The Stovebolt Site Forums The Shop Area Driveline What am i doing wrong

Truck has been recently rebuilt,new lines and disc front brakes.
A short ride last week, brakes work.
Jacked it up to check rear brakes and they are not engaging,so I adjust to drag point and try,still not working on rear.
Pedal is solid,not mushy.
Can't get parking brake to engage either ,but since all of that linkage is new it may need a lot of adjustment.
Has anyone had a similar issue ?

May need a proportioning (sp) valve. Disc / drum systems usually require them to allow proper line pressure.

There is one in place,maybe needs adjusting ?

the one in place may be a left /right for fronts only

Are you getting fluid to the rears? The distribution blocks have a valve in place to block front or rear lines in case of failure. If this valve as moved, it could be blocking the rear lines.

I will check,
Also trying to get parking brake to engage...not sure how far off cables and linkage are from engaging. ( all replaced)

My bet is you have lost the 50-50 master cylinder lottery. Seems like the odds of getting a good brand new master cylinder these days is a crap shoot.

does the parking brake adjustment need to be done first on these brakes ?

no on parking brake adjustment

does the parking brake adjustment need to be done first on these brakes ?

The parking brake cables must be completely loosened prior to adjusting brake shoes.
Do you have a dual (front/rear compartments) master cylinder?
Can you bench bleed it to insure that fluid is coming out of the port which leads to the rear brakes? This will let you know if the master cylinder is defective (an unacceptably high percentage of new ones are defective).

Carl,

It is a dual master cylinder,I will try bleeding.

The reason I asked about the parking brakes is the service manual mentions adjusting parking brakes to adjust this style brake ?

Which service manual and what style of brakes do you have?

HUCK, I will photo pages

Huck brakes are very unforgiving when replacing shoes on well-worn or turned drums. They have a solid pivot point at the bottom and the shoes don't slide around to better engage the drums like Bendix brakes do.
What I do is tighten up the cylinder stars (2 per wheel) until I can't move the tire by hand, then back them up until there is only slight drag, then drive it for a while until the drums act as a milling machine and form-fit the shoes into the same conture as the drums. Then I adjust them again. You may have to do this procedure two or three times before you match the drum/shoes conture to each other. You will notice an improvement in braking action after each time you do this. Once they match, you will have as good of brakes as any kind out there for a truck like these.
Carl

Ok, since my helper(wife) is spending time in Maine, I took the wheels and drums off to look at brakes and cylinders, the cylinders looked nasty(sitting for 9 months at body shop) so I un hooked brake shoes and cleaned up adjusters and cups to assure they are moving freely.
I reattached parking brake linkage after retracting adjusters.
I then pulled parking brake and I think the cables are long.
the threaded section at crossmember end is hitting link pin and still not tight.
I was going to try tightening at center pull,hopefully it will do the trick without a problem.
When helper is home I will check fluid flow and cylinder movement. ( I had bled with MightyVac,so not a test of Master)

ok, good news, brake pedal produces flow at rear brakes, so Master cylinder working
Also discovered one parking brake line was connected, adjustment needed.

I think the rear brake cylinders may be done (look original)
not leaking ,but do not seem to be moving

I am going to replace shoes and cylinders.

I just reread the this entire thread, including the title "What am I doing wrong?"
Short answer is: You should have replaced the read wheel cylinders if you thought that they were original.
That is the first rule in Old Truck Repair 101.
All is well. You got it figured out and maybe someone was entertained by us chasing our own tails for quite a while.
Carl

Carl,
thanks,you are correct,I should have but thought they were ok,one of those jobs where 2 people are really needed to check

now to figure out which are the correct shoes and cylinders for my '49 3100 , they don't seem to be listed