Is a brake caliper pressure seal directional?

chrismckay · Jan 15, 2020

Question on the orientation of the pressure seal in a brake caliper.

When replacing the pressure seal is it possible to insert them upside down?. I have been searching google for ages and get conflicting advise.

One youtube video says that there is a bevel on the seal not visible to the human eye and that you should feel a lip on the seal once inserted dragging your finger from the inside of the caliper over the seal to the outside of the caliper.

Another website suggests that the recess for the seal is angled so as to cause a lip on the hydraulic side of the seal.

Anybody know???

Chris...

ChazzyB · Jan 15, 2020

All the calipers I have overhauled have a raised 'bevel' across one corner at the bottom of the seal groove. It doesn't which way up the seals themselves are installed (in my experience).

captaindan · Jan 15, 2020

Hi Chris
I sell this type of seal at work but for industrial, not automotive.

Best description is that if you had cut through it and looked at the end of the cut, it outlines like a slice of bread.

The pressure goes to the wide end of the profile or it just won’t work.

Some pistons I have seen just use a round section o ring, so that can go in any way round.
Hope that helps you
Dan

Daffy · Jan 15, 2020

I’ve never seen a round or bellows type calliper seal (not saying they dont exist), they are square or rectangular to facilitate the running clearance of the pad when released, in my experience there is usually something built into the metallic parts to allow more retraction when realeased.

As above, I dont think you can fit them the writing way round unless it is very obvious which way they go..

What’s the worst that can happen??

captaindan · Jan 15, 2020

Good point Daffy, there are square types known as Julio seals or quad rings, they can go either way, really need to know what type of seal you have there Chris. Photo perhaps ?

clutchspring · Jan 16, 2020

Try having a look on utube & search Delboys garage motorcycle front brake caliper rebuild part one.
Although in this particular example he only explains one type of seal, some caliper seals are square edged & can be put in either way.

Hope this helps.
Ian.

Is a brake caliper pressure seal directional?

chrismckay

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ChazzyB

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captaindan

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Daffy

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clutchspring

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