Front Brake Question

[shade]

I have very limited experience and I'm trying to reinstall the front brakes on my 1983 XS650. The pads won't seem to separate enough to fit around the rotor. They also are coming together at an angle rather than parallel to each other. Can anyone suggest a video I can watch or a detailed explanation on how to properly mount the brakes?
Thanks

 

[richardthemotorcycle1]

I would look in the Tech section.

 

[xjwmx]

There is a little screw that has to be inside a hole in one of the pads. If it isn't the pad will be at an angle like that. It takes some finangling to get it right.

Before you start, one thing you can do is push the piston all the way back with a c-clamp. Pad everything with scraps of wood.

 

[jd750ace]

Have you disassembled the caliper, cleaned it out, and inspected it for corrosion? If you are re-habbing a bike that has been parked, you should, for your safety. It is very common for these to have some internal corrosion. If you can't push your piston back far enough to get the caliper on the disc with a slip fit, your piston is binding in the bore, or, like mine, there's a bunch of sediment in there that won't compress.

You also get this gunk built up behind the piston seal that forces the seal out so it won't let the piston retract normally.

When it's all clean and happy, you can push the piston easily to the bottom of the bore. Also, in this last pic, you should pull the carrier pin (the lug with the sleeve busing and rubber grommet) and make sure that it is lubed with grease behind the rubber seals and slides freely.

 

[gggGary]

+1 Exactly what he says, do the the MC too. But hey it's just the front brake, and only thirty year old rubber parts and fluid what could go wrong?

 

[shade]

I have disassembled the caliper and it is not bad. The black plates that fit over the pads are not in great shape. I will take them apart again when I get back to the bike in a week or two. (Unfortunately I live about 2 hours from where it is located.)
Thanks so much for this information, I was wondering about that screw pressing against the brake pad.
The master cylinder had some gunk in it but I flushed it out and put in new brake fluid. What else should I do to it?

 

[gggGary]

Disassemble the master cylinder too. You will be amazed at what all is in there even after flushing it. Bill has an excellent how to.
30 year old brake lines are very suspect also, the rubber swells and flakes on the INSIDE.

 

[aldo5468]

I have disassembled the caliper and it is not bad. The black plates that fit over the pads are not in great shape. I will take them apart again when I get back to the bike in a week or two. (Unfortunately I live about 2 hours from where it is located.)
Thanks so much for this information, I was wondering about that screw pressing against the brake pad.
The master cylinder had some gunk in it but I flushed it out and put in new brake fluid. What else should I do to it?

Many of us replace the OEM rubber hoses with stainless steel ones. You can get S/S replacements for the factory 2-hose setup and keep the splitter, or just one longer hose to eliminate the splitter.

 

[shade]

I am really glad I asked about this. I got the rubber seal off and it is filled with gunk. I can't seem to move the piston at all. Is there a suggested way to remove it so I can clean it out?
Thanks

 

[5twins]

If you're referring to the MC, the piston is retained in its bore by a snap ring. Remove that and it will come out.

 

[shade]

This is what I'm talking about:

 

[retiredgentleman]

You should soak the piston/cylinder seal area with penetrating fluid of some type.............maybe for a few days.

You can use air pressure, but it can be dangerous, if the piston flys out suddenly. Put lots of cushioning material/cloth for the piston to land into. Use low pressure for safety.

Some lads use a grease gun to apply hydraulic force.............could be messy, but likely safer than using air pressure.

 

[gggGary]

usually you can move it IN a bit with a c-clamp then loosen the clamp a ways, apply some air get it move out a bit, repeat; c-clamp in air out till it comes all the way. Yes rag and the piston pointed down the bench so it doesn't fly and damage anything.
I believe: No penetrating oil on brake parts but some brake fluid dribbled on the outside will help lube a stuck piston while you are trying to free it up.
I like to mention that spray brake parts cleaner is NOT for use on rubber parts!

 

[shade]

When using an air compressor how do you attach it to the caliper to form a good seal?

 

[jd750ace]

I use one of these.

 

[retiredgentleman]

When using an air compressor how do you attach it to the caliper to form a good seal?

You don't want or need a good seal. Just push the tapered air nozzle into the brake line entry point.

If penetrating oil is not compatible with the piston seals, it does not matter. On brake caliper over hauls, you definitely want to toss the old cruddy seals and use new piston seals. Old seals might appear useable, but they have lost their elasticity, and that is what causes brake rotor drag.

 

[shade]

The forced air method worked and I was able to remove the piston. Thanks for the advice.
When I put the piston back in it gets stuck and I have to use air to force it back out. I've cleaned it all out but there seems to be some pitting in the piston itself. Perhaps it needs to be replaced? It is very interesting to learn how this stuff works.
Thanks

 

[jd750ace]

Depends on where the pitting is. If it's on the flat at the back of the piston, it can be cleaned up and used. if it's on the sides of the piston body where the sealing surface is, it should be replaced, or they can gouge your caliper bore and ruin the caliper.

 

[gggGary]

Try the piston in the caliper without the seal in place. see if it moves freely. Yes more often than not a new piston is needed, at least here in Wisconsin. I will buff minor pits on the wheel with compound or 1000 grit paper to remove sharp edges, what is a re-usable piston is a matter of personal tolerance for "good enough". I will also do a light clean up of the caliper bore with 1000 grit.

 

[ridgerunner1965]

i did like these guys said on my rear caliper.piston was a bit iffy.had a few pits in it, i buffed it good on my polishing wheel but not enuf to get out the pits.cleaned everything up and put it back with a new seal ring.works awesome with no drag like before and no leaks.i think the key is to get out all the crystallized brake fluid from the caliper.lots of soaking and flushing and using a pick in the grooves to loosen the crud. this winter ill be adding the new brake hoses it needs, that should give a even more firm feel to the brakes.