Brake question

[Jack H.]

I replaced my master cylinder with one that I had rebuilt at Lone Star Caliper. After replacing the master, the car would creep ahead when stopped (it's a powerglide) even though I had the pedal depressed hard. Always had lots of pedal, not going to floor or anything like that. Talked to the owner of Lonestar thinking it may have been a master cylinder issue or maybe air in the lines. After the discussion it was decided it could be the hoses since they are 50 years old. Didn't like replacing original parts but I don't like stopping even more. Car just acted like it had bad fade all the time.
Hoses replaced, shoes dressed and cleaned, and dust removed from drums. It still doesn't stop like I want. Maybe I'm just used to power disc and am expecting too much from manual drum brakes. Really don't know what else to check.
Any ideas?

[Joe R.]

Re: Brake question

First, the car should hold and NOT creep forward. It very well could be the rubber lines but more than likely it is air in the lines. It is very difficult sometimes to rid the MC of air because it is horizontal.
I am assuming that you did not use silicone brake fluid. I'm not a fan as I have never been able to get a satisfactory pedal feel with silicone fluid.
If all else fails, ask Lonestar to replace the rebuilt MC. It could be a problem with it but I doubt it!

JR

[Jack H.]

Re: Brake question

No silicone fluid. Doesn't creep with new brake hoses but it does take a lot of pedal pressure to keeping it from moving.

[Joe R.]

Re: Brake question

No silicone fluid. Doesn't creep with new brake hoses but it does take a lot of pedal pressure to keeping it from moving.

Jack,

Did you bench bleed the MC before installing it?

JR

[Michael G.]

Re: Brake question

I am assuming that you did not use silicone brake fluid. I'm not a fan as I have never been able to get a satisfactory pedal feel with silicone fluid. JR

I would be an avocate of silicone brake fluid systems. No issues to date and pedal pressure is no more difficult than the use of dot 3 or 4. Car stops wih no additional pressure than would be required of the aforementioned.

Jack............Would recommend additional bleeding of the system as the brakes will never be effective unless as air is removed.

[Paul J.]

Re: Brake question

Jack, is there any decrease in the pedal after you have stopped and are sitting still? If so, this is caused by a small leak, fluid in the MC or WC bypassing the seals, air in the lines, or collapsing hoses.

If the you've checked everything above and the pedal is solid and the car moves, it's your linings. If the car does'nt move, it's you.

Paul

[Domenic T.]

Re: Brake question

Jack,
Let the car sit for a short short time then push the pedal down once then let up and do it again.

If the pedal is much higher the second time you will have to adjust your brakes.

Reason is that it takes 2 pumps, 1 to get the shoes against the drum and the other to apply the pressure.

That may be why you creaped when you only pushed once because when your creaping its mentally hard to let up and get more fluid to the brake cylinder.

DOM

[Domenic T.]

Re: Brake question

First, the car should hold and NOT creep forward. It very well could be the rubber lines but more than likely it is air in the lines. It is very difficult sometimes to rid the MC of air because it is horizontal.
I am assuming that you did not use silicone brake fluid. I'm not a fan as I have never been able to get a satisfactory pedal feel with silicone fluid.
If all else fails, ask Lonestar to replace the rebuilt MC. It could be a problem with it but I doubt it!

JR

Joe,
I felt the same thing on my 67 when I used silicone. I used it because I was at the honing limit and knew that the next time meant calipers.

I would bet that the guys that feel no difference have power brakes?

With standard brakes and 0 air in my lines my pedal felt like I had mechanical brakes.

Now I have SS liners and have not shot the fluid to it as I am thinking that rust will not be that much of a problem with SS liners with dot 4.

Michael,
I do use silicone in hydraulic clutches and in a pinch one day I was out of fluid in my tug and had to do something fast so I added silicone over dot 3 and got the brakes back. that was 7 month ago and they have never lasted this long without adding fluid.

I am not recomending that, just find it funny that they are getting along with each other. So I am not touching a thing or flushing the system.

DOM

DOM

[Michael G.]

Re: Brake question

Joe,
I felt the same thing on my 67 when I used silicone. I used it because I was at the honing limit and knew that the next time meant calipers.

I would bet that the guys that feel no difference have power brakes?

With standard brakes and 0 air in my lines my pedal felt like I had mechanical brakes.

Now I have SS liners and have not shot the fluid to it as I am thinking that rust will not be that much of a problem with SS liners with dot 4.

Michael,
I do use silicone in hydraulic clutches and in a pinch one day I was out of fluid in my tug and had to do something fast so I added silicone over dot 3 and got the brakes back. that was 7 month ago and they have never lasted this long without adding fluid.

I am not recomending that, just find it funny that they are getting along with each other. So I am not touching a thing or flushing the system.


DOM

Interesting Dom. Always understood dot 3 and 4 could not be added to silicone.

btw.....I do have PB on my '66. This was my first use of a silicone brake system. So far so good.

[Domenic T.]

Re: Brake question

Michael,
Supprised me too, but its only in a tug that gets up to about 15 MPH.

I didn't say that someone also put dot 3 in my dot 5 bleeder and the purple color was almost gone.

I did this in front of another mechanic and initially I didn't want him to see me do such a thing. But he said what have you got to lose you have to fix it any way.

DOM

[Jack H.]

Re: Brake question

Jack,

Did you bench bleed the MC before installing it?

JR

Yes but may need to do it again.

Now my electrical system quit charging. I think I'm snake bit.

[Paul J.]

Re: Brake question

Interesting Dom. Always understood dot 3 and 4 could not be added to silicone.

Supposedly you can't do it, but somewhere back in the archives is a reference to a test by the military that all that it does is form a black residue in that is harmless to the system. There was also discussion about swelling of the seals, but I don't remember much about it.

[Domenic T.]

Re: Brake question

Supposedly you can't do it, but somewhere back in the archives is a reference to a test by the military that all that it does is form a black residue in that is harmless to the system. There was also discussion about swelling of the seals, but I don't remember much about it.

Paul,

I don't know what the long term affects are but if it swells the seals that may be why I am not leaking and still have brakes.

I wouldn't do it on a car but this old tug has the brake pedal that go's thru the floor (not the swinging type) if you remember those, and the clutch pedal also does the same and is part of the master cylinder if you can believe that.

DOM