The 1947 - Present Chevrolet & GMC Truck Message Board Network

The 1947 - Present Chevrolet & GMC Truck Message Board Network (https://67-72chevytrucks.com/vboard/index.php)
-   The 1967 - 1972 Chevrolet & GMC Pickups Message Board (https://67-72chevytrucks.com/vboard/forumdisplay.php?f=3)
-   -   CPP Rear Disc Brakes not bleeding!! (https://67-72chevytrucks.com/vboard/showthread.php?t=838464)

Tx70Gmc 11-19-2022 07:15 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by 72c20customcamper (Post 9145953)
I was just rereading this thread . Yours are positioned just like mine on my Chevelle . And just realized that when I bleed my rears I had to remove the front bolt and spin the caliper up I put a piece of plate steel in between the pads . As the bleeder is below the top of caliper . The bleeder needs to point straight up .

I copied your picture . If you look at it it’s pretty clear the bleeder is about midline in relation to the piston .

After I did the one I rotated the bracket so the bleeders point straight up so in the future I didn’t have a problem


Could you send me a picture of how yours is installed?

kwmech 11-19-2022 09:17 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Good grief...swap the calipers side to side so the bleeder is on top of the piston hole. The levers should be on the bottom, not going over the top of the housing.

nikwho 11-19-2022 09:52 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
I didn't read through your entire thread, but when I did my disc brake swap on my '59, I used brand new rubber brake hoses from NAPA, front and rear. After trying to figure it out for a long time, I removed the new NAPA rubber brake hose and tried to blow through it. Nada. I went to NAPA, swapped it for another hose, which allowed the brakes to bleed appropriately. So, even if brand new, if you are still stumped, trying replacing the hose. Or at least remove it and see if you can blow air through it.

Tx70Gmc 11-19-2022 09:58 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by kwmech (Post 9146194)
Good grief...swap the calipers side to side so the bleeder is on top of the piston hole. The levers should be on the bottom, not going over the top of the housing.


Dont good grief me....Please do not respond if you do not know what you are talking about. The calipers are on the correct sides and installed correctly.

Tx70Gmc 11-19-2022 10:01 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by nikwho (Post 9146207)
I didn't read through your entire thread, but when I did my disc brake swap on my '59, I used brand new rubber brake hoses from NAPA, front and rear. After trying to figure it out for a long time, I removed the new NAPA rubber brake hose and tried to blow through it. Nada. I went to NAPA, swapped it for another hose, which allowed the brakes to bleed appropriately. So, even if brand new, if you are still stumped, trying replacing the hose. Or at least remove it and see if you can blow air through it.

That was the last thing i did, now i am getting fluid to the calipers, which is one more step closer, but the calipers still won't move. I think that these calipers are just very difficult to bleed.

Jason Banks 11-20-2022 09:54 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
Did you get a Motive power bleeder like this one?
https://smile.amazon.com/gp/product/B00CJ5E1GS/

It includes the flat plate that you would clamp to the top of your Wilwood master. You do have the oval type Wilwood master that has 4 allen head screws holding the top on?


EDIT: Just found this video... I'm interested in being able to pressure bleed the Wilwood with a Motive power bleeder too. This guy says the plate I was talking about won't fit the wilwood. https://www.youtube.com/watch?v=cUOMt-81RiM

Edit again: This the the vacuum bleeder from harbor freight I have - https://www.harborfreight.com/brake-...der-92924.html - I usually use this on the longest run and then the other 3, but end up finishing with this type bleeder - https://www.autozone.com/test-scan-a...-kit/46839_0_0 -

72c20customcamper 11-20-2022 10:08 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
1 Attachment(s)
Quote:

Originally Posted by Tx70Gmc (Post 9146167)
Could you send me a picture of how yours is installed?

My car is put away at my rental next time I go down I’ll snap a few .

Edit :Found it prior to install . I used adjustable upper control arms to angle the rear as the pinion was angled to far down . Which angled the bleeder more to the top but the rotation of the bracket was still needed

72c20customcamper 11-20-2022 10:10 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
1 Attachment(s)
Quote:

Originally Posted by kwmech (Post 9146194)
Good grief...swap the calipers side to side so the bleeder is on top of the piston hole. The levers should be on the bottom, not going over the top of the housing.

The way the caliper is orientated if you put the ebrake on the bottom the bleeder is also on the bottom .

Jason Banks 11-20-2022 10:12 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
I think 72c20customcamper is onto something. It appears the hose attaches on one side and horizontally straight across is the bleeder. The bleeder is not at the top of the caliper, so you have the top half of the caliper still
filled with air. You might need to rotate the brackets on the rear end to get the bleeder to be in the highest position possible. Which, might require swapping the calipers from side to side also.

Edit: after seeing the new pic 72c20customcamper posted, I see I'm wrong about it being horizontal with the hose, but the rotating of the bracket on the rear end still probably needs to happen.

72c20customcamper 11-20-2022 10:14 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
1 Attachment(s)
All I did was rotate the bracket to the next hole . I used the same clamps also as I forgot to weld on the line keeper brackets which came with the rear .

Jason Banks 11-20-2022 10:46 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
Here's the motive bleeder that should work with the Wilwood - https://www.motiveproducts.com/produ...c_id=61f139fc6

Tx70Gmc 11-20-2022 11:33 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by 72c20customcamper (Post 9146462)
All I did was rotate the bracket to the next hole . I used the same clamps also as I forgot to weld on the line keeper brackets which came with the rear .

If i rotate the bracket will it impede the ebrake cable from working properly?

Tx70Gmc 11-20-2022 11:35 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by Jason Banks (Post 9146466)
Here's the motive bleeder that should work with the Wilwood - https://www.motiveproducts.com/produ...c_id=61f139fc6

I wonder if i need to rotate the bracket if i use a power bleeder, wouldnt it force the air out? Or is that just wishful thinking?

72c20customcamper 11-20-2022 12:15 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
1 Attachment(s)
Quote:

Originally Posted by Tx70Gmc (Post 9146478)
If i rotate the bracket will it impede the ebrake cable from working properly?

If the cable moves smoothly it should matter if there is a bend in it . Mine I had to get new longer cables . Since my car sits high in the rear and I rotated everything

72c20customcamper 11-20-2022 12:19 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by Tx70Gmc (Post 9146479)
I wonder if i need to rotate the bracket if i use a power bleeder, wouldnt it force the air out? Or is that just wishful thinking?

That should work . The first time I did mine I just took out the front bolt and put some plate steel in between the pads . From my memory which isn’t great half the pad was still on the rotor .

HO455 11-20-2022 03:42 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
1 Attachment(s)
Wishful thinking.

Using the photos you posted I made this crude representation of how the air is trapped in your caliper. I orientated the caliper to match the axle mounted caliper in the photo.

The lower half red circle is full of fluid. The upper purple part is where air is trapped. When you pump fluid into the caliper the air compresses into the top. The oil will not compress and is forced out of the open bleeder leaving the air trapped. All a power bleeder will do in this situation is compress the air the same way the master cylinder does.

To verify hold a torpedo level level next to the caliper. Keep the top even with the bleeder. If any of the caliper's piston is above the level you will have trapped air.

A power bleeder can be helpful in vehicles where the brake tubing is ran higher than the master cylinder and the fluid wants to flow back into the master cylinder between pump strokes. Oh, and when your working for flat rate it helps make you money.

It's not common but, there are vehicles that the factory requires the calipers to be removed from their mounts in order to completely bleed the air.

Tx70Gmc 11-20-2022 04:14 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by HO455 (Post 9146555)
Wishful thinking.

Using the photos you posted I made this crude representation of how the air is trapped in your caliper. I orientated the caliper to match the axle mounted caliper in the photo.

The lower half red circle is full of fluid. The upper purple part is where air is trapped. When you pump fluid into the caliper the air compresses into the top. The oil will not compress and is forced out of the open bleeder leaving the air trapped. All a power bleeder will do in this situation is compress the air the same way the master cylinder does.

To verify hold a torpedo level level next to the caliper. Keep the top even with the bleeder. If any of the caliper's piston is above the level you will have trapped air.

A power bleeder can be helpful in vehicles where the brake tubing is ran higher than the master cylinder and the fluid wants to flow back into the master cylinder between pump strokes. Oh, and when your working for flat rate it helps make you money.

It's not common but, there are vehicles that the factory requires the calipers to be removed from their mounts in order to completely bleed the air.


Im going to try and rotate the bracket and see if that will work to get the bleeder higher.

RichardJ 11-20-2022 05:21 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
1 Attachment(s)
>>Im going to try and rotate the bracket and see if that will work to get the bleeder higher.<<

About time.

As early as post #12, you were advised to make sure the bleeders were UP. Several posters since then suggested switching calipers to other side in order to get the bleeders UP.
Post #65 again ask if you had the bleeders UP. You responded in post #66 with
>>The bleeders are facing towards the front.<<

Front is not the same as UP

A couple of more posts followed, questioning the bleeder position and you responded with,

>>Don't good grief me....<<

CPP instructions said to make sure the bleeders are at the TOP.

Tx70Gmc 11-20-2022 10:18 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by RichardJ (Post 9146573)
>>Im going to try and rotate the bracket and see if that will work to get the bleeder higher.<<

About time.

As early as post #12, you were advised to make sure the bleeders were UP. Several posters since then suggested switching calipers to other side in order to get the bleeders UP.
Post #65 again ask if you had the bleeders UP. You responded in post #66 with
>>The bleeders are facing towards the front.<<

Front is not the same as UP

A couple of more posts followed, questioning the bleeder position and you responded with,

>>Don't good grief me....<<

CPP instructions said to make sure the bleeders are at the TOP.

I have installed the calipers and brackets per CPP instructions. Again please do not respond if you have comments to make and DO NOT know what you are talking about.

Move along

Tx70Gmc 11-23-2022 12:36 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
2 Attachment(s)
Quote:

Originally Posted by HO455 (Post 9146555)
Wishful thinking.

Using the photos you posted I made this crude representation of how the air is trapped in your caliper. I orientated the caliper to match the axle mounted caliper in the photo.

The lower half red circle is full of fluid. The upper purple part is where air is trapped. When you pump fluid into the caliper the air compresses into the top. The oil will not compress and is forced out of the open bleeder leaving the air trapped. All a power bleeder will do in this situation is compress the air the same way the master cylinder does.

To verify hold a torpedo level level next to the caliper. Keep the top even with the bleeder. If any of the caliper's piston is above the level you will have trapped air.

A power bleeder can be helpful in vehicles where the brake tubing is ran higher than the master cylinder and the fluid wants to flow back into the master cylinder between pump strokes. Oh, and when your working for flat rate it helps make you money.

It's not common but, there are vehicles that the factory requires the calipers to be removed from their mounts in order to completely bleed the air.

Before i try to disconnect the front pin and rotate the caliper to bleed i want to make sure that the rotating the bleeder would make a difference. See the picture of the current installed position. It looks to me like the bleeder is at the top.

I just want to make sure before i take the time to remove everything.

Tx70Gmc 11-23-2022 12:38 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
Quote:

Originally Posted by Tx70Gmc (Post 9147392)
Before i try to disconnect the front pin and rotate the caliper to bleed i want to make sure that the rotating the bleeder would make a difference. See the picture of the current installed position. It looks to me like the bleeder is at the top.

I just want to make sure before i take the time to remove everything.

For whatever reason the pictures are rotated 90 counter-clockwise

Jason Banks 11-23-2022 11:16 AM

Re: CPP Rear Disc Brakes not bleeding!!
 
It is not possible to determine from the pictures if the bleeder is at the top.

It still looks to me like the bleeder still has a little bit of the piston above it, but the pictures make it impossible to know for sure.

kwmech 11-23-2022 12:46 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
I have installed the calipers and brackets per CPP instructions. Again please do not respond if you have comments to make and DO NOT know what you are talking about.


Cuz everything you've done so far has worked out for you


Flip the brackets side to side so the long leg curls underneath--that will rotate the caliper the needed distance

72c20customcamper 11-23-2022 02:53 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
2 Attachment(s)
I would try to clock it a bit worst case is you still don’t have brakes . I’m assuming this is the passenger side since there’s a big R on the bracket . Take the top caliper bolt out and rotate .

HO455 11-23-2022 07:30 PM

Re: CPP Rear Disc Brakes not bleeding!!
 
While you have the caliper unmounted here are a couple of things to consider looking at.

Watch the caliper piston while having someone slowly push the brake pedal down. SLOWLY you don't want to blow the puck out of the caliper. When you see the puck stop immediately stop pushing the pedal. It's a good idea to check the fluidl level in the master cylinder after doing this.

The caliper puck should move out approximately the the same distance as the thickness of the brake pads. In other words if one pad's lining is 1/4" thick the caliper should move out about 1/2 inch. (1/4 x1/4 = 1/2) A 3/8 inch at a minimum of move should be expected.

Once you have fully extended the puck use a brake caliper compressor (or a C-clamp and a plate) to move the puck back into the caliper body as far as possible. Open the bleeder before pushing the puck back in and hold the caliper with the bleeder at the very highest point. Use the compressor to push the fluid and hopefully air out. Once the puck is completely compressed shut the bleeder.

Pay attention to how far each puck extends. It is possible that the pucks are at their limit of extension and that may be causing problems.

By compressing the puck you are minimizing the amount of air that can be trapped inside fr when you. When reinstalling the caliper with the compressed puck pay attention to how much play there is between the disk and the pads. With new pads and a proper new rotor there should be about 1/4" of play.

When doing these checks do them one caliper at a time. After the first one is reinstalled pump the brake pedal to get the pads pushing against the disk again before starting on the 2nd one. Again keep an eye on the master cylinder fluid level.

After doing all this and you have no change I would dive into the master cylinder as I would expect it to have a problem. All it takes is a fiber like a paint brush bristle under one of the master cylinder piston seals to foul things up.

If things are better but not great then you likely will need to bleed the caliper unmounted with the bleeder as high as possible and a plate of similar thickness between the pads.

I hope this makes sense. Your looking for a caliper that is not responding as expected indicating a problem inside.

Good luck and keep us posted.


All times are GMT -4. The time now is 02:56 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com