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Discussion Starter · #1 ·
Contributed by kenessex
I think this should be in the FAAMTQ, F'n already answered a million times questions. However maybe this will make it easier to find in the search function. This style brake was used on the CB350G, CB350f, Cb360, CB400f, Cb450, cb500t, cb500f, cb550k/f, and cb750k/f.

This style Honda front brake can be fixed very easily. The squeaking and dragging or locking up, comes from the caliper mount not being able to pivot freely on the pin that mounts to the fork slider. It is also caused by a sticky caliper piston and sometimes it is not helped by a partially clogged master cylinder bleed back orifice. If you are careful, this will require no new parts, just brake fluid.

1. Remove all of the parts, including the pivot pin from the aluminum bracket that bolts to the slider. Clean polish and lube the pin and hole in the bracket. On reassembly I leave out the felt washer. The bracket should just flop around freely if it is done right.
2. Pump the piston out of the caliper. Carefully remove the square piston seal from its groove and clean all the gunk out from behind it and all the crusty stuff off of it. If it still has square sharp edges, you can just reinstall it. If it is worn, replace it. Polish up the piston and the bore. If there are big pits on the piston, you should replace it. Polish the edges of the brake pad where it rubs against the caliper.Sand the glaze off of the pad. If it is worn at too much of an angle, you will need to replace them.
3. Sand the disk to break the glaze on it. You can chuck it up in a big lathe and hit it with a body grinder while it is spinning if you have access to that kind of equipment. Otherwise an orbital sander will be ok.
4. Disassemble the master cylinder and check for crystalized brake fluid in any orifices and for worn rubber seals on the piston. If the edges look good you can reuse them.
5. Reassemble the whole mess. I usually leave the screw with the spring that goes between the caliper bracket and the slider off too. A properly set up and lubed system doesn't need it.

Now you can feel free to replace all of the seals and o-rings with new ones if it makes you feel better. Most people don't advise reusing these parts and I wouldn't do it on customer bikes but on my own stuff I do it all the time if the edges of the seals look good.

The key to this system is to keep it lubed and clean. That is why I don't keep the felt washers and dust seals in place. I believe they trap water and dirt causing problems. There are only a few bolts holding this together, so take it apart periodically and lube it up and clean it up.

At its best, this brake system is marginal so it needs to be maintained. On the 550 and 750, I would double disk it and it will look cooler too. I also like to reverse the fork legs so the caliper is positioned behind the fork leg instead of in front of it. I think it looks better. If you do this, in order to use the front fender, you need to grind off the rivets that hold the fender o the fork brace and turn it around so the fender mounts properly. In that case you can also mount a cafe looking fender to that brace instead. I also like the looks of the cl350 fender on the CB. It is smaller and looks better to me.

There you go, It won't squeak or drag or lock up any more.


Vintage racing - old guys on old bikes

· Banned
6,272 Posts
I thought I would add to this.
A stainless steel line makes a big difference on feel for these brakes.Get a single line from the MC to the caliper and bypass the junction block that has the brake light switch. Either get a new MC that has a switch activated by the lever or get a new banjo bolt that has the pressure switch built into it.
Try a new master cylinder from one of the newer motocrossers, too. They are cheap on e-bay and many of them are more compact and have adjustable levers.

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