Front brakes almost locked up today.

Im cutting to the chase.
They were smoking at the stoplight a few minutes ago and the bike would barely roll.
Suggestions or Answers appreciated.

Thanks, Bill

 

Sounds like a stuck caliper or brake hose problem. See if you can push the caliper piston back.

 

Caliper rebuild time.

That happens with great frequency; it happened to me with both of my 550s, to differing degrees.

Usually, you notice it when trying to roll the bike backward; it will go forward but not back.

What happens is this: Over time, and with sitting, crud consisting of dirt and old solidified brake fluid builds up behind the seals in the channels they reside in. Meanwhile, those same seals have dried out or at the very least become stiff. The combination of these two things causes the piston to come out, only under braking force, but not "relax" to any degree when the lever is released.

You can pop the caliper off, clean up everything, and put it back together and it might work for a while (I tried that the first time) but it will start hanging up again.

The only true solution is to rebuild the calipers (they're very simple, it's the cleaning that's the PIA) and probably the M/C too. Rubber that's been immersed in brake fluid for 25+ years gets a bit tired. Especially if the brake fluid was less than wonderful for the last how many years?

One lesson I've learned going through this (rebuilding old XJs) twice now (and am on the third one) is that you simply have to resign yourself to a complete rebuild of the brakes and the associated hydraulics. Lines, caliper seals, master cylinder, etc.-- it's all going to HAVE to be done. I tried the "quick and easy" route on the front brake on my '81, after all, the PO WAS riding it...

No uh uh. Ended up rebuilding everything one component at a time as fixing one thing led to a failure elsewhere. I JUST got it right, finally.

So when I did my '83 I just rebuilt the whole shooting match to begin with. Trouble free since. Shoulda done it on the '81 but I was pinching pennies. False economy, just gotta do it.

Lesson learned.

 

Thanks,
I let the thing cool off before reading this, unscrewed the bleeder valve gave the front break a few squeezes and it released.
I took the pads out for a inspection. Knocked off the metal shavings with some heavy sandpaper. Took it down to the car wash and blew everything out.
I ordered new pads and found a set of forks I want from Craigslist with dual discs. Going to pick them up tomorrow.
Now I am researching rebuild info for the calipers and master cylinder.

 

chacal carries all the parts, and they will be the correct ones. Read the section on brakes in his catalog forum: http://xjbikes.com/Forums/viewtopic/t=14561.html

Do a forum search and you'll find pictures of both the master cylinder and caliper apart. Both are quite simple.

 

i had a v65 magna that did the same thing.

you have 2 holes in the master cylinder. one for the fluid to activate the brakes. the other for fluid to release back into the master cylinder. it was that hole that was plugged up so the pressure wasn't releasing. everytime the handle was pulled more fluid was pressured into the brakes. but nothing was releasing.

i took a pin needle and scraped out the second hole. it was full of rust. all systems a go after that.

try that first.

i rebuilt the caliper, then the master. and the problem still existed. that was time and money wasted to not fix the problem.

pop the cap off and y ou should see two holes at the bottom. one will be hard to find as it's filled with rust. but you can see the obvious difference in color as rust is brownish and the reservoir is grey.

 

Snowwy66,
Great idea, I LOVE a easy fix.
Thank you for you 2 cents!

 

"easy fix" not recommended when it involves your front brakes, and therefore your safety and well-being.

 

While I applaud the ingenuity, it really is paramount to fix the problem with brake systems, not just the symptom. I'd rebuild the master cylinder straight away, paying very close attention to the ports Snowwy mentioned. If possible, a complete system overhaul is "cheap" insurance when compared to a hospital trip. Please take this advice as the cost is your well being.

 

Thanks Robert,
I took the lid off the brake fluid and its no surprise that the fluid is milky brown. I emptied the fluid box and there were some chunks at the bottom that easily wiped out with a few q-tips.
Im guessing that the air port in the box is plugged up because I can not get the new fluid to pump back through the line.
(I ordered new brakes front and rear and researching the best master cylinder rebuild kit.)

 

Plan on rebuilding the calipers too; and replacing lines soon.

ALL the rubber parts in the brake system will end up needing to be replaced, one way or the other.

Rebuilding the M/C may not completely cure the sticking caliper issue.

 

I cant take much more bad news !!! hahaha

I finally got the caliper release hole unplugged, now Im in the process of building the pressure back up.

I read on here somewhere that if you hold in the brake handle over night the pressure will come back on its own?
Is that with the cap on or off?

 

I'm glad I read this. I was wondering why my bike was tough to roll backwards.

 

Yeah Heel... one of the holes was clogged in my master cylinder causing the caliper to stay engaged. I mean FULL of black and brown solidified crap !!!


The hole closest to the fluid line is the one that WAS plugged. I used a small guitar string to swab it out... after that a brown cloud was puffing back from the hole when I pulled on the brake.

I emptied alot of the fluid out so you could see the hole. Soaked up the bad fluid and flushed with new.

 

if it's not recommended then how do you propose that he fixes his problem as he already did. even though he still needs a complete overhaul. he just saved himself a lot of frustration trying to figure out why the problem wasn't solved.

 

Bill those bits and pieces are worn rubber pieces from the rubber cups and such. NEVER leave the brake fluid open to the atmosphere it sucks moisture from the air which lowers the boiling point of the fluid. The rust is from the lines. If your fluid was a milky color you had moisture in the fluid The lines are dated check them out they are probably as old as the bike. Check this out:
http://www.aa1car.com/library/bfluid.htm

 

I think there should be a screen in the master cylinder to keep the air hole from plugging.
I know the oil should never get to that point BUT, %&*# happens.

 

Ok Snowwy, the point is that your idea is great to troubleshoot the problem, and I'll give you major props for that.
What I think Fitz is leading on too is that it should be a troubleshooting procedure only and the only way to fix this correctly is to rebuild the master cylinder since a clogged port is an indicator of a braking system in poor health. Given the importance of this system operating perfectly each and every time, I definitely think a rebuild is indicated. Wouldn't you agree?

 

That's exactly what Fitz is saying. Just because they start working again, they're NOT healthy (good term) and need to be rebuilt for safety's sake.

Based on the condition of the fluid you showed us, the system needs to be rebuilt before you should trust your life to it. Remember, you're stopping a motorcycle that weighs 500 lbs before you get on it and fill it up with gas.

I understand wanting to ride but riding with shaky brakes could turn into a ride in an ambulance. You can't take shortcuts or do easy fixes and be safe.

Fitz just doesn't want to see anybody get hurt.

Did you check the REAR brake for delamination yet?

 

Are you referring to yourself as a third person? LOL

All pads are on their way. Rear brakes started squeaking 3 days ago.

This bike runs ok, looks ok, but if were worth anything Id be driving a new one. So, I will limp it along keeping everything working just good enough to ride it. I love the forums on here for that.

 

Brakes are only as good as the weakest link in the system. I have recently bought everything for overhauling the complete systems front and back. the soles on my boots are only so thick and I don't even want to think about trying to stop that way or even worse lay it down to keep from running under the backend of a semi. I spent 22 months healing from a shatered elbow could not work or even think about riding, and that was from falling off my flatbed trailer I want to Thank XJ4Ever for having all the parts I have needed Thanks Len for the fast delivery on all my orders

 

with the crud that he's got in his system. sure, he needs an overhaul.

i didn't have to rebuild mine. nothing looked bad but got new seals anyways. i only had dark fluid and a rust filled hole that caused my problem.

it happens to everyone. first thing thought of is frozen calipers. next is master. it never occurs to anyone to check the holes in the master first. it surely didn't occur to me. and took me a month of internet research before someone finally dished out the answer to all my problems. not even the dealer could figure it out. and they were the last hope for a solution.

i'm not saying NOT TO REBUILD the system. all i'm saying is check the master first. that's probably what the initial problem is. i've been reading lots of stories lately.

 

Snowy where do you think the rust is coming from?

 

BillB PLEASE read this thread; I'm not referring to squeaking or how they "feel" I'm talking about immediate catastrophic delamination and possible rear wheel lockup: http://xjbikes.com/Forums/viewtopic/t=15874.html

Read what happened to other people. Are you ready for the rear wheel to suddenly lock up with no warning? Check the rear brake NOW.

It's a motorcycle not an old car; this stuff can hurt you.