Rear Brake is driven me crazy

[DRACOCOSTARICA]

Hi all, here I am with another issue.... the rear brake of my Electra Glide Classic 1991 one day locked up and the brake pads almost caught fire, I did open the bleed screw and release the pressure (no more rear brake) once I got home I dissambled the master cylinder and a mud like fluid came out so I rinsed all the system with new DOT 5 brake fluid and every thing was ok.....
Another day I took the bike for a ride and the rear brake almost caught fire again so this time I took out the caliper and rebuilt it (seals and piston wore bad) changed brake pads, change brake line from MC-caliper, change banjo bolts and washers, cleaned the rotor, flush the system with new DOT 5 (is what the reservoir cap says) bleeded a lot of times to get the air out....checked for dragging pads and OK all good so far BUT.... If I take the bike for a ride and I press the rear brake...guess what? It gets locked again little by little until the brake foot lever is completely stiff (doesn´t move at all) so the rotor is very hot, when the temperture goes down the caliper released again....
Anyone can help me??? Thanks a lot in advance

 

[fin_676]

The only thing that springs to mind is that there is no free play at the brake pedal the brake pedal should move a wee bit loosely before it starts to push the piston in the master cylinder if not as the brake disc heats up and expands the pads will be held lightly against the disc causing more heat and expansion and lock the brakes
so the wee bit of free play helps allow for heat expansion of the brake system

Brian

 

[Hoople]

Like Brian said, the piston in the master cylinder is not returning to it's final rest position like it should.

The compensator port in the master is remaining covered (a slightly depressed piston). When that happens, any fluid expansion within the entire system has no where to go. Fluid is prevented from being pushed back into the master cylinder reservoir and the brakes lock up.

 

[glider]

Check out the bleed holes in the master cylinder.

Harley Davidson Community

 

[Breeze3at]

Like Brian said, the piston in the master cylinder is not returning to it's final rest position like it should.

The compensator port in the master is remaining covered (a slightly depressed piston). When that happens, any fluid expansion within the entire system has no where to go. Fluid is prevented from being pushed back into the master cylinder reservoir and the brakes lock up.

That's what I was gonna say, but it would have taken more words.:newsmile011:

 

[Hoople]

That's what I was gonna say, but it would have taken more words.:newsmile011:

Brian said it using X amount of words.
I said it with 2X amount of words
Glider said it with X divided by 8 amount of words.
You wanted to say it with 2X times 2 amount of words.

It's all Good!

 

[fin_676]

Brian said it using X amount of words.
I said it with 2X amount of words
Glider said it with X divided by 8 amount of words.
You wanted to say it with 2X times 2 amount of words.

It's all Good!

Some people are better with the choice and order of the words used and can give the full answer to a problem with a simple sentence i am not very good at that so i can often ramble through what i am trying to say
However as long as the person with the problem understand what i am saying then i have achieved the correct result

Brian

 

[Jack Klarich]

Replace the Master cylinder and check the free travel on the push rod

 

[karlsbike]

Just in support of the others (who definitively do not need it:
I had the same problem with mine after I adjusted the pedal stop too far in to have the pedal as low as possible with minimum travel before engaging. After a while that thing started locking up...
The hose beteen the reservoir and the master cylinder is not pressurized, btw, and would only need replcament if you're as stupid as I am, and manage to re-route the hose so that the belt wears through it...

 

[mat 60]

Some people are better with the choice and order of the words used and can give the full answer to a problem with a simple sentence i am not very good at that so i can often ramble through what i am trying to say
However as long as the person with the problem understand what i am saying then i have achieved the correct result

Brian

I think you do a fine job with your words...