First ride of summer didn't go so well - Brake locked up

Posted: Mon Jul 13, 2009 11:12 pm

I was riding along quite nicely, thinking to myself, "You know what? This bike is running pretty good!" Throttle was pulling strong and responsive, life was good.

About 5 minutes later, it seemed to hesitate. Well, maybe hesitate isn't the right word, more like it was being bogged down. I also smelled something burning, but I didn't think anything of it. I recently removed my headers and repainted them with VHT black paint. This was the frst ride since the re-paint, so I figured it was just the paint curing. I figured wrong.

I pulled in the clutch to gently coast to a nice stop at a stop sign and found I actually stoppped way ahead of where I intended to. Tried to start out again, and stalled. Being a newb, I shook my head at myself, and started it back up, except when I squezzed the front brake, I noticed it was locked up - the lever wouldn't budge. I managed to force the bike into a parking lot, where it promptly fell over on me (try moving a bike without stalling it at low speeds with the front wheel locked up - not fun.)

As the straw that broke the camels back, the end knob of my clutch handle broke off when the bike tipped over - again. I had just put a brand new bikemaster clutch lever on last week. I don't think I got 5 miles out of it and its broken again. That alone was enough to piss off the pope.

So, to make a long story short, my right (as sitting on bike) rotor/pad was smoking, so I ascertianed it froze up on me. So, I shamefully limped over to a chiapatric office and called the wife to come bring me a wrench. I was able to crack open both bleeder valves and the front brake un froze. It was definetly the right one that was stuck. I rode home just on the brack brake alone.

So, Looks like I will be rebuilding both calpers for safety, and the master cylinder "while I'm in there." Any body have any suggestions on which is a good but cheap rebuild set?

Posted: Mon Jul 13, 2009 11:52 pm

The reason has been posted numerous times.

There is a small "release hole" inside the MC front or rear that plugs up.

Now of course the pistons can also be at fault,but they can be dead free and it does just what you describe.

The hole is so small just like the idle jet and often the release hole does not even look like it is a hole so is ignored.

Posted: Tue Jul 14, 2009 12:47 am

sonicrete wrote:

The reason has been posted numerous times.

There is a small "release hole" inside the MC front or rear that plugs up.

Now of course the pistons can also be at fault,but they can be dead free and it does just what you describe.

The hole is so small just like the idle jet and often the release hole does not even look like it is a hole so is ignored.

Bill,

I have never encountered this - I am not denying that it occurs to many - where are these openings located?

Posted: Tue Jul 14, 2009 1:26 am

The front MC is different model to model.

Some can access the hole direct from the reservoir. These are the solid metal kind.

Others have a plastic reservoir with an "O" ring to "shove" it onto the MC.

Access to the part the piston moves by what ever is needed you will find a large hole near the hose and the small hole near the lever. Usual the fluid is dirty and the small hole looks like just a drill spot,ie divot.

The rear MC has a hose from the reservoir down to a flange held on with two screws. Inside this flange same deal,top hole is large and the bottom hole is the small one,that plugs up. Obviously the crap goes to bottom right where the small hole is located.

Posted: Tue Jul 14, 2009 1:58 am

The MC small hole being plugged is common but does not seem like he likely cause this time. If it WAS a plugged MC it would have to affect BOTH brakes equally, some law of fluid dynamics I think. You might want to read through this recent thread.
http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=50209 HTH Gary

Posted: Tue Jul 14, 2009 2:49 am

[quote="sonicrete"]The reason has been posted numerous times.

Now of course the pistons can also be at fault,but they can be dead free and it does just what you describe.

[quote]

Didn't know that - but then again, I'm not a mechanic (I'm actually an accountant)

I will check into that. I thought it was odd that the brake lever was "stuck" and would not budge when pulled in. Proabably shitty brake fluid (it very well may be the original. I also thought it odd that merely reliving fluid pressure let the brake off (the bike actually drifted and almost fell off the kickstand when I cracked upon the bleeder valve) I would think a frozen caliper would be frozen regardless of fluid pressure or not.

If it woud save me caliper rebuilds, that would be great. Is there are way to test a caliper other than just moving the piston, and checking for obvious damage? Neither of them leaked fluid.

And question number 2 - should I just clean the master cylinder, or overhaul?

Posted: Tue Jul 14, 2009 3:12 am

As gggGary pointed out, the problem is likely in the caliper, since only rt. side locked up. That said, you'd be wise to overhaul the whole system - otherwise you'll have this problem again.

Posted: Tue Jul 14, 2009 3:21 am

Here's another thread to check out:
http://www.cb1100f.net/modules.php?name=Forums&file=viewtopic&t=49294&postdays=0&postorder=asc&start=0

Posted: Tue Jul 14, 2009 3:21 am

I recently bought brake parts from partsnmore the back brakes went together and work excellent with their parts.

Parts N More

Code Name Quantity Price/Ea. Total
-------------------------------------------------------------------------------------------
29-0002 Front Dual Disc Caliper Kit 1 $35.00 $35.00
29-0011 REAR CALIPER REBUILD KIT 1 $20.00 $20.00
29-3532 Brake Pads 2 $16.00 $32.00
27-1029 FORK SEALS - 39mm x 52mm x 11mm - 1 $10.00 $10.00
Shipping: 1. Continental US - Flat Rate $5 Shipping: $5.00
Sales Tax: $0.00
-------------------------------------------------------------------------------------------
Total: $102.00Parts N More

Posted: Tue Jul 14, 2009 3:30 am

Overhaul is not really true.

Disassemble clean and reassemble is closer.

Usually the calipers are full of a white residue from the brake fluid. It is common trapped behind the square ring.

After disassembly I use a motorised wire brush to polish the pistons. Same deal like a nice fiber brush to polish the hole after you use a pick to get the square ring out of the groove. When finished the pistons will just drop in and fall back out. It is the wedging action of the square ring that withdraws the piston and needless to say it does not travel far.

Disassembly of front requires two pices of wood in place of the pads. You pump the MC and the loosest one moves first,so it strikes the wood and then the other and other moves. By using thin pieces of wood the pistons will come almost fully out of the hole. Using the MC is the easy way. If you dump the fluid then it is harder taking say a grease gun on each caliper and pump it full of grease to get the pistons out,real messy. Air pressure is a waste of time,because if it is stuck they won't come.

Regardless you need to clean or make sure the release hole is open.

The release hole IS plugged because the heat of rubbing the disk expands the fluid and the loose one moves to lock the wheel. Otherwise releasing the bleeder would not release the wheel,it would be mechanically stuck. Having 4 pistons they are not all equally loose.

Posted: Tue Jul 14, 2009 3:40 am

dyrrtmann wrote:

As gggGary pointed out, the problem is likely in the caliper, since only rt. side locked up. That said, you'd be wise to overhaul the whole system - otherwise you'll have this problem again.

I'm thinking more fluid problem then caliper. Remember, I said the bike moved when I cracked the bleeder valve, and i didn't have to pull the lever to bleed any out. I only noticed smoke coming from the one side, it very well could have been both locked up. After reading a few posts about the return fluid hole to the master cylinder, I am leaning toward that being clogged. If a caliper was frozen, it would not have freed up by reliving fluid pressure.

At any rate, I have it all apart, I will clean a reassemble, then flush/fill with fresh fluid and let you guys know. Thanks for all your input!!! You guys are the best!

Posted: Mon Aug 10, 2009 9:20 pm

Okay, put everything back together, and the brake still locks up. Loosen the bleeder valve and let the fluid out, brake releases.

Two questions: If there is gunk in the "fluid return hole" to the master cylinder, does it require the MC to be rebuilt? If I unclog it, will it just clog up again but crud in the piston, etc?

Also, I put DOT 5 brake fluid in, for ABS brake systems. Could that be causing the problem? Fluid too thick, not compatible, etc? God only knows what was in there before, it was very tan-colored.

Posted: Mon Aug 10, 2009 10:11 pm

spartan8ball wrote:

Okay, put everything back together, and the brake still locks up.

What did you take apart, clean, and re-assemble with new seals etc?

--
Mikko

Posted: Mon Aug 10, 2009 10:20 pm

removed master cylinder, dumped it out, cleaned out resevoir, tried to take off the resevoir, but it wouldn't budge and I didn't want to bust it. Also draind all lines and bith calipers, and flushed a whole lot of lfuid through to make sure I pushed all the old fluid out.

I'm susspecting the master cylinder fluid return hole (the tiny one no one can see) is plugged up.

Posted: Mon Aug 10, 2009 10:43 pm

I view brake fluid flush as preventive maintenance (do it on all my vehicles at least once per 2 years).
And most definitely on every used bike/car I buy as soon as I get the thing home.

Once you already have a problem it's generally too late for simple flush.
You better get the rebuild kits for AT LEAST the master and do the disassemble + clean + inspect + re-assemble.
While at it, (especially since the brakes were ignored for too long) I'd do the same for the calipers too.
The kits are quite reasonably priced.

--
Mikko

Posted: Tue Aug 11, 2009 2:18 am

You CANNOT use DOT 5 in a system that had DOT 3 or DOT 4 in it. They are not compatible.

The entire system must be completly cleaned of the old fluid. This does not mean "flush". Good chance the old fluid is "soaked in" to the old hoses. At this point I cannot really say,but it is not good to have combined them. Dot 3/4 is glycol based and Dot 5 is silicon based,think enamal and laquer paint.

The reservoir will come off. Only an "O" ring holds it. It is really hard to do though and make crack the plastic after this many years.

The release hole is plugged,or replugged. Next version is the rubber cup on the piston is stuck so the release hole cannot "move it" to release the brakes.

At this point it really does not matter the entire thing needs to come apart. The hose could be disolved inside so it cannot release,the front hoses on the RV did this,so could be same deal here.

Posted: Tue Aug 11, 2009 3:05 am

spartan8ball wrote:

removed master cylinder, dumped it out, cleaned out resevoir, tried to take off the resevoir, but it wouldn't budge and I didn't want to bust it.

What you can do is use a broad flat blade screwdriver between the MC body and the metal base it sits in and gently apply pressure (lever-wise) and the MC body will pop out exposing the 2 fluid release holes. Unless the MC is really sun-rotted, it should pop out OK.

Posted: Tue Aug 11, 2009 11:05 pm

Well, just checked the bottle (brake fluid, that is) and it says, synthetic, exceeds Dot 3 and 4, so it must be DOT 5.1. It also wasn't purple (else I wouldn't have poured it in) and isn't ALL DOT 5 supposed to be purple?

In any event, I'll pry the resvoir off and take a look in there.

Posted: Wed Aug 12, 2009 2:17 pm

My dot 5 silicone was pale yellow.

Posted: Wed Aug 12, 2009 3:04 pm

If the bottle says "DOT 5" I personally would go by the assumption it's DOT 5 Very Happy

And you have to take those brakes apart anyways, you really need to.
Brakes are one part of the bike people shouldn't "mess with" and half-ass gobble together. YOUR life is on the line.

Order the rebuild kits (they are cheap), take apart both calipers and the MC, clean all (including the inside of the hose) and re assemble.
The all will work and you can feel confident about the brakes.

--
Mikko

MB-5 Joined: Aug 01, 2009 Posts: 6 Location: Hellertown Pa

The DOT5 I have is blue. It may be the manufacturer is different. Dot 5 won't soak up moisture, but I'm told that it doesn't work as well as Dot 3 or 4
Only time I've used it was when I overhauled the brake system on my daughters 67 Firebird. But that sets quite a bit.
You may want to check the brake hoses, I've found some that were degraded and wouldn't let the fluid return

Posted: Wed Aug 12, 2009 3:51 pm

Being a relatively simple hydraulic system...remember this:clean,clean and
more clean........if the master and calipers are clean and the inside of the hoses
are in good shape and not deteriorated...then it HAS to work.
I recommend that the brake fluid be changed every year...it is too simple
not to do.....Glenn our site Leader here believes in speed bleeders and so do I..
it makes a simple task too easy not to do....
I know that alot of members here have to store there bike in places that they wish that they did not have too.....that makes it all the more reason to flush
this important system....take care of the brake system and it will take care of
you. Very Happy

Posted: Sat Aug 15, 2009 1:22 am

UPDATE:

I wasn't able to get the damn c-clip out (I dont have circlip pliers, and I'm too lazy to go looking for any) But I did get the reservoir off and it cleaned out throuroghly. Looks like the hole was clear, but you can never tell. I can see how you guys could miss the fluid return hole, its very small in a little recess, while the fluid out hole is rather large.

I filled the whole master cylinder (Minus the resevoir) with brake parts cleaner and let it soak for a bit, then spray canned air into the fluid outlet to simulate brake fluid returning to the MC, and my cleaner started to bubble, so I know the return hole is clear now.

Also found out the fluid I put in previously was DOT 4 synthetic, it just doesn't say so on the bottle, all it said was compatible with DOT 3 and DOT 4, I looked it up on the internet, and it is in fact DOT 4. Just to be safe, I'm draining the lines and cleaning them too, and refilling with brand new plain old DOT 3.

When I clean the lines out, will the brake parts cleaner hurt the rubber hoses? Its the typical BRAKLEEN stuff that all auto parts sell for cleaning calipers, pads, rotors, MC, etc but it doesn't say it can be used on rubber brake lines.

Posted: Sat Aug 15, 2009 2:46 pm

Jebbysan wrote:

Being a relatively simple hydraulic system...remember this:clean,clean and
more clean........if the master and calipers are clean and the inside of the hoses
are in good shape and not deteriorated...then it HAS to work.
I recommend that the brake fluid be changed every year...it is too simple
not to do.....Glenn our site Leader here believes in speed bleeders and so do I..
it makes a simple task too easy not to do....
I know that alot of members here have to store there bike in places that they wish that they did not have too.....that makes it all the more reason to flush
this important system....take care of the brake system and it will take care of
you. Very Happy

If you are going to have an old bike you need the tools to work on them or pony up the money to have them done by someone. Being able to stop when you want to is good. Learn from your locked up brake and get them cleaned out completely!

Buy the retaining ring pliers and rebuild everything. There could be some dirt or solid matter inside the master cylinder. When I rebuilt my 750, there was solidified brake fluid in the whole system. It looked like brake fluid crsystals. I should have saved them maybe they could be polished and used as jewelry.

Posted: Sat Aug 15, 2009 6:30 pm

Dot 4 is better than Dot 3 and they are compatible.

It is the Dot 5 that must be only used where it was completly clean and only Dot 5 used after.

Assemble in sections,putting the open end of the hose back into the reservoir. Pump the lever. Eventually the MC will be free of bubbles. Called "bench bleed" in auto.

The front manifold deal is a big source of places to trap air bubbles.

Messy at best,protect the paint,but crack the bolt and pump the MC,to remove air bubbles here.

I have run clear hose from the caliper bleeder back up to the reservoir,and pump the MC.

All of this is basic to get rid of the BIG bubbles,then you can do the pump and release deal.

Some times you need to lean the bike over to get the bubbles to move.

Seems it takes a lot of effort to get all the air out of the manifold deal.

Another handy tip is after you clean the gunk out of the caliper,push the piston(s) fully to bottom. With the bleeder open you pump fluid into the caliper. This will move fluid down the hoses and hopefully with it the air in front of it,to come out the bleeder. Now when the bleeders are closed it will move the pistons filling full with fluid.