Power Brakes not working

[Data Plate]

Im not taking the drums off just wanted a little extra stopping power so I am trying to add the booster easy to do I thought but now running into all these problems.

 

[1968rt]

Did you set the pushrod depth? Need this tool. Setting brake booster pin depth

 

[1 Wild R/T]

Did you set the pushrod depth? Need this tool. Setting brake booster pin depth

View attachment 1421239

Need???? I've set probably 50-60 pushrod adjustments... Never used that tool...

 

[68 Sport Satellite]

agreed.

@1STMP
Can you please share with us your brand and source for the dual diaphragm booster setup you have? Also curious what calipers you're running.

 

[1 Wild R/T]

agreed.

@1STMP
Can you please share with us your brand and source for the dual diaphragm booster setup you have? Also curious what calipers you're running.

His whole build is rather unique.... And over the top...

 

[Data Plate]

I tried the rod at different depth which I know isn't correct I just ordered a tool to do it, I bought the booster MC kit from Roseville Moparts they already send me another booster but same results. I spoke with them today they think im not getting enough vacuum to the booster told me to buy a vacuum motor and put it under the battery tray, im going to recheck with the gauge how much I have they said at least 20 is that correct

 

[Data Plate]

My cam is 484 lift

 

[Kern Dog]

I didn't put the cam in but the guy said like a 450 lift

My cam is 484 lift

If that is the Mopar Performance 284-484, you will NOT have sufficient vacuum. You stated earlier that your cam was a 450 lift...
You are all over the map on this.

 

[Data Plate]

I thought it was but found the paper with the lift its the purple cam

 

[Data Plate]

so I would need a vacuum pump to make the brakes work ?

 

[Data Plate]

If the booster is leaking vacuum your
engine may be running slightly
rough and rich. Try disconnecting
the hose from the booster and
blocking the hose off with your thumb.
Your engine idle should smooth out,
which means the booster is bad.
If it doesn't, there's either a crack in
the hose or a bad connection at the
vacuum source.
(edited)
This of course,
assumes all other vacuum lines
and/or connections are good.
Another leak source to check is
the intake manifold.

I started the engine with it idling I pulled off the check valve motor ran ruff covered the check valve withy finger and it smoothed out

 

[68 Sport Satellite]

it's a rabbit hole. If I were you I would stick with the stock manual drums and use a more aggressive pad compound. I have driven a members car here with 4 wheel non-power drum and my last car was 4 wheel non-power drum and they work well and stop fine if you have good pads and drums. If you haven't replaced the drums ever, you might want to measure the diameter to see if there's still plenty to correctly engage with the pads. If the drums are worn too much, you can improve things with new drums. Check your wheel brake cylinders also to make sure no leaks.

 

[Data Plate]

Your right I think at this point ill pull out the power booster and master and put back the manual brakes just didn't work out to bad

 

[1STMP]

Your right I think at this point ill pull out the power booster and master and put back the manual brakes just didn't work out to bad

Seems like the booster was not
leaking.
I didn't realize you're trying to convert
from manual to power drums all
around. The main culprit now is
pedal ratio. Where a manual system
utilizes a 6:1 ratio, a power system
requires a 4:1 ratio.

 

[1 Wild R/T]

Seems like the booster was not
leaking.
I didn't realize you're trying to convert
from manual to power drums all
around. The main culprit now is
pedal ratio. Where a manual system
utilizes a 6:1 ratio, a power system
requires a 4:1 ratio.
View attachment 1421630

As Greg (Kern Dog) mentioned the pedal ratio on Mopars of this vintage was handle by adding a bellcrank that alters the leverage...

 

[dadsbee]

Im not taking the drums off just wanted a little extra stopping power so I am trying to add the booster

Booster isn't going to give you any extra stopping power, it's only going to reduce how hard YOU have to push the pedal.

 

[1STMP]

As Greg (Kern Dog) mentioned the pedal ratio on Mopars of this vintage was handle by adding a bellcrank that alters the leverage...

Thanks for pointing that out
1 Wild R/T.
I hadn't realized the bellcrank reduces
the ratio. The pedal assembly in my
truck is out of a '85 Diplomat. It
has the bellcrank.

 

[Kern Dog]

The published numbers for pedal ratios are wrong…..
Using the method above, I come up closer to 7 to 1.

 

[1STMP]

The published numbers for pedal ratios are wrong…..
Using the method above, I come up closer to 7 to 1.

Thanks KD. I posted those numbers
as they are what most engineers
would agree are optimal for the
different configurations. Many
variations can occur when deviating
from factory systems and/or
components.
An example would be the system I
pieced together.
I've read some articles where they
recommend moving the booster/MC
to obtain the 4:1'ratio, and drilling
a new hole in the pedal arm.
The bellcrank changes the
ratio of the pedal arm as the
bellcrank pivots. The ratios
are taken from the attachment
of the bell crank as the pedal arm's
revised pivot.
Consider me lucky ?
I mounted the dual diaphragm
booster in the designated location
for a manual MC in a 1940 Plymouth
pickup. Then mounted the brake
pedal assembly (cut down to fit
under the dash) from a 1985 Dodge
Diplomat. The booster rod lined up
perfectly with the booster, and the
rod was the correct length. I used
the bellcrank from the Diplomats'
set-up.
Went with a four disc system. (Ford
Granada front, Jeep TJ rear).
After install, there was a minute
amount of pedal travel before
brake pad contact, so I installed
2# residual check valves in each line.
(keeps the pads from backing off the
rotors), and placed an adjustable
proportioning valve for the rear
circuit. The brakes work flawlessly.
MC is a 1-1/8 bore, the booster is
a rebuilt CORDONE unit from a 1985
Chrysler LeBaron. Brake lines are
steel 1/8" I'd. (note pic 2).

 

[Data Plate]

Thanks for all the information I really appreciate the help. Is it ok to leave the power set up in and use the car until I can figure out the pedal problem or is it dangerous to use like that