CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

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!

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

He said Wilwood adjustable Valve.

Re: CPP Rear Disc Brakes not bleeding!!
 

I have the Wilwood adjustable proportioning valve installed.

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

This is my setup.

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

Re: CPP Rear Disc Brakes not bleeding!!
 

Nice stuff. Good luck

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

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

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
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Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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?

Re: CPP Rear Disc Brakes not bleeding!!
 

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.

Re: CPP Rear Disc Brakes not bleeding!!
 

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

Re: CPP Rear Disc Brakes not bleeding!!
 

I know you said it's all new and you are getting fluid at the caliper. But, since I cant see it in your pictures I'll throw this out. The rubber line between the frame and rear end is many times plugged not allowing enough fluid to the rear brakes.

Re: CPP Rear Disc Brakes not bleeding!!
 

The rubber lines are brand new from the kit and they have fluid coming out of them.
Which is why its weird the calipers arent working

Re: CPP Rear Disc Brakes not bleeding!!
 

I looked through the CPP kits and it doesn't look like the rubber line that I'm talking about is included in any of the kits.


I'm talking about the one that goes from the frame to the rear end.


The CPP kits look like they include hard lines that connect to the TEE at the end of the hose I'm talking about and it looks like they include the rubber lines to go to the calipers.

Re: CPP Rear Disc Brakes not bleeding!!
 

If the rubber line at the frame is old there is a strong possibility that it swells up when your brake pedal is pressed and there isn’t enough fluid or pressure to operate the calipers.

Re: CPP Rear Disc Brakes not bleeding!!
 

I had the exact same problem on my 66 when I replaced everything including a new dual reservoir master cylinder. The front brakes bled instantly but even with a friend pumping I couldn't get a drop to the rear brakes. Bench bled it a second time and still nothing. I only had one idea to let gravity help so I opened the rear bleeders and disconnected the hardline from the master cylinder. Luckily I had a length of clear tubing big enough to fit tightly over the flared end of the line I removed from the master cylinder. I then filled a bottle that resembled a ketchup bottle with brake fluid, stuck the hose to it and hung it from my open hood like an IV bottle. It took a minute or two till it started running out of the bleeders but I then closed the bleeders and hooked the line back to the master cylinder and voila I was able to bleed out the remaining air bubbles like normal. Sounds janky but it worked.

Re: CPP Rear Disc Brakes not bleeding!!
 

Okay, i know what rubber hose you are talking about.
Ill replace it, but i am getting fluid to the rear brakes, so i think it is working properly

Re: CPP Rear Disc Brakes not bleeding!!
 

Having a LS engine would make no difference.
I would try a Mity Vac vacuum bleeder or a Motive pressure bleeder. I think some of the parts stores have loaner tools. Check with them.
Back in the day I made a pressure bleeder. I took a piece of 1/4" steel flat stock sized a bit bigger than MC cover. Drilled and tapped two 1/8" NPT holes in the steel plate. Then I screwed in two 1/8" nipples. Then using rubber hoses connected the two nipples to a "T" to a single piece of rubber hose with a air hose fitting. On the under side of the plate I glued a piece of inner tube to seal it to the MC. I used a couple of c-clamps to clamp it to the top of the MC. Ran about 30-40 PSI. Worked great. You just have to refill the master as you bleed.

Re: CPP Rear Disc Brakes not bleeding!!
 

I have one of these that I always use when bleeding a new system.

https://www.harborfreight.com/brake-...der-92924.html

I don't use the bottle, just the vacuum part.

I revert back to pumping the pedal and the one-man bleeder bottle for the final bleed.

Re: CPP Rear Disc Brakes not bleeding!!
 

Having an LS would make difference in what....bleeding?

Re: CPP Rear Disc Brakes not bleeding!!
 

I have tried to use (rent) a vaccum bleeder without success.

Re: CPP Rear Disc Brakes not bleeding!!
 

Is this hose you are talking about?
Will it work with disc brakes or is there another hose i need to purchase for disc brakes?

Re: CPP Rear Disc Brakes not bleeding!!
 

Where in Dallas are you? I'll loan you my harbor freight one...

Here's an example of the hose. It doesn't matter if disc or drum, it's just passing fluid from the hard line on the frame to the hard lines on the rear differential.

https://www.classicparts.com/1967-70...ctinfo/71-361/

Here's another...
https://www.rockauto.com/en/moreinfo...t=1792&jsn=937

And another
https://www.oreillyauto.com/detail/c...ckup-rwd?pos=1

Re: CPP Rear Disc Brakes not bleeding!!
 

Those do not work with my setup.
I have a union that connects the hard lines on either side of the gear on the axle cover.

https://www.summitracing.com/parts/d...RoCbWwQAvD_BwE

This is what i have on my setup from the frame hardline to the axle hardlines

Re: CPP Rear Disc Brakes not bleeding!!
 

Ok, I thought your truck was a 70? I think the one with the "TEE" built in is 71-72...

https://www.classicparts.com/1971-72...ctinfo/71-365/

Either way, if that line is original, you want to replace it.

Re: CPP Rear Disc Brakes not bleeding!!
 

Here's the "TEE" that goes on the other line style...

https://www.classicparts.com/38-70-T...ctinfo/71-882/