Hydroboost Brakes

[pomai]

New calipers, rotors, pads, master cylinder, hydroboost.

I bleed the brakes until no bubbles, I thought the bleeding proses went perfect but the pads are dragging on the rotors, I cant spin the hubs with my hands, on both sides, I have to use a crow bar with the wheel studs to spin it.

Any ideas on what happened?


Thank you,
Ed

 

[frankin5]

Got to break in the pads. EBC has to be bedded in to get break in coating off.

 

[Tnsejed]

If you pop the bleeder is it holding pressure? If there is no pressure there make sure where your calipers ride is cleaned smooth of rust or scale and thoroughly greased with silglide or similar. The last bit is a maintenance item that needs to take place in between pad or rotor changes, especially in rust belt areas.

 

[pomai]

I benched bled the MC & checked the runout after installing the hubs, .003 on one side and .004 on the other, both sides feel the same, unable to spin by hand. the caliper brackets were sand blasted, I made sure the slides were very clean and smooth on both the caliper and caliper brackets. I used the slide grease that came with the EBC pads.
I'm going to see what happens when I open the bleeder.

Thank you,
Ed

 

[imiceman44]

I benched bled the MC & checked the runout after installing the hubs, .003 on one side and .004 on the other, both sides feel the same, unable to spin by hand. the caliper brackets were sand blasted, I made sure the slides were very clean and smooth on both the caliper and caliper brackets. I used the slide grease that came with the EBC pads.
I'm going to see what happens when I open the bleeder.

Thank you,
Ed

You might have stuck calipers which will be evident when you loosened the bleeder

 

[ridenby]

The calipers are new/rebuilt?

 

[imiceman44]

The calipers are new/rebuilt?

Did you hear me hesitate?
These days you have 50% chance of getting a defective new part

 

[ridenby]

I was just wondering if these had been on for awhile or where just purchased. I recently went through new-rebuilt calipers leaking after bleeding.

 

[pomai]

You might have stuck calipers which will be evident when you loosened the bleeder

The calipers are new/rebuilt?

Calipers are rebuilt. I loosened the bleeders on both sides and was able to spin the passenger side by hand, Driver side was still unable to spin with out the crow bar.
On the proportioning valve there is a button that is covered by a rubber plug. What position should that button be in?

 

[diesel4me]

If loosening the bleeder allowed you to turn the rotor by hand,then its a good bet the rubber brake hose on that side has failed internally,and is acting like a one way valve,it'll let pressure apply the brakes,but not release when you let off the pedal..
One hose doing this may affect both sides,but mostly on the caliper that hose goes to..

Some aftermarket brake pads are "too thick" too,and will drag awhile until they "wear in",or in extreme cases,you may need to file off some of the friction material to even get the calipers to go on..

That pin on the proportioning valve is only used in cases where you cant get sufficient pressure to re-center the valve inside that operates the "brake" light on the dash to let you know when you have lost pressure on either the front or rear brakes--though many manuals say to hold that pin in while bleeding the brakes,in my experience you can bleed them fine without touching it,and if you do,you risk messing it up internally--I've had to replace a few after messing with that pin..my advice is don't touch it!..

 

[dremu]

On the proportioning valve there is a button that is covered by a rubber plug. What position should that button be in?

That's a reset button, so to speak, if the valve gets popped because of a pressure imbalance. You press it in with your thumb to reset. It should never be in any other position.

-- A

 

[imiceman44]

Calipers are rebuilt. I loosened the bleeders on both sides and was able to spin the passenger side by hand, Driver side was still unable to spin with out the crow bar.
On the proportioning valve there is a button that is covered by a rubber plug. What position should that button be in?

So yeah the one that loosened up when you bled it the hose is bad the other side the caliper is stuck.
If it was a used one and your stuck somewhere I say try messing with it, but it's new return it.
And press the button in like dremu explained

 

[imiceman44]

So yeah the one that loosened up when you bled it the hose is bad the other side the caliper is stuck.
If it was a used one and your stuck somewhere I say try messing with it, but it's new return it.
And press the button in like dremu explained

Oh and just press it in and leave it.
Don't touch when bleeding or pumping the brakes.

If it pops up again you have a blockage somewhere and obviously here you do

 

[YOUNGBLOOD13]

The hose is a possibility, but more likely it is your master cylinder to power booster being a little long and preloading.
With everything together, press brakes firmly. Verify wheels are still stuck. Then Loosen the nuts that bolt the master to the hydroboost and slide master forward about 1/8 ". If your wheels spin, you need to adjust the pushrod.

 

[pomai]

If loosening the bleeder allowed you to turn the rotor by hand,then its a good bet the rubber brake hose on that side has failed internally,and is acting like a one way valve,it'll let pressure apply the brakes,but not release when you let off the pedal..
One hose doing this may affect both sides,but mostly on the caliper that hose goes to..

Some aftermarket brake pads are "too thick" too,and will drag awhile until they "wear in",or in extreme cases,you may need to file off some of the friction material to even get the calipers to go on..

That pin on the proportioning valve is only used in cases where you cant get sufficient pressure to re-center the valve inside that operates the "brake" light on the dash to let you know when you have lost pressure on either the front or rear brakes--though many manuals say to hold that pin in while bleeding the brakes,in my experience you can bleed them fine without touching it,and if you do,you risk messing it up internally--I've had to replace a few after messing with that pin..my advice is don't touch it!..

The rubber hoses are brand new, from ORD.

The caliper with pads went on without any problems and was able to spin freely, but the brake system was open for about 6 months without any fluid in the system. I installed the hydroboost from a 86 K-30 1031 military truck, I used the bracket under the dash, push rod and peddle, new hydroboost, master cylinder and the rest of the brake system.

The rear turns freely.

The only thing I didn't replace was the proportioning valve. Before bleeding the system the brake light was on, and went off as soon as I started to bleed it.

I did push that button in hoping that it would help.

Thank you for all the help, Ed

 

[pomai]

The hose is a possibility, but more likely it is your master cylinder to power booster being a little long and preloading.
With everything together, press brakes firmly. Verify wheels are still stuck. Then Loosen the nuts that bolt the master to the hydroboost and slide master forward about 1/8 ". If your wheels spin, you need to adjust the pushrod.

I'm going to try this, but I did use the bracket under dash, push rod and peddle that came out of the donor truck, 86 K-30, 1031 military truck. I did match up the master cylinder and hydroboost with the new ones. Thank you, Ed

 

[imiceman44]

The rubber hoses are brand new, from ORD.

The caliper with pads went on without any problems and was able to spin freely, but the brake system was open for about 6 months without any fluid in the system. I installed the hydroboost from a 86 K-30 1031 military truck, I used the bracket under the dash, push rod and peddle, new hydroboost, master cylinder and the rest of the brake system.

The rear turns freely.

The only thing I didn't replace was the proportioning valve. Before bleeding the system the brake light was on, and went off as soon as I started to bleed it.

I did push that button in hoping that it would help.

Thank you for all the help, Ed

Well a system that is open for 6 months is full of moisture.
You need to flush everything out and run clean fluid thru every new part you got the old fluid in, I woul use a full quart to clean the contamination.
You possibly caused the new caliper to seize.
Even if that wasn't your problem you need to do it.
You should have flushed before you put new parts

 

[diesel4me]

I agree--those old steel lines may well be full of rusty scabs on the inside now ,that are restricting the return flow of fluid,and they will probably fail in a short time in the future--may pay off to replace them all now,and avoid any future headaches..(copper-nickel lines are well worth the few extra bucks)...

I also didn't think of the master cylinder push rod ,it is possible the new master may have the piston "seat" for the push rod a bit different height,and if pressure stays applied to it,the brakes will drag or stay applied..the pedal should have a bit of free play before you feel the push rod made contact with the master cylinder piston..

 

[imiceman44]

I agree--those old steel lines may well be full of rusty scabs on the inside now ,that are restricting the return flow of fluid,and they will probably fail in a short time in the future--may pay off to replace them all now,and avoid any future headaches..(copper-nickel lines are well worth the few extra bucks)...

I also didn't think of the master cylinder push rod ,it is possible the new master may have the piston "seat" for the push rod a bit different height,and if pressure stays applied to it,the brakes will drag or stay applied..the pedal should have a bit of free play before you feel the push rod made contact with the master cylinder piston..

I agre on mc except when he bled the calipers one released the other did not.

 

[dremu]

Yeah, 6 months open is enough to clog all of the brake lines until the next millenium, especially in a humid location. Brake fluid is hygroscopic as all getout, meaning that if there is water within a ten mile radius, the fluid will suck it up, and then rust out whatever metal it's left sitting in.

I'd re-bleed all four corners, especially the sticky one, until the fluid comes out entirely clear. Then bleed it some more.

-- A