Brake problem??????????

[bagged69c10]

Most of you probably saw the 69 sub I just posted pics of. I put discs brakes on the front and when it was all said and done the pedal goes to the floor. Here is the list of everything replaced during this ordeal.

Master cylinder
Both rear wheel cylinders
rear rubber line
and all the front setup is a brand new kit from Mcgauyes (spelling?)

I took the proportioning valve off of my old 69 so I know it worked, and we switched out the booster that was on it for one that had been taken off another truck thinking that was the problem. The pedal still goes to the floor before it stops. I can pump it three times and the third pump the pedal feels solid and stops it. ANY help would be greatly appreciated.

[project 67 sub]

did you forget to bleed the brakes by some chance?

[bagged69c10]

No I've blead them more times than I could count. I also bench blead the master cylinder.

[JimKshortstep4x4]

The problem you are having still sounds like air in the lines. The rear brakes can be very difficult to bleed. My suggestion would be to try gravity bleeding the rear brakes for a period of time.

Also, since a 69 did not originally come with a prop valve, was there a disc brake setup on your 69?

Jim

[bagged69c10]

Yes, it had basically the same setup except it didn't have a booster. What exactly is gravity bleeding?

[Long Roof]

You may have a bad MC. Is it a reman unit or brand new? I have never had luck with reman MCs. Had to take two back before I bought a new one on my 80 vette. Good luck.

[JimKshortstep4x4]

bagged69c10,

To gravity bleed, all you have to do is open the bleeders and let the fluid run out. If the fluid does not run out then there may some other problem.

Gravity bleeding usually works well because there is less chance of reintroducing air in the system when pumping the brakes. Pressure bleeders work well, also. (If you have one available).

Jim

[MrBeast]

get a pressure bleeder kit, it is worth the money you will spend. Also I think the advice about the master cylinder is spot on, I will never use a reman ever!

[bagged69c10]

I dont think it is the M C because I put another on off of a truck that got a chrome one. It was supposed to have worked when they put the chrome one on. That was my first suspicion to. I will try gravity bleeding them tonight then maybe go buy a pressure bleeder.

[cparman]

the proportionong valve could be tripped. Try gravity bleeding just the rears. the fluid will trickle out if the prop valve is tripped. let it trickle for a good bit. close off the bleeders. have a drink of water, and then STOMP HARD on the brake pedal a couple of times. then try and bleed the brakes again. when bleding the brakes make sure not to let the pedal go all the way to the floor. If you push really hard on the brake pedal while bleeding, and the pedal goes to the floor quickly it will trip the prop valve.

[bagged69c10]

Thanks for the help. I will give that a shot. So should I just put a 2x4 under the pedal or something.

[bagged69c10]

I have another question now. Would it make a difference if the calipers were on the wrong side? A guy told me yesterday that the bleeder screw can't be pointed down it has to be up. Im gonna change it anyways but figured I would ask.

[Longhorn321]

Originally Posted by bagged69c10

I have another question now. Would it make a difference if the calipers were on the wrong side? A guy told me yesterday that the bleeder screw can't be pointed down it has to be up. Im gonna change it anyways but figured I would ask.

I would think that yes it would make a difference. All of the calipers I have ever seen have had the bleeder on top. The air in the system is going to rise to the highest point so it makes sense. I have however seen a bleeder on the bottom of a slave cylinder for the clutch.

If that does not do it, try this: 1. Open the front bleed screws and leave them open. 2. Bleed the RR and then the LR using a vacumme hose from the bleed screw into a plastic bottle with the end of the hose submerged in fluid in the bottle when you pump the brakes. Keep an eye on the level in the resevoir while doing this since the fronts are open. You may want to put a hose on the fronts too so that you don't make such a mess. 3. Close the bleeders in the front and then bleed the RF and finally the LF as you did the rears. Hope this helps.

[Long Roof]

Yes, bleeder on top for sure.

[bagged69c10]

Tomorrow afternoon Im gonna try everything mentioned and hopefully something will work.

[bagged69c10]

Good news. I swapped the calipers and gravity bled it and it works great. Thanks for all the help guys!