Brake Problem

[paperpusher]

Hi guys,

This is my first post hear, I've been reading it for a short while and have learned a lot from you all. Now I've come upon a brake problem that I could really use a hand with. This is what I have:

I just purchashed a 1965 Chevy Fleetside. I've been bleeding the brakes on this thing since last Monday (LOL). It has a 350 V8, auto transmission, and front disc brake, rear drum barkes.The pedal you can feel some resistance, but goes to the floor.The master cylinder and booster are from a 1984 Chevy C-10. I replaced the master cylinder thinking that it was bad. Bench bled it, installed it, same results.I can barley get fluid out of the front calipers mostly continuous air.The back, I can get some fluid, but there is all ways air. A couple of things that I noticed about this truck. (1)The brake line at the master cyl closest to the fire wall comes out and goes into the front of the control valve, and the brake line in the front of the MC comes out and goes into the rear of the control valve. Making the front section of the reservoir go to rear and the rear section of the reservoir go to the front Could this be a problem.(2) The rod that push the mc in,only stick out about 1/4 of an inch. Is this enough? By the way, I looked under the dash and the rod is coated in a black material, is this normal? I would appreciate any help that anyone can give me. Also, I did replace the brake fluid thinking that it may be contaminated, but didn't help.

Thank you

 

[dvalentine]

Hi guys,


I just purchashed a 1965 Chevy Fleetside. I've been bleeding the brakes on this thing since last Monday (LOL). The pedal you can feel some resistance, but goes to the floor.The master cylinder and booster are from a 1984 Chevy C-10. I replaced the master cylinder thinking that it was bad. Bench bled it, installed it, same results.I can barley get fluid out of the front calipers mostly continuous air.The back, I can get some fluid, but there is all ways air. A couple of things that I noticed about this truck. (1)The brake line at the master cyl closest to the fire wall comes out and goes into the front of the control valve, and the brake line in the front of the MC comes out and goes into the rear of the control valve. Making the front section of the reservoir go to rear and the rear section of the reservoir go to the front Could this be a problem.(2) The rod that push the mc in,only stick out about 1/4 of an inch. Is this enough? By the way, I looked under the dash and the rod is coated in a black material, is this normal? I would appreciate any help that anyone can give me. Also, I did replace the brake fluid thinking that it may be contaminated, but didn't help.

Thank you

The front reservoir goes to the front brakes, the rear, goes to the rear brakes. There should also be a proportioning valve very close to the master cylinder.
If the person that did the brake conversion in the front did not change the pedal rod ( thrust rod) going into the master cylinder ther is a good chance it's not long enough.

Now, that said, none of the above explains why the pedal is going to the floor. If you replaced the master cylinder with a rebuilt from one of the major corner store auto parts places, there is a real possibility that it arrived DOA.

Check all the brake line connections for leakage as well as the master cylinder.

dv

 

[paperpusher]

Thanks for your response,

I have checked for leaks, and there is a porportion valve connected to the MC. That's what I was saying that the rear outlet line is connected to the front inlet of the porportion valve, and the front outlet line coming out of the MC is going into the back inlet of the valve. I figured it should be reversed. When I bench bled the MC, brake fluid was shutting up from inside the reservior at the rear hole. Is this supposed to happen?

Thanks for your help DV

 

[2tons of fun]

The front reservoir goes to the front brakes, the rear, goes to the rear brakes. There should also be a proportioning valve very close to the master cylinder.
If the person that did the brake conversion in the front did not change the pedal rod ( thrust rod) going into the master cylinder ther is a good chance it's not long enough.

Now, that said, none of the above explains why the pedal is going to the floor. If you replaced the master cylinder with a rebuilt from one of the major corner store auto parts places, there is a real possibility that it arrived DOA.

Check all the brake line connections for leakage as well as the master cylinder.

dv

that is not always true. the lines have specific fitting and will not swap. some masters have the front as the bigger res and some hav ethe back as the bigger res. doesnt matter, the front line will only fit the res that is intended for the front brakes.

they use some special fittings that are the same size tube hole but the next size up thread diam.

you will get a llooooooooooooooooooooottt of air out of a fresh system .

 

[drabo]

Try using a vaccuum bleader. Sold at sears. It will allow you to suck the air out. Just have someone add fliud as you go.

 

[paperpusher]

I tried the vacuum thingy, didn't work. I ordered the power bleeder yesterday,however, I still don't think that's the only problem. The booster pin only sticks out about 1/4". Hey, when I bench bled the Master Cyl, brake fluid shoots up out of the rear port each time I push in the phillips screw driver. Is fluid supposed to shoot up from this port? And very little fluid comes out of the tubes going back into the reservior.

 

[drabo]

When you are bench bleeding don't push too hard. A nice slow and steady push is the way to go. The same applies to the vaccuum bleader. Don't use too much a vaccuum while bleading. It sounds like your push rod is also too short.

 

[paperpusher]

Ok,

Thanks for the tip on how much force to use. I pulled the booster off yesterday and the part that pushes the master cylinder in is shaped like a 210 shot gun shell with a tip on it and there is no way to adjust it. It looks like the person that had the truck may have the wrong booster on it.

Is there a certain year model truck that I can match the Master Cylinder/Booster up with for this 1965 Chevy Fleet Side. I think I'm just going to start all over at this point.

Thank you