Project is stalled. Cannot solve brake problem

[Peter coppola]

So regarding the firewall, I have the power brake bracket on the firewall. I am checking the push rod tomorrow when the checking tool arrives. I will send photos. I change combo valve already once as another buddy told me his issue with the combo valve. I will see if depressing the combo pin while bleeding. I can make a tools from some small square stock.

 

[Peter coppola]

Thank you for sketch. Will work on that bracket as well.

 

[Peter coppola]

OK, got home late from work and its cold in the barn. Won't have time to rig up a pedal bracket as recommended till the weekend as I am working late next two nights and Friday date night with wife.

I did three simple things as follows:

1. I got the push rod checking tool from Amazon today. Cost $12 bucks delivered. I unbolted the master and confirmed the push rod and the master are good. About .020 gap as stated. The rod on the booster is not adjustable in any case.

2. I removed the rear brake line and plugged rear master port. Started truck - pedal to floor.

3. I swapped lines and plugged front master port. Started truck - excellent pedal.

4. I removed both lines and plugged both master ports. Started truck - rock hard pedal.

I think therefore the master is good.

Above took me all of 10 minutes after dinner.

Any thoughts?

 

[WatfordJohn]

Sidebar as to not detract from all the master cylinder/booster talk: Do your front brake lines match the size of your banjo? (10mm vs. 7/16")

 

[Peter coppola]

using ac delco front lines, new copper washers and new callipers, the bolt fits snugly in the line banjo and I have no leaks. No air comes out on pressure bleed or vacuum bleed.

 

[Ricko1966]

Have you checked pedal pushrod clearance? There should be practically non you shoukd just barely feel it when you move the pedal with your hand you may even have to touch the pushrod it's self while moving the pedal,to feel the clearance.

 

[Peter coppola]

just got home from work. Checked the pedal/pushrod clearance. There is no slop. Pedal and rod move together into the booster and there is no freeplay. The rod screws on to the back of the booster. If the plan is to increase the rod travel. It might be quicker and easier for me to extend the rod length with a threaded couple and a threaded rod.

Any thoughts that I have pedal with front port blocked but not with rear port blocked?

 

[Ricko1966]

just got home from work. Checked the pedal/pushrod clearance. There is no slop. Pedal and rod move together into the booster and there is no freeplay. The rod screws on to the back of the booster. If the plan is to increase the rod travel. It might be quicker and easier for me to extend the rod length with a threaded couple and a threaded rod.

Any thoughts that I have pedal with front port blocked but not with rear port blocked?

Changing the pushrod length does not increase the pedal throw it moves the starting point and ending point,but it still moves the same amount. If you put too long of a pushrod in the mastercylinder, it doesn't return fully in its bore and causes more problems. Which is why I told you to make sure there is a tiny tiny bit of clearance at the pushrod end,so we know it's fully returning. As for pedal with blocked ports your front and rears do not have the same type of brakes,they do not use the same pressure or volume. Haven't you already seen with your own eyes the factory moved the pushrod location? Also isn't that the only thing you haven't changed?Isn't it also what I asked you about in my very first post to you? Do you think I just took a wild guess,or do you think maybe I know something about automotive brakes? You didn't even tell us this was after a manual to power swap,I had to ask. Why did I ask? Because you have a symptom that matches not having the pushrod travel correct.

 

[DoubleDingo]

Honestly, blocking ports, to me doesn't solve anything. It's a comprehensive system. A system that you changed, but didn't change completely to what GM engineers designed. i.e.: rod pin location on the pedal.

And still, no pics of what is on your rig. Post up the pics!

 

[Peter coppola]

Like I said, I will work on the bracket this weekend. Cold here and working late. Supposed to be warm on Friday and Saturday. I do appreciate the help and advice. I am not arguing with anyone. I think I provided all the info that I had. I hope I do not give the impression that I doubt your knowledge and experience.

 

[Ricko1966]

Like I said, I will work on the bracket this weekend. Cold here and working late. Supposed to be warm on Friday and Saturday. I do appreciate the help and advice. I am not arguing with anyone. I think I provided all the info that I had. I hope I do not give the impression that I doubt your knowledge and experience.

Read your post one,you left out the most important part. All this happened since I attempted to change from manual brakes to power brakes,I've changed everything but the pedal.Im not sure how many posts before we got that,and I think if I hadnt asked we never would have got that info Seriously you wouldn't go to the doctor with a pain in your side and not tell him the pain didn't start until after you fell off a ladder.

 

[Peter coppola]

Ricko1966,

I am not looking for any animosity here. I posted in the afternoon on Sunday, you put me onto this issue with your post at 8 pm on Sunday, I sat down on Sunday evening and wracked my brain as to what I was missing and sent a reply 1 am on Monday about reusing the pedal. I agree this will fix my problem and you deserve the credit for this. I have been stuck with this issue for almost a year and worked on other stuff because I was getting nowhere. Now I just want to get back to it so I can move forward. I got a three day weekend coming up and and I will message you back with the outcome. Thank you again for putting me on this. In over a year of talking with people at shows and swapmeets and where ever, no one ever suggested this issue.

 

[Tonimus]

Read your post one,you left out the most important part. All this happened since I attempted to change from manual brakes to power brakes,I've changed everything but the pedal.Im not sure how many posts before we got that,and I think if I hadnt asked we never would have got that info Seriously you wouldn't go to the doctor with a pain in your side and not tell him the pain didn't start until after you fell off a ladder.

It was like 11 hours and the third post (including the original) from the OP. For a new guy to the forum, and likely new to converting brake system styles, not that big a deal. When I was new to brake systems, I didn't know that manual brake rods were almost always in a different spot.

 

[DoubleDingo]

It was like 11 hours and the third post (including the original) from the OP. For a new guy to the forum, and likely new to converting brake system styles, not that big a deal. When I was new to brake systems, I didn't know that manual brake rods were almost always in a different spot.

The frustration comes from pointing out the rod is most likely in the wrong location on the pedal after the conversion, and then the OP treating it like the current setup is fine, and then blocking ports to check front, then rear, when it's a system that functions as a system, and needs to be setup as a system. Rod length to the master cylinder, as well as the rod location on the pedal need to be correct, as well as drum adjustment and proper bleeding of the system.

When I did my conversion to front disc, I questioned needing to drill a new hole for the rod. I didn't want to do it because I couldn't get a drill up in there to drill the pedal. I ended up getting a drill with a pivoting head and then cut down a drill bit to get up in there. It was still a pain, but I got it drilled, and adjusted the arm to have the recommended amount of play in the pedal, and brakes were solid from the first bleed.

 

[Keith Seymore]

Joining late; skimmed the thread and didn't see where he admitted going from manual brakes to power brakes - but - by way of help:

Manual brake pedal ratio (A/B) = 6.5:1
Power brake pedal ratio A/B (vacuum boost) = 4.5:1
Power brake pedal ratio A/B (hydroboost) = 5.6:1


K

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