Brake Pedal Not Returning & Weak Braking – ’73 Dodge Charger (Black Out Booster + Wilwood MC & Brakes)

• Car: 1973 Dodge Charger, factory power-brake car
• Drivetrain: 512 stroker big block, Tremec T56 swap
• Brake system:
  • 1962–74 Mopar Black Out Series Power Brake Booster Kit (POL)
  • Wilwood master cylinder
  • Wilwood proportioning valve
  • Wilwood 6-piston front brakes
  • Wilwood 4-piston rear brakes
• All new parts, recently installed

• The brake pedal doesn’t always return fully to the top. Sometimes while driving, it sticks partway down and I have to pull it up with my foot.
• I also cannot get the brakes to lock up, even when standing on the pedal. With 6-piston fronts and 4-piston rears, I’d expect way more bite, but stopping power feels weak.
• When the proportioning valve was set more toward “decrease,” the pedal sat closer to the floor. I adjusted it toward “increase,” which improved pedal travel somewhat, but the pedal still occasionally sticks and braking performance hasn’t improved much.

• Vacuum is connected from the intake manifold (engine has a big cam, so idle vacuum is lower than stock).
• To rule that out, I added an external vacuum pump, but it made no difference.
• The master cylinder was bench-bled before install.
• Lines are fully bled, no fluid leaks.
• I’ve already checked the pushrod length between the booster and master.
• Pedal feel is firm but not confidence-inspiring.

1. Since my car is a factory boosted car, is there anything different I should be checking with pedal ratio or linkage geometry when using this Black Out Series kit?
2. Do I still need to add an external pedal return spring?
3. Is it possible my master cylinder bore size is mismatched for the 6-piston/4-piston Wilwood setup?
4. Could there be an issue with the booster itself not providing assist?

Eddym98 said:

Hey everyone, I’m having trouble getting the brakes on my 1973 Dodge Charger to work the way they should, and I’m hoping someone here has run into the same issue.

Setup:

• Car: 1973 Dodge Charger, factory power-brake car
• Drivetrain: 512 stroker big block, Tremec T56 swap
• Brake system:
  • 1962–74 Mopar Black Out Series Power Brake Booster Kit (POL)
  • Wilwood master cylinder
  • Wilwood proportioning valve
  • Wilwood 6-piston front brakes
  • Wilwood 4-piston rear brakes
• All new parts, recently installed

The Problem:

• The brake pedal doesn’t always return fully to the top. Sometimes while driving, it sticks partway down and I have to pull it up with my foot.
• I also cannot get the brakes to lock up, even when standing on the pedal. With 6-piston fronts and 4-piston rears, I’d expect way more bite, but stopping power feels weak.
• When the proportioning valve was set more toward “decrease,” the pedal sat closer to the floor. I adjusted it toward “increase,” which improved pedal travel somewhat, but the pedal still occasionally sticks and braking performance hasn’t improved much.

Other Notes:

• Vacuum is connected from the intake manifold (engine has a big cam, so idle vacuum is lower than stock).
• To rule that out, I added an external vacuum pump, but it made no difference.
• The master cylinder was bench-bled before install.
• Lines are fully bled, no fluid leaks.
• I’ve already checked the pushrod length between the booster and master.
• Pedal feel is firm but not confidence-inspiring.

Questions:

1. Since my car is a factory boosted car, is there anything different I should be checking with pedal ratio or linkage geometry when using this Black Out Series kit?
2. Do I still need to add an external pedal return spring?
3. Is it possible my master cylinder bore size is mismatched for the 6-piston/4-piston Wilwood setup?
4. Could there be an issue with the booster itself not providing assist?

Any advice, experiences, or troubleshooting tips would be a huge help. I’m trying to get this car road-ready but the brakes are holding me back.

Thanks in advance!

Click to expand...

Eddym98 said:

Hey everyone, I’m having trouble getting the brakes on my 1973 Dodge Charger to work the way they should, and I’m hoping someone here has run into the same issue.

Setup:

• Car: 1973 Dodge Charger, factory power-brake car
• Drivetrain: 512 stroker big block, Tremec T56 swap
• Brake system:
  • 1962–74 Mopar Black Out Series Power Brake Booster Kit (POL)
  • Wilwood master cylinder
  • Wilwood proportioning valve
  • Wilwood 6-piston front brakes
  • Wilwood 4-piston rear brakes
• All new parts, recently installed

The Problem:

• The brake pedal doesn’t always return fully to the top. Sometimes while driving, it sticks partway down and I have to pull it up with my foot.
• I also cannot get the brakes to lock up, even when standing on the pedal. With 6-piston fronts and 4-piston rears, I’d expect way more bite, but stopping power feels weak.
• When the proportioning valve was set more toward “decrease,” the pedal sat closer to the floor. I adjusted it toward “increase,” which improved pedal travel somewhat, but the pedal still occasionally sticks and braking performance hasn’t improved much.

Other Notes:

• Vacuum is connected from the intake manifold (engine has a big cam, so idle vacuum is lower than stock).
• To rule that out, I added an external vacuum pump, but it made no difference.
• The master cylinder was bench-bled before install.
• Lines are fully bled, no fluid leaks.
• I’ve already checked the pushrod length between the booster and master.
• Pedal feel is firm but not confidence-inspiring.

Questions:

1. Since my car is a factory boosted car, is there anything different I should be checking with pedal ratio or linkage geometry when using this Black Out Series kit?
2. Do I still need to add an external pedal return spring?
3. Is it possible my master cylinder bore size is mismatched for the 6-piston/4-piston Wilwood setup?
4. Could there be an issue with the booster itself not providing assist?

Any advice, experiences, or troubleshooting tips would be a huge help. I’m trying to get this car road-ready but the brakes are holding me back.

Thanks in advance!

Click to expand...

chrger1967 said:

I was having the same problem with the booster that was installed in my Charger. I found the rod on the booster was resting on the firewall and was pushing into the master cylinder. I had to put in ¼ of spacers to solve that issue.

Click to expand...

• Verify non-faulty booster and check valve doing a vacuum check (and no other leaks elsewhere)
• Monitor what your idle and cruising vacuum is – with the pump though you should be getting the necessary minimum that is required
• Recheck your pedal position, two things – it has a bit of free-play not binding against the brake light switch and that the pedal isn’t giving a pre-charge to the booster
• Make sure the pads are releasing nicely, remove the wheel and with a helper watch that action of the pads, no binding going on

gtxdana said:

I think you'll find the pedal sticking down problem is the booster itself. The market is flooded with those boosters and most all are made MBM out of China. I had a couple of eight-inch chrome ones on one of my cars and even adding an extra return spring, like a lot of people try, couldn't keep the pedal from sticking down. Those boosters are junk.

If you have power steering, go with a hydroboost setup and don't look back, especially if you have a big cam.

I have two cars with Wilwood brakes and I'm not really impressed with them. One has the 13" six piston front/12" four piston rear. That car has an eight-inch dual diaphragm booster which is probably too small for the master cylinder bore size.

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Eddym98 said:

I think I’m going to go with the hydro boost setup, do you know where I can purchase a kit for my 1973 Dodge Charger that also includes hoses and fittings? Is sweeting performance a good kit?

Also do you know if I’ll have to install a return spring with the hydro setup?

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