When to rebuild calipers?

[B D]

I'll be doing a flush, replacing the pads, inspecting the rotors, and replacing the brake lines but how do you know when it's time to rebuild your calipers?

The brakes work ok, but I have nothing really to compare it to.

[MysticLlama]

On mine it was readily aparent by the dust seals being malformed and pretty trashed, but sometimes they may need it before that.

[LakeCleElum]

I rebuilt mine when they started "dragging" - Not releasing all the way...That was when the car was about 25 years old....This will vary with whatever part of the county you live and if the car is driven in the winter where salt is used on the roads....

[Navaros911]

Like Mystic says; check the dust seals for damage... if any visual damage, replace/rebuild them.

If any pistons are stuck I suggest you rebuild them. It isn't very difficult and doesn't take too much time when they are off the car already.

How to check for a stuck piston: If you're having problems pushing one or more pistons back for the brake pad removal rebuild; the caliper.

Good luck.

- Michiel

[B D]

Thanks for the input. I'll inspect them soon.

[anthony]

How to check for a stuck piston:

Just jack up the car and turn the wheels by hand to see if you notice any drag.

[Erakad]

Also look at the pads, if they're wearing unevenly could be due to a sticking piston or caliper hardware...also trashed dust seals (as mystic said) are usually a tipoff.

[Navaros911]

Originally posted by anthony
Just jack up the car and turn the wheels by hand to see if you notice any drag.

Why do it the easy way when there's a difficult way... LOL

[Superman]

Originally posted by B D
I'll be doing a flush, replacing the pads, inspecting the rotors, and replacing the brake lines but how do you know when it's time to rebuild your calipers?

The brakes work ok, but I have nothing really to compare it to.

If you don't know when they were rebuilt last, then it's time. A kit costs just a few bucks, and it can be a very easy job. Rebuilding does more than avoid brake problems or improve performance. It also helps extend the life of your calipers.

[island911]

how do you figure, supe?

[slater]

When it came down to my car, I figured if I had to ask, it was probably not a bad idea. For the price of the rebuild kits, it was worth the peace of mind. That may just be me.

[ianc]

the job is not trivial, but the parts are cheap.

For me, I'd say it's time when they start leaking brake fluid, and not before,

ianc

[LakeCleElum]

Originally posted by ianc
the job is not trivial, but the parts are cheap.

For me, I'd say it's time when they start leaking brake fluid, and not before,

ianc

They will drag and not release the pads a long time before they will leak!!!!!!!

[ianc]

They will drag and not release the pads a long time before they will leak!

Hmmm... Good to know. I had three start to leak before they dragged.

ianc

[B D]

Just got off the phone with Pelican and they say there is no rebuild kits for the rear caliper for the 911L same as a 1968 911S. How can this be? What's the diffrence between the front and rear caliper?

[LakeCleElum]

Originally posted by ianc
Hmmm... Good to know. I had three start to leak before they dragged.

ianc

IANC: Thax for the education. Must be the difference in our climates. Up in the soggy NW, the rust up long before the seals dry out....Take care......

[Superman]

Originally posted by island911
how do you figure, supe?

As you know, brake fluid is hydrophilic or hygroscopic or some other two-dollar word. Means it loves water. Water then gets into the calipers, and it is difficult or impossible to effectively flush it out of the calipers. Pushing the pistons all the way into the caliper bodies, and bleeding with them in this position does the best job of evacuating old fluid and water, but the best way and the only way to truly replace all the fluid is to remove the pistons and flush them out with brake cleaner. When you do this, you are likely to find some rusty gunk on the pistons. Pistons can be replaced of course, and usually they just need a good wiping down. folks sometimes think that bleeding brakes renews the fluid and this is 90% true but not 100% true. And when it comes to brake systems, water is not your friend. Warren recommends rebuilding calipers annually or biannually. If this is done, your brake calipers are always in good shape and they should last forever.

[ianc]

Warren recommends rebuilding calipers annually or biannually

Ha! Haha!

ianc

[Superman]

Originally posted by ianc
Ha! Haha!

ianc

Laughter may indicate an opinion that this level of maintenance is overkill. And yes, annual caliper rebuilds are uncommon in the general population. But I think Warren may have some aluminum calipers which are fairly difficult to source and vulnerable to corrosion. And if the laughers raced the maintainers to Peru and back, the maintainers would win by not having a spec of mechanical trouble. I probably rebuild my calipers every 2-4 years, and I find rust. Also, when you rebuild calipers from time to time, it becomes a very easy task. I could probably rebuild my rear calipers in an hour easy, start to finish, taking my time. It's a zen thing.

[island911]

Originally posted by Superman
As you know, brake fluid is hydrophilic or hygroscopic . . .. Water then gets into the calipers, and it is difficult or impossible to effectively flush it out of the calipers.

. . . folks sometimes think that bleeding brakes renews the fluid and this is 90% true but not 100% true. .. .

Thanks for the explaination; though I think that your mental-model of what's happening is off a bit.

brake fluid is hydrophilic . ..that does NOT mean that it some how collects water, carries it to the calipers, and then leaves it there . .. like a puddle. .. .somehow tough to flush. NOT AT ALL.

Just flush the system with new brake fluid. The hydrophilic nature of the new ("dry") fliud will act like a dry sponge to any remaining "moist" brake fluid.

Thing is, your not ever going to keep all the moisture out of the system. All you can do is be reasonable about it. (change the fluid)

Else, I suppose you could rebuild them only in Arizona .. .and be certain not to breathe on them during the rebuild (you've seen what happens when you breathe on a mirror; haven't you?)