Spongy brakes

[kurifu]

Ok, so I failed my safety for spongy break lines, the lever could be pulled back to the handle bar with a little bit of force, though the brakes seemed to work sufficiently well. I removed the brake level and put a dime in on the plunger and this has helped a bit, if I put two dimes in the brakes are always engaged (but makes the travel very difficult about half way down).

The the one dime in there though it I still have a lot of travel, and if I pull really hard I can get the brake back to the handle again.

I bled the brake lines until all the old fluid was out of the system yesterday, but I it is still spongey, I don't think this made very much difference in how it operates.

When I pull the brake lever repetitively to try and pump up the pressure it doesn't seem to be getting more difficult to pull the lever back, not building additional pressure (or building only a very very small amount), the only thing I notice are that my hands get tired.

No doubt the brake lines and master cylinder are all originals. I was anticipating replacing the brake lines in the winter, but REALLY didn't want to touch them until than (cost). Now, if that is the problem, I don't mind fixing them early to get my safety, butI don't want to replace them and find out it is my master cylinder.

The only other thing I noticed is that when I was bleeding my brake lines (keeping the bleeders open and using a submerge tube in a bottle) I had a fair bit of travel before the brake fluid would really pick up pace and start to move, and when a let the brake lever go, the brake fluid would start to back up into the bleeder again.

Any ideas what I should be looking for?

[kurifu]

I also should add that there do not appear to be any leaks at all. And when I bled the lines there was no air in it, only the odd speck of dirt.

[oldschoolorange]

The only other thing I noticed is that when I was bleeding my brake lines (keeping the bleeders open and using a submerge tube in a bottle) I had a fair bit of travel before the brake fluid would really pick up pace and start to move, and when a let the brake lever go, the brake fluid would start to back up into the bleeder again.

Any ideas what I should be looking for?

Ditch the bottle and just bleed the brakes normally as you may have some air in the lines, once they are bled try squeezing the lever and feeling the brake line for flex, if it is expanding the lines are shot and need to be replaced.

[kurifu]

Where can I get a brake line kit for this bike without going OEM? I didn't see anything for a GS1000GT on z1enterprises. My brake lines flex a little bit, I have to sqeueeze them in the palm of my hand to feel it, but I guess over the length of the line this absorbs a lot of pressure. However it doesn't explain my inability to build pressure, I am still thinking that I will have to rebuil my MC, Z1 has a kit for $20, doesn't seem bad.

[Suzuki mad]

Sounds like you have rubbish in the system. Possibly in both the master and the callipers.

I would suggest (allowing on cost) that you would be best on stripping the callipers and master cylinder and fitting new pistons kits and seals.

Suzuki mad

[SPARKSS]

You mentioned the bike failed for "spongy brake lines". What you need to realize is WHY your brakes are spongy. You input mechanical movement to a hydraulic cylinder full of essentially incompressible fluid which then forces a column of fluid to the caliper at the wheel which must then extend to apply the brake......ANY expansion of ANY part of the hydraulic system not ment to move causes wasted motion (sponginess). As well, ANY air in the system causes sponginess because it IS compressible (wasted motion again). Further to the above, ANY undue movement of the caliper OR the mastercylinder OR worn pivot at the lever/pedal causes wasted motion which may cause braking to feel spongy (sometimes just a lot of stroke). There are other less usual causes such as water or other contaminents in the fluid which, under extreme heat at the caliper end, can boil or expand causing either wasted motion or locked brakes which return to normal after.

What I didn't see you mentioning was that you looked at those brake hoses for example (as noted). For what it's worth

[kurifu]

I am still concerned that I am unable to build any excessive amount of brake pressure by pumping the brake... I am going to test this on a friends bike and see how it is supposed to respond.

But I do think I am going to have to change those brake lines as a start and work from there... but still I don't know where to pick up a new set of brake lines appropriat for this bike.

If I could get a get with the proper sizes/hardware that would make my life much more pleasant, anyone know what I should be looking for?

[SPARKSS]

I am still concerned that I am unable to build any excessive amount of brake pressure by pumping the brake... I am going to test this on a friends bike and see how it is supposed to respond.

But I do think I am going to have to change those brake lines as a start and work from there... but still I don't know where to pick up a new set of brake lines appropriat for this bike.

If I could get a get with the proper sizes/hardware that would make my life much more pleasant, anyone know what I should be looking for?

I'm guessing you meant brake "lever" in your original post. What you want to be careful about is causing a preload or prestroke to exist on the master cylinder input (from your lever). This can, if enough, cause the master to not open up to it's resevoir when returned....causing slow, poor or incomplete brake retraction......Just take a little time and look it over while working the brakes and see where the wasted motion occurs (assuming you're bled ok of course.....which doesn't change unless the hydraulic system has been opened below the master).

[Nice Lad Kev]

Had problems with my 550 .

Try taking the reservoir top off, pulling the lever back as far as it will go and hold it in that position with cable ties over night.

[DaveDanger]

For what it's worth, I think your hoses are old and swelling when you pull the lever, allowing the spongy feel.
A quick and dirty check to help determine if the problem is the hoses or the MC, disconnect the hose at the end of the master cylinder and plug the fitting at the master cylinder with an appropriately threaded plug or cap. Then squeeze the lever. If the lever still moves with the spongy feel, you are bypassing pressure through the inside of the MC, if the lever is firm, then your MC is fine and you're losing the pressure in the hoses.
Purchase the appropriate parts and fix it

[kurifu]

You know, I can't believe I didn't think about doing that.

Anyway, this just got bumped down to a low priority, looks like my TDI beetle is having problems with short on the EGR and Wastegate valves that need to be fixed ASAP. This makes me really appreciate how easy it is to work on and maintain my GS1000.

[t3rmin]

Hey I tried the zip-tie the brake lever down overnight thing again last night and this time it did make a difference (had tried before without much success). Maybe I'll try it a few more times and see if it keeps getting better.

Also I pushed the rear brake pedal down and wedged something in there to keep it down overnight. It seems to feel a bit stiffer today, too.

[kurifu]

I just used vice grips, you can put small pieces of rubber to pad the grips if you need to, or use a firm cloth or piece of fabric in there, clamped it down on the hose by the MC and I could barely move the brake lever more than 1 mm or 2, so that pretty much says brake lines.

Worked like a charm.

[oldschoolorange]

you really want to watch out using anything to clamp brake lines as you run the risk of crushing the internal structure of the hose

[beby99]

Check your phone book for local hydraulic shops or large tool supply houses. Most should be able to make you a set of braided lines. I found a place locally that made me a front clear coated steel braided line for $16. pluse 2 banjos @ $13 each. while I waited for 10 mins. :-D Now I can do stoppies.