Sticky brakes

[Jarcaines]

Took my Camaro out for a drive for the first time since installing disc brakes all around. I noticed that the brakes where sticking, but when I lifted on the back of the brake pedal with my foot they would release. Where should I start with diagnosing this problem? Is this a master cylinder issue?

Any advice would be great. I am new to all of this and learning as I go.

[WallaceMFG]

Are you running a booster or manual brakes?

[Jarcaines]

Are you running booster for manual brakes?

Booster

[Twentyover]

Pedal pullback spring still attached?

[Jarcaines]

Okay, noticed that the brakes are always binding a little bit and the pedal seems super high, so I started looking into the booster rod length. It seems too long, but I don’t see how to adjust it. Any suggestions?

[eville]

https://www.summitracing.com/parts/b...SABEgKETfD_BwE

[Jarcaines]

Okay, did some more digging and I got the caliper torn apart. I am not familiar with C5 brakes at all and what I am seeing is the pads just set in the bracket loosely and the pistons press against the back of the pad, but I don’t see anything to keep the pad off the rotor when the piston is not pressed. Am I missing something or do I just not understand how these brakes work?

[eville]

There is no mechanism to retract the pistons in any disc brake caliper. If you’re brakes are sticking unbolt the mc a little. If the brakes release the rod in your booster needs to be adjusted. Use the tool I posted above to measure.

[Jarcaines]

There is no mechanism to retract the pistons in any disc brake caliper. If you’re brakes are sticking unbolt the mc a little. If the brakes release the rod in your booster needs to be adjusted. Use the tool I posted above to measure.

Thanks for the feedback.

I did have the master cylinder totally unbolted and it still seemed like the pads were rubbing the rotors a little bit when I spun the wheel by hand.

[WallaceMFG]

Thanks for the feedback.

I did have the master cylinder totally unbolted and it still seemed like the pads were rubbing the rotors a little bit when I spun the wheel by hand.

Disc brakes will always have the pads drag on the rotors a little. They are not like drums that have springs to pull the shoes back. Nothing wrong there.

If the issue goes away when you lift up on the pedal then it should be related to the MC, not the calipers. Which brakes are sticking, front or rear? What MC are you using? What kind of booster are you using? Some drum brake cars had a residual valve in the lines to hold about 10psi of pressure in the lines to keep the springs from compressing the wheel cylinders. Those have to be removed with disc brakes or they will drag. Was the car originally drums all corners or discs/drums?

Need more info on your brake system to try to help.

[Jarcaines]

Disc brakes will always have the pads drag on the rotors a little. They are not like drums that have springs to pull the shoes back. Nothing wrong there.

If the issue goes away when you lift up on the pedal then it should be related to the MC, not the calipers. Which brakes are sticking, front or rear? What MC are you using? What kind of booster are you using? Some drum brake cars had a residual valve in the lines to hold about 10psi of pressure in the lines to keep the springs from compressing the wheel cylinders. Those have to be removed with disc brakes or they will drag. Was the car originally drums all corners or discs/drums?

Need more info on your brake system to try to help.

So, there are a couple things happening.
First the pedal issue, but that’s been fine since I lifted it with my foot the first time.
Since I’ve been trying to diagnose that issue, I have noticed that none of my wheels spin super freely when they are off the ground, all sorta rub a bit. I was concerned this would cause over heating. I removed the master cylinder and tried to measure the rod and cylinder depth with a caliper gauge (not ideal, but what I had on hand) and it seems like there is about a .185” gap. So, not sure what the issue is.

Here are the details about the brake setup:
Originally 4 wheel drums
C5 style brakes all around now.
Not sure on the master cylinder or booster, they were found by the shop who installed the brakes. Here is a pic if that helps.
Also did not know about the residual valves. I’ll have to check on that. What would I be looking for?

[eville]

Disc brakes will always have a little drag. Don’t worry about it.
I’d pull the mc and measure the diameter. The c5 system will work better with a 1” master with vacuum assist. . My guess is that’s a 1.25” mc.

If the booster rod is .185 shorter than the hole in the master then it needs to be lengthened. You’d be pushing the pedal a long way before the brakes engaged.

[TheBandit]

Firewall hole clearance Does your master have a boot/bellows that passes through the firewall or does it mate up and seal against the firewall? If it passes through the firewall, make absolutely sure it doesn't hang up in the firewall hole when your are depressing the brakes. I had this issue and it made my brakes slow to release or drag. I was using a Tuff Stuff dual 9" booster meant for a '69 Corvette. I opened up the firewall hole but didn't open it up enough. Later I switched to a different type of boot & seal plate from DSE that seal against the firewall rather than passing through. Here's a video of the problem I had with the Tuff Stuff booster and boot/bellows passing through:

https://www.youtube.com/watch?v=8US4...ature=youtu.be

Booster Pushrod Clearance I suggest using the proper tool to check for pushrod length and get that adjusted accordingly. I just did this recently using a tool I bought on Amazon for $20 (photos below, search for "Power Brake Booster Pin Adjustment Tool") and a set of feeler gauges. Ideal clearance is around 1/16in (0.063in). If you really have 0.185, then you have too much gap. If you actually have interference, the compensating port may not open completely which can lead to fluid going back to the reservoir slowly or not at all.

Caliper Sliding Pins Make sure the sliding pins on the calipers, which allow them to float, are well lubricated and are not binding.

Brake Hose or Lines Make sure the brake hoses are not collapsed. Sometimes internal defects in the hose will not be obvious, but may keep the brakes from getting fluid or may hold pressure in the caliper if they act like a check valve. Also look for kinked lines.

Caliper Pistons/Bore If the bore or seals have issues, the pistons themselves can get stuck.

Internal Rubber Parts If you cleaned any of the bake parts with petroleum distillates like brake cleaner or mineral spirits, this can cause seals and hoses to swell and/or crack. That's why brake cleaner is for external parts only. Once the rubbers are damaged they may need to be replaced altogether.

Here are some photos of the tool for measuring pushrod clearance:

[TheBandit]

Also did not know about the residual valves. I’ll have to check on that. What would I be looking for?

Residual valves for disc/drum applications are often installed in the rear port of the master cylinder. Drum/drum applications may have residual valves in both front and rear. What they do is keep a few psi held in the line for drum brakes so the shoes are held ready to apply. If you have them installed on a disc line, the calipers will always get a few PSI that will cause drag. You can check for them using a paperclip or a small prob through the outlet of the master.