Front Brake Pad Replacements

[uknowme2goog]

1980XS650...
I took off the front brake caliper, removed the pad screw and removed the old pads.. I took off the shims from the old pads. i put them on the new pads and installed them into the caliper. However, the space between the new pads is too small to slide over the brake rotor. So i figured the piston has to be compressed.. i tried to push it out with a screw driver and then a C clamp...it moved a little, but not enough to get the caliper over the rotor.
How do i know if the piston is fully depressed?
What is the best why to compress it?

 

[Unfocused]

Do you have the cap off the master to allow the fluid to pass back through the line? Be careful not to spill any fluid onto painted surfaces. It eats paint.

 

[uknowme2goog]

no i didnt take off the master cylinder cover. you really think that wil lprevent me from compressing the piston?

should i be ale to compress it by hand or will i need a clamp?

 

[azman857]

You'll need the clamp. Make sure your pushing the piston straight in and not crooked.

 

[retiredgentleman]

Use a C-clamp to push the piston back. Yes, its a good idea to remove the master cylinder cap as you push back the piston.

 

[jetmechmarty]

The spooge hole in the master cylinder might be plugged and not allowing fluid to return.

There's a tiny hole like the one pictured under the plastic reservoir.

 

[Unfocused]

If you don't have a C-clamp you can use a pair of channel locks, but carefully. You don't want to tear the boot.

 

[uknowme2goog]

once i use the c clamp how flush will the piston be in the caliper?
right now i see the rubber around it sticking up, will the rubber go all the way down?

do i have to do anything to the new pads before i install them?
Someone said i should sand the pads a little?
them someone said i should sand the rotor a little??

 

[jetmechmarty]

If you sand the rotor, use garnet paper. It's not a bad idea to do that. Don't sand the pads.

 

[Royboy]

Here's a little trick I've been using for years. When ever I remove a caliper I insert wooden door frame shims, (one from each side, thin end first) in between the pads. Tap them in until they are fairly snug, they will force the pads back and the piston in.
They will keep things in place and where they belong and are easily removed when you are ready to slip the caliper back over the rotor. Shims are available at your local lumberyard for about 50 cents a pack of 10.

roy

 

[5twins]

Yes, I have some brass ones a machinist buddy of mine gave me years back. You may actually need to remove a little fluid from your reservoir depending on how worn your old pads were and how much you need to force the piston back in. With the reservoir cover removed, keep an eye on the fluid level as you force the piston in or you may end up making a mess, lol.

 

[xjwmx]

once i use the c clamp how flush will the piston be in the caliper?
right now i see the rubber around it sticking up, will the rubber go all the way down?

I seem to remember the piston ends up about flush with the caliper face. The rubber accordions down into the recess for it. It wouldn''t be a bad idea to back the clamp up with wood if you're using a lot of force.

 

[Tomterrific]

The tiny pressure relief hole in the caliper is too small to past the volume of fluid when teh pads are forced back. Also a dirty system is likely to force a speck of dirt into teh tiny hole blocking it, making for a dangerous ride. It is better to crack the bleeder on teh caliper and let the excess fluid out there.

Tom

 

[uknowme2goog]

once i removed the master cover and pressed down on the the piston it moved and i was able to open the space between the new pads enough to slide over the rotor. the brake pads are installed....ok... but for the test ride i went around the block a few times doing a few soft braking and then a few hard brakes and the brake still feel soft. I sanded the rotor with 180 sand paper to clean it up... what can i do to make them grab better?

 

[jetmechmarty]

Did the sandpaper you used look like this?

The black stuff can leave unwanted deposits.

I had good results with a paint stripping wheel.

Once the pads bedded in, the pads grip very well.

 

[uknowme2goog]

the sand paper it self didnt change much...it just scratched up the rotor a little...i had very little black marks on the rotor... so u think using a wire wheel will improve the stopping...what is that all over the wire wheel?

 

[jetmechmarty]

the sand paper it self didnt change much...it just scratched up the rotor a little...i had very little black marks on the rotor... so u think using a wire wheel will improve the stopping...what is that all over the wire wheel?

That is not a wire wheel. It's a paint stripping wheel. You buy one at your local hardware store and chuck it up in your drill. That picture is one I found using Google.

 

[uknowme2goog]

ok... i will try it..let you know....

 

[Unfocused]

Did you bleed the brake once it was reassembled?