Front brake issue

[Crasm]

I have an 05 gs500 k4
Nearly owned if for 12 months and had no real issues with it other than having to change the battery and the pain in the arse it was to fit my full stainless exhaust system.

However just recently I thought my front brake light switch had failed and the brake light was stuck on , so I changed the switch but it was still not going out.

I found the fault to be that the brake leaver was not returning completely to deactivate the light switch. I've replace the fluid in the system with new and bled it out correctly but it's made no difference .

The brake seems to be operating as normal but just not returning enough To turn the switch off.

My question is what would be the problem ?? Would it be the master cylinder or caliper that needs attention?

Any help or advice is much appreciated

Cheers

[mister]

First, welcome to the forum.

Full stainless exhaust system. Would you have some pics of the system to share with us? Maybe a "just installed" pic and a more recent "how it looks after a thousands miles" pic.

[Crasm]

Hi cheers for that totally forgot about an hello post lol

I do have pictures but there on my phone do need to put them on my PC and upload them to photo bucket.

It's a 3 piece delkavic system consisting of headers link pipe and end can with removable baffle brand new cost £250 (British)
Removing my standard system was a pay in the arse all the standard bold were rotten so had to be drilled out and the head had to be recapped and helicoils installed .

Just the issue with the front brake is causing me a headache at the min .big problem because I use the bike daily

[Joolstacho]

Is it just the brake light that's not right? Are the brakes working properly... coming on and releasing freely? If it's just the light, the switch could be faulty.
If the lever isn't returning fully it could be the return spring in the master cylinder has lost it's tension, or there's corrosion/muck in the cylinder bore inhibiting the piston retracting.
Looks like a stripdown and reco kit.

[the mole]

The light works off both front and rear brakes, so disconnect the wires to one and check if the problem goes away. Once you've worked out which brake is causing the problem, the most likely cause is a stuck switch. The rear is the more likely culprit IMHO. The rear switch can be adjusted to change the point at which it turns the light on, that may be all you need to do.

[adidasguy]

It is easy to over tighten the brake lever bolt and it will not return correctly.

[mister]

Who gives a crap about brake lights? We want to see shiny bling.

Pics or it didn't happen. Bring on the bike porn 

[Crasm]

thanks for the replies , much appreciated.

its definatly the front brake , ive had no issue with thr rear brake at all
its definatly not the switch as i also thought that first and fitted a new oem park

the brake is working but feels spongy and the lever does not return to its normal position
so is not pushing the micro switch back in and not turning the brake light off which is obviously a big problem.

it is going to need  either a caliper or mastercylinder rebuild but dont no which 1 to do first
time down will be the problem because i use it every day for work

[Joolstacho]

My money is on the mastercylinder. (I haven't actually done GS brakes, but have done plenty of others, so if the GS setup is different someone please correct me).

Easy enough to check the caliper, -pull it off the disc but leave the fluid line connected, get/make a packer a touch thinner than the disc, put the packer between the pads, pull the brake, let it off, now remove packer and use a clamp or whatever you can rig up to squeeze the pads/pistons back into the calliper, repeat the process a few times, you should get some idea if they are moving in and out properly. (They're supposed to be tight, but free moving). Have the reservoir lid off so you can see if fluid is returning when you release lever pressure and push the pistons back into the callipers.

The master cylinder has a light spring inside the bore that helps return the lever (assisted by fluid pressure) back to extended position, -the spring may have lost it's tension. On some master cylinders there is also a tiny fluid return hole drilling (as well as a bigger hole) inside the bore through which the fluid returns back up the lines/bore to the reservoir when you let off the brake. If this little hole gets blocked it could be inhibiting the piston returning because the fluid can't get back up into the reservoir when you let the brake off. If it's blocked sometimes it's difficult to see it. A guitar B or high E string may be used to clean the hole. (But the GS might not have this drilling?)

If you need to ride in the meantime, disconnect front brake light connectors from the lever, and just make sure when you brake, that you use the back brake as well so your brake light will come on.

[gl0ckage]

I'd say either your spring, or the bolt I'd too tight on your lever. If your saying you defo know it's the front. I'd check everything first, I had a similar problem with a aftermarket taillight which originally were wired wrong and we're touching.

Your lever shouldn't feel spongy, If you have bled them correctly then it'd defo your cylinder.

[adidasguy]

Caliper would not cause what you see.
First, loosen the bolt holding the lever. If all works OK , then that's it. So often is all the bikes here at the Bike Cave, the bolt too tight for the lever is 98% of problems with the brake lever not coming back. The other 2% is cheap Chinese levers made out of spec so they bind up.

Spongy brake is often air in the line. Second would be a bad master cylinder. Rebuild or buy a replacement from a bike breaker off of a newer model. Then just swap them. While you're at it, why not put on stainless lines? Makes for a firmer brake (front and rear). Downtime however you do it would be a couple hours at most.

98% sure it is the brake lever bolt is too tight.

PS: With all the bikes that have been to the West Seattle Bike Cave (mine and others) there must have been 30 brake lever replacements or swaps in just the past 3 years so I am speaking from experience regarding the bolt. Usually any bike that wanders in and has a defective brake lever (bent, scratch, etc.) will get a newer one just because that's the way we are here in West Seattle. Brakes are important.

[Crasm]

thanks for your imput folks very much appreciated
ive got a new set of front and rear pads on order so when they
arrive im going to do the techique mentioned to check the front caliper is working
correctly then clean up the front caliper and fit the new pads and then rebleed it out
if that doesnt work ill strip and rebuild the master cylinder . a friend of mine mentioned about
the return spring in the master cylinder previously so i no it could be an issur
ill have a go at it over the weekend and report back to you guys.

thanks again for your info

[Crasm]

Right then. I had the front caliper off and checked operation of pistons and all was well so I cleaned and regreased and fitted new pads and gave it another bleed, also changed rear pads and did a fluid change while I was at it.

However front brake still not returning properly so took it to a garage and they confirmed that it's the return spring in the master cylinder so ordering a rebuild kit shortly.

Are all gs500 master cylinders the same?? There's rebuild kits on eBay sayings years from 89-05 but thought it best to ask first before buying??

Cheers