Topic: General Brake Advice Please

[Stev-o]

+1 to replace the brake lines, here is the link to Apex....

http://www.apexbrakes.com/custom.asp

[Kelly E]

Modern brake lines are an improvement over stock. Running original brake lines that are 40 to 50 years old is just dumb. No nice way to put it.

[HondaMan]

Without excerpting from my book: Honda was scared to death that riders were going to somersault over the handlebars upon applying the front disc brake.
(If only?).
So...they used rubber lines from the master cylinder, with its oversized piston to fight back a little at the rider, and stainless steel on the disc - for 2 reasons: the Cosmetics Department didn't want any rust, and the aforementioned engineers didn't want the owners to run over themselves, so the brake lost efficiency.
(Isn't politics and engineers' worldview odd?).

For racing apps back in their day, we used shorter flexible hose portions between the banjo mount (under the triple tree) made from stainless overbraid (truck, in those days) flex lines. To make up the fork-travel distance we made the lower steel lines a little longer. Then the line from the master cylinder to the banjo mount was replaced with hard line. We called this the "power brakes mod", and it really changed the brake: I should add we also added the other side, for dual brakes. Then it became a 1-2 finger brake, still very progressive feel, that could lock the front wheel.

In street use, I've found that at some point, the system suddenly needs a lot more grip to stop like it once did. My own did this, but it was after it sat 5+ years when I had cancer and was out of the riding thing for a while after, healing back up. When I came back, my front brake acted like yours. I pulled apart the (quite cruddy!) caliper and cleaned it all, put in a new seal, replaced both flex lines and rebuilt the master cylinder. That was in 2005 or 2006, and was the first time this had been done to the bike (126k miles). Since then it's been my old 2-finger, 3 if danger looms, front brake.

[rotortiller]

Why and how lwould Honda be worried about people flipping off the bike from the #$%*ty front brake? Didn't the ride the thing? 0lol!

[Deltarider]

What Hondaman said, makes sense imo. For Honda the US was to be the biggest market by far and you can't sell rusty things to Americans. They want shiny things. That goes so far that - purely for marketing reasons - the wonderful fork gaiters which protected so well, had to move for shiny legs. Even the bumpers of US utility vehicles, like ambulances and fire trucks, are shiny! The better disks were Brembo like, but they rust. I can also understand that Honda, who were the first to put disk brakes on bikes for the consumer market, were reluctant to go to the edge. As long as performance was well within what the law required, why would they risk it, by having bad press because of accidents due to locked front brakes? It all made sense. Then - just to remind you - in all the reviews - and I have quite a few in my archives - those same disk brakes that meet so much criticism here now, were... praised.
Even today, I am not short of stopping power and - when really pushed in a serie of repeated hard braking - I can even make the disk sing, be it that I almost need two hands to arrive there.
I've put it before that in todays traffic I fear more to be rear ended as a result of too aggressive braking.
You know, I sometimes wonder, all these people that go to modify that front brake, what is it they really want? Could it be they just can't wait to do another job on their bike, which so often is more of a project than a riding machine?

[HondaMan]

Why and how lwould Honda be worried about people flipping off the bike from the #$%*ty front brake? Didn't the ride the thing? 0lol!

...and that wasn't all! Honda was worried about 'too much acceleration', which became the 2-or-3-regrips of the throttle to reach full carb opening.

- They couldn't decide if the bike was going to become the world's tourer (which it did) or the world's Saturday Night stoplight racer (it did) or if it was going to be carrying heavy loads (it did), so the front trail of the forks, which should be like in the F0 and later ones (4.0"+), became something less than 3.6" (most are 3.25" - (K0 thru K3) to 3.5" (K4 thru K6)). Too much trail makes for heavy handling at low speeds, too little makes for squirrel-y handling at speed.

- They couldn't decide if the bike should be geared so as to reach redline in top gear (too racer-ish?), or should it be overgeared to prevent "frivolous" engine speeds in fifth. Too racy? / Not enough performance?

-They were unsure of how the bike would be perceived by the non-riding public: the fiberglass stuffed inside the HM300 pipes was there for those folks, to quiet the bike while riding thru the neighborhood (presumably in 3rd gear?). This led to the expensive decision to employ American-like cosmetics, as USA was the lion's share of the market, and at the time the Japanese people weren't allowed (but for a few elite) to ride such a monster bike there. (Have you ever seen Kawi's 4-cylinder 750 that was going to be in the same show as the CB750 in 1968 - but was pulled out at the last minute? It was Japanese styling thru and thru).

Yep, Honda basically 'bet the farm' on this bike. The upper management at Honda was steam-rollered by Sochiro and his financier best-friend, and most of Honda Management of the time was not in favor of this bike. Not one bit!

[rotortiller]

Fingers are too big for the phone keypad and the eyes are too weak (like the front brake) for the small text, sorry for the messy text. lol

[BenelliSEI]

The Brakes on my '78 K8.  Are dangerously ineffective.  I mean it.  Very poor.  Front brake only slows the bike down a bit.  I can't imagine how much pressure on the lever would be needed to lock up the front wheel.  Probably enough to break the lever.  Rear brake works better than the front, but still pathetic.  I know these brakes are now disappointing by today's standards but I have to believe they are not working as designed.  Back in the day, it seemed to me my '75 CB750K had "Hand of God" brakes.  Quite effective, for its time. 

I swapped out the front pads a few years ago but I do not recall rebuilding the caliper or MC.  Rear brakes very well may still have the original 45 year-old shoes.  What can I do to improve braking performance?  Here are a specific couple of questions:  Do you suppose the age of those rear shoes could have made them too hard?  Are there particular brands of brake shoes or pads that are known to be more effective for these bikes than others?

Just reread the original post….. Try rebuilding or replacing your master cylinder. Clean out your caliper and install a new seal. Order a set of Apex lines and new pads. I suspect your neglected braking system might really impress you with some overdue attention.

P.S. Just read that is your plan. Good Luck.

[BenelliSEI]

Reading these posts reminds me I still want to try one of those cast iron discs the guy in Australia sells on EBay. This winter…….

[Kelly E]

For Honda the US was to be the biggest market by far and you can't sell rusty things to Americans. They want shiny things. That goes so far that - purely for marketing reasons - the wonderful fork gaiters which protected so well, had to move for shiny legs. Even the bumpers of US utility vehicles, like ambulances and fire trucks, are shiny!

Why do you constantly go out of your way to bash America?

You would have a flaming hissy fit if I talked like that about your country.

Like momma said, "if you can't say anything nice keep your damn mouth shut".

[jonda500]

I didn't know liking shiny stuff was a bad thing? I refuse to be ashamed of my love of chrome and all things shiny!
John

[Deltarider]

I didn't know liking shiny stuff was a bad thing? I refuse to be ashamed of my love of chrome and all things shiny!
John

I don't mind shiny stuff at all. But I do when it stands in the way of higher quality, like with better quality cast iron disks and those useful gaiters. On the other hand: shiny bumpers on utility vehicles, who needs them? I mean bumpers?!

[newday777]

I didn't know liking shiny stuff was a bad thing? I refuse to be ashamed of my love of chrome and all things shiny!
John

I don't mind shiny stuff at all. But I do when it stands in the way of higher quality, like with better quality cast iron disks and those useful gaiters. On the other hand: shiny bumpers on utility vehicles, who needs them? I mean bumpers?!

Here in the states there are a lot of utility pickups and vans with black bumpers and grilles sold, not all chrome as you think and have said..... please be careful when you generalize accusation

[BenelliSEI]

I didn't know liking shiny stuff was a bad thing? I refuse to be ashamed of my love of chrome and all things shiny!
John

I don't mind shiny stuff at all. But I do when it stands in the way of higher quality, like with better quality cast iron disks and those useful gaiters. On the other hand: shiny bumpers on utility vehicles, who needs them? I mean bumpers?!

What nonsense.

[Deltarider]

Accusation? I referred to Honda's strategy in marketing. But maybe one of you can give me a rational technical reason to abandon those harmonica rubbers which had served for decades and decades on a wide variety of motorcycles?
Asked for a reason why European cars that were so successful here and had such a good reputation that the manufacturer could maintain the same model for years and years, didn't sell in the States, an importer once responded sighing:
"We always hear this in our showrooms: "Where is the chrome?!" or "What?! Four cylinders only, do you hold me for poor?!"
Conclusion: it's a matter of taste and de gustibus non est disputandum.

[Kelly E]

As the southern boys say, "Well bless your heart"

[Rosinante]

Just reread the original post….. Try rebuilding or replacing your master cylinder. Clean out your caliper and install a new seal. Order a set of Apex lines and new pads. I suspect your neglected braking system might really impress you with some overdue attention.

P.S. Just read that is your plan. Good Luck.

Yup.  This is also HondaMan's suggestion and this is my plan.  Parts are on their way.  Fresh pads are not on their way but I could order them once I look at the current ones.  Which are sintered, I believe.  I might ask the Brain Trust here about pad preferences.

I am once again stunned at the contributions of HondaMan here.  Truly a treasure.  I am very glad he is so generous with his knowledge and time, and that he likes to write.

+1 to replace the brake lines, here is the link to Apex....

http://www.apexbrakes.com/custom.asp

Rather than try to find specs for this brake hose so that I could have Apex custom-fab one for me, I found this unit which should fit and function nicely:

https://oldbikebarn.com/products/honda-77-78-cb750a-78-cb750k-front-brake-hose

As it turns out, this is a single-year hose (1978) at least for the K bike.  One long hose from the MC to the caliper.

I also ordered shoes.  Even though nobody is suggesting this, I just think that 45 year-old friction material cannot be ideal.

And, anecdotally, as all of you know, stopping is maximized by a balanced application of both the front and rear brakes.  Back in the day, and with all due respect to today's universally negative impressions, I found this technique to be actually quite effective.  I suspect that once I have implemented my plan, I will have pretty good braking.  Perhaps not as good as modern bikes, but still pretty good.  This is my expectation.  At least....far better than the current pathetic braking.  Current braking is not two or three fingers as HondaMan describes.  Currently, four fingers and a firm pull gets only a sort of "slowing down" action that can result in stopping, but only after considerable distance.

[scottly]

Bad brake hoses usually give a "spongy" feel at the lever, as they swell under pressure. Is your lever firm?
The bottom line is that your '78 brakes should be just as good as the '75 brakes were.

[calj737]

Asked for a reason why European cars that were so successful here and had such a good reputation that the manufacturer could maintain the same model for years and years, didn't sell in the States, an importer once responded sighing:
"We always hear this in our showrooms: "Where is the chrome?!" or "What?! Four cylinders only, do you hold me for poor?!"

Pssst…. It’s 2023, aBhat. Most every vehicle (sedan, coupe, etc) are sold with painted bumpers. Some trucks still do have partial plated bumpers but that is entirely a design aesthetic. Back when you last bought anything new (you know, when Columbus sailed the seas) chrome was very popular in Europe, Asia, America and the UK.

[BenelliSEI]

That hose looks perfect! When I order from Apex I lay the old hose out on a sheet of scrap cardboard and mark the centre line on both ends and write the actual measurements. I send Raymond an email with a photo, plus photos of the fittings. He always gets it right! They also include the correct banjo bolts and washer. Great Service.

[Kelly E]

That hose looks perfect! When I order from Apex I lay the old hose out on a sheet of scrap cardboard and mark the centre line on both ends and write the actual measurements. I send Raymond an email with a photo, plus photos of the fittings. He always gets it right! They also include the correct banjo bolts and washer. Great Service.

7 out of the 9 bikes in the shop have Apex lines. One hasn't been resurrected yet and the other one has cable operated brakes.

[BenelliSEI]

Raymond at Apex has been making lines for our bikes and race cars for years.
Hard to beat great product and even better service. Last year I needed some odd ball lines for the little Toyota “rent a racer” and he built them up in a few days.

[rotortiller]

Current braking is not two or three fingers as HondaMan describes.  Currently, four fingers and a firm pull gets only a sort of "slowing down" action that can result in stopping, but only after considerable distance.

The only time I use 2 fingers is to hold on a hill, especially so because I know if and when I have to slow down it will often take a mitt full. With these heavy poor braking tanks I plan carefully, however there is not much a fellow can do when a cage does something sudden and unexpected. The tire and wheel will certainly handle better front brakes as will the front end.  The ideal situation would be a newly cast caliper with dual pistons, longer pads coupled to a suitable master cylinder. SOHC forks with the swinging caliper arm prevent the easy adaptation of modern bike technology unfortunately. Anything we do to improve (while implementing the POS single OEM caliper design) is minor in nature by comparison.

[Deltarider]

Asked for a reason why European cars that were so successful here and had such a good reputation that the manufacturer could maintain the same model for years and years, didn't sell in the States, an importer once responded sighing:
"We always hear this in our showrooms: "Where is the chrome?!" or "What?! Four cylinders only, do you hold me for poor?!"

Pssst…. It’s 2023, aBhat. Most every vehicle (sedan, coupe, etc) are sold with painted bumpers. Some trucks still do have partial plated bumpers but that is entirely a design aesthetic. Back when you last bought anything new (you know, when Columbus sailed the seas) chrome was very popular in Europe, Asia, America and the UK.

Pssst... You've missed that my post was in the past tense. Also phrases like "the same model for years and years" and "once responded" were clear indications for anyone who masters reading.
That nowadays bumpers are in the same color as the body, I'm ofcourse well aware of. I was in the US (Southwest) last April. You're such a humorist, Cal, I dunno how you do it, but you always make me laugh.

[calj737]

Current braking is not two or three fingers as HondaMan describes.  Currently, four fingers and a firm pull gets only a sort of "slowing down" action that can result in stopping, but only after considerable distance.

The only time I use 2 fingers is to hold on a hill, especially so because I know if and when I have to slow down it will often take a mitt full. With these heavy poor braking tanks I plan carefully, however there is not much a fellow can do when a cage does something sudden and unexpected. The tire and wheel will certainly handle better front brakes as will the front end.  The ideal situation would be a newly cast caliper with dual pistons, longer pads coupled to a suitable master cylinder. SOHC forks with the swinging caliper arm prevent the easy adaptation of modern bike technology unfortunately. Anything we do to improve (while implementing the POS single OEM caliper design) is minor in nature by comparison.

Dead right. 2 finger braking while “capable” is NOT recommended by professional instruction because it does not provide the same level of control as 4 fingers. And these antique brakes won’t do crap in an emergency braking situation with 2 fingers. Tires a too thin, bias ply, single caliper and disc, spindly forks. All add up to substandard by todays standards of traffic and travel conditions.