Power disc brake conversion kit troubles.

[Moparmadness408]

The brake pedal sometimes does not return causing the brake lights to stay on. It seems like with the engine off it works just fine. I don’t see a return spring on the pedal and do not know what would cause this. The caps on the master cylinder reservoir leak out brake fluid as well. The car originally had no power drum brakes all the way around. All the brake components are new, other than the warning switch. It’s got discs in the front and drums in the rear. And it had none of these issues beforehand.

 

[Moparmadness408]

I also drove it just up and down the street and the car doesn’t seem to really coast, it almost will stop on it’s own. And if pull up on the brake pedal it doesn’t seem to drag as bad.

 

[Demonic]

No return spring on a Mopar brake pedal. Sounds like the MC pushrod is too long, which will cause a drag usually. But...

The caps on the master cylinder reservoir leak out brake fluid as well.

That's a big problem also. Should absolutely not be, so maybe start there.

 

[Moparmadness408]

Ok I put a return spring on it, and it appears that the pedal still doesn’t always return like it’s supposed to. The thing is, this engine doesn’t really make enough vacuum for the power brakes to work that well, and for the most part, the car stops very poorly, to the point to where it’s not really safe to drive. And every once in a while the power brakes seem to kind of work, and that’s when I notice the brake pedal not returning properly and the brakes not releasing all the way until I pull up on the pedal.

 

[72bluNblu]

Ok I put a return spring on it, and it appears that the pedal still doesn’t always return like it’s supposed to. The thing is, this engine doesn’t really make enough vacuum for the power brakes to work that well, and for the most part, the car stops very poorly, to the point to where it’s not really safe to drive. And every once in a while the power brakes seem to kind of work, and that’s when I notice the brake pedal not returning properly and the brakes not releasing all the way until I pull up on the pedal.

Remove the return spring. You don’t need one if the brakes are working properly. So if you think you need one, what you actually need is to fix your brakes still.

It sounds like you may have multiple serious issues. The pushrod for the booster must be the right length, otherwise the brakes will not work properly, can drag, etc. If you have leaks, you need to fix those. And if you don’t make enough vacuum to power the booster, you either need a vacuum reservoir, a vacuum pump, or to remove the booster entirely because you don’t have enough vacuum to run it. With a properly sized master cylinder these cars will stop just fine with manual brakes.