Sticking rear brake caliper caused a small fire on 80 CBX

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Duffey Lake rd.
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Sticking rear brake caliper caused a small fire on 80 CBX

Post by Duffey Lake rd. »

Recently, after they did a valve adjustment, my Honda shop also wanted to do a brake fluid flush.
A few days later, I noticed my rear caliper was intermittently sticking and the rotor getting hot.
At this point, I should have pulled the caliper but took it out for a test drive instead.
Unfortunately, about a mile away from my apartment, in a construction zone, it stuck again, and a couple of blocks later, when I pulled off onto a side street and stopped, my rear brake plastic rotor cover melted and caught fire.
So, that little plastic rotor cover is an Achilles heel of the braking system; it's something to watch out for.
The other problem was that the previous owner had let the pads go down to the bare metal in spots, scoring the rotor, so I ordered a new one.
The caliper also had some black sludge, dirty fluid in it, even after the brake flush, possibly because the bleed nipple is higher than the caliper.
This sludge might have caused the rear brake caliper to stick.
- Scott
CBX fire.jpg
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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by steve murdoch icoa #5322 »

Glad the damage wasn't any worse.
I would be going back on the shop that did the fluid flush. Obviously a rebuild that you are doing now would have been the preferred plan of action but if you were still seeing contaminated brake fluid it doesn't sound like they did a very good job.

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by CBX1000FAN »

Thanks - valuable information!

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by daves79x »

I’d be wondering about the valve adjustment too. Most dealers will not work on anything remotely as old as these.

Dave

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Jeff Bennetts »

Make sure your rear brake hose is okay and doesn’t have an obstruction in it somewhere!

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Duffey Lake rd. »

Jeff Bennetts wrote:
Sat Aug 07, 2021 9:53 am
Make sure your rear brake hose is okay and doesn’t have an obstruction in it somewhere!
Ok, I'll take it off and check; plus take look at the master cylinder.
The bike was repainted in 2015 and was sitting in a motorcycle museum in Calgary for a number of years.

The Honda shop originally told me they don't like working on old bikes and to come back in the fall, but then I pointed out a picture of their mechanic on the wall posing with his CBX to the service manager. lol
I also had brought in all the gaskets so he adjusted 18/24 valves and after, he changed out the rock hard rubber sleeves between the carbs and motor. (which I also brought)
The idle was at 3000 rpm before and about normal after. They want me to run with Seafoam carb cleaner before they sync them in the fall.

-Scott

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Duffey Lake rd. »

Jeff Bennetts wrote:
Sat Aug 07, 2021 9:53 am
Make sure your rear brake hose is okay and doesn’t have an obstruction in it somewhere!
It turns out the 40-year-old rubber brake hose was deteriorating and shedding rubber bits that were clogging the caliper piston seal.
I'm replacing it with an aluminum mesh hose from Webike Japan.
-thanks

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Jeff Bennetts »

Duffey Lake rd. wrote:
Sat Sep 18, 2021 2:56 pm
Jeff Bennetts wrote:
Sat Aug 07, 2021 9:53 am
Make sure your rear brake hose is okay and doesn’t have an obstruction in it somewhere!
It turns out the 40-year-old rubber brake hose was deteriorating and shedding rubber bits that were clogging the caliper piston seal.
I'm replacing it with an aluminum mesh hose from Webike Japan.
-thanks
We have members who sell them or jut go to their website, I’ve been swearing by them since they came out, originally out of Cleveland, don’t know where they come from now but the only way to go!

https://spieglerusa.com/

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Larry Zimmer »

Best I know, Spiegler is located in Dayton, OH. I think they make their own.
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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Jeff Bennetts »

Larry Zimmer wrote:
Sun Sep 19, 2021 11:13 am
Best I know, Spiegler is located in Dayton, OH. I think they make their own.
You’re correct Larry, I knew they were north of me, the USA rep used to come to Vintage Days and setup in vendors row, that’s how I met him, got a nice venue discount and did all my lines on my CBX, then later my ZRX. Dennis McCarthy met him that weekend also and became a Spielberg dealer and gave ICOA members a nice discount!

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Duffey Lake rd. »

Related video of 20-year-old Mercedes Rubber Brake Hoses clogged.
The guy cuts up a new-looking rubber brake hose that's clogged internally with rust particles and decomposed rubber bits.

Why Change Old Flexible Rubber Brake Hoses?
https://www.youtube.com/watch?v=MHghO7DTses

If you want to keep your bike looking stock; Spiegler https://spieglerusa.com/ or https://www.timscbx.com/ @ $195 is the way to go.
Last edited by Duffey Lake rd. on Mon Sep 20, 2021 6:36 pm, edited 4 times in total.

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Rick Pope »

Spieglar is indeed on the outskirts of Dayton, owned by Mattias Shaub. (sp?) That gray toy hauler I had came from him.
Rick Pope
Either garage is too small or we have too many bikes. Or Momma's car needs to go outside.

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Jeff Bennetts »

Rick Pope wrote:
Mon Sep 20, 2021 7:25 am
Spieglar is indeed on the outskirts of Dayton, owned by Mattias Shaub. (sp?) That gray toy hauler I had came from him.
I remember when you bought it, Mattias has always been personable and good to the CBX community!

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Duffey Lake rd. »

Disk brake / Floating caliper brake - How it works! (Animation) on youtube
It shows how the CBX single-piston brake caliper slides back and forth on pins when the piston is pushed against the rotor with hydraulic pressure and then slides back when the piston is disengaged.
Releasing the pressure from the master cylinder, the fluid inside the caliper/slave cylinder returns back to the master cylinder.

https://www.youtube.com/watch?v=1y17pDLC0E0

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Re: Sticking rear brake caliper caused a small fire on 80 CBX

Post by Larry Zimmer »

Nice animation. One thing not mentioned is what caused the piston to retract -- it is the piston seal!! That's why the 'release' is very small. And, with any amount of contamination or surface damage in the piston bore (or to the piston) the piston may not contract and will, then, drag. The worse the contamination/corrosion (internal) the worse the drag. To the point of just not releasing to any degree.
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