Gs750 rear brake binding?

[THUNDERPIPES]

Now that i have managed to sort out the valve clearances, i now need to prepare the bike for its MOT. I have dismantled and cleaned the rear brake caliper as it was binding but it is still holding on to the disc. Can anyone please offer me advise what might be wrong?

[cowboyup3371]

Have you thoroughly cleaned the master cylinder and replaced all of the seals in both the caliper and MC?

[TheCafeKid]

The pressure return port in your master cylinder is probably clogged. There are two holes in the cylinder. One is the main port for fluid to go through from the res, the other is for over-pressure to return to the res. if its plugged, the fluid has nowhere to go and will keep pressure in the caliper. This will cause it to heat the fluid, which will then expand and exert more pressure, etc etc till the disc is locked tight, and the fluid will start to boil and smoke and generally make a mess of itself.

It's wise to completely disassemble the MC, clean it, replace the piston cup and such, and make absolutely sure it's clear. That return port is tiny, if you don't look close you won't even see it if it's full of gunk.
I'd also suggest replacing your brake lines as they are probably garbage. Suzuki suggested replacement every two years...heh. Stainless steel lines are cheap, compared to OEM rubber junk and are a way way better product.

Lastly, if you've boiled that fluid, it's garbage and the whole system will need flushed out anyway.

[G. Bruns]

Does the front master cylender have a return as well? Or just the rear?

[TheCafeKid]

Does the front master cylender have a return as well? Or just the rear?

All MC will have a return. Front, rear, if you have an hydraulic clutch (you don't on a GS) it would too...

[hjfisk]

Now that i have managed to sort out the valve clearances, i now need to prepare the bike for its MOT. I have dismantled and cleaned the rear brake caliper as it was binding but it is still holding on to the disc. Can anyone please offer me advise what might be wrong?

Is the foot pedal moving freely where it goes through the frame mount? sometimes they rust up where it goes through the frame. I take them apart and clean them up and the hole in the frame grease it up and reassemble.

[keman]

What does this have to do with GS photo of the month?

WTF, just post wherever.

[1_v8_merc]

Check your brake lines, if they are clogged, your brakes can lock.

Disconnect the line, then spray bolt penetrator or something foamy threw one end.
Now blast some carb spray threw the same hole and see if it comes out the other end.

Or just stick one end of the brake line in a bottle of water, and blast compressed air threw the other end, it should bubble and practically blast that water up like crazy!
(provided your using at least 40lbs of air)

[platinum2]

What does this have to do with GS photo of the month?

WTF, just post wherever.

i was wondering that as well lol

[Billy Ricks]

Guys, don't respond with answers to questions when people don't post them in the right place. Kindly inform them they have posted in the wrong place and direct them to the right part of the forum for technical questions.