Changing pads - advice

[dishman]

Going to do my first front pad change. The disks are fine, so just going with pads.

I have all the equipment I need and have carefully watched a few guides on my car/model.

There is one area there there seems to be a bit of opinion on.

When I push the piston back should I.....

A) open the brake fluid cap and just let the fluid be pushed back into the system.

or

B) Crack open the bleed valve and let it bleed out (using bleed hose) a bit as I push the piston back.


Option A seems to be the most common approach. The downside some suggest is the risk of pushing dirty fluid near the caliper into the system and potentially mess with the ABS.

Option B seems to be the by the book method, but some say this is over the top and introduces other risks. 1) getting air into the system 2) The added risk of the bleed nipple breaking or the chance it will never seal properly afterwards.

The car last had new fluid 2 years ago and has had three changes of fluid in 8 years, so the system should be pretty clean.

Thoughts?

 

[Mottie]

I’ve used method A exclusively for 40+ years in the motor trade. Put some rag around the reservoir in case it overflows.

 

[Lower]

Why would the fluid in the caliper be dirty? The caliper end of the system is completely sealed until you open the bleed nipple.

Just push back the piston and check for overflows which shouldn't happen unless the brake fluid has been topped up.

Its unlikely to mess with the abs. The abs has to be able to accommodate a bit of reverse flow of brake fluid every time you take your foot of the brakes and the run out in the discs pushes the pads back.

 

[Stivino]

Depending on the car I sometimes open the nipple, just to make sure it is free and clear more than anything else.

 

[dishman]

Thanks for that.

As it's my first attempt doing this, I'm obviously making sure I'm doing it correctly, but then it becomes easy to over complicate something.

For example, if I am doing the pads only, is it worth my time removing the caliper bracket as well as the caliper and thoroughly clean them both?

Or is it a waste of time and i should just remove the caliper, clean the bracket in situ, apply the grease as needed and slot in the new pads.

 

[Stivino]

I usually clean the caliper up with a wire brush and these. There should be no need to remove the carrier.
What type of grease are you thining of, and where do you intend on putting it?

 

[dishman]

I have bought the correct greases for each specific purpose.

I actually bought the proslip grease pack, which makes it easy. I know it's cheaper per kg buying larger tubs but I'd never get through it.
There is enough in these tubes to probably do half a dozen pad changes.

It has one for pad ears, one for pins and one for pad backing. All specific to each.

This is the guide i have been following

Obviously he is going the whole hog doing the discs too.

(I think he switches to using the silicone grease for one of the pad backs as Citroen have that piston insert design). The pad backing grease is a EP Moly and I don't think he wanted to get it near the rubber boot. Which seems sensible.)

 

[Stivino]

Like the manufacturers, I use no grease anywhere when I fit new pads. The only place I lubricate, like the manufacturers, is the slide pins.
Where does it say to put grease on the back of pads or pad ears?

 

[Avocet]

Personally, I'd prefer Option B). The dirtiest, most contaminated fluid in the system is likely to be at the wheel cylinders where all the water gets thrown around. However, I have used both methods in the past, with no ill effects. Some older cars need weight on their back wheels for the fluid to flow, but if you're only doing the fronts, it should be straightforward.

 

[dishman]

Like the manufacturers, I use no grease anywhere when I fit new pads. The only place I lubricate, like the manufacturers, is the slide pins.
Where does it say to put grease on the back of pads or pad ears?

You have a good point there.....and yet nearly every guide I can find says to use grease.

Could it not be that fresh out of the factory, with OEM parts and no wear and tear (rust/dirt) there is no need for it and the parts wear in unison.

But on a car that has reached a certain age, the grease compensates for corrosion and slightly poor fit of new vs old parts. Hence why squeaks and squeals can occur.

Interesting none the less.

 

[Stivino]

New pads are not "old parts" so you can only be refering to the carriers, which if worn, need to be replaced. Grease is not a replacement for metal.
Grease only attracts crap.

 

[Lower]

Just clean the caliper

Personally, I'd prefer Option B). The dirtiest, most contaminated fluid in the system is likely to be at the wheel cylinders where all the water gets thrown around. However, I have used both methods in the past, with no ill effects. Some older cars need weight on their back wheels for the fluid to flow, but if you're only doing the fronts, it should be straightforward.

The dirtiest fluid is likely to be at in the calipers, mainly because any water in the system will migrate to the lowest point. But it won't be getting in there from water thrown around from the road. If it was, you're brakes would have already failed!

 

[Lower]

You have a good point there.....and yet nearly every guide I can find says to use grease.

Could it not be that fresh out of the factory, with OEM parts and no wear and tear (rust/dirt) there is no need for it and the parts wear in unison.

But on a car that has reached a certain age, the grease compensates for corrosion and slightly poor fit of new vs old parts. Hence why squeaks and squeals can occur.

Interesting none the less.

Grease used to be a thing when you had anti squeal shims and you needed grease in between them. Modern brake pads don't tend to have shims any more but come with an anti squeal backing on the pad itself. If you clean the sliding areas of the brakes of the baked on brake dust, you shouldn't need grease.

 

[dishman]

Maybe I just don't use any grease after all (other than the slide pins). It makes a lot of sense really.

I guess it's just one of those things that is passed down from how it was always done in the past. Hard to break with a convention. No pun intended,