47-55.1 Brake Drag?

[ChevDog1]

Drove the 55.1 to work today (30 miles) to shake it down after replacing the suspension, adding power brakes, and power steering. Wire fell off of the electric fuel pump at about mile 8 (easy fix). At about 25 miles, while in stop and go traffic I started smelling hot brakes. A couple of miles later at a stop light I could see smoke rising from the left front wheel. Couldn't tell if only one wheel was dragging or more.

Brakes are stock drums all around with a new CPP booster and MC in the stock location. Vacuum bled very thoroughly, and adjusted to where they spun freely and just barely touched the drums. When I first installed this kit the pedal would go all the way to the floor and only barely stop the truck. I discovered that I had too much free play in the pushrod so I tightened it up until "I think" it was just barely touching.

Did I go too far? Is it likely that the MC is applying slight pressure causing the brakes to drag? I have taken it on a bunch of small trips (7-10 miles) without issue, but today's longer drive was not good. I am going to have to nurse it home as I don't have any way to adjust it here.

[nvrdone]

I have the same setup on my '49 AD. When I did the conversion I had the same problem on the left rear wheel. I found 2 problems. First, even though the spring kit was new, the rear springs were not pulling the shoes back from the drum far enough. It took replacing the springs, turning the drums and re adjusting the clearance.
2nd problem was that the push rod was causing a little too much pressure on the m/c diaphram causing a drag. There is a tool available that is shaped like an "H" for adjusting how far the push rod goes into the m/c. I think I got mine from Napa.
Once you get the brakes fine tuned, they are much better than the stock system. But not as good as a disc / drum setup.
Good luck & hope this helps.

[mr48chev]

You should be able to feel or see the pedal/push rod move before making contact with the piston. It doesn't have to move much someting like .020 but you have to have that bit of clearance as Nvrdone said.

You should be able to get under it and reach up and pull the pedal down grabbing it up by the brake light switch with your fingers and feel when the pushrod makes contact and you should be able to feel that tiny bit of slack.

The other thing is that you still need a return spring or the weight of the pedal will push slightly on the piston.

Last, make sure that the pedal doesn't hang up in it's hole in the floor. I've fought that one before when I didn't have the rod from pedal perfectly lined up in the hole and if the truck has had an automatic in it and has some miles on it the cab can sag with the weight twisting the mount brackets on the frame causing missalignment. That is one way I figured out that my cab was sagging on the mounts when I had a 350/turbo 400 in it. The other being that the hood wouldn't fit right.

[leegreen]

grab that wheel and shake back and forth vertically to make sure you don't have a loose wheel bearing before driving home, that is something you may not want to try and nurse

brakes so hot that they smoke may have baked/glazed the shoes on that wheel, when you get it apart check the shoe surface, compare to the other side. If it is shiny, cracked or harder to scratch than the other side you probably want new shoes or you may forever fight having different braking power L-R

[mr48chev]

It's a good idea to pull the drum (s) off and look before doing much else anyhow as something may have come loose. That especially comes into play if ony the left is having an issue and not both front brakes.

The other thing that we often overlook is the condition of the brake hose. More pressure on the line may have enhaunced issues that the brake hose already had going on and the lining of the hose may be breaking up on the inside.

Pull the drum and look at everything inside the drum. Check the shoes and check the springs to make sure that they look to be in good shape.
Make sure that there is no grease or other contamination on the linings

Pull a (or the) shoes off and look at the pads that the shoes ride on on the backing plates The ones I marked with blue arrows. Make sure that they do not have grooves worn in them that the shoes can catch on and hang up. That especially happens when you put new shoes on worn backing plates and the sharp edges of the new shoes catch on those grooves that the old shoes had worn smooth right along with the grooves wearing. If there are grooves there you will need to dress them up smooth and that can be done with a flap wheel. I've done it with a file way back when i didn't have anything else but that is a lot of work. Sometimes you have to build it up and slick it back off. Smear just a tad bit of lithium grease on the pads with your finger tip before you put the shoes back on.

If it still has non self adusting brakes Tighten the aduster up until you just can't turn the wheel and then back it off 11 clicks as that is the adjustment that you want, what I was taught in 1962 and what I have done on hundreds of brake jobs and taught hundreds of students to do.

[dsraven]

all the stuff mentioned above is great advice. you may also consider these tips
check all the brake pedal linkage to ensure the pedal returns to the top every time without any drag.
install a pedal return spring that is strong enough for the task
install a pedal stopper to ensure the pedal stops at the same place each time when you take your foot off. possibly there was one on the pedal arm on the firewall side that simply buimped against the firewall
once the pedal linkage, stopper and spring are all in order, ensure there is free travel in the linkage so that the first tiny bit of pedal travel actually does nothing but take up that slack space. this ensures the linage isn't holding the master cyl piston from fully returning
check the rubber brake hoses for kinks or soft/hard spots that may indicate an internal problem. sometimes they can get a flap on the inside that works like a one way valve and doesn't let all the pressure back out of the wheel cylinder
if it is a rear wheel, ensure the park brake cables are free to return easily, as well as the rest of the linkage

[ChevDog1]

I think I have solved it. I didn't know that the booster pushrod had to be adjusted to match the master cylinder (not in the instructions). Took master off and used the proper tool to set the pushrod length. Then readjusted the linkage from the pedal to the booster. Everything seems to work properly now. Will take it on a longer test drive later this week.

[mr48chev]

That is far more common than you would ever believe.