Vacuum brakes is this normal

[87 GN WE2]

I converted to vacuum brakes and I have a question about pedal travel. Is it normal to have the pedal travel almost to the floor (end of pedal travel) to stop the car. If you slam the brakes the car does stop and sometimes locks up the tires. I installed a reman brake booster and master cylinder. I have checked for air several times and I have now replaced the master cylinder with a brand new ac delco. Still have the same issue. It feels almost like there is not enough resistance when pressing the pedal. The pedal doesn't feel firm. It doesn't feel like your normal vacuum brake setup. I have 16'' of vacuum in park and 13'' in drive. Any help would be great.

 

[Squid4life]

1. Did you replace the pedal with the vac setup? Vac setup takes a diff pedal than the other setups.

2. Did you bench bleed the master cyl before putting it on?

3. When you bled the brakes did you do anything with the little poppet valve deal on the prop valve? I forget which, but you are either supposed to hold it in or out while bleeding the brakes.

4. When you installed the master cylinder, did you check the rod travel before bolting it down? Sometimes when changing the master the rod inside is maladjusted making the pedal have to move more to make contact with the inside of the master.

 

[87 GN WE2]

Yes I did replace the pedal and I did bench bleed both masters. No I did not do anything with the poppet valve while bleeding. The original reman booster and reman master came assembled together. So I didn't do anything with the rod adjustment. I did measure up the piston depth on both masters and they were the same. I am thinking that the rod was never set up properly on the reman combo I originally purchased. Are all the rods adjustable?

 

[Squid4life]

I think so... On nearly every one I have seen they were adjustable to ensure there was no slop. Does it feel like you are moving any fluid or air the first part of the pedal travel? If the rod was not touching, all you would feel is the spring that holds the pedal up.

 

[87 GN WE2]

I will double check how the pedal feels once applying. Thanks

 

[87 GN WE2]

Okay I checked it without driving it. When you start the car and start applying the pedal it feels like some resistance but not much. I am not sure if it feels like air or fluid. When you put the pedal all the way down and place the car in drive as you start to let the pedal come up about 1/2 inch the car will start to move. I would have expected the pedal to come up a lot more than 1/2 inch before the car starts moving. The pedal just doesn't feel firm. It feels to easy to apply the pedal to the floor. Maybe there is still air in the system.

 

[williambavila]

ok try this.. remove brake lines from master cylinder and let fluid run out for about a hour with top off. Then finger tighten lines in the master cylinder,now crack all 4 bleeders on brakes,let all fittings and bleeders leak for about another hour. Finally have someone sit in car and slowly push pedal to the floor as they do that tighten lines on master cylinder when the pedal hits the floor have them hold it and tighten all bleeders. then have them pump pedal 5-10 times and hold bleed each bleeder and your pedal should be firm. I just did mine today and the brakes work great.

 

[Red Regal T]

How are your rear brakes, adjustment, and drums? This what seems to affect most pedal position.

 

[87 GN WE2]

Here is some feedback on the brake issues. After using a vacuum pump to remove all air from each wheel cylinder. The pedal does feel a lot firmer than before. The pedal travel still feels to low to me. I will have to drive it in order to feel if it is any different. Due to the weather that will have to wait.
Red Regal T the shoes and drums are new and they are adjusted so when you spin the rear tires there is just a small amount of rubbing on the rotors.

 

[Red Regal T]

I remember that technique of spinning the wheel while adusting the brakes. I don't do that on the TRs because you can't reach the adjusting star from behind the backing plate, but I suppose it's the same as adjusting the shoes to a point where you can just about slide the drum into position on the axle. It's good you at least achieved some improvement with the last bleeding. Perhaps that all important test drive will provide a positive outcome.