Seized rear caliper, boiling brake fluid

alpental

Turbocharged
Joined
Feb 22, 2015
Messages
784
Location
Alexandria, VA
Ride
2014 Rocket III Roadster
Last night I was cruising home from the Long Beach Int'l Motorcycle Show and my Rocket must've gotten jealous of me looking at other bikes. While hitting a little traffic on the freeway, I pulled in the clutch and noticed the bike decelerating more than normal. Front brake seems fine. Rear brake pedal won't budge - won't go down or up. I look back and my rear rotor is blazing red hot. I pulled over and saw brake fluid dripping down from the rear master cylinder. It eventually cooled and released so I could drive home but I had no rear brakes.

This morning I'm checking out the situation and the rotor is wavy and damaged, one piston in the caliper looks seized, pads have been obliterated (I change them every 5,000 miles with every rear tire change), the caliper even looks a different color, and there's still brake fluid dripping from the rear master cylinder. WTF could've happened? The bike is 21 months old with 20,800 miles, and was just about to get the 20,000 mile service.




 
Someone else here had that same problem. As I recall he took it to the dealer and was of course told he's an idiot, not supposed to rest his foot on the rear brake . . . DUH

I do wonder if this is a fundamental weakness of the Rocket.

I hope the folks who know things chime in here.
 

I never use the rear brake except when I want to change leaning angle while in a turn. still think rear brake are as useful as screen door on a submarine .
 
This happened with my feet on the highway pegs, so no chance of riding the rear brake. My current thinking is that one of the inside caliper pistons seized while retracted, causing the opposite piston to extend farther than normal, and it got stuck in that position unable to retract. Look at the difference in piston positions in the third pic.
 
Wrecka said:
Something similar happened to @ RKTNMYPKT maybe he can let you know what his final outcome was
Click to expand...
That's right, I forgot about that. Jim's post is here: Broke down
The final outcome for @RKTNMYPKT was the dealer flushed his brake fluid and put on new pads, only addressing the symptom and not the root problem, and he sold his Rocket and got an Indian. Meanwhile, @jpool was with me and was laughing at me from his new FJR, and is about to sell his Rocket after his transmission (and other) issues.

This is going to need a new rotor, pads, fluid, lines, caliper and master cylinder rebuild (possibly new ones)... Good thing last week I already ordered some Hel Performance stainless steel lines as replacements: Triumph Rocket III Roadster ABS (2011-2013)
 
I have had exactly the same thing happen with the front brake caliper on a Busa . 50 mph and a mere finger touch to the brake lever caused the brake to seize solid . Had I been in the twisties I prob wouldn't be writing this . On strip down , oxide had accumulated behind the piston sealing rings causing them to tighten on the piston until it could no longer return , this caused friction between the pads and rotor which in turn produced heat which warped the disc followed by total seize up . The fluid boils and evacuates everywhere it can ! Your rotor is toast . The discolouration is heat burning off the finish .
Whatever the cause , which could be from unintentionally riding the rear brake , you are gonna need to strip the caliper and replace the seals . If the seal grooves are clear of gunk and no obvious reason for failure of the caliper , you may have to check your riding style and or brake pedal adjustment ?
 
Apologies , I was still writing when your post went up about not riding the brake !
 
I can remember as a youngster hearing folks talk about how they kept the Red Ball Express running during WWII, keeping the front lines supplied following D-Day, as they advanced toward Berlin.

They couldn't afford for things to break down, and had regular schedules on the trucks for repacking the wheel bearings, relining the brakes, and so on.

I'm thinking there are parts of the Rocket that need to treated the same way, such as the calipers, not just the pads. And the TPS exposed to weather. And . . .
 
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