brake caliper rebuild

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Stigmata

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Im going to rebuild my rear brake caliper. Any sugessions on a good kit? I saw a kit from the UK called brakemasters but don't really want to wait that long to receive. Saw another brand from Brake Crafters that I can buy in the USA.
 

DreamV4

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Usually no parts needed, just cleaning.
 

Stigmata

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I took it apart, cleaned everything and only replaced the seals. The pistons didn't look bad but I cleaned them anyway with 3M scotch brite pads. I also installed a new master brake cylinder and bled the system. The rotor still gets way too hot. I'm thinking the only thing left to do is replace the pistons.
 

Fire-medic

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02GF74

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The pads rub on the disc if there is not enough clearance, this causes the disc to get hot which results in the disc expanding so the clearance gets smaller which causes the pads to rub even more and so it goes.

Have you checked brake disc run out?
Have you checked pistons are withdrawn when brake is released?
Is there free play in the rear brake mechanism?
Is your foot pressing down on the rear brake as you ride?
 

Fire-medic

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Have you cleaned the rear master cylinder? Does it have fresh fluid? There may be debris blocking a port.
 

02GF74

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Rear calliper clean - ya made sure the grooves where the seals sit were clean of corrosion.

What was the surface of the pistons like, all shiny chrome or pitted?

If you are going to replace the pistons, get stainless steel ones.
 

Stigmata

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Have you cleaned the rear master cylinder? Does it have fresh fluid? There may be debris blocking a port.
I put in a new rear master cylinder and changed the fluid 3 months ago. I held the other piston in with a piston spreader while I pumped the brake and the other piston popped right out. The piston was clean and no debris or corrosion inside where the seals are. I'm going to pop the seals out next.
 

Stigmata

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Rear calliper clean - ya made sure the grooves where the seals sit were clean of corrosion.

What was the surface of the pistons like, all shiny chrome or pitted?

If you are going to replace the pistons, get stainless steel ones.
When I did a rebuild 3 months ago I cleaned the grooves with a dremel. The pistons where a little corroded so I cleaned them with a 3m scotch brite pad. When I popped out the piston yesterday it was clean. No sign of corrosion or debris. The inside where the piston sits was also clean. I'm going to pull out the seals and check them also.
 

Stigmata

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I noticed that the OEM caliper rebuild kits are about $200 for a full kit with pistons. I can get a full kit from Brake Crafters for around $78. Is there really a difference? Has any one used this company?
 

Fire-medic

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It's possible that your hose has delaminated inside and the lumen (the passage) has become narrowed (not blocked) and may-not be allowing a full retraction of the calipers once you release foot pressure. That most-likely would put a lot of drag on the wheel, and the caliper and rotor would be hot! I think this is one of those times I'd be investigating everything from one end to the other. It sounds like you've done a pretty-thorough overhaul. You saw on one pic where I removed the entire system from a SOHC Honda, to work on it. That was more because of it being in a storage facility and you aren't supposed to do mechanical work. I don't want to get in trouble there, so I removed the front brake system, did the repairs at home and re-installed it.

I may be lucky, but I've never had a caliper so-bad that a seal kit didn't fix it, though I have replaced on a car, a 'loaded' caliper (remanufactured caliper and new pads).

What I see when I release pedal pressure, is a small amount of retraction from the caliper. Do you achieve that? The radial run-out of the rotor will also push-back the pads, even if it's only thousandths of an inch. It's enough to allow free-turning of the wheel, if you had the rear wheel elevated (centerstand or track stand). Is your drag significant-enough that it presents rolling-resistance to rotating the rear wheel, off the ground?

The Brake Crafters kit looks decent as it has SS pistons.
It's worth a try. I think I'd make sure that the brake hose doesn't have any issues first.
 
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Stigmata

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Also when rebuilding brake caliper is it best to lubricate the seals and pistons with brake fluid or the red rubber grease?
 

Fire-medic

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Also when rebuilding brake caliper is it best to lubricate the seals and pistons with brake fluid or the red rubber grease?
They supply it to you, I'd use it. I wouldn't put it on thick like you're frosting a cake. I would apply a thin skin to the entire surface of the square O-rings, and just a thin skin to the lips of the dust seals. Do a dry-assembly to the pistons, to see where the O-rings would be riding, and add more at that point to the pistons. There is no-need to coat the entire outer circumference of the pistons.

I've always just used brake fluid to provide the lube, and have never had any issues. If the new pads came with brake grease, use it, just sparingly, and on the surfaces where the rubber rides. It's also for the backs of the pads, and the edge of the pistons, and on any shims, to prevent vibrations causing brake squeals.
 
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Stigmata

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It's possible that your hose has delaminated inside and the lumen (the passage) has become narrowed (not blocked) and may-not be allowing a full retraction of the calipers once you release foot pressure. That most-likely would put a lot of drag on the wheel, and the caliper and rotor would be hot! I think this is one of those times I'd be investigating everything from one end to the other. It sounds like you've done a pretty-thorough overhaul. You saw on one pic where I removed the entire system from a SOHC Honda, to work on it. That was more because of it being in a storage facility and you aren't supposed to do mechanical work. I don't want to get in trouble there, so I removed the front brake system, did the repairs at home and re-installed it.

I may be lucky, but I've never had a caliper so-bad that a seal kit didn't fix it, though I have replaced on a car, a 'loaded' caliper (remanufactured caliper and new pads).

What I see when I release pedal pressure, is a small amount of retraction from the caliper. Do you achieve that? The radial run-out of the rotor will also push-back the pads, even if it's only thousandths of an inch. It's enough to allow free-turning of the wheel, if you had the rear wheel elevated (centerstand or track stand). Is your drag significant-enough that it presents rolling-resistance to rotating the rear wheel, off the ground?

The Brake Crafters kit looks decent as it has SS pistons.
It's worth a try. I think I'd make sure that the brake hose doesn't have any issues first.
When I rebuilt the caliper 3 months ago I also installed a Galfer braided line. I will measure the thickness of the rotor. It's an EBC. Once I change out the piston and seals I will rotate the wheel on a stand to check for any drag.
 

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