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Discussion Starter · #1 ·
The front brake is not performing the way I would like. It doesn't have the bite it should and this is making me not want to ride her. When I built the bike I replaced everything in the front brake system, master cylinder kit, new SS hose, new David Silvers brake line, new caliper piston, all the rubber parts and of course new pads. The disk is very low mileage. It came on the wheel purchased on ebay. The grease in the factory wheel bearing was still white. The disk was buffed on the wire wheel to remove any old pad material.
In search of better braking, I'm looking at an upgrade to the pad to a better material. Durability is not an issue, this bike has seen about 1600 miles over the two seasons it has been back on the road. I see different materials, EBC Kevlar, Brembo Carbon Ceramic, Metal Sintered and organic. What are the differences?

My 1975 CB360T bought new back in the day would chirp the front tire at 30 MPH. This bike has the same front brake and is no where near this powerful. I think it is an organic pad. Does anyone have any thoughts or experience on these materials? What is the up or down side to them? Or am I missing something?
 

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I had enough spares from 3 750 front ends and 2 450s that I picked the ones that worked the best. I can lock the front brake and get the rear to step out if I'm not careful. I'm not sure what material they are. I'll bead blast the discs when they're apart. I think vintage brake sells pads that'll work, but not sure what year. You could retro fit though. Maybe asbestos was key?
 

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Is the wear pattern on the disc as wide as the pads, both sides?
In my experience, organic pads have the least braking power, and the sintered pads have a lot more. I haven't tried Kevlar pads, but the carbon ceramic pads I put on my roadster kick in the ABS sooner than stock pads, as they warm up. And that is an issue - many of the high performance pads only get strong after a good warmup, which seldom happens on the street; something to check for when reading the specs.
 

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Discussion Starter · #4 ·
I've been doing some reading on various Web sites. EBC has a lot of information. It comes down to disk material. Two basic types, cast iron and stainless steel. Honda used stainless. Iron has a higher drag coifficent than SS, but is softer and will wear sooner. Organic is easier on the disks than metallic, but has less bite. The bottom line is for our stainless steel rotors, we should be using metallic. Sintered metallic pads run 30 to 65% metallic. So far all I have seen is 30% semi-metallic. I have the later stye calipers with the alignment pin.
I need to take the brake apart and see if there is something causing the poor performance. Lefty, I will check as you suggest.
 

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Discussion Starter · #5 ·
The Fix is in!

I managed to get a couple of free afternoons to work this problem. Turns out the majority of the problem was the front caliper leaking. I knew it, but was ignoring it. I started by removing the the caliper, bagging the brake hose. Then I cleaned up the caliper castings, running them through the ultrasonic cleaner and painting them. I hve been getting good results when painting below 60 degrees by bring the paint and parts into he house the night before, then quickly painting the parts out in the garage. Then I ordered a new brake line pipe and caliper seal. I did this back in November.

Here are the overhauled and new parts ready for assembly:

1 New and refirbished parts for the Caliper 2.jpg

Here are the EBC semi-stintered pads for the CB450 K5:

2 EBC Semi Stintered Pads.jpg

EBC got a little sloppy with the paint. This was disappointing:

3 EBC Pads Orange Paint disapointment.jpg

The pad face was cleaned with 100 grit sandpaper:

4 EBC Brake Pads after cleaning with 120 grit sandpaper.jpg

More disappointment, the piston side pad would not fit into the caliper because the paint was too thick. The paint was removed. Bare steel is not the best. It would be better if EBC would give the steel some kind of phosphate treatment and leave it as that.

5 EBC Pads Orange Paint disapointment 2.jpg

Caliper and mounting bolts ready for installation:

6 Caliper Ready for installation 2.jpg 7 Caliper Bolts with anti-copper seize.jpg

Clean the rotor with simple green:

8 Cleaned rotor with simple green.jpg

Reverse bleeding the brake:

9 Reverse Bleeding 2.jpg

Reverse bleeding is good to get the brake lines filled with fluid. It was still a problem to get the master cylinder primed and the caliper piston moved out to contact the rotor. After it was bled, the lever remained mushy. My son went over to the Goldwing and told me it should feel like this. I immediately realized the GL had stock Honda parts in the master and the CB has pattern parts in it. Before the spring rolls around it will get the proper Honda parts.

The clutch was adjusted and I took the bike out for a short test ride. The brake was mushy, but I did a few stops and pumped the brake. It felt good to get the 450 out. I hadn't ridden it since October. 44 degrees outside, dark and cold. I put about four miles on it. The front brake works OK, more to come on the mastercylinder.
 

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.. you said you spent money on a rebuild kit.. I am assuming it was for the brake master... my wife's 450 had issues with the front disc not releasing, constantly having pressure.. but after resting it was fine.. thought it was from my not adjusting proper or heat... Especially after the front master rebuild. Seemed to work proper after, but it was short lived. Not sure if the kit (valve) wasnt working properly, or if the lines or switch was causing problems.. Did I mention I replaced the caliper AND pads?...
Well, after replacing the master... everything works like new... Brakes will lock up when grabbed hard, and release just as they were intended to....
Has anyone had "issues" good / bad with master brake rebuild kits? I read multiple threads / forums that rebuilds some were great, some not so much? Any suppliers to avoid?
The kits are half the price of a "replica" / replacment. Making a rebuild inviting... but not if the parts aren't up to snuff..
 

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Jim- did you try bleeding under pressure into a line while cracking the bleeder and watching for air bubbles? Maybe the vacuum isn't doing the job. I have a master that works fine but leaks pretty good waiting for a rebuild.
 

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Discussion Starter · #8 ·
.. you said you spent money on a rebuild kit.. I am assuming it was for the brake master... my wife's 450 had issues with the front disc not releasing, constantly having pressure.. but after resting it was fine.. thought it was from my not adjusting proper or heat... Especially after the front master rebuild. Seemed to work proper after, but it was short lived. Not sure if the kit (valve) wasnt working properly, or if the lines or switch was causing problems.. Did I mention I replaced the caliper AND pads?...
Well, after replacing the master... everything works like new... Brakes will lock up when grabbed hard, and release just as they were intended to....
Has anyone had "issues" good / bad with master brake rebuild kits? I read multiple threads / forums that rebuilds some were great, some not so much? Any suppliers to avoid?
The kits are half the price of a "replica" / replacment. Making a rebuild inviting... but not if the parts aren't up to snuff..
Rob,
This bike went through a full restoration between Spring '13 to June '15. I rebuilt the master cylinder during that time. It has a pattern piston kit in it. Over the last winter I re-commissioned a '85 GL1200I. The 1200 has the correct OEM rebuild kit in it and the front brake is sharp. The 450K5 front brake is safe and stops the bike, but it feels mushy.
 

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Discussion Starter · #9 ·
Jim- did you try bleeding under pressure into a line while cracking the bleeder and watching for air bubbles? Maybe the vacuum isn't doing the job. I have a master that works fine but leaks pretty good waiting for a rebuild.
I'm pretty sure I got all the air out of it. The bleeding process was started started by reverse bleeding up from the bleeder screw. Then a Mity Mite was used to draw fluid down from the master. Once air bubbles quit coming out the bleeder was closed. The lever was still pulling to the bar. Then we would pump up the lever 3-5 strokes and held. Then the bleeder was cracked and the lever pulled back to the handle bar.

The 1200 has a single side front (left disk) brake, combined front (right disk) - rear and a hydraulic clutch. On this bike all three of the calipers (double piston), the clutch slave cylinder and all three of the master cylinders were rebuilt, the lines were replaced with stainless steel and bleed. Don't ask me why because I really don't remember. The clutch and rear master got pattern rebuild kits and the front got an OEM Honda rebuild kit. All of the calipers and clutch slave cylinder got pattern seal kits.

From this I have deduced the Honda OEM master cylinder kits are better. The pattern master cylinder kits are hard to bleed and they feel mushy. They are a waste of money. The problem appears to be in the check valve at the end of the master cylinder piston. It is hard to get it to 'prime' (as in pump) and once it is primed it takes part of the lever stroke to get it build pressure and does not completely seal This makes the lever mushy and if you pull hard on it, the lever can be pulled to the handle. So far the pattern caliper seals are holding up.

My kid broke the front master on his XR650 last summer. to get quickly back on the road he pulled the front master from his CR250. He had it bled in 10 minutes. The front brake master on the 1200 took 10 minutes to bleed. Of course he lectured me on this while showing how nice the front brake worked on the 1200. I'm so proud :)

When I rebuilt the front caliper on the 1200, I was wondering how to get the air out. The bleeder is at the top of the two pistons and the hose connect between the two pistons. The 1200 caliper has a 10mm set screw on the end opposite of the brake line. Front (left) and rear calipers are the same. The front is mounted behind the fork and nearly vertical. The picture shows the reverse bleed on the rear caliper, I don't have a picture doing the front. The point being is the front caliper was bled from the set screw and required no further screwing around.

My advice for those who are faced with overhauling the Honda Motorcycle master cylinder is to keep the stock piston unless it is not serviceable. Only replace the rubber seals. Upon teardown inspect the piston for corrosion and any wear. If it is good, replace the rubber. Or just buy the Honda OEM rebuild kit.

The plan forward for both bikes is to obtain the correct Honda OEM kits. The 450 shares the same front brake master cylinder as all of the 1970s hydraulic disk brake models. They appear to be available from Honda. More to come.
 

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As far as mushy goes, are you sure you got all air out of the MC banjo fitting? That is always a trouble spot. I've had the best luck tilting the MC so the fitting is below it, maybe 30 degrees tilt; make sure the reservoir cap is tight, or the level low enough. Then VERY slowly squeeze the lever until tight, hold a count of ten or so, then release it as quickly as possible. This should draw some air out, and, since it's the brake, takes a lot more pulls than a clutch MC. Also, the air is now trapped again in the MC, so you may have to gently move the lever in and out a bit to expel it into the reservoir.

Another improvement for soft brakes is to replace the flexible line, as they turn into balloons with age. I replaced mine with the stainless-wrapped ones from Motion Pro, and it really improved the feel.
 

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I’ve rebuild master cylinder and brake caliper of my 500t and the caliper of my 450 recently. I’ve used proper Honda and aftermarket parts and can’t tell the difference so far. I just guess the Honda brake caliper will probably last longer. My key takeaway of the brake projects was patience, patience, patience. At first brakes weren’t great after bleeding so I went back to the garage for a painstakenly long brake bleeding. I let them rest overnight, tipped the brake lines over and over again and let it bleed until I couldn’t see the slightest bit of a bubbles in the reservoir. Then after slowly riding them in, both worked fine.


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Discussion Starter · #14 ·

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Wow, I'm saving for a lathe that is big enough to turn a brake disk. This one has a 17" swing with the gap removed: 12" x 24" Gear-Head, Cam Lock Spindle, Gap Bed Lathe | Grizzly Industrial
Yeah, I think ebc makes modern stainless discs too. Even the earlier bigger stock disc would be a good improvement. Honda must have thought it was too much so they shrunk it. In any event, check your bore good before you install the Honda label parts. Maybe a resleeve is in order.
 

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I have the same front end on my CB360. I also did a complete replacement of the entire front brake assembly with new/reproduction parts. Still feels a bit mushy, but better than what I had before!
 
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