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Discussion Starter · #1 ·
Kind of a general question here:

Maybe it is the fact that I haven't ridden any other vintage bikes like mine to compare it to for a benchmark, but I have not been a fan of the weakness of my front disc brake.

Things I have done in the past:
- Ditched the old swamp-muck filled OEM master cylinder with a CB400 eBay special
- Replaced banjo bolts and brake lines with stainless steel braided hoses
- Replaced brake pads with EBC
- Replaced brake "pipe" with a brand new one
- Replaced caliper seal
- Replaced caliper piston with a brand new one
- Bled brakes annually

The only thing I haven't done was replace the caliper body itself.

Still, I am not feeling super happy with my front brake compared to my other bikes, and every time I come to a traffic light, I decelerate in preparation of coming to a long stop. Is this something that I am going to have to live with, or is there something else I should try out?

For a time, I wondered if my clubman bar setup (which angles the master cylinder reservoir 30 degrees or so) was hindering the fluid flow to the caliper, but if the brake lines were properly bled and the reservoir topped off, there should be no air in the system.
 

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Break up the glaze on the disc with some good abrasive made for metal. Glass beading would be excellent but requires removal. Avoid using brake cleaner spray on the disc.

Check the size of the piston on the master and compare it to what the guys at Vintage brake suggests. I have also found that using the CB600RR rear caliper piston is an improvement in feel and response.
 

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Like Boomer said. Your replacement lever assy. may not be compatible with your brake set up. Glazing on your pucks or rotor will contribute to problems with effectiveness also.
 

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Since they are stainless rotors you can actually just take a orbital sander and some 100 grit and go to town on them to get rid of the glazing.

They were never really all that good in the beginning. It's been said many times on the forums that the drum front brakes when set up correctly were better. Do make sure you have it properly adjusted as that can make a difference.

Sent from my SAMSUNG-SM-G891A using Tapatalk
 

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Kind of a general question here:

Maybe it is the fact that I haven't ridden any other vintage bikes like mine to compare it to for a benchmark, but I have not been a fan of the weakness of my front disc brake.

Things I have done in the past:
- Ditched the old swamp-muck filled OEM master cylinder with a CB400 eBay special
- Replaced banjo bolts and brake lines with stainless steel braided hoses
- Replaced brake pads with EBC
- Replaced brake "pipe" with a brand new one
- Replaced caliper seal
- Replaced caliper piston with a brand new one
- Bled brakes annually

The only thing I haven't done was replace the caliper body itself.

Still, I am not feeling super happy with my front brake compared to my other bikes, and every time I come to a traffic light, I decelerate in preparation of coming to a long stop. Is this something that I am going to have to live with, or is there something else I should try out?

For a time, I wondered if my clubman bar setup (which angles the master cylinder reservoir 30 degrees or so) was hindering the fluid flow to the caliper, but if the brake lines were properly bled and the reservoir topped off, there should be no air in the system.
I have stock, rebuilt master cylinder, stock rebuilt calper, ebc pads, ss lines. I can lock the front brakes with a lot of pressure. This is better than the old stock setup, and better than it ever was. I bought my bike in 78, it was a year old. Front brakes were always weak. You have the best setup in a stock config. I am happy with the present setup but admittedly, it is not as good as my nh750, or any new motorcycle. I do feel they are good enough though. And riding ahead of yourself, anticipating braking and situations is a good practice.
These bikes were never high performance racing bikes, and today's technology 40 years later is better, but the bike is reasonably safe and fine for normal riding, imho.

Delaying the disk should help. I did that to mine, calibrated sandpaper, and overall, am pleased how good the brakes are now compared to out of the factory performance.

Sent from my SM-T800 using Tapatalk
 

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Discussion Starter · #6 ·
Sounds good everyone. I checked the specs and the bore of the CB400 master is the same as stock, so there isn't an issue there. I will hit the pads and disc with some coarse sandpaper to scuff them up some and see what difference I feel when the bike is back together.
 

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Check the surface on the brake pads. Also, they should be sintered or semi-sintered. Back in the day I had a CB360T new and it would chirp the front wheel at 30 MPH.
 

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One thing not mentioned, check the 'swing arm' pivot as they are often seized or sticky. I fit a grease nipple to pivot on mine (and all the others I've worked on)
'Fixed' pad should be 0.006" clearance to disc and checked/adjusted every 1,500 miles
 

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Have you rebuilt the "ebay special" CB400 MC? If not that may be an issue.
The other guys give good advice. From what you describe there is some room for improving your existing setup.

The disk brakes on these old bikes aren't as responsive as modern brakes however they are generally more than adequate for the job.
You may have to adjust your braking "style" as well. I know some guys who are only used to modern bikes say they hardly ever use the rear brake.
Do you ever use your rear brake at all in conjunction with the front brake?
 

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Discussion Starter · #10 ·
Yeah I use both brakes. Upon bike disassembly, i have noticed an irregular wear pattern on the disc brake pads, which suggests that the caliper was improperly aligned by me, meaning that only a fraction of the brake pad surface was coming in contact with the disc (on an angle). I will be sure to adjust it properly this time around!
 

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Pads will always wear at an angle due to the type of mounting. As long as it is only 'front to back' it's normal. Top to bottom wear is a problem but I've seen it when mudguard stay/fork 'brace' was fitted wrong
 

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Hello Gents,
first generation of Honda-discbrakes are junk anyway. I replaced the front forks with nearly same period Bol d'or forks (35mm) and clamps. You have to lower the forks a bit. Then you can mount a more modern doublepiston caliper (I used one from a GB500/XBR500). For a rotor you can then use the brakespider from the original frontwheel (remove the rivets of the original outer disc) the boltpattern of the spider is 6bolt/150mm which means you can now use a lot modern rotors from Yamaha (you just have to machine the spider to adapt to the 132mm inner circle of the Yamaha-rotors). One finger stoppers!!
 

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Back in the day, I traded in my CB175 against a CB250G5 ( same as CB360 except for smaller capacity ). Big mistake, but that's another story.

I can confirm that the front brake was crap, right from brand new. Made even worse because I never did any maintenance on it, just rode the bike in all weathers. When I finally took the bike back to the dealers, in a vain attempt to discover why it would only run on one cylinder whenever it rained ( happens a lot over here ), mechanic nearly had a fit. Front brake seized on its pivot, basically not working at all. And I'd been blissfully unaware, thought that 'they were all like that'.
 

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Stainless steel is a bad material if you want effective brakes. Italians knew that, and Brembo used cast iron or steel for the disc (Grimeca even used hard chromed steel discs which were brilliant until the chrome wore off). Because of that, any classic Italian bike that is not ridden regularly has a lot of rust on the discs - but comparing them to stainless rotors is like night and day (and that is the reason why Brembo is so well known now too).
Modern discs are also some mild sort of stainless steel, as they are sometimes also prone to rusting. Standard car discs (where the rusty discs are out of sight) are all still mainly cast iron too.


So, you cannot expect an early 70's disc to be really effective. Pads also make a difference - organic pads give a bit more braking force, but they do not handle heat well, and they work much worse in wet conditions. You probably have sintered or half-sintered pads that work the same in most conditions, but do not break that well (I'd go for the semi-sintered ones, as a compromise - these old discs are notorious for not working in wet).



The master cylinder makes a big difference on the lever feel. I have no idea what ratio old Hondas had. But it is probably safe to assume the slave to master cylinder size ratio was nowhere near the ratios that are used today. Using a larger master cylinder will make the lever firmer (you have to squeeze more, and it will have less travel). If you use a smaller one, you will have more travel, but it will be easier to apply more force (like a longer leverage).
Fitting a smaller one is the way to go if the brakes are not very effective. It is also possible to sleeve a master cylinder to a smaller diameter if you want to retain the stock look (but that also requires you to make a custom piston and seals - you can get the seals in various master cylinder rebuild kits, for all kinds of sizes and brakes).

I think the stock CB360 master cylinder had a 14mm bore. If you fit stainless lines (they make the lever firmer since they do not flex as much), you can probably go down at least one size (perhaps two) to 13mm, without the risk of excessive lever travel (you do not want it hitting the bar without griping the wheel). Perhaps get a dirty cheap used 13mm master cylinder from some 90's bike, to test it out.
 

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One major improvement is to cross drill rotors.
DO NOT chamfer holes just de-burr them.
Try and get some EBC 'HH' or similar pads (sintered bronze particles in them) or original Honda organic pads (originals contain asbestos so be a bit careful)
EBC 'organic' pads don't last very long but do work very well when wet.
I'm using Suzuki RM master cyl at present, 11mm bore is slightly small but provides enough pressure to actually feel flex in the clamp bolts. ('modulation is OK)
The pads are getting plenty of pressure,(much higher than with stock M/C) the caliper design is the weak point now
 

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I've also experienced a "stuck" piston in the caliper which also adversely affects braking performance.

You'll have to remove the caliper and pump the piston out with the master cylinder. Once apart, pull the seal out too, and you should be able to see any clinging or aged-on brake fluid both in the bore and seal groove. If you carefully remove the crud via gentle application of scotch brite (not sandpaper!) and soft scraping in the seal groove, will allow that piston to freely move in response to the lever.

To reassemble, I use either krytox (or other Teflon based lube like Braycote) or a silicone grease to just film the seal before it goes into the clean groove and slide the piston past until it bottoms. Do Not use petroleum jelly or other grease as they're incompatible with the seal material (EPDM rubber) and will cause it to swell, sticking the piston or failing the seal.

Other folks may recommend using brake fluid as the lube and that's Ok, but, I've not had much success with that so now I use krytox or other EPDM compatible grease, or oil, and it makes assembly really easy.
 

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Back in the day, I traded in my CB175 against a CB250G5 ( same as CB360 except for smaller capacity ). Big mistake, but that's another story.

I can confirm that the front brake was crap, right from brand new. Made even worse because I never did any maintenance on it, just rode the bike in all weathers. When I finally took the bike back to the dealers, in a vain attempt to discover why it would only run on one cylinder whenever it rained ( happens a lot over here ), mechanic nearly had a fit. Front brake seized on its pivot, basically not working at all. And I'd been blissfully unaware, thought that 'they were all like that'.
Richard,
I bought a new CB360T (Red) from the US Navy Exchange at NB Subic in the RP. I remember pulling liberty in Hong Kong and seeing the 250 version of my 360. I didn't understand at that time why, but now I understand it was a market based approach to UK law. When I got the bike back to the US the Navy required safety training which included a riding skill test. I was able to get the highest braking score of our group of about 20 1975 contemporary Japanese bikes. The big four manufacturers were represented and some had drum front brakes. I have always believed you should be a proficient rider and braking practice is part of that. The 1975 CB360 will never compare to modern brakes, but they are more than adequate and should be capable of locking the front wheel. My new CB360T would do that.
 

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The 'stuck brake piston' was so common it was aj bad oke. Using brake fluid as a lube for seal is terrible advice (bad service manual :D) as being hygroscopic it causes te seal groove to corrode and the oxides push seal even tighter onto piston. It was pretty much a 6 month or annual job to clean out seal groove. I still have the 'dovetail' scraper I made while working at Honda dealers, saved a lot of time. If Teflon based grease had been easily available in 70's~80's we would probably bought it by the truckload but AFAIK only te military could get it at that time?
 

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using any grease, or oil, be an extreme minimalist in application so it's applied in a transparent film. Thicker doesn't help.
 
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