No rear brakes

[Guest]

Today I was riding, had to stab the rear brake kind of hard, and lost my rear brakes. I don't see any signs of a broken line, pads look like they have a little left on them, but not much, and the reservoir cup has a little fluid left in it as well. Should I suspect the master cylinder or the pads themselves? Maybe the brake cylinder at the caliper? I can push the foot brake all the way to the exhaust pipe and not get any response from the brakes.

Luckily I still had my front brake and made it home safely lol

[BigD_83]

1. How old is the brake fluid?

2. Top it off.

3. Bleed the brakes.

4. Report back

[shameless]

I have no clue how old the fluid is, for all I know it could be the original, (34 year old) fluid, could be a few years old.

[BigD_83]

There's a red flag right there.

You can start by flushing the line with new brake fluid, but if it is brown and/or sludgy looking, that might not be enough. Start with refilling the brake fluid with the appropriate DOT 3 or 4 (check your service manual), then bleed the brakes until you have pressure, with no air moving through the system with the fluid.

If this still doesn't do it, you could have problems in the master. I recently had to pop open the one on the 550, as the rear brake was alternating between locking up and zero stopping power. Turned out the piston had seized in the master. A little cleaning up of that area solved the problem.

[Steve]

Brake fluid should be changed every couple of years because it absorbs water. You can judge the time by the color of the fluid. New fluid is virtually clear. After a couple of years, it will look like ginger ale. Older than that, it will start looking like root beer.

You say you have "a little [fluid] left" in the master cylinder? That is WAY too little, it should be about 3/4 full. It's possible that the piston sucked some air when you stepped on the pedal, then some of the fluid came back into the reservoir when you released it.

It sounds like the bike is relatively new to you and you have not caught up on ALL the maintenance that has been neglected for the last 30+ years. I am amused by the number of new riders that are anxious to hear the engine roar to life and hop on for a quick ride before checking the condition of the STOPPING system, too.

At the very least, you need to add fluid and bleed the air out of the system. It is not much more effort to pump a bit more fluid through and replace the aged fluid, then bleed the air out. It would be wise to replace the pads before doing that. In fact, one reason the fluid was low in the first place, is worn pads. If you want to do it a little more correctly, it would be good to inspect the condition of the pistons and seals in the caliper(s) and the master cylinder(s). Yes, I used plurals there because you should do the FRONT brakes, too. While you have them apart for inspection, it is no more effort (and just a modest amount of money) to replace the seals. If you want to do the job VERY correctly, replace the brake lines, too. Suzuki recommended changing them every two years. It is quite amazing to see how many original brake lines are still fitted on our bikes.

As shocking as that is, what is really shocking is your last statement: "Luckily I still had my front brake ..." Are you saying that you don't use your front brake? Yes, you should use BOTH of them regularly, but most of your stopping ability is in the front brake, it is the rear brake that should be treated like a "reserve" brake system, since it does so little to stop the bike.

.

[tkent02]

Holy crap man, original fluid??? Take the brakes apart and clean the whole system, get new brake lines, new pads, all of it front and rear.
Brakes locking up out of the blue can kill you. Brakes not coming on at all when you want them to can be bad too. Both of these can easily happen due to the particles blocking the tiny passages inside. Motorcycle maintenance is important. Brake maintenance is the most important part.

Once that is done replace the fluid every year or two.

[shameless]

With the exception of new lines, pads, and fluids. Is it possible to take the rest of the system apart, clean it, and put it all back together, without spending a ton of money? The budget for the bike is pretty well shot at this point, this is a huge setback, (probably entire riding season,) if it gets expensive. I'm not balking at the necessity of safety by any means, just cant afford much more for quite a while and the bike will have to sit.

[tkent02]

Motorcycling is expensive, but pads don't cost too much. Brake fluid only a few bucks. The time and effort is free. The lines cost a bit, but not as much as broken bones.
Suzuki recommends changing out the rubber lines every couple years. Once in thirty years isn't too much. Braided steel lines cost more but you can safely use them forever if you change the fluid regularly.

Seriously if you can't afford to maintain an old bike, get one a lot newer. Ten year old mid sized Japanese street bikes are dime a dozen. It will be cheaper overall, easier to maintain and a heck of lot safer.

[shameless]

I meant, other than spending the money on the pads, lines, and fluids, (which I'm doing,) can I clean the brake cylinders and master cylinders without having to spend a lot of money doing so? or is just replacing the lines, fluids, and pads, and flushing the cylinders well, enough?

[eil]

If you cannot afford to rebuild the brakes properly at this point in time, then stop riding the bike. Seriously. I don't know you, but I still don't want you to die, which is what could very well happen if you ride a bike with dodgy brakes. There's a very good reason all motorcycles have independent front and rear brakes and you just found it out. Don't press your good fortune any further.

First, take the all calipers and master cylinders apart and inspect the contents therein. At a minimum, you want to clean everything as well as you possibly can (and I mean spotless) and replace the caliper seals and the piston and cup set inside the master cylinders. When you have it apart, you can inspect the caliper pistons as well but there's a very good chance they need to be replaced. They need to be perfectly smooth but at 34 years old, they are probably pitted. Especially if the brake fluid has not been changed.

You might get away with using the old lines for a little while longer if they are in excellent condition. But I don't advise this.

Whether or not you need to replace the pads depends on how much meat is left. They tend to last a while unless you're like me and spend your whole first riding season using way too much rear brake.

Only once everything is cleaned/inspected, do you then place your parts order. Not sure if we have a MC rebuild guide banging around anywhere but here's the caliper rebuild guide: http://members.dslextreme.com/users/...r_overhaul.pdf

Get cracking!

[Steve]

Rebuild kits for the master cylinders are in the $25-30 range, you will need one kit for the front, one for the rear. Seals for the calipers are also in the $25-35 range, again, one for the front, one for the rear, but which kit will depend on what bike you have. We have not seen what bike you are riding, and are only assuming that it's a GS. Who knows? Might not even be a Suzuki. Please update your profile by adding your location and your bike in a signature.

Pads can be gotten for about $30 for a full set. Stainless brake lines tend to be just over $100 for the set.

Any suggestions with more details will be pointless until we know exactly what details are necessary, so there will be no more help until we know what bike we are talking about.

.

[jbird7262]

Yes, by all means clean the master cylinders, tear them apart...carefully, disassemble, soak the metal componants in solvent, clean all passage ways, make sure the tiny return holes are clear. use a single strand of wire pulled from a scrap of common wire used on your bike, feed that through the small return hole. use compressed air to blow all passages clear of dirt and solvents, reassemble with new seals/cups in the order you took apart, use a little clean brake fluid on the rubber parts as you replace parts. Same goes for your calipers, replacment seal kits are cheap insurance.

[jbird7262]

As eil said... SPOTLESS

[Grimly]

The handy thing about the GS brakes is they were used on so many models that NOS is constantly coming up on ebag, for very little money. Last year I scored enough high-quality front pads to last me the rest of my life, I think. Pads that, back in the day, I wouldn't have fitted because they were just too expensive at the rate I went through them, then.

[shameless]

Ok, I sold a couple pistols, I'll be doing front to back complete. Any suggestions on brands to use or not to use? Companies that I can get everything in one order, etc? Also, can a brake piston be smoothed? Or is this a must replace part as well?