brakes... thought I knew what I was doing...

[BigRed]

I'm performing a resurrection on an '80 Special, and I thought that while I was waiting for my parts to come in, I'd bleed the brakes and exercise the pistons to see if I need to order some rebuild kits. As I was doing the front brakes, I noticed some fluid dripping out of the actuating hole on the master cylinder. I figured "well I guess I need a new front MC". Then, once I closed everything up, there was no more leaking, and the MC seemed to hold pressure fine.

My crime is that I didn't read the tech tips before bleeding the brakes (thought I knew how). I see that I must have overextended the MC, and popped a seal. My question is... can this seal re-seat itself? It seems to be working fine once I got everthing back together. Is this an illusion, and my MC is waiting to spew fluid when I really need it, or was it only dripping momentarily while I had pushed past the seal?

In any case, given the amount of brown goo and chunks that came out of the system while I was bleeding it, I suppose I should take things apart to clean everthing out. I am mechanically inclined, but I've never taken apart a caliper or MC before, so I try to keep putting that off for fear that I'll wreck something. I'd much rather ride for the summer, and take this on next winter. That way, I'll have lots of time to locate my special calipers if I need to.

Thanks in advance,
Brian

[mro]

the amount of brown goo and chunks

Brakes and tires are about the two single most important elements on a bike to keep you from "crash and burn".

I don't think the MC is a concern, if it is I hope some one will correct me.
BUT I would remove and clean out the calipers and MC.
Inspect if not replace the brake lines and flush them out while you have the MC and calipers apart.

Don’t skimp here, the life you save maybe your own…


mro

[psycoreefer]

I agree, don't skimp on the brakes, if your reasonably mechanically inclined you shouldn't have any problems.

The calipers are super super simple, just a piston and a round rubber seal.

The master cylinder is a bit more complex but if you pay attention, take some pictures and most of all, ask questions here you shouldn't have any problems at all.

The worst part of the whole thing is bleeding the system.

[DGXSER]

Another county heard from.....

If these bikes have one major short coming it is their brakes. They are IMO overpowered and under braked. So, I would strongly suggest you not ride that bike till you go through both front and rear braking systems and get them cleaned out and operating well.

I have had alot of car brakes apart, cleaned and reassembled including an MC or two. The systems on these bikes are VERY simple as stated.

For the calipers, if you have good pressure at the MC, then pull the caliper off the bike with the brake line still attached, then use the MC to push the piston out of the caliper. With that much goo in there, keep your hands away while you do this as the piston may POP out and could hurt you. Then remove the brake line and I use a piece of rubber and a clamp to keep it from draining all the brake fluid from the system.

Clean that one caliper good, (on the front system) then reinstall it (I reuse the seals with no problems as long as they are not torn or rough) and repeat the process on the other side. Then after both calipers are clean, remove the MC and clean it. and flush all the lines as well.

[BigRed]

Thanks, guys. you've got me convinced. I'm waiting for parts anyways... may as well see what damage I can do in the meantime

[fredintoon]

Brown chunks and goo?

Hi Big Red,
brake fluid should look like new Crisco cooking oil.
As yours looks like the stuff in a hobo's old frypan, tear the whole brake system down and clean it like your life depended on it, because it does.

[DGXSER]

One thing nto mentioned before in my description. When you have the piston out of the caliper, be sure to pull the rubber ring out, that is your seal it is a square shape in a circle. Behind that rubber is where all the crap collects that must be comepletely cleaned out. That is how the brakes work. They push that seal forword and it has to spring back into place to releive the pressure on the rotors. If it is dirty back there, it will not fully seat and properly release the pressure.

[BigRed]

Well, I took the calipers apart last night. Where the heck does all that crap come from? Anyways, they're cleaned out, and slide nice and smooth. I also took the MC off, cleaned the spooge hole, and blew out the cylinder with compressed air, but I didn't take it apart for fear that I'd lose something. It seemed to be moving freely and properly, so I think I'll put it all back together and see how it goes. I'll be working on the rear brake tonight.

[TADracer]

Where the heck does all that crap come from?

We are supposed to use DOT3 fluid which is alcohol based and the crap actually develops from moisture that the brake fluid attracts. Over time it deteriorates every surface inside of the system and appears as crud and off colored fluid.

If you want to avoid alot of brake failure and cruddy fluid, change the fluid once a year. It will flush out alot of the contaminants that develop over time. Its easy to do and takes only about ten minutes with a hand held vacuum pump and a fluid catcher cup. I change mine every 'Spring' tuneup and never have brake problems.

[Jerry]

Where the heck does all that crap come from?

As stated, it comes from the inside of the brake lines, as well as misture attracted to the brake system by the fluid.

In addition to the other comments posted, if you can afford it, change brake lines. If you are running OEM lines, they are now 20+ years old and will have lost something over the years. Best replacements are SS lines. These will take care of the internal deterioration problem and improve the feel of the braking system. Do both front and rear calipers.

[xj11john]

Stainless Steel lines

I replaced my XJ lines with stainless steel, using lines from Hel USA and they weorked well, definetly more firm brake pedal and lever.

The xj has the linked front left and rear brake system, with a propertioning valve to distribute the brakeing front to back, I was able to use one line from the back master cylinder (propertioning valve) to the front left caliper even though the original brake lines had two or three small lines joining together under and in front of the gas tank. I just measure the routing and called Hel Usa, and gave them my dementions for front and back lines, and the angle for the banjo fittings. I am very satified.

Also If your pistons are pitted up badly you can get new pistons online from hvccyle.com each piston was about 25.00, again very satified with this purchase as well,

The first time I cleaned by brake capipers I just hit them (pistons) with a wire wheel, then this year, about 6 years later, after both front and rear calpers were stuck on the rotors, I tried to clean again, and this time I have to grind to get all the rust and pits out, and I feared removed too much for the pistons not to leak, even with new o-rings/seals.

As stated earlier brakes on these big heavy bikes could be better so any upgrade and precaution you can do to them is a plus.

Keep the shiney side up, and good luck with the brake fix.

[DGXSER]

Great info!! Just as an FYI, how much did the lines cost?

I spent the $70 to buy the lines offered on E-Bay and basically I got screwed. So I'm interested in how much a set of line should cost to be sure you get the right pieces. Sometimes money saved is money wasted.

[DeanR]

If you do the stainless brake lines it will pretty much feel like a new system. Well worth it.

[fabricgator]

If you want to avoid alot of brake failure and cruddy fluid, change the fluid once a year. It will flush out alot of the contaminants that develop over time. Its easy to do and takes only about ten minutes with a hand held vacuum pump and a fluid catcher cup. I change mine every 'Spring' tuneup and never have brake problems.

Always use new fluid from a sealed container....

[xj11john]

SS lines

Great info!! Just as an FYI, how much did the lines cost?

I spent the $70 to buy the lines offered on E-Bay and basically I got screwed. So I'm interested in how much a set of line should cost to be sure you get the right pieces. Sometimes money saved is money wasted.

IIRC about $150.00 but well worth it for good blakes.

Ride safe!