Topic: 1976 CB750 - Front Brake Pads

[Jim Harris]

I replaced the front brake pads on our K6. Of course the new pads are thicker than the worn pads. I have the new pads in place, but I can't get the caliper screws to go back in (see photo). Is that an indication that the caliper piston is stuck and not going back far enough into the housing?

[bjbuchanan]

Take the caliper off and compress with a c clamp. It shouldn't take much effort at all. You don't have to disconnect anything to check it out

[BobbyR]

+1

You should  take of the MC suck out all of the fluid in it. Lay the cap back on to stop fluid from spurting out of the return hole and getting on everything.

You can replace the pads and the fluid in one shot.

[Jim Harris]

It's not moving with reasonable clamp pressure, but I don't know how much movement to expect (see photo). The well is about .75" deep, the brake puck is about .75" deep. The recess on the back of the brake puck is about .25". The cap on the piston is currently only down about .25 below the rim of the well, so the brake puck is proud of the well by about .5" currently. How deep should the brake puck be when the piston is at it's low position?

[ekpent]

Whenever I change pads I also remove the piston as I pump out all the old brake fluid also. Its a good time to pull the seal and give the groove and everything a very good cleaning. Upon reassembly I make sure the new pads will easily fit into the caliper first. Some need to have paint and excess brake material removed around the outside edges etc. to float properly. A quick cleaning overhaul is quick and easy to make sure all is good up front.

[Stev-o]

^^^ good advice

[Jim Harris]

I'm convinced that the piston must be stuck. I've read the posts about blowing the piston out with air or grease pressure, I'll try one of those methods over the weekend. Do you think it would help to fill the well with grease to see of it soaks in and loosens the piston, prior to the compressed air process?

[bjbuchanan]

Does the brake system still work? Pump it out using the hydraulic pressure then. Grease gun is last resort, especially if you have a functioning brake system. IMO the air setup isn't an option because 1. its stupid, you just made a rocket and 2. it usually doesn't work anyway.

Pump with the lever, maybe you jammed the piston a little? Not sure if it is possible that far in but you never know. Either way I think it is a good opportunity to do a quick overhaul

[ekpent]

As BJ said the time to roll the piston out is when the hyd pressure is rolling. I will say though that you will need to add more brake fluid as this happens because as the piston starts moving forward fluid has to be added to keep the pressure and action going to "fill the gap' of the piston travel. Run out of fluid its game over.
   I always like to see those dirty/ rusty little turds fall out of the calipers, almost like watching a birth     
  The bike in your sig though looks fresh, when was the last time the caliper was stripped ?

[PeWe]

I lubricated my piston with thin layer of lithium grease when out, pressed with a c-clamp, pumped out, C-clamp ... a few times until it moved smooth.

Brake pads had to be sanded to fit when they were powder coated that had to be removed on the pads sides

I applied a dot of copper grease under pads as common on cars (anti squeel)

Cover tank and other painted details when you have brake fluid cap off and excersice the pad, make sure that the level never is too low so you get airbubbles in the hose. When too much it can fload painted parts which is not nice. Brake fluid is often used as paint remover...