Push Rod Single to Dual Conversion

[The Dart GT]

'63 Dart with four manual drum brakes.

I converted my single MC to a dual MC and I'm using the original push rod.

How do I know the original push rod is the correct length? I installed everything and there appears to be too much "slop" in the pedal. The pedal does not push tight against the brake light switch the way it did before I disassembled it.

Mancini makes an adjustable push rod that I might try.

 

[cudamark]

It should work fine as long as you get the proper master cylinder. Measure and compare the hole depth before you install it. The only real mod you may need to make, is to figure out how to use the coil return spring on the new master cylinder. They usually aren't drilled and tapped for the early type piston and rubber boot retainer. I'm assuming that you're staying with manual brakes. If you get the later dual master cylinder it should have a piston with the retainer groove for the push rod. Most of the time, the master will come with a new rubber lock ring for the push rod. Test fit everything without the lock ring first. The push rod can be a ***** to get back out of the piston if you need to remove it again. You might damage it in the attempt too.

 

[The Dart GT]

Thank you for your help. The rubber lock retainer fits and works. The boot fits. I'm thinking about a more aggressive return spring to force the pedal back against the brake
switch.
I don't have the original MC so I don't know the depth of the original piston.

Mancini makes an adjustable push rod. I might give that a try.

 

[cudamark]

You're missing the rear spring seat. It fits around the push rod so the spring stays compressed. That's usually enough to return the pedal back and operate the brake light switch.

 

[The Dart GT]

I should be all set. I attached the push rod to the bake pedal and let the pedal hang in a "neutral" position. Then I loosened the brake switch bracket and moved it forward against the brake pedal and then retightened the bracket.

 

[AJ/FormS]

How do I know the original push rod is the correct length?

After the brake pedal is parking correctly; and after the brake-bleeding is done; You should have a hard high pedal. BUT
The pedal should do nothing in about the first inch, during which the pistons are self-adjusting in the M/C. By stroking the pedal rapidly several times in a row, you can pump extra fluid down the line and MAKE the pedal hard and high. But when you release the pedal, and wait a few seconds, that fluid should return to the reservoirs, and the pedal should again do nothing in about the first inch.
>If the pedal stays hard and the brakes are locked, then the fluid has Not returned and the compensating ports are on the wrong side of the pistons, because the P-rod is too long, or the pedal is not properly parked at the top..
>If the brakes do nothing for MORE than one inch, and /or the pedal does not return to the top, then the P-rod may be too short.