Brake Caliper Pistons

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John Vardanian
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Brake Caliper Pistons

Post by John Vardanian »

Would someone please explain how the piston comes apart so I can replace the two rubber parts; i.e., the seal and the dust hood? Thank you in advance.

john
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

How do you separate the steel piece (#8) from the brass piece (#10)? The Ferrari pistons do not have the screws that go thru the brass plate (#13). You just have three small hols in this plate. This is a general diagram from the internet. Thanks.

john

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tyang
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Re: Brake Caliper Pistons

Post by tyang »

Hi John,

The parts you're asking about are pressed out to change out the dust boot.

Tom
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

Tom, thanks. Sorry, I can't follow, can you explain please? Pressed out on an harbor press? How do you separate the steel piece from the brass piece?

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tyang
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Re: Brake Caliper Pistons

Post by tyang »

Hi John,

You have to make a jig to hold the steel piece in place on you Arbor Press, and a pin to push it out past the brass piece. You'll need a new jig or collar for each size piston. I have only done this once since I didn't want to make separate collars/jigs to hold the several pistons sizes. I send the whole piston out to the brake rebuilder and they come back assembled. Saves me time to do something else.

Tom
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

Thanks Tom, so you have to do all this just to replace the rubber pieces?

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tyang
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Re: Brake Caliper Pistons

Post by tyang »

Hi John,

Some people have successfully replaced the boots by stretching them over the pistons, but it's nearly impossible. The piston seals stretch on and off without a problem.

Tom
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

Thanks Tom, appreciate the advice. I'll let someone else do it then. Do you just send out the pistons or the entire brake assembly?
My cylinders are fine, they were lined with stainless by the previous owner.

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tyang
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Re: Brake Caliper Pistons

Post by tyang »

John Vardanian wrote:Thanks Tom, appreciate the advice. I'll let someone else do it then. Do you just send out the pistons or the entire brake assembly?
My cylinders are fine, they were lined with stainless by the previous owner.

john
Just the pistons is usually fine.

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David Booth
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Re: Brake Caliper Pistons

Post by David Booth »

Hi John:

I just put my caliper assemblies back together a couple of months ago, which included separating the parts you mention.

My 1-ton arbor press probably isn't mounted in the best location (on a rolling bench). So I used my bench vise to press the piston out of the backer plate and black-oxided the plates while they were off. Selected a 3/8" drive socket to fit over the retractor button, but just small enough in diameter to clear the hole in the backing plate. Used a large-diameter "close nipple" pipe from The Depot to press the piston into.

I have copper jaw covers on my vise to help prevent damage to parts - just have to make sure everything's nice and straight before you start to apply pressure.

Make sense?
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

Another question: There are two sizes of lines, the smaller one is called the 3/16" line, is that correct? What size is the bigger line that connects to the vac booster? I am going to order some lines from Fed Hill and am trying to do my homework. Thanks.

Tom, I believe you used the all copper lines, how did that work out?

john

PS. Dave, thanks for the tip, I haven't tried your trick yet, but I will this week and will report.
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tyang
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Re: Brake Caliper Pistons

Post by tyang »

Hi John,

Fed Hill has copper alloy lines that work really well. The color is not quite like the original copper plate that was done to the original steel lines, but is close. I've heard some shops sending this copper alloy lines out for copper plating to get closer to the original look, but that's up to you.

Tom
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

Thanks Tom. I'd appreciate suggestions and any advice on flaring tools, which supplier, etc.? I got one many years ago from Mini Mania, but after doing the steel lines for a complete car, the 3/16" die is worn out. Thank you.

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tyang
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Re: Brake Caliper Pistons

Post by tyang »

H John,

Fed Hill sells a nice one we bought several years ago. It's not cheap, but we do a lot of flares!

Tom
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John Vardanian
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Re: Brake Caliper Pistons

Post by John Vardanian »

I wanted to report back that I managed to separate the front pistons on my vise and a simple jig made from 2" exhaust tubing. Of the four two came out with some moderate force, one required heating by propane torch and the last one took the higher heat of ox-acetelene and even then with quite lot of force. The back pistons, I do not think they separate, and you don't really need to because you can just pull the dust boot over the head. Thanks Dave and Tom for the pointers.

I'd like to ask another question... the equalizer/booster cylinder in the front of the chassis, can anyone tell me where I can get the seals? Has anyone ran their system without sealing this cylinder (just as a dummy)? Thanks.

john
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