Front Empi Disc Brakes locked

[65VWBugTemecula]

I have a set of aftermarket Empi disc brakes that are locked. Here is my setup

Stock 65 Bug Master cylinder (Single master cylinder)
Empi Disc brakes
Stock drum rear brakes.

Currently, only the FRONT disc brakes are locked the rear brakes work great. I have tried to bleed the brakes many times without any luck. I even compressed both pistons and bleed the brakes. No matter what I try, the brakes are locked. Once I apply pressure the only way to get the wheels to spin freely is to release the pressure via the value on the caliper.

History of car:
I first installed these brakes about 2 years ago. The brakes worked great for the two years I drove the care. However, I have since pulled the body off and did a lot of repairs on the pan. The pan is now powder coated. I installed everything back on the car I removed (same brakes front and back). I did replace all the brake houses (flex and solid). Once I installed everything, the brakes are now locked.

Has anyone seen this problem on this style of brakes? Does anyone have any thoughts on how to fix this problem?

Thank you
Jeff

[Steve22]

flex hoses are probably collapsed. Happened to me on the rear of my '73 super.
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'65 Karmann Ghia 'vert
'73 Super Beetle
'59 Beetle ragtop
'73 Sunroof Transporter

[slalombuggy]

Check the free play in your brake pedal, if you don't have any it won't let the pressure release.

brad

[drscope]

There are a few things that can cause this. The flex lines as previously stated are a common problem.

But there is another issue with discs. There is a rubber boot around the piston which is supposed to keep dirt and grime out of the bore. It normally does.

But those rubber boots can also trap moisture in there. That is usually not a problem on a car that is used often as the intense heat from the brakes boils that moisture off.

But when a car is only used occasionally or sits for a long time, that moisture can start to rust the lip on the casting where the piston goes into the bore. When that happens the pistons often get frozen in the bore.

Some folks just replace the calipers at that point. But you can easily rebuild them if you have compressed air and a rubber tipped blow gun.

Take them off the car.

You can clean things up before you go any farther. Hot water and dish soap will remove much of the crud, brake dust and grease that may be on them. Don’t be afraid to get them wet or even for water to go inside. It won’t hurt anything during this procedure.

You can use a parts cleaning brush too, just be careful not to damage the rubber boots.

If they are really dirty, or greasy, you can also clean them with parts cleaner. But after using that I would again clean them with the soapy water to get the parts cleaner off. It makes the rest of the job a little easier.

Once they are cleaned up, carefully remove the rubber boot. They normally have some sort of snap ring or wire ring holding them on.

Now spray them liberally around the piston with PB Blaster, WD-40 or whatever penetrating oil you have.

Before going any farther you need to look at the face of the pistons. Some are smooth, or have a raised ring that goes all around the face.

But some have a raised ring that only goes about 3/4 of the way around. If you have that style of piston, it is VERY important that the piston goes back in the hole in the exact same way!

Most of the ATE's are this way.

There is a gauge to help get the correct orientation on the piston.

You can make one easily out of sheet metal. Its a 20 degree angle. The gauge sits flat on the caliper and you rotate the piston to match the gauge then push the piston in. Or you can use pliers to rotate the piston after its in to fine tune it.

Anyway, be aware if you have that style piston you need to get that angle correct on re-assembly.

Now, with the pads removed, stuff a rag into the caliper so when the piston pops out it isn't going to go flying and crash into the other side of the caliper.

If you are doing a dual piston or multiple piston caliper, (some of the Porsche stuff we mess with has 8 piston calipers) you need to use a C-clamp to hold the other piston so it won't pop out.

Clamp the caliper in the vice. Keep your fingers OUT of the caliper.

Make sure the bleed screw is closed.

Put your rubber tip blow gun into the brake line hole and let her rip.

The piston should pop out with a big noise that will almost make you pee your pants the first couple times you do this.

If it isn't moving, give it some more penetrating oil and then try to push the piston back or even rotate it in the bore to try to get it to free up and try the air again.

Sometimes if they are really stuck it will take a few tries before they give it up.

Once you have the piston out, look into the bore. The outer lip of the bore which is causing all the trouble is about 1/4 inch long usually. And that is normally where you find most of the problems.

Just behind that lip you will find a square cut O-Ring in a groove. Using a small pick, carefully pry that O-Ring out without hurting it clean it and inspect it for damage. If its good, you can reuse it.

Now, that square cut O-Ring is basically the only thing that pulls the piston back when you let off the brake pedal. There are no real springs in this system. Some do have spring clips that go in between the pads, but most of them don’t do much after a while.

So now that you have everything apart, clean the piston and if it has corrosion on it, use some fine emery paper to get it clean. If it looks OK, it can go back into service. But if its all pitted up, you need a new piston.

Wipe the bore clean and inspect for pitting. If the bore is good, the caliper can be reused. Usually even if you have pitting in the bore, they will work just fine. But if its severe, you may want to consider a new caliper.

Next make sure you get the groove for the O-Ring clean. Make sure the corners of the groove are clean. Sometimes its difficult to see in there, so be extra careful making sure you get all the crud out.

Now its time to address that outer lip that is causing all the trouble.

What you want to do is use a piece of fine wet or dry paper. I often use a piece about an inch square for this. You want to carefully clean that lip without sanding on the bore behind the lip.

Pits and scratches are NOT a problem on this lip. It is simply there to hold the O-Ring in place. You are just trying to remove the corrosion that has built up to the point that it is not allowing the piston to move freely.

Once you have that lip clean, give everything a good rinse with hot water again.

Now blow everything dry with the blow gun to make sure you have the water out of all the bores.

Lube the O-Ring with brake fluid and install it back into its groove.

Now lube the bore with a little more brake fluid. (there is also some inert silicone grease you can use as a lube when doing this, but if you don’t have it just use brake fluid)

Lube up the piston and position it in the bore. If you have the type that need to be aligned, use your 20 degree gauge and align the piston.

Now trying to keep the piston straight and square, push it into the bore with your fingers. It should go in with not too much force. If it resists, check the O-Ring to make sure its OK and in the groove where it belongs and try again.

They do need a strong push but you shouldn’t be straining to get it in.

Once you have the piston back in place, install the rubber boot and retaining clip.

If you are doing a single piston caliper, it is now ready to go back into service. If you are doing a multiple piston caliper, you need to do the other pistons and bores as well.

This should get you back into service for a long time again and it only cost you a little time, sand paper, compressed air and brake fluid.

Or you could whip out that credit card and simply order new calipers. Or send it to a shop that will order new calipers and then charge you $100 an hour or more to put them on and bleed the system.
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Mother Nature is a Mean Evil Bitch!

[50sboy]

Take the master apart and make sure that the residual valve has been removed - if not, remove it. You can see the procedure on the empi web site youtube brake video.

[bill may]

[mrmarcdude]