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Funky brake behavior?

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Morris

Morris

Yoda
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This is related to my other brake thread, but because the purpose of that thread is to collect info on brake mods, I wanted to start a separate thread to get some advice on some funky brake behavior.

The back story: everything in my braking system is new or rebuilt. All rubber bits have been replaced. I have been working on my hubs, so I have bled my front brakes a few times recently. Once bled, the brakes partially lock up. The only way I can get them to release is to loosen the bleeder and let it suck up a little air. Afterwards, everything appears to work as well as it did before, except the pedal travels a bit when you first apply, but it stiffens up thereafter. Even with the travel I am capable of locking the front brakes (see my other thread).

Any thoughts as to what is going on? Should I be worried, or keep driving it as is?
 
Maybe your brake switch is preventing a full return of the MC push rod.
 
Trevor! That is brilliant! I will check it out.

Also... A while back I painted my car flat black. You suggested that I would be happier with satin black... well I just re-painted my car satin black and even though the satin shows off my horrible body work skills more, I am much happier with it than the flat black. So 5 points to Gryffindoor! And thank you for the good advice even though I did not have enough sense to listen to it the first go round.
 
With any luck the satin will fade a bit and hide the flaws. ;)
 
Right now the pollen is doing a great job of hiding the flaws.
 
You may have the brake rods on the master mis-adjusted so the hole to the reservoir is still blocked when you let off the pedal.
Or....did you rebuild the master, or buy new. Are you sure all the bits went back in the master correctly?
Don't drive the car......park it until it is fixed.
You don't want to mess up that new paint job do you?
Scott in CA
 
Another cause for the brakes to not release when letting up the pedal is collapsed hoses. Disks especially don't exert force to push the fluid back.
 
Last edited:
smaceng said:
You may have the brake rods on the master mis-adjusted so the hole to the reservoir is still blocked when you let off the pedal.
Click to expand...

Or the return spring on the MC is not pulling it back far enough.
 
Morris said:
This is related to my other brake thread, but because the purpose of that thread is to collect info on brake mods, I wanted to start a separate thread to get some advice on some funky brake behavior.

The back story: everything in my braking system is new or rebuilt. All rubber bits have been replaced. I have been working on my hubs, so I have bled my front brakes a few times recently. Once bled, the brakes partially lock up. The only way I can get them to release is to loosen the bleeder and let it suck up a little air. Afterwards, everything appears to work as well as it did before, except the pedal travels a bit when you first apply, but it stiffens up thereafter. Even with the travel I am capable of locking the front brakes (see my other thread).

Any thoughts as to what is going on? Should I be worried, or keep driving it as is?
Click to expand...

Funny, I bled my brakes last night and have the same problem, both front brakes are now dragging. Haven't tried opening the bleed valve to see if it goes away (of course this induces air and need to rebleed).
 
A rash of the same problem apparently. My Bug Eye is sidelined after the winter with the same problem. Have done enough diagnostic to narrow it down to master cylinder not letting the fluid bleed back. Kit on the way.


Kurt.
 
nomad said:
A rash of the same problem apparently. My Bug Eye is sidelined after the winter with the same problem. Have done enough diagnostic to narrow it down to master cylinder not letting the fluid bleed back. Kit on the way.


Kurt.
Click to expand...

How did you figure out the master cylinder not letting the fluid bleed back?
 
I removed a caliper and tried to pry the pistons back. No go so next problem spot could be a collapsed hose so I cracked the line loose above the hose and discovered no resistance to fluid flow or caliper piston movement. Only thing left is the master cylinder.

Kurt.
 
I would guess that your calipers need to be rebuilt but without removing one and trying to pry the piston's back you can't be sure. They should pry open easily. You don't need to disconnect the hose...just get them out where you can get at them. Maybe you can get a large screwdriver in where you won't damage the pads and pry without removing them.

Kurt.
 
nomad said:
I would guess that your calipers need to be rebuilt but without removing one and trying to pry the piston's back you can't be sure. They should pry open easily. You don't need to disconnect the hose...just get them out where you can get at them. Maybe you can get a large screwdriver in where you won't damage the pads and pry without removing them.

Kurt.
Click to expand...

Thanks, was planning to make that my next step to look at.
 
And, rebuilding calipers is not hard to. I have a copy of the article from the Classic Motorsports Midget rebuild series on rebuilding calipers (MGB) but they are the same. PM me your email if you want a copy.
 
Rebuilt calipers < $40 ea Rock Auto plus cores. NFI.
 
Did you guys all check to see that your peddles were swinging freely and that the peddles were not holding the pushrod into the master cylinder? (happens a lot)
BillM
 
Billm said:
Did you guys all check to see that your peddles were swinging freely and that the peddles were not holding the pushrod into the master cylinder? (happens a lot)
BillM
Click to expand...

Yes. There is also some freeplay in the pedal before it starts to push the cylinder rod.
 
First thing I checked, Bill. The push rod had lost its slack when I noticed the brakes dragging and I loosened it off so that there is plenty of slack in the push-rod. Don't know whats going on with that master. Spring is finally here and I've been too busy with other things to work on it so I'm waiting for a rainy day!

Kurt
 
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