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VTR fighter
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1,391 Posts
Discussion Starter · #1 ·
I thought I'd make a how to and what not to do thread! as a lot of people tend to pick up bad habits.

A customer brought a brake calliper in today, it's pretty knackered but it's salvageable.

Firstly pistons can be a pain to remove so if it's on the bike (this one wasn't) pump the pistons out before you flush the fluid out. Next it's easier to loosen the banjo bolt and brake pad pins before taking the calliper off, Then take off the calliper (discard the copper washers, never EVER! reuse them).

So now the calliper is on the table, incase your doing it like me (wasn't connected to the bike) you can use a few methods to get the pistons out, first take out the pads (don't get your dirty hands on the pad material and lay em out as you removed them), put everything aside (pins, sliders, bolts etc.) i use a magnetic tray for this.



As you can see it's pretty seized up ^

Here is a rubbish tool you can use to remove pistons (personally I think it just rips your pistons apart but might be one of your only choices on a monoblock opposing calliper) this is a sliding calliper so you can use a proper piston removing tool.



Alternatively you can blow it out with compressed air. Or fit it to a bike and pump it out with fluid in. I ended up reconnecting it to a bike, it doesn't damage anything and is easier (if you have a vacuum pump).

Get a clean area in your garage to put all cleaned parts (i use paper towels), then remove the seals (never reuse the same ones) i usually use a small flathead screwdriver to take them out (but be careful not to scratch the calliper)



Next give your calliper a right good clean with brake cleaner (never use carb cleaner or petrol based solvents it leaves a residue and your brakes become spongy!) ensure all dust or grit is out the calliper and the white salty stuff (oxidisation) in the lips where your seals go is out, next put some red rubber grease on the back of the new seals (prevents corrosion behind them and lengthens the life of your seals)



push them in with your fingers (ensure your hands are clean clean CLEAN!) no need for tools. and wipe off any grease visable.

Next clean the pistons up good, you can use a scouring pad but NOT wire wool as it damages it. If there's any rust or pitting on the outside of your pistons BIN EM! otherwise they will just kill your new seals.



Smear some brake fluid on the outside of your pistons and carefully push them back in the callipers. I just use a paper towel with fluid on (don't do it with your finger as the fluid can dry up your skin)

Next put some copper grease on the bleed nipple (i use copper grease tin and a brush, the spray can is messy, crap and expensive)



put rubber grease on the slide rubbers (if it's a sliding calliper)



And on the slider.



smear a bit of copper grease on the back of the pads (not too much as it can go on the disk etc..) as it stops sweaking and reduces friction. And fit them (the right way)



put plenty of copper grease on the pins (as they seize easily)



Put the calliper back together and wipe all excess grease off.



fit the calliper back on with NEW crush (copper) washers and torque the banjo bolt up (goodridge recommend 18-21ft lbs torque).



Then the best tool I've ever bought! once it's all fitted fill reservoir with fluid and use a vaccuum pump to pump it all through (keep the fluid topped up) until there is NO air in the system and the brake feels good. With this tool it literally takes a few minutes!

Ensure the brake works properly, retracts well and everything is fitted properly (don't leave the little 8mm spanner on the bleed nipple, yep iv'e done it before)

ENSURE NO FLUID SPILLS, it it corrosive to paint, put rags around and have some paper towels at the ready.
 

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VTR fighter
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1,391 Posts
Discussion Starter · #5 ·
Nice write up. +rep :thumbsup:

Might want to add a warning about brake fluid and its paint eating ability.
Good idea, will do, i'll edit it, it's not quite soo bad when it's new (but still avoid getting on paint) but used brake fluid is a lot worse, especially when people never change em and they are BLACK! iv'e seen a few.

And customers say i dunno why it's like this, i didn't know you were supposed to change fluid!
 
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VTR fighter
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1,391 Posts
Discussion Starter · #6 ·
Well done. I have a vacuum bleeder but I have never been able to bleed with it.
Your best putting a ring spanner on the bleed nipple (quick to shut off) then the clear tube, then the bottle (ensure the rubber seal is on and it's sealed tight) then another tube, then the vacuum pump (the cheap £20 pumps are SHIT! get the metal ones). Ensure the bottle stays upright (otherwise it will suck up to the vacuum pump) and dont let it get too full. Then pump it, ensure the reservoir stays topped up and the lid off, don't do it outside or in a damp garage as the fluid is hydroscopic (absorbs water). Should take about 15mins to completely fill the system with no water in it!
 
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