Poor stopping with front disc brakes

[Steve L]

I just bought my 2nd SOHC 750 and have the same problem with both. My front brakes don't grab. In both bikes, I have rebuilt the master cylinders, rebuilt the calipers and adjusted the caliper to the rotor so that it is just a partial turn from rubbing the rotor. I both cases, the master cylinders were all clogged up and the calipers had large amounts of glop in them. I cleaned up the pads, which had some electrolysis between the aluminum caliper housing and the steel pad back. I replaced the upper and lower rubber hoses. I bled the systems with Amsoil brake fluid and have a firm feel to the brake lever.......but the brakes don't stop the bike well.

I have other disc brake bikes with which I can lock up the front brakes. Not so with my Honda CBs. You could not possibly lock up these front brakes. The pads in my K5 are newer and the pads in my K1 might be original but have lots of pad.

I have a '71 BMW 750 with drum brakes that stop better than my CBs. Any feedback? Are all SOHC CB750s poor this way? Are there new pads that work better than the OEM pads?

 

[motogtp]

Are the pads glazed maybe? I had a similar problem on my mountain bike after a lot of downhill braking. I roughed up the pads and rims with some sandpaper and they were much, much better.

 

[Daren]

Also people find the steel braided hydraulic lines add some more pressure to the system.
Apparently the rubber lines flex too much. May also try that.

 

[Steve L]

Dear CB SOHC 750 riders:

Tell me how your front brakes work. Many of you have owned more than one bike. How do you think these front brakes stack up? Both of my CB 750s have crappy front brakes. My '71 BMW is really more crude than the Honda in most ways. But it's drum brakes stop faster than the Honda's. Maybe I'm expecting too much from a 43 year old bike. But excellent brakes are a requirement.

 

[dirtdigger]

The brakes are not great by todays standards but they are decent. You would be hard pressed to ever lock up the front brake on the cb as it was actually designed to be forgiving in that respect. More then likely you have glazed pads along with a glazed surface on the rotor. Cheap pads have poor stopping power on these rotors as they are stainless steel and it in itself is not the best material for brake rotors.

 

[Steve L]

Dear DirtDigger:

Thank you for your thoughts. My pads didn't look too glazed, but my rotor does. I didn't realize that these rotors are stainless, although I've never seen rust on them. My '88 K75 must have stainless rotors, too. But the brakes stop very well. Where do you go for replacement pads & rotors? Cycle X?

Sincerely, Steve

 

[Pinckney]

Dear DirtDigger:

Thank you for your thoughts. My pads didn't look too glazed, but my rotor does. I didn't realize that these rotors are stainless, although I've never seen rust on them. My '88 K75 must have stainless rotors, too. But the brakes stop very well. Where do you go for replacement pads & rotors? Cycle X?

Sincerely, Steve

Before you try anything else replace your brake lines with braided stainless steel lines. I could have saved myself much time and money if I had done that first instead of last on my ‘82 R100RS!