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Discussion Starter · #1 · (Edited)
Really stiff front brake question; on my other bike-1970s CB (with Pics)

My wife recently expressed interest in learning how to ride, so we borrowed a fun little 1970 something Honda CB125 from her brother. It will be a good first riding experience, and seems to be in good working order except that the front brake seems really stiff (nearly unusable). I have ridden this bike in years past and know it was not always that way.

My question is; what would be the best way to go about fixing the stiff brake?? I am no stranger to working on my bikes, but I have not worked on a brake system that uses a wire rather than a master cylinder. I would like some advice before I just take some tools to it lol.

I know there are people on hear that have owned older bikes and can help me out.

Here are some pics:







 

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Well, I think I'd start by making sure the cable and the lever are not binding/seized, and then move on to the caliper.
 

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Not sure how those old mechanical brakes work personally. I was going to suggest bleeding the brake but that wouldn't apply.

By the way, it is BRAKE... not break.

A brake is a device used to slow you down. Break is what happens to a beer bottle when you throw it at brick wall.
 

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Psst! There's no fluid to bleed on a cable-actuated brake. :)
Yeah, I noticed that and edited my post. :naughty: I haven't seen mechanical front brakes on a motorcycle, well... ever.
 

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Discussion Starter · #6 ·
Not sure how those old mechanical brakes work personally. I was going to suggest bleeding the brake but that wouldn't apply.

By the way, it is BRAKE... not break.

A brake is a device used to slow you down. Break is what happens to a beer bottle when you throw it at brick wall.
Corrected, thanks.
 

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I imagine (though I really have no clue) that it works similarly to rear brake calipers on a car that have the parking brake built-in. The cable causes the piston to unscrew, giving you the clamping force.
 

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I'd start by pulling the brake lever, clean & grease the pivot and the fitting on the end of the cable that attaches to the lever. The cable probably needs a good lube too, but you'd want to make sure none of that lube finds its way to the pads/rotor, so I guess if it were me, I'd look online to find out how to disassemble that caliper & service it, so that I could lube the cable while it's detached from the caliper.
Cool bike! Hope you get it working for her!
Also couldn't hurt to clean the rotor with some brake cleaner.
 

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Interesting, don't think I'd heard of bikes with cable actuated discs before. BMWs use a cable actuated master under the tank, but that's as close as I've seen.
 

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I'd unbolt the caliper and pull the lever. The pad should move easily when you do it, and the caliper looks like it should slide side to side so make sure that is free. Once you are satisfied that it is moving as it should you are left with the friction surfaces not doing what they are supposed to do. Sandpaper is your friend on the pads and Scotchbrite (or the like) on the disc. Scrub them both to remove the glazing and they should work as well as they are going to. Remember the old bikes did NOT have brakes even remotely as good as our modern versions. I have fond memories of CB100's and 125's. They are indestructible motorcycles if there ever was one.:)
 

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Had a mini bike once with cable brakes. Lubing the cable may fix your issue. An easy way is to disconnect the cable from the lever. Extend the cable vertically. Where the cable enters the cover, make a funnel out of duct tape, fill it with WD40 and let it sink in overnight. As said, clean any wd40 off the disc or pad with brake cleaner or contact cleaner.
 

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I'd take a look at the cable and make sure its lubed and the point where it contacts the lever well greased. With the caliper, you can remove the three outside bolts and that cover will come off so you can take a look at the guts of the caliper. You can then see if there is anything preventing it from moving smoothly.

I don't have an electronic manual but I do have a paper copy of a Clymer for the CB350 line and the G model used the same type brake. Let me know if you'd like me to take pics of the relevant pages for you.
 

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My CB250 (93') has the cable driven drum brake- its stiff as a mofo- I just put a new cable on it... oiled it up.

Gonna put new pads- but that just seems to be the nature of cable operated... Friends CB200 is similar...
 

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Pull the brake such that the cable is exposed, and apply a few drops of motor oil. Gravity will over time pull the oil down the length of the cable, hopefully lubricating it and easing the stiffness.
 

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Discussion Starter · #16 ·
UPDATE

Following some of the great suggestions I received I went ahead and opened up the casing on the break caliper. Well, to my mild surprise there was a great abundance of rust covering everything. After giving the internals a health blast of PB Blaster I started looking around. Apparently, there are two wheels that turn when depressing the brake lever. The first wheel is attached to the brake cable, and turns when pulling the brake lever. The second locks into the front of the first wheel, but when turned it screws in and puts pressure on the back of the brake pad.

I took about 3 hours, and with the help of PB Blaster worked the wheels in the brake caliper free from being frozen almost solid to having fairly free movement.

I went for a ride on the bike today and it is working great!! Well not great for a modern bike, but pretty damn good for 1975 lol!! Funny thing is, I got more looks on that bike than I ever did on the SV! A good looking girl even came up to me and asked me if it was my bike, when I said yes she said "you have a really cute bike" lol :naughty:

Damn, I should have taken pics of the inside of the break caliper. If some people want to see what a wire driven caliper from 1975 looks like let me know and I will take some snapshots.




On a side note:

As I was fixing the brake problem I was fiddling with the right hand controls (checking the cable, etc.) and noticed that the throttle cable wasent returning. I though "oh great, I F'd something else up" lol. I opened up the throttle enclosure on the bars and found that there is no throttle return cable on these bikes. After a great deal of research I found that the bike must have a return spring, but on these bikes they are located in the carb. I checked EVERYTHING and I just could not understand why the cable was not all of a sudden returning. Came back inside and with the help of Google, and another CB125S owner who suffered from the same problem and just about pulled his hair out resolving it, discovered that if you screw in the carb to much it warps the casing and pinches the throttle cable. Well, a few days before I posted my brake question I cleaned out the carbs (which made the bike run MUCH better). To my amazement, I backed the screws holding the carb onto the block off a half turn and heard the throttle cable snap back into position!!

Gotta love the old bikes, and how finicky they are ;) Just think of all the crazy crap we would be talking about on SVRider if our bikes were not so modern and well engineered.
 

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Just imagine how much hair you'd have left on your head if you didn't have SVR, google, or the internet to help you

Glad to see you got it running. Makes me wnat to pick up one of those things for around town.
 
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