Brakes! cannot bleed.

[mahimahimahimahi@hotmail.]

Help, I have a 70 Chevelles SS 396. Back in the day I removed the brake booster because of a large cam. I recently bought a new master cylinder and a 8" booster.
The problem that I am having is that I cannot bleed the rear brakes. The pedal won't got to the floor but it will go to the floor to do the fronts. Fluid is coming out of the
rears but the pedal goes only approx 2/3 of the way down.

Thank You Ivan.

 

[Chevelle_Nut]

Bleeding the rear brakes can be tough. What is your setup, all drums, all disks or front disk, rear drum. Do you have a proportioning valve in line and if original what was it used for? Front disk rear drum or 4 wheel drum brakes?

 

[Nashville Cat]

Do you have a proportioning valve like this ?



You'll need a tool like this if you do :

https://www.amazon.com/WISPAUSU-Compatible-Proportioning-Combination-Replacement/dp/B08N6C1YP3/ref=pd_bxgy_sccl_1/130-1076379-2177167?pd_rd_w=2opcV&content-id=amzn1.sym.43d28dfc-aa4f-4ef6-b591-5ab7095e137f&pf_rd_p=43d28dfc-aa4f-4ef6-b591-5ab7095e137f&pf_rd_r=QPY9DFZWDVKX09ZGWY8S&pd_rd_wg=pmHTs&pd_rd_r=29e5052f-8d39-466f-82f3-6df61f9e8e6b&pd_rd_i=B08N6C1YP3&th=1

 

[Chevelle_Nut]

Here is an OEM Kelsey Hayes front disc, rear drum valve

 

[mahimahimahimahi@hotmail.]

I have disc in the front and drums in the back. I also have a proportioning valve under the master and one like the picture under the frame.
I have already replaced the one under the frame.
I also bought that blue screw in tool that goes into the proportioning valve. I removed the switch from the new valve and it looks fixed to me. I don't think there is a shuttle valve in there. I also took out the switch from the old valve and there isn't anything that I can move in there.
There is a boot and a button that you can depress behind the valve under the master. That's what I pressed to get fluid to the rear wheels but I can't get the pedal all the way to the floor. Like something is stopping it from going pass maybe 1/2 way.

 

[Chevelle_Nut]

Ok, try this. Crack the rear brake main line at rear axle block and try to get fluid through it. Once fluid is coming out there reattach the line try to crack the bleeder on pass rear and try to bleed fluid and then drivers rear. It may take time, a lot of pumping but it will bleed, eventually.

 

[Nashville Cat]

I have disc in the front and drums in the back. I also have a proportioning valve under the master and one like the picture under the frame.
I have already replaced the one under the frame.
I also bought that blue screw in tool that goes into the proportioning valve. I removed the switch from the new valve and it looks fixed to me. I don't think there is a shuttle valve in there. I also took out the switch from the old valve and there isn't anything that I can move in there.
There is a boot and a button that you can depress behind the valve under the master. That's what I pressed to get fluid to the rear wheels but I can't get the pedal all the way to the floor. Like something is stopping it from going pass maybe 1/2 way.

Usually the proportioning valve is next to the master cylinder and the distribution block is down under them attached to the frame.
Is that how yours is setup ?

 

[mahimahimahimahi@hotmail.]

I actually have a lot of fluid coming out of the right rear and the left rear. I did it the one man brake bleed style where I put a clear plastic tube over the wheel cylinder and a Dasani plastic water bottle which I submerged the other end inside the bottle. Then I recorded it with my phone until all of the bubbles disappeared. It did take a long time. I went through a quart of brake fluid. I m on my second one now. But I did it on all 4 corners ... I just somehow cannot get the pedal to the floor in the rears.

 

[mahimahimahimahi@hotmail.]

Usually the proportioning valve is next to the master cylinder and the distribution block is down under them attached to the frame.
Is that how yours is setup ?

Yes

 

[mahimahimahimahi@hotmail.]

Usually the proportioning valve is next to the master cylinder and the distribution block is down under them attached to the frame.
Is that how yours is setup ?

Yes.

 

[Chevelle_Nut]

I actually have a lot of fluid coming out of the right rear and the left rear. I did it the one man brake bleed style where I put a clear plastic tube over the wheel cylinder and a Dasani plastic water bottle which I submerged the other end inside the bottle. Then I recorded it with my phone until all of the bubbles disappeared. It did take a long time. I went through a quart of brake fluid. I m on my second one now. But I did it on all 4 corners ... I just somehow cannot get the pedal to the floor in the rears.

Pedal should not go to the floor. How does the pedal feel? As the brake shoes press on the drums, the pedal will stop due to the hydraulic pressure.

 

[mahimahimahimahi@hotmail.]

The pedal feels like a brake pedal, although I have a feeling if I put the 4 tires on and take it on the road the fronts will lock up but the back won't.

 

[Nashville Cat]

The pedal feels like a brake pedal, although I have a feeling if I put the 4 tires on and take it on the road the fronts will lock up but the back won't.

That's the way it's supposed to work ? You don't want the rears to lock up first because the fronts do 75% of the braking.

 

[Chevelle_Nut]

How old are your rear shoes? Are they new and broken in yet?

 

[mahimahimahimahi@hotmail.]

Okay thank you so much...I'll try again this weekend. The brake shoes are actually new although installed in the mid 80's. Since then it has only been
miles around the block a few times a year.

 

[Shovelrick]

The rear brake shoes might be adjusted to tight, check to see if the rear wheel will turn freely with the car in neutral, Im assuming the cars on jack stands?

 

[mahimahimahimahi@hotmail.]

It is very tight, hard to spin the brake drum in neutral. I'll try and back it off a bit.

Thanks