Topic: Front brake pad retracts too much, CB550F

[gears77]

Hi, 1975 CB550F Super Sport… not a typical brake bleeding issue, I don’t think.
The inner pad is adjusted til it just touches. I can see that the outer pad has a noticeable gap to the disc. The result is that the first pull has to take up that gap, the second pull it works properly.
Maybe it is air in the system but I have never seen a pad retract so that you can see a gap??
Any ideas?
Many Thanks

[dave500]

is it a new seal?

[gears77]

It is a new caliper, new seal.

[dave500]

it might just sort of bed in?try squeezing it really hard,find a long steep hill and tax it.

[newday777]

It is a new caliper, new seal.

How about the master cylinder? Has it been rebuilt or new? If the rubber piston puck is damaged that would be the 1st place to investigate. Then new brake hoses, old rubber hoses collapse internally, stainless steel hoses are far better choice to get the most braking performance.
When bleeding an empty master cylinder, you have to start bleeding at the master cylinder banjo bolt 1st, then I will bleed at the center pressure switch block banjo bolt followed by the caliper to get all the air out. Use rags to capture the brake fluid around and under the banjo bolts as you bleed it.(cover the painted parts to protect from brake fluid spills and drops!!). I keep a spray bottle of water to rinse off well after wiping the areas of brake fluid to prevent damage.
Reply back how you make out with it. I noticed you don't always reply back in your posts....

[BenelliSEI]

When parked, can you actually watch that pad gap open up when you release the lever? If so,, something is assembled incorrectly in the master cylinder. It should not pull back on the  caliper piston when released. Your symptoms suggest the master is drawing fluid back when released. Check both holes in the bottom of the reservoir are clear.

[Rookster]

You might also want to remove the adjuster screw and spring from the caliper and give it a few really hard pulls on the lever.  Then see where the piston and pad end up.

Scott

[gears77]

Thank you everyone for your advise. I tried the things you suggested. About the same but I no longer see the gap. I agree that it might be a defective master sucking it back it. I have never seen a pad retract like that.
I did loosen the adjuster hit it hard a few times and readjusted. I will see if it breaks in. It has no miles since the new caliper.
I can't get to the master for a while.. the brakes work, just not on the first pump.

Thanks again.

[gears77]

Here is the bike.. Not perfect but I just painted the tank and restored the emblems. Didn't paint the side covers. Happy with the color match.

[MauiK3]

Very nice!

[scottly]

Maybe it is air in the system

Possibly. Try bleeding the system again.

[dave500]

great paint match

[jlh3rd]

Hi, 1975 CB550F Super Sport… not a typical brake bleeding issue, I don’t think.
The inner pad is adjusted til it just touches. I can see that the outer pad has a noticeable gap to the disc. The result is that the first pull has to take up that gap, the second pull it works properly.
Maybe it is air in the system but I have never seen a pad retract so that you can see a gap??
Any ideas?
Many Thanks

that is a 1976 "F" paint color, not a '75 color. The bike itself may or may not be a 1975.

but nice job.

[Don R]

 Pump it up and leave a couple rubber bands holding pressure. Tap the hoses if you walk by and leave it overnight. This collapses any air bubbles since they compress, and fluid does not. When the bubbles are smaller, they float to the top easier.
 Just in case it is air. Also watch the hoses for bulging when you apply pressure.