Brake caliper piston

[Merritt5]

I have a 93 Fox that I have upgraded the brakes to a 94 mustang system (mc, calipers front and rear).

On the driver rear, when you press the brake (you have to pump, but we'll get to that) it clamps the rotor like normal. As you release the pedal, the piston retracts 100%.

I know the piston is supposed to retract some to free up the rotor, but go all the way back in? I will also add this is a new caliper from the parts store (2nd one to be exact, 1st one had the same issue.)

Anyone else had this issue and is it normal?


Merritt

[spode]

Parking brake part of the caliper causing issue or master cylinder not uncovering the transfer port. Make sure the rod pushing on the master cylinder has free play and is not applying the brakes. Just a small adjustment issue could cause that.

[Merritt5]

I currently don't have the parking brake hooked up (haven't got the right cables yet). As for the rod, I adjusted it to have about 0.020" clearance.

Now, is there a way to adjust the parking brake on a mustang caliper?


Merritt

[Merritt5]

I'll post an update.

The day I started the thread, I gravity bled the brakes and was having the piston issue.

Next day I got out and the piston seems to be working fine.

If anyone else is having this issue, check out the link. It gives you a few things to try with integrated parking brakes

http://hydratechbraking.com/braketech1.html



Merritt

[GregWeld]

Originally Posted by spode

Parking brake part of the caliper causing issue or master cylinder not uncovering the transfer port. Make sure the rod pushing on the master cylinder has free play and is not applying the brakes. Just a small adjustment issue could cause that.

Not sure how that could or would be the issue -- he's asking about whether or not the puck should retract all the way like it's doing.... your suggestion would be the opposite of that - that the brakes were NOT releasing...

The brake pads should always be "pretty close" to engaged but without any pressure on them whatsoever.... Generally to get the pucks to retract you have to PUSH THEM back. There's also puck knock back, but that's another issue.

Be certain you're not looking at a single sided brake system where only the one side actually has moving parts -- the other side is "fixed" -- when the brakes are applied only one side of the caliper actually "works" and just pulls the other fixed side into the rotor and then they clamp. Perhaps what you're seeing is ONE side moving and the other side just "relaxing" without any pressure being applied?

[GregWeld]

The only other explanation I can think of is that you've got some kind of vacuum situation created.... and to cure that (which would be odd as all get out) is to just simply release the master cylinder cap and see if it stops.... which would also give you a chance to check the fluid level and condition.

[Merritt5]

Originally Posted by GregWeld

The brake pads should always be "pretty close" to engaged but without any pressure on them whatsoever.... Generally to get the pucks to retract you have to PUSH THEM back. There's also puck knock back, but that's another issue.

Be certain you're not looking at a single sided brake system where only the one side actually has moving parts -- the other side is "fixed" -- when the brakes are applied only one side of the caliper actually "works" and just pulls the other fixed side into the rotor and then they clamp. Perhaps what you're seeing is ONE side moving and the other side just "relaxing" without any pressure being applied?

Never heard the term single sided brake system before, but it is a stock 94 mustang caliper. So only one piston and its on the inside.

I know the piston should retract a little once you let off the brake, but this one was retracting 100%. You could watch the piston move back and forth with each push of the pedal.


Anyways it seemed to fix itself, I've just never seen that before and was curious if anyone else has.



Merritt