Another brake question

[85gs550]

I researched the forums and ran some searches but wasn't really able to come up with anything specific to my issue.

I'm resurrecting my '85 GS550, which had been left to sit a while by the time I bought it. Everything's pretty much ready to go with the exception of the brakes.

Both the front and rear brakes seem completely frozen/stuck. The front lever won't budge and the old fluid in the MC seems to have crystalized (water/humidity issue from sitting?). And, the rear brake pedal won't budge either. The pieces are all there except for the dust covers over the pads, and a quick look in there looks a bit greasy.

My question is, do they sound too far gone for a rebuild kit? I'm not a genius when it comes to brakes. Or, do you think it would be worth my time to dismantle and try to clean out the old material for a rebuild?

Thanks!

 

[Steve]

You don't have to be a genius to work on brakes, but you should know which end of a screwdriver to pound on.

You can remove the master cylinder from the handlebars and take it apart to see if it will clean up. If you need a rebuild kit, they are about $20 or so. Remove the calipers from the forks. See if compressed air will blow the pistons out, if not, you will have to try to work them out without scratching them. Some have used channel-lock pliers, but they tend to scratch the pistons. Since I don't have compressed air available, I usually leave them connected to the master cylinder and use brake fluid to push the pistons out. Watch the pistons, make sure they come out about equally. You can clamp a piston to prevent it moving to allow the other piston to come out. When they are just about completely out, you should be able to wiggle them out of the bores. Clean the pistons with a ScotchBrite pad, inpect for pits on the surface, replace the pistons if necessary. Remove the o-rings from the caliper bores. Clean the bores with a ScotchBrite pad, flush with brake fluid, inspect for pits. Replace with new o-rings. When you are ready to re-assemble, lube everything (except the pads) with fresh brake fluid so it goes in easily. Before attaching the brake line to the master cylinder, fill the reservoir in the master cylinder, squeeze the lever to prime the piston bore. Remove the brake lever, use a long screwdriver to push the piston as far as it will go. This is usually a bit farther than the lever will push it, and will eliminate a nagging air bubble that is a pain to get rid of by any other method. Now you can attach the brake hose and bleed the lines. A Mity-Vac is a wonderful tool for this, but it is still beneficial to have a helper to monitor fluid level and add as necessary. Oh, and if the fluid is crystallized as you say, you would probably be better off replacing all the rubber hoses, too. Whether you replace them with rubber or stainless lines is up to you, but please change them.

Now answer the question...which end of a screwdriver do you pound on?

.

 

[seuadr]

I researched the forums and ran some searches but wasn't really able to come up with anything specific to my issue.

I'm resurrecting my '85 GS550, which had been left to sit a while by the time I bought it. Everything's pretty much ready to go with the exception of the brakes.

Both the front and rear brakes seem completely frozen/stuck. The front lever won't budge and the old fluid in the MC seems to have crystalized (water/humidity issue from sitting?). And, the rear brake pedal won't budge either. The pieces are all there except for the dust covers over the pads, and a quick look in there looks a bit greasy.

My question is, do they sound too far gone for a rebuild kit? I'm not a genius when it comes to brakes. Or, do you think it would be worth my time to dismantle and try to clean out the old material for a rebuild?

Thanks!

i agree with steve.. give it a go. my master was seized and turned out it was just full of crap. cleaned it up and it worked fine. i used rubber roller cleaner/refurbisher and it brought the rubber right back to life, although i'm not sure if you will be able to find anything like that.. check with local copy machine stores/repair shops. once you have the piston out ( don't forget to take the snap ring out before you start pounding! ) inspect the inside of the cylinder with a flashlight and make sure there is no pitting. if there is much of any, say goodbye to a good seal.

 

[spyug]

Not too far gone for some exploratory surgery.

Big word of caution before we start. Brakes are life and death component. They need to be reconditioned properly and short cuts and or sloppy work can kill you. If you doubt your wrenching ability take them to a pro.

Having said that, they are not difficult to work with. First, if you don't have one, get a shop manual. I believe our buddy Mr. BassCliff has a reference to online sources.

Pull everything off. Calipers, hoses and master cylinders. Careful of any hydraulic fluid as it will remove paint in a flash. Cover or remove any painted parts.

When working with brake parts be aware that you must not clean any interior parts with anything other than brake fluid as other chemicals if not cleaned out can cause problems when reassembled.

Start by cleaning the outside of calipers and master cylinders. I use mineral spirits but kerosene or diesel work well too. don't dissamble them until clean and crud free.

Take a caliper and remove pads. For specifics you will need to refer to your manual.

You will need to get your pistons out and this might be tricky if your master cylinder is frozen too. Remove the bleed nipple and try shooting in compressed air. Hold a shop towel over the caliper as you do this to keep the pistons from flying out and maybe hitting you. I've never been able to get this to work so another alternative is th find a grease nipple that will fit the thread and pump in axle grease. The only problem with this is you now have lots of grease to get out of the caliper. Messy and time consuming.

The preferred method and one that always works for me is to attach a working master cylinder and pump them out. so having said that perhaps you should start with the master cylinder.

Common to both caliper and master cylinders is that all accumulated junk needs to be cleaned out and any worn seals replaced. Rebuild kits are available from the likes of Z1 Enterprises.

Once you have the piece apart check the bores for any rust or crud and remove. I use small dental picks and an assortment of gun brushes. Try not to scratch or gouge the walls.

In the case of caliper pistons, you will find a lot of crud commonly under the rubber seals. This is what usually causes them to stick. you might also find rust and or pitting on the piston and on the walls of the bore.
The pistons are hard chromed and you can usually clean off any rust or crud. If you find pitting or cracks or chips on the skirt of the piston ( part that is actually inside the bore) it is toast and you must replace it. The reason being is that on reassembly rusting which can lead to locking the piston can happen again very quickly.

With calipers and masters that have been sitting for ages rebuild kits are really a must and cheap insurance.

Your hoses are likely crap as well and I recommend they all be changed as well. Stainless steel/kevlar are the best but oem rubber will do and might be a little cheaper. There are tutorials on Mr. BassCliff's page for making your own stainless steel lines.

This kind of project is not cheap but just remember your life can depend on them so don't skimp. On every new to me bike, dissassembly, cleaning and rebuild is the first thing I always do. My GS had sat for seven years and the back master was frozen and one front piston was pitted.

If you are not sure about any component take pictures and we will guide you.

There is more to discuss about brakes but this will get you started.

Keep us informed of how it goes for you.

Good luck,
Spyug.

 

[85gs550]

You guys rock, thanks for the patience and great advice. I'll definitely give it a go, not much to lose at this point! Not sure if I'll get to it this weekend due to a more pressing project (dead tree, meet mr. shed), but I'll post once I get in there with an update.

spyug -- no worries, I'm a big fan of having good brakes!

steve -- let's say I at least try not to pound on either end of my screwdrivers!

 

[rustybronco]

steve -- let's say I at least try not to pound on either end of my screwdrivers!

Why not? they're good for prying, loosening screws, and alignment tool, heck you can even use the handle to whack things.
not the least, you can throw them at critters doing damage in the garden.

p.s. they even make great spare tent stakes!

 

[85gs550]

LOL. When you put it like that, I'll admit I have at least one or two bent, broken tipped "prydrivers."

 

[Barneycanoe]

What does a rebuild kit consist of?

What does a rebuild kit consist of?

Is it the piston seal and boot or is there more? Should I get the Suzuki OEM parts?

 

[hampshirehog]

Is it the piston seal and boot or is there more? Should I get the Suzuki OEM parts?

You can buy a combination of what you want, though usually it's the boot and seal or the piston or all 3.

Some of the rubber bits in pattern kits, particularly the boots are total cr*p - you can spend hours trying to get those boots in until you realise that they have swollen (I reckon some are made fom jelly!). OEM isn't too dear anyway.

I would however recommend stainless pistons - remove the threat of rust forever.

Another dodge if your caliper pistons have seized is to use a vice to push / squeeze the piston in. I know it's 'the wrong way' but it can often relieve what's causing it to stick.