drum brake

[saber]

Newbie here. I have a 1979 CB650 that I owned for 20 years that has been sitting in my garage for the last 8 years. Decided to get it back on the road. Tank looks clean so I got a new battery and started the bike. Got gas from 3 carb drains so let it set. Tried to start it again a week later and got lucky. The carb overflows were dry and it actually started and idled ok with the choke on. The 650 has 9100 miles on it. Here is my question. The drive chain was loose so I adjusted the tension by 2 notches. Since the rear wheel was moved back what do I need to do to check and maybe adjust the rear drum brake? I have to admit this forum is really helpful.

[Mainerider]

You're probably fine but it is still a good idea to check everything after a bike has sat for that long. Put it in neutral and up on the centerstand and turn the key on. First, make sure your brake light activates shortly after the brake pedal begins its downward path.

Next, spin the wheel by hand and slowly apply brake pressure; braking should be smooth, progressive and linear. When fully applied, your panel brake arm and the brake rod linkage that connects to it should form a roughly 70-90 degree angle. I believe the '79 also had the brake lining wear indicator pointer at the top of the panel brake arm, so you can check that also but with 9,000 miles they should be okay.

Just remember, your front brake is by far the more effective brake and after sitting so long it should absolutely have the fluid bled and replaced, at a bare minimum. Braake fluid is hygroscopic ( collects moisture from the atmosphere) and is undoubtedly contaminated by now. Water settles at the lowest spot so most of it will be sitting in your brake caliper, rusting and pitting your piston and cylinder (and perhaps seizing it). Not good...

[saber]

Thanks for the great advice. I will take your advice on the rear drum. Also need to address the front disk brake. The front brake reservoir looks yellow and dry. I did not remove the cover yet. Also will need to replace the tires. They are at least 20 years old but still look new.

[saber]

Mainerider...nice bike. Is that Bar Harbor? Visited there about 5 years ago.

[Mainerider]

Thanks; Actually, it's Bush's home in Kennebunkport. I used to live in the ''Port and now live in Saco, about 10 miles and $10 million dollars away. I do go up to Bar Harbor at least once a year, though; the carriage trails in the park are some of the best places to ride a mountain bike.

[saber]

Mainerider, I checked the rear brake as you suggested. Everything seems like it is still in adjustment. Brake light went on and there was a little play in the pedal before the rear wheel tightened. So far so good - now on to the front brake. Thanks

[Mainerider]

Good work and good luck with the bike; Ride safely.

[onepieceatatime]

Another thing to be aware of, is that on a lot of these old bikes, the brake material separates from the metal in the rear brake. It can then jam up the rear wheel while riding. It means pulling the rear wheel to check, and re-doing your chain and brake linkage adjustment, but well worth it to know you will be safer while riding.

[saber]

great point....I added that to my list of things to do to get ready to ride. I need new tires (20 years old) so that would be good to do at the same time. Thanks

[saber]

well on to the front disk brake. What a mess. Took the master cylinder cover off and the bleeder valve off. The master cylinder was basically empty so I added some fluid to try to flush the system. Brown crud rose to the top and nothing is moving through the system. Looks like everything must be taken apart and cleaned. Never did this before...any advice?

[Mainerider]

well on to the front disk brake. What a mess. Took the master cylinder cover off and the bleeder valve off. The master cylinder was basically empty so I added some fluid to try to flush the system. Brown crud rose to the top and nothing is moving through the system. Looks like everything must be taken apart and cleaned. Never did this before...any advice?

Well, to do it right, you should really disassemble the entire brake caliper and clean it thoroughly. If you do proceed, you may find the piston is more or less seized into a narrow range of travel ; if so, you will need to use compressed air or a grease gun to pop out the piston. You will also want some silicone-based grease on hand, such as NAPA Syl-Glyde.

It can seem a bit daunting if you don't have the right equipment or experience; Most likely due to liability concerns the manual gives you very little DYI guidance for this and suggests dealer-service only.

If you decide to jump in, just look it over really well before starting so you can see how it all fits back together afterwards. If you get really hung up or just don't want to tackle it you can send it to me and I will do it for you at a good rate.


Good luck.

[Volker_P]

Welcome here!

Looks like everything must be taken apart and cleaned. Never did this before...any advice?

Just carefully disassemble and make sure you get it together again. Making pictures may help.
Hava a look to the three brake topics in the "internal technical links" topic.

Inspect the rubber parts carefully, they may need to be replaced. Also flush the hoses or get stainless steel braid brake lines instead. Everything has to be really clean before reassemble.

Be careful with compressed air, the piston may be blown out quite powerful!

[saber]

Thanks for the advice. It is good to know there are people and resources that can help keep you out of trouble. I will attempt this myself. The challenge is to see if I can do what is needed to get the bike on the road. Actually I am having a lot of fun working on this bike ...its all new to me.

[saber]

well the front brake is not going as good as expected on the 79 CB650. I removed the total brake and took it to the local bike ship to have them clean and blow it out. A master cylinder rebuild kit was installed. Took it home and hooked everything up and topped off the master cylinder with fluid. I can't get the brake fluid in the master cylinder to flow into the lines. Only opening and closing the bleeder when the brake is fully pressed. The only thing I get is some tiny air bubbles rising in the reservior. Any thoughts?

[Mainerider]

well the front brake is not going as good as expected on the 79 CB650. I removed the total brake and took it to the local bike ship to have them clean and blow it out. A master cylinder rebuild kit was installed. Took it home and hooked everything up and topped off the master cylinder with fluid. I can't get the brake fluid in the master cylinder to flow into the lines. Only opening and closing the bleeder when the brake is fully pressed. The only thing I get is some tiny air bubbles rising in the reservior. Any thoughts?

Did they also disassemble the caliper and clean it, or just the master reservoir? Given the state of what you found in the master reservoir the caliper is undoubtedly a mess internally, also. You might also want to consider replacing that 34 year-old brake line with new stainless-braided line.