Flushing the system

[dahondaboy]

What is a safe cleaner I can use to thoroughly flush the rear brake system without eating or drying the seals? I got the setup off a 80 xs and it was sittin a long time, the fluid inside is the color of used tractor oil. Should I just completly dissassemble and use soapy water and a brush / pipe cleaner and go to town?

 

[ReycleBill]

The same kind of brake fluid as you run in the bike is the safest flush.

 

[5twins]

If it's all gunked up inside, flushing won't be enough. You will need to disassemble it. Actually, it's best that you do, that way you'll be sure it's completely clean inside. You could use brake cleaner for the metal parts but I would just use brake fluid on the rubber ones.

 

[dahondaboy]

thanks guys, i guess i will just order new seals and replace everything while its apart so i dont have to worry later.

 

[Tomterrific]

I've had good luck cleaning brake parts with alcohol. I buy teh 91% rubbing alcohol at the drug store and have used this as a cleaning liquid. It drys clean and fast and is safe for brakes. I use brake fluid to condition the parts after cleaning.

Tom

 

[larksnostril]

81 Special: 9500 mi.
Repalced brake lines about 250 miles ago..steel braided now...real nice feel...yesterday front brake caliper stuck all of a sudden, partially gripping disc....able to ride it home, it smelled a little hot but no aparent problem..tokk caliper off and found inside the rubber sleeve for the piston that it was full of redish brown fine sawdust like stuff...tasted kind of good so I ate it...(just kidding)..what would that be from?
The piston was pitted/rusted just above the groove....I think the piston is a goner.
I read a note from PamCoPete who recommended just starting over totally..with a bike you're not totally knowledgable about previous maintainance and repair...throw out the mastercyclihnder and claipers...I'm kind of inlcined to do just that since I want to do some long trips on this bike this summer.
Any thoughts?

 

[5twins]

I use stock components and feel they work very well. However, I disassemble and thoroughly clean them before using. I think that was your mistake. Over time, dried brake fluid builds up in the piston seal groove and forces the seal out more. This is the main cause of sticking pistons. Changing or flushing fluid through just cleans a straight shot from the line connection to the bleed nipple. It won't clean this seal groove or all the other nooks and crannies in the caliper.

Once pressurized, the piston moves very little. Only a small portion of the piston moves through the seal and that's the only section that needs to be in good shape. Corrosion and/or pits above and below that don't matter. If the caliper isn't leaking fluid from around the piston then it's a pretty safe bet that the piston sealing area is still OK. If you really do need a new piston, they sell S.S. replacements for a lot less than the cost of a new caliper.

 

[dahondaboy]

I found out what the thick stuff in my caliper fliud was.... Some "awesome" mechanic put a grease gun to the bleeder(I guess it looks like a grease fitting) and pumped it full of grease! looks like they opened the bleeder to get it to pump in too! Yup grease in my brakes. AWESOME! never seen this one before. I have seen diesel in gas tanks and vice versa, water in oil, oil in water, oil topped off in radiator. but grease in the brakes!!??? wow find that guy and keep him away from all tools and vehicles. I first noticed the bleeder was plugged. Thought it was dirt till I cleaned it out then when I pulled it out sure enough, the cavity behind it is packed with red grease.

 

[larksnostril]

Man you never know what you are going to find cropping up some days.
Thanks for the tip..I suspect that's what it was in there..amazing.

So I'm still into the front disc brake situation...never done this before.
I've got a question about this '81 special..replaced both front brake caliper/pads using the old shims and new MC...new parts from MikesXS....already had braided brake lines on. there are no leaks anywhere..using correct DOT3 fluid
Problem:
I'm almost done with bleeding the system and the front caliper does not consistently release so wheel will run free. Right now its closed up pretty tight. I can roll it with much effort but from the sound its obvious the pads are pretty tight against the disc...it sort of releases a little then gets tight again as I roll it
Should I have left the shims out?
Is this the normal way with brand new pads?
What can cause this and what area my next moves to figure out and fix?
I'll be much ablated for any help.

 

[1974jh5]

larksnostril, I'd put a few miles (50 or so) on the bike and recheck. The rotor and pads need to seat to each other, they will have only a tiny bit of clearance, like .002 or so.

Red grease in the brake hydraulics? Well, Girling supplies a red 'rubber grease' that works great on caliper seals and pistons. I need to order another big tube...

 

[larksnostril]

larksnostril, I'd put a few miles (50 or so) on the bike and recheck. The rotor and pads need to seat to each other, they will have only a tiny bit of clearance, like .002 or so.

Red grease in the brake hydraulics? Well, Girling supplies a red 'rubber grease' that works great on caliper seals and pistons. I need to order another big tube...

Well that helps me a bunch, here. I suspected that might be the case but when you don't know you just don't know.
and I'll track the greaswe down too.
Charlie

 

[dahondaboy]

but this aint no brake grease, its thick and plugged the cavity behind the bleeder. rendered the whole "bleeding " process useless. not too worried though. I will just dissassemble and get new seals and rebuild it.

 

[gggGary]

I have had two bikes now where it was obvious the PO had greased the brake bleeders. I guess I must be lucky, they didn't open them and force the grease inside the brake system like the dahondaboy's PO's did! Fools and motorcycles.....

Yes a full brake R&R is in order for any 30 year old bike. I am guilty of not always replacing the brake lines. After an R&R with a tube on the open bleeder the MC reservoir should drain out into a catch container with no pumping. IE all lines and ports are free flowing. If fluid won't gravity flow through the entire system you aren't done yet.

+1 the calipers always have to come apart, and you gotta get all the crap out of the groove behind the seal.

 

[weekendrider]

I found out what the thick stuff in my caliper fliud was.... Some "awesome" mechanic put a grease gun to the bleeder(I guess it looks like a grease fitting) and pumped it full of grease! looks like they opened the bleeder to get it to pump in too! Yup grease in my brakes. AWESOME! never seen this one before. I have seen diesel in gas tanks and vice versa, water in oil, oil in water, oil topped off in radiator. but grease in the brakes!!??? wow find that guy and keep him away from all tools and vehicles. I first noticed the bleeder was plugged. Thought it was dirt till I cleaned it out then when I pulled it out sure enough, the cavity behind it is packed with red grease.

Common practice(by some) to force/push the piston out (if stuck) with grease.
But I think it is supposed to be cleaned up before assembling.

 

[dahondaboy]

Common practice(by some) to force/push the piston out (if stuck) with grease.
But I think it is supposed to be cleaned up before assembling.

that makes sense. i bet that is why its in there.