CPP Rear Disc Brakes not bleeding!!

[Tx70Gmc]

I apologize if this has been discussed before, I have searched the forums and outside the forums with no luck.

I am currently trying to install the CPP Rear Disc Brake Conversion on my 70 C10.
I have the Ebrake adjusted properly and it works great, but I cant get fluid to come out of the bleeders.

In fact when I step on the brakes nothing happens, the pistons do not try to squeeze at all.
I have tried to bleed the rear brakes using gravity, vaccum, pushing the brake, etc. Without success.

I installed the Front CPP Disc Brake conversion and they work great.

I have the Wilwood master cylinder and booster with a Wilwood adjustable proportioning valve.

Anyway any help we be appreciated.

Thanks

[davischevy]

I know absolutely nothing about Wilwood brakes, but did you try adjusting the proportioning valve all to the rear?

[HO455]

A couple of basic questions.
Did you bench bleed the master cylinder?
Is the adjustable proportioning valve for the rear brakes fully open?
Is this an entirely new brake system?

Welcome aboard!

[Tx70Gmc]

Originally Posted by davischevy

I know absolutely nothing about Wilwood brakes, but did you try adjusting the proportioning valve all to the rear?

Yes, I tried it with the knob turned all the way to the rear, no rear and even middle adjustment.

[Tx70Gmc]

Originally Posted by HO455

A couple of basic questions.
Did you bench bleed the master cylinder?
Is the adjustable proportioning valve for the rear brakes fully open?
Is this an entirely new brake system?

Welcome aboard!

Yes, I bench bled the master and yes an entirely new brake system. I am getting fluid all the way to the back calipers but nothing from the bleeders.

[KQQL IT]

Stock proportioning valve ?
It's over centered in safety mode

[davischevy]

Originally Posted by KQQL IT

Stock proportioning valve ?
It's over centered in safety mode

He said Wilwood adjustable Valve.

[Tx70Gmc]

Originally Posted by KQQL IT

Stock proportioning valve ?
It's over centered in safety mode

I have the Wilwood adjustable proportioning valve installed.

[KQQL IT]

I didn't know if it was an adjustable unit inline with the oem proportioning valve.

[Tx70Gmc]

Originally Posted by KQQL IT

I didn't know if it was an adjustable unit inline with the oem proportioning valve.

This is my setup.

https://www.summitracing.com/parts/wil-261-13270-bk

[KQQL IT]

Nice stuff. Good luck

[Sheepdip]

Not being familiar with your particular set up, are you sure they/calipers are installed right on right, left on left? Some set ups if you reverse them it puts the bleeder too low and you will bleed and bleed and never get the air out. Just a suggestion for something else to look at.

[leddzepp]

I’m assuming the calipers are 1979 Cadillac? I believe they are the ones used in cpp and other vendors kits. If you are getting fluid all the way to the calipers then I would guess something is blocking a passage. I’ve also read there is a “trick” to bleeding them and it has something to do with the e-brake. I haven’t had a chance to dig that deep into it yet. I was planning on getting this kit myself and just started looking at reviews, etc.

[CC69Rat]

The Wilwood MC setup requires the addition of an extender to make the pushrod length long enough to run rear disc. (See pic) This is a small bullet shaped extender that comes with the kit. Drop this in to extend your stock pushrod and you'll be all set.

The stock pushrod just isn't long enough to give you enough push to engage the rear disc and push fluid to the rear calipers.

[Joyridin]

Well, if CC69Rat solution does not work, I would try pushing the E-brake in quite a few times to get the piston to move out of it's seated position. I have had it where the piston is so far in, the bleeder is blocked.

[PbFut]

If you are getting pressurized fluid at the brake line to caliper connection, but nothing at the bleeder, then the blockage must be in the caliper. I would bleed as best you can at the brake line connection to eliminate as much air as possible. Connect caliper and bleed the caliper. If it will not bleed than the previous comment may be correct that the piston is too deep and blocking any incoming fluid.

[Tx70Gmc]

I emailed CPP today and they told me to take the banjo and bleeder screws off and blow air from the banjo bolt side. I am going to try that.

I have tried everything else everyone has posted already.

[Tx70Gmc]

Originally Posted by Sheepdip

Not being familiar with your particular set up, are you sure they/calipers are installed right on right, left on left? Some set ups if you reverse them it puts the bleeder too low and you will bleed and bleed and never get the air out. Just a suggestion for something else to look at.

That would have been my first thought, but i have the ebrake hooked up and working great.

[Tx70Gmc]

Originally Posted by Tx70Gmc

I emailed CPP today and they told me to take the banjo and bleeder screws off and blow air from the banjo bolt side. I am going to try that.

I have tried everything else everyone has posted already.

Just tried blowing out the banjo bolt and still doesnt work....any ideas??

[Tx70Gmc]

Originally Posted by CC69Rat

The Wilwood MC setup requires the addition of an extender to make the pushrod length long enough to run rear disc. (See pic) This is a small bullet shaped extender that comes with the kit. Drop this in to extend your stock pushrod and you'll be all set.

The stock pushrod just isn't long enough to give you enough push to engage the rear disc and push fluid to the rear calipers.

The little bullet is installed in the MC and I measured the booster nut tolerance as well.

[rockyrivermark]

Originally Posted by Sheepdip

Not being familiar with your particular set up, are you sure they/calipers are installed right on right, left on left? Some set ups if you reverse them it puts the bleeder too low and you will bleed and bleed and never get the air out. Just a suggestion for something else to look at.

This is what burned me on a disc conversion on a ‘67 cougar.
Used S10 calipers but mounted in front of disc rather than behind so stamped R actually went on left side
Make sure bleeders are I'm
Posted via Mobile Device

[Jrainman]

I am not familiar with that proportion Valve , but the standard P valves have a shuttle valve, the shuttle valve has the ability to shut off your front or back fluid pressure .this is designed for if a leak occurs (detected) , this is activated by your brake switch witch is wired to your Brake dash lite , So what happened in your case is when you bled the front you tripped the shuttle Valve , if you have a brake lite switch remove it from the P block look down in the block you should see a rod at the bottom of the hole , get a pick or small screwdriver and move the rod to the opposite direction from where it sits now ,this will open the port to your rear lines and you should be able to do your bleed procedure , There is a plastic device (tool) that you are suppose use , you are suppose to take out your brake switch and thread this plastic tool in when doing a installation as you are doing , this plastic device (tool) locks that rod in position so what you are experiencing does not occur. I find that all the brake conversion kits never have this in there instructions.

[Tx70Gmc]

Originally Posted by Jrainman

I am not familiar with that proportion Valve , but the standard P valves have a shuttle valve, the shuttle valve has the ability to shut off your front or back fluid pressure .this is designed for if a leak occurs (detected) , this is activated by your brake switch witch is wired to your Brake dash lite , So what happened in your case is when you bled the front you tripped the shuttle Valve , if you have a brake lite switch remove it from the P block look down in the block you should see a rod at the bottom of the hole , get a pick or small screwdriver and move the rod to the opposite direction from where it sits now ,this will open the port to your rear lines and you should be able to do your bleed procedure , There is a plastic device (tool) that you are suppose use , you are suppose to take out your brake switch and thread this plastic tool in when doing a installation as you are doing , this plastic device (tool) locks that rod in position so what you are experiencing does not occur. I find that all the brake conversion kits never have this in there instructions.

Yes i am familiar with what you are talking about. It is called portioning valve bleeder tool. I contacted Wilwood and they said it wasnt needed with this portioning valve. Also i have LS swapped the motor, so would that matter in tripping the shuttle valve?

[Joyridin]

Blowing air int he banjo bolt will not make the piston move far if it is all the way back. Did you try moving the e-brake lever back and forth to "ratchet" the piston out? The piston is set-up on a ratchet mechanism. When you pull the e-brake, the piston ratchets out without rotating. You may have to do it quite a few times to get it out a bit.

[Tx70Gmc]

Originally Posted by Joyridin

Blowing air int he banjo bolt will not make the piston move far if it is all the way back. Did you try moving the e-brake lever back and forth to "ratchet" the piston out? The piston is set-up on a ratchet mechanism. When you pull the e-brake, the piston ratchets out without rotating. You may have to do it quite a few times to get it out a bit.

Yes, i have done that and have the ebrake adjusted perfectly. The ebrake works great