soft brake at low speeds

[young99]

I have a 1969 Coronet that was converted to front disc brakes before I got the car. I am not very familiar with what all is needed during this conversion and think something could be missing. I removed all the old brake lines and replaced them with new lines and fittings + hoses. I also added a new master cylinder.

When at higher speeds 35+ the brakes work well. At low speeds the brakes hit the floor and tough to get to stop. The car has a cam in it and I added a Jegs Vacuum reserve can hoping it would help.

I am wondering is there anything else I can check on why it is so hard to stop the car at low speed?

 

[monaco66coupe]

This is an old problem,,,,,,,,,,,, high lift cams decrease the vacuum available under 2000. Stock original cars had around 15-16 Inches at an idle. HP cams struggled at 7-10. No brakes at that. Choose your poison,,,,,,,,,,,,,

 

[Matrix2]

You need to get an electric vacuum pump. There a switch that turns them on when the vacuum is low. Comp cams makes one, available at Summit. Right stuff and others make them. Solves the problem of performance cams with low vacuum and power brakes.

 

[young99]

If I were to switch the car over to Manual Brakes would I get better brakeing with the cam? Sorry for all the questions I am still learning on this. I went out to a car show over the weekend and the exit was downhill and she was not stopping no matter what. Luckily no traffic was coming, squeezed to the ground and still rolling.

 

[Xp29h]

If your brake situation changed from first post. Little brakes at low speed certainly sounds like age old issue of little vacuum. But if pedal has changed from first post ...couple thoughts...

Manual brakes would stop you. Some believe that disc brakes should never be manual. Depends who you talk to. Couple thoughts that I ran into with this same situation. Larger cam no vacuum no brakes. Turned out master was not bench bled and nothing I did was going to fix. Did you get a good bench bleed on the master?Second, are there any leaks anywhere? Check all your basics then go back to the vacuum. The p.o. of my car put a vacuum pump on it to fix issues, but brakes weren't any better!

Keep in mind if you decide to go manual brakes, the plate that attaches to the firewall for the brake booster/master will need to be changed out for a manual one. You can find them on eBay or I'm sure someone here has one that may be able to part with it.

Good luck!