Caliper rebuild

[no1joey]

Calipers finally stripped! 

 

 

 

 

Pick tools were essential

 

 

 

 

And these two 3mm metal rods saved my life. I couldnt get the caliper pistons out with just compressed air, they wouldn't come out all the way, & I couldnt pull them out with my fingers, these two pieces of metal got them out, just put the piston groove in the middle of the two, squeezed to grip and pulled them out pretty easily. 

 

 

 

 

 

 

Question re cleaning, is it ok to get brake cleaner/suds inside the caliper piston bores or do I need to plug it up? If yes what should I use to plug it up? I'm guessing tape won't really make it water tight...I want to clean them completely and not sure how to go about this... also what is the best way to clean the pistons? 

 

[JFP in PA]

We solvent clean the calipers and components, and then blow out the passages with compressed air.

[no1joey]

Thanks. Can you just tape them off or you have to clean the inside of the calipers? i was thinking when you flush the brake fluid that might be a way of cleaning the inside...

 

 

Do you use solvent on the pistons as well? Do you need to use a lint free cloth to wipe, do I need to make sure there is no lint on the pistons when reinstalling? 

Edited November 19, 2015 by no1joey

[JFP in PA]

Thanks. Can you just tape them off or you have to clean the inside of the calipers? i was thinking when you flush the brake fluid that might be a way of cleaning the inside...

 

 

Do you use solvent on the pistons as well? Do you need to use a lint free cloth to wipe, do I need to make sure there is no lint on the pistons when reinstalling? 

 

Yes, and then we blow them dry with compressed air so there is no lint.

 

We flush solvent through the calipers as well, also followed by compressed air.

[no1joey]

Thanks. I hope my air compressor is strong enough, its just a cheap 150psi one... 

[no1joey]

Argh help, found this on the side of one of the piston bores, 100% sure I didn't do it as I didn't go anywhere near the inside of the bores, I picked the dust boots out from the outside - 

 

 

 

Running my finger over it I can't feel it at all but I can just feel it with my finger nail.

 

I know a scratch on the piston itself needs to be replaced as it can carry fluid past the pressure seal, but taking into account where this scratch is (above the pressure seal on the bore) & how the piston caliper works, is this ok or needs to be replaced? I don't even know if the sides of the piston that touch the bore even go that high...

Edited November 19, 2015 by no1joey

[JuncoJones]

Argh help, found this on the side of one of the piston bores, 100% sure I didn't do it as I didn't go anywhere near the inside of the bores, I picked the dust boots out from the outside - 

 

 

 

Running my finger over it I can't feel it at all but I can just feel it with my finger nail.

 

I know a scratch on the piston itself needs to be replaced as it can carry fluid past the pressure seal, but taking into account where this scratch is (above the pressure seal on the bore) & how the piston caliper works, is this ok or needs to be replaced? I don't even know if the sides of the piston that touch the bore even go that high...

 

 

I don't think that scratch will have any impact on your project, no1joey.

 

Your comment above is right, as both the seal AND the piston are the areas that need to be perfectly flat. There should be no fluid pressure built on that part of the caliper. I also suggest to make sure that scratch is perfectly flat, so you don't run the risk of scratching your piston while its moving up and down.

[no1joey]

Thanks. I might do a few passes over it with some 2500 grit wet and dry to make sure the scratch is clean. Talk about dodging a bullet!

[no1joey]

If anyone else has any other suggestions or evidence that it should be replaced please let me know as I am rebuilding my calipers over the weekend. 

Edited November 19, 2015 by no1joey

[Hilux2400]

When you put the pistons in you should lubricate them with rubber grease or something similar. You can use brake fluid, but that gets messy.  

[no1joey]

Thanks I got a lubricant with the centric caliper kit... lube pressure seals and bottom of piston, slide on, don't get any on dust boot.

I also got a ceramic brake lubricant for the shims. Speaking of shims do I pop those back in the caliper before putting the caliper back on the suspension or after? Once everything is back on I bleed the system straight away right? The Pistons will be compressed is this ok or do you have to extend them before bleeding?

Edited November 20, 2015 by no1joey

[Hilux2400]

I now use a vacuum bleeder as I don't like pressing the pedal to the floor as this forces the m/cyl piston through a long travel along parts of the bore that it doesn't not normally use. As your system is now mainly empty it will take some time to bleed it and you might have to bleed corners more than once.  Once the system begins to fill the pistons will move out towards the discs once the m/cyl is able to exert pressure in the system. 

 

I have to say I have never experienced bleeding a system when all callipers have been removed and emptied. I have only ever done one corner at a time. Don't be tempted to pump the system continuously on a dry m/cyl bore.  You might overheat the m/cyl rubbers and end up with another problem. 

 

If you don't have a vacuum bleeder you could do it by gravity alone at the start.  This process works well if you have time.  You crack open a corner and just let the fluid bleed out and continually top up the reservoir.   It can take a day or more, but if you are not in a rush it does work on some vehicles.

 

Good luck    

[no1joey]

Thanks, I have a power bleeder, planning on using 1 litre, then turning engine and pumping brakes a few times, then bleeding another litre. 

 

Should I fill the reservoir up past the max mark before bleeding since the lines will fill up all 4 calipers that are now empty? 

[JFP in PA]

Thanks, I have a power bleeder, planning on using 1 litre, then turning engine and pumping brakes a few times, then bleeding another litre. 

 

Should I fill the reservoir up past the max mark before bleeding since the lines will fill up all 4 calipers that are now empty? 

 

Not really necessary with a power bleeder, just put the fluid in the power bleeder and have at it.

[no1joey]

I was going to try the empty bleeder method and just re fill the reservoir as I go...

[no1joey]

Came off guards red, going back on speed yellow :)

 

[no1joey]

guys im putting everything back on today, with the flex line nuts, how tight? As tight as I can possibly get it using the strength I have?

[JFP in PA]

guys im putting everything back on today, with the flex line nuts, how tight? As tight as I can possibly get it using the strength I have?

 

Make them tight, but don't try to kill them.

[no1joey]

I put everything back together yesterday. I did probably go overboard with the tightening... i was afraid of leaks and wasn't sure how tight to go. Since I was replacing the flex lines I figured I wouldn't be doing this again so I went as tight as I could go. Hopefully they'll be ok no leaks so far about to bleed them now...

[no1joey]

What does it mean when the brake pedal goes right to the floor with no resistance? 

 

It did this twice when I pushed the brake pedal after bleeding the system and turning the engine on for the first time. 

 

After a few pumps it then hardened up. I also noticed the brake fluid level dropped slightly so I checked for leaks and there were none. I pressed the pedal down for about 20 seconds with the engine running, still no leaks.  

 

If there was air in the system then wouldn't the level dropping mean the air escaped and the fluid filled that gap? 

 

If this is not normal I don't know why as I bled 2 litres through the system. Every drop of fluid in the system is fresh. 

 

I just got back from a test drive, brakes work perfectly, hard braking all ok, ABS works fine, no squeaking everything seems perfect. I checked the brake fluid level and it actually rose a little after the test drive. 

 

I don't know if the pedal feels spongy or I can't remember how it felt before (been nearly two weeks since I last drove it), or maybe I'm just expecting a completely different feel after replacing the flex lines and rebuilding the calipers...

 

Would the pedal going all the way to floor when I first pressed mean it needs to be bled again? 

Edited November 25, 2015 by no1joey

[Hilux2400]

The pedal should be hard to press with the engine off and all the vacuum assistance removed.  Get in the car.  Don't turn the engine on.  Press the pedal a few times and it will stiffen up as the mechanical assistance of vacuum is removed.  When you start the engine it will be possible to press the pedal further down as the vacuum assists.

 

If the pedal is not hard without vacuum you need to bleed again.     

[JFP in PA]

I sounds like you still had air in the system.

[no1joey]

Ok i will bleed again.

Just bleed as per normal? Outer nipple, then innner nipple, rear left then right. Front left then right.

Should I do anything different before hand or just start bleeding? Im using the dry power bleeder method and I always refill the reservoir when it needs it. I had to do this about 7 or 8 times during the bleed.

[no1joey]

I sounds like you still had air in the system.

Would you say that it just needs another bleed?

[JFP in PA]

 

I sounds like you still had air in the system.

Would you say that it just needs another bleed?

 

 

To be safe, yes.  And this time, I would open the inner bleeder first, then the outer bleeder last on each caliper.