Removing brake calipers advice.

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Soldato
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I changed the pads recently on our X-Trail and noticed that the caliper pistons were very stiff on one side. Given that rebuild kits are pretty cheap, I want get them off and replace the pistons and seals, as well as giving the mounting brackets a good brush down to make sure the pads are all sliding nice and smoothly.

I've got no trouble doing it, looks like a fairly simply job. My only question is...is it necessary to completely drain the brake fluid from the system when changing them? I know it's a bad idea to clamp the brake lines in case they get damaged. And whenever I've bled the system, brake fluid only really escapes if the pedal is pressured.

So should I be okay to remove the caliper without brake fluid going everywhere? Obviously there'll be some excess, but I'd like to mitigate as much loss as possible. And yes, once the calipers are back on, I'm aware they'll need to be bled again.
 
It will leak continuously when you remove the brake line so you'll want to minimise the loss, with a cap over the end or clamp. Ideally you do not want to completely dry the system as air could get trapped and be difficult to bleed again.

I've heard some people use a bit of wood etc to hold the brake pedal down to minimise loss, poor description but think of it like using your finger over the end of the straw to keep the liquid inside.
 
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I wouldn't push the pedal down without the caliper on the end as you can damage the brake cylinder diaphragm doing that.

I would try and minimise fluid loss by working quickly and leaving the reservoir cap done up tightly and topping it up if/when it gets low - you don't want to have the hassle of bleeding the ABS system etc by letting it completely drain.

Carefully flush the system afterwards with cheap fluid and then flush that out with good stuff if you're planning on running better fluid.
 
I've no issue with clamping a rubber hose as long as you don't go silly. Make sure the tool you use does not have sharp teeth and there's no need to clamp it stupid tight. If you're that worried there are clamps available that are designed for this job.

On the race car I have braided hoses and clamping those isn't an option. If the caliper will only be off for a few seconds (say I'm swapping it for a different one) then I just let it drip and clean up afterwards. If I know the caliper will be off for a while then I usually put a nut and bolt sealed with some spare copper washers through the end of the banjo and nip it up to stop leakage. If I have to remove brake lines I've got a selection of various blocked off old fittings that I can use to seal the lines up too.

As said don't let it drain too low, even just getting air in the master cylinder from letting the reservoir drain completely can leave you with a load of trouble trying to bleed everything properly.
 
I was thinking of this earlier actually as ive just changed the front calipers on my WRX but want to recon the rears myself. Could you not get a bolt the correct size/pitch and thread it into the banjo? Others suggest a sandwich bag and cable ties which could work too, i really don't want to clamp the lines either as i think its just asking for trouble.
 
Oh and you need to accept the following if you're going to open up brake circuits:

1) Brake fluid is nasty stuff and you don't really want it getting on anything.
2) Brake fluid will somehow end up everywhere despite your best efforts to observe point 1. Have plenty of absorbent rags around and wipe down everything you've touched including all of your tools when you've finished.
3) It will rain and you'll end up with visual evidence of brake fluid getting everywhere including the soles of your shoes which are now leaving oily footprints all over the drive and anywhere else you go to get things to help clean up the ever growing mess you've made.
 
Whenever I've done it I've just swapped the hose from the old to the new caliper quickly, with a pot underneath to catch fluid. You won't lose much that way. It can then just be bled and topped up.
 
Make up a section of copper brake pipe with a connector on it at one end that will fit your hoses.

Fold the other end over and hammer it flat to ensure a seal (Or put a plug of solder in it).

Use this to prevent fluid loss until you are ready to refit the callipers.
 
Cheers for the advice all. I have a couple of earplugs sitting around, I was considering using them and wrapping the end of the pipe with a sandwich bag, then just leaving it over a glass container to slow any loss.

Howard said:
Whenever I've done it I've just swapped the hose from the old to the new caliper quickly, with a pot underneath to catch fluid. You won't lose much that way. It can then just be bled and topped up.
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The issue is that I'm not swapping calipers, I'm intending to rebuild them, so it could be off the car for a fair while.
 
I wouldn't bother with a rebuild kit. It might well work but there's a good chance once you get it apart there will be corrosion. Quicker and easier just to take it off bolt a new one back on cost a little more but no mucking about if the caliper is knackered and you'll have the car back on the road in a couple of hours.
 
kaiowas said:
Oh and you need to accept the following if you're going to open up brake circuits:

1) Brake fluid is nasty stuff and you don't really want it getting on anything.
2) Brake fluid will somehow end up everywhere despite your best efforts to observe point 1. Have plenty of absorbent rags around and wipe down everything you've touched including all of your tools when you've finished.
3) It will rain and you'll end up with visual evidence of brake fluid getting everywhere including the soles of your shoes which are now leaving oily footprints all over the drive and anywhere else you go to get things to help clean up the ever growing mess you've made.
Click to expand...

I see you've had the same experience as me... :P
 
ONLY if the caliper seals are leaking would I ever fully strip a caliper to clean it up or refurbish it with new parts.

If there is no leakage and it is purely that the pistons are slightly sticky, then just fold back the rubber boot carefully, get someone else to press the brake pedal very slowly until the pistons have almost come out further than they would in operation but not fully out of the caliper, then clean the piston with brake cleaner and if really necessary very lightly with extremely fine wet and dry paper, wipe down with rag,.

Then cycle the piston a few times by pressing piston back into caliper and then pushing out with brake pedal.

Wash out with brake cleaner and wipe with rag each time, again if really necessary very lightly rub with wet and dry.

I have done this hundreds upon hundreds of times over the years and it never fails to cure the issue and is quick simple and gives great feeling brakes for many years after.
 
marcus25 said:
you get specific brake line clamp tools so if you;ve got rubber hoses i'd get some brake line clamps and use them.
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This! No need to complicate it with anything else.

Or drain all the brakes, and do a full bleed once new caliper is ready, might as well.
 
Conscript said:
I changed the pads recently on our X-Trail and noticed that the caliper pistons were very stiff on one side. Given that rebuild kits are pretty cheap, I want get them off and replace the pistons and seals, as well as giving the mounting brackets a good brush down to make sure the pads are all sliding nice and smoothly.

I've got no trouble doing it, looks like a fairly simply job. My only question is...is it necessary to completely drain the brake fluid from the system when changing them? I know it's a bad idea to clamp the brake lines in case they get damaged. And whenever I've bled the system, brake fluid only really escapes if the pedal is pressured.

So should I be okay to remove the caliper without brake fluid going everywhere? Obviously there'll be some excess, but I'd like to mitigate as much loss as possible. And yes, once the calipers are back on, I'm aware they'll need to be bled again.
Click to expand...
Stick on the brake pedal will stop it dripping. Just crack off the bleed nipple to release the pressure on the brake line your playing with.
You need to pop the Pistons out but as there are a bit stiff you might want to use brake line pressure to pop them out, hot water will clean the spilt fluid it will damage paint. Might be better to replace the caliper tbh.
 
Rainagul said:
This! No need to complicate it with anything else.

Or drain all the brakes, and do a full bleed once new caliper is ready, might as well.
Click to expand...

This, if the calipers sticking is the water the fluid has absorbed corroded the insides way overdue a fluid change
 
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