only the axle torqued to align that fork.

 

I'm religiously following the procedure described in the workshop manual.

I even aligned the fork tubes, not by the length of forks protruding from the upper triple clamp but by the axle holes. the axle slides in and out effortlessly.

 

Check the rotor with a straightedge. I had a daytona that some how ended up with a rotor that got shaped like a dinner plate. The upper edge was closer to the right pistons and the lower edge was closer to the left side. I couldn’t see it until I pulled the rotor and laid it flat on the ground. I could stand on it and it would flex back to normal but when I moved off of it it would snap back into the plate shape. I figured it out after going into 10A at Rd. Atlanta having to pump the brakes once or twice! I imagine the heat from braking allowed it to temporarily stay flat shaped and after turn 7 it would cool enough to spring back into the mild cone shape.

 

Use a machinists ruler and make sure the wheel is centered in the forks, if it is verify the rotors are also. If they aren’t find out why. Swap them, measure again. Isn’t that hard...