Front Brake Issues

[welshrob]

I`ll give as much info as I can here, my missus` bike is an 05 GS500E, she hasn`t been riding it that much over the last couple of months, due to the weather, floods etc.

We went out on a day ride and under hard braking there was squeak coming from the front brake master cylinder, the lever felt solid, not spongy but the bike was hard to pull up. The pads were low but not dangerously so. I figured that the pistons had come out further than before and were sticking, so I invested in some top quality $14.99 (free postage) from ebay brake pads.



The pistons seemed to move OK, I wound them in and fitted the new pads, everything seemed ok, but after a ride today the front brake seems to have developed a delayed action, ie you squeeze the lever till it it bites, then a second or two later it bites harder and the forks dive. I`m guessing the pistons are sticking, then releasing?

1. Anyone experienced anything similar?
2. Can you replace the seals in the master cylinder
3. Any issues with ebay pads?

Thanks for your help, and yes, I tried the search function first!

[burning1]

Did you clean the rotors and bed the pads in after installing them?

Some of your demonology is confusing... You said that there was a squeek from the front master cylinder. Do you mean the front calliper?
You said that the bike was hard to pull up. What does that mean? Hard to stop? Hard lever pull?

For what it's worth, a squeak is not a sign that the pads are due for replacement. Sintered brake pads contain a lot of metal, and tend to make some noise. It's normal. I generally replace my pads when performance falls off, or when the pads material is nearly gone.

[welshrob]

Did you clean the rotors and bed the pads in after installing them?

Some of your demonology is confusing... You said that there was a squeak from the front master cylinder. Do you mean the front calliper?
You said that the bike was hard to pull up. What does that mean? Hard to stop? Hard lever pull?

For what it's worth, a squeak is not a sign that the pads are due for replacement. Sintered brake pads contain a lot of metal, and tend to make some noise. It's normal. I generally replace my pads when performance falls off, or when the pads material is nearly gone.

Sorry, I`ll try and elaborate. The squeak is from the master cylinder, NOT the front calliper. When you apply pressure to the lever you can hear/feel a squeak from the master cylinder. You can feel a 'creak' through the lever on the last few mm of squeeze. It is almost as though the lever is grinding on a rusted pivot bolt. That was initially what I thought it was, but that`s not the case. So I wondered if something was sticking INSIDE the master cylinder?

Yes, the rotors were cleaned and the pads bedded in.

Hard to pull up, means that IMHO, you had to pull REALLY hard, to stop the bike effectively. I have other bikes, Speed Triple, Bonneville, Vstrom and I can two finger brake on any of them, not on the GS though. A full 5 finger squeeze is required. It has been like that since we bought it, but I put that down to old school, low budget brakes. After reading this board, I`m reevaluating my opinion, lots of members seem to think the OEM brakes are excellent.

I initially replaced the pads, not because of any noise from the calliper, but because there was hardly any meat left on them. I thought the pistons would be further out than normal, which may be causing them to stick and cause this unusual squeak.

So, IMHO, something might be sticking in the master, or sticking in the calliper or maybe the 'Shanghai special' brake pads have some weird properties causing bizarre two-tier braking behaviour. I want to try and avoid a full brake system overhaul, if someone can point me in the right direction.

Hope this clears up the "Demonology!" 

[burning1]

You're right - 5 finger braking is atypical for a GS500. With a few minor modifications, I can lift the rear wheel on my GS500 track bike using 2 fingers.

I had problems with the stock caliper on my 93 GS500. The pistons didn't seem to want to retract all the way, and the front brake ended up dragging very badly. I ended up replacing the entire caliper to resolve the issue.

If I were you, I would go for the full overhaul. You can order a complete caliper rebuild kit, and I think a kit for the master cylinder. You might also check to see if you can simply swap out the entire master cylinder for a known good unit.

The only other advice I would offer is to make sure you haven't over-filled the brake fluid reservoir. Doing so will prevent the pads from disengaging, and will quickly overheat and glaze the pads.

[Paulcet]

In some parts of the world, "pull up" means "stop".

I'm inclined to suspect a problem with the master cylinder. The cheap pads might be a problem, too.

[gsJack]

Try soaking the pivot pin of the front brake lever with WD-40 and see if that helps.  Gets sticky there from time to time and squeaks too.  I've put 390k miles on 6 bikes including over 80k miles each on 2 GS500s and never touched a master cylinder yet except to fill it.

Never had a motorcycle caliper piston stick except a couple times the pistons were not totally clean before I pushed then back into the seals when installing new linings.  I now pop the pistons and clean them thoroughly before pushing them back in and then have to bleed after I'm done, some fresh fluid won't hurt it anyway.    Another thought, the outer wiper seals can twist and bind the piston causing the same problem after they get many miles on them so I just take them out and throw them away after a while.  They are to wipe the dust from the piston as you push the piston back in but they will only wipe dust and not that hard crud that builds up on the pistons too.

One more thought, make sure your front wheel is tight and doesn't wobble on the shaft due to a bad wheel bearing.  Can cause similar problems and also delay front brake action until front pads dry when riding in the rain.  Had that happen a couple winters ago.

[burning1]

A badly dished rotor might also cause problems. When the rotor warps, it takes a good bit of force from the calipers to straighten it out so that you get stopping power.

[welshrob]

Thanks for all the helpful replies, it obviously isn`t a common issue. It looks like a master and calliper rebuild is on the cards, plus a PROPER set of pads.

[Aussie GS500F 06]

I seem to have had similar issue, after washing my bike. I found that the break mastercylinder was squeaking add breaking was jerky, to fix it I sprayed silicone spray on the lever pivot and all was good again. I must have washed the lubrication away when washing it. Now I lube after I clean and never had a problem since

[noiseguy]

I know exactly what you're talking about; my bike is doing that too. Modulation is gone and lever "creaks" when you pull it. I've greased the MC pivot and am convinced issue is due to old fluid and who knows what else in the master cylinder. Am planning to rebuild it with other work I'm doing to fix it.