Manual to power disk brakes help?

[74broncodude]

Currently swapped front end brakes to power disk.. rear is still drum .. New
Power booster proportion value and new rotors and calipers but the brakes
Still suck?? Help

 

[DuctTape]

Hard to help without more information. First thing I would suspect is bleeding. Make sure you work from longest line to shortest line when bleeding, and don't stop just because you don't see bubble on a couple of pumps.

 

[74broncodude]

Have bleed the brakes several times hasn't helped I adjusted rear brakes
It helped some but still doesn't stop like a 450$ new brake booster should. It's getting
Vacum to the booster so I don't kno if it's a bad booster or what..
Was hoping someone else had similar problems.. Everything came
From toms bronco parts

 

[bteutsch]

What size tires are you stopping? Also what master cylinder ?

 

[Timmy390]

Ford or Chevy conversion?

Tim

 

[74broncodude]

Just 35's and master cylinder came with the kit and ford

 

[broncodriver99]

Just 35's and master cylinder came with the kit and ford

35's are a pretty big tire for the Bronco brake system.

 

[broncodriver99]

Are your rear brakes adjusted properly? While the fronts do much of the work the rears still need to work properly. What kind of pads are you running? Fresh pads will take a few miles to seat and really grip properly.

 

[broncodriver99]

What kind of shape are the rubber hoses that run from the frame to the axles in? They do get spongy over time and can swell when the pedal is depressed loosing some of the brake pressure. Are the slide areas of the calipers and caliper brackets clean and lubed so the caliper and pads can center and give you good pressure on both pads?

 

[broncnaz]

Vacuum booster dont increase braking ability they only decrease pedal effort. As was said 35's are kinda big but you should still get decent braking. You need to check all your connections make sure the front brakes are hooked up to the rear port on the MC.
Also what brake pads did you use? some of the so called Hipo pads really only work good when they get really hot. The old standard semi mettalics tend to work better.

As was said a little more info can be helpful. like hows the pedal feel? pedal travel?
Also to check vacuum booster operation have your foot on the brake pedal when you start the engine you should feel the pedal go down slightly.

 

[stlo]

I have the toms kit with 36's and mine stops great no complaints here.....did u bench bleed the master cylinder before u installed it?.....toms no mod kit comes with the bigger booster than most others

 

[stlo]

U may check to see if the rod from master to booster is adjusted right as well

 

[74broncodude]

Metallic pads all hoses and brakes lines are new hooked to the rear of master
Clyinder . And petal is hard soon as you push on it but to completely stop you have
To push it threw the floor petal is very hard . Yes bench bleed the cylinder then the brake
Lines twice .. Yes calipers are clean pads look evenly worn .. STLO I have the no mod.. Motor is bored 20 over with cam would that any anything to do with vacuum pressure. ? I have a vacuum gauge only getting 10 pounds of vacum

 

[Apogee]

Are you sure you're getting 10 psi of vacuum...that's really high, and vacuum is typically measured in inches Mercury (Hg), not psi. If you're only getting 10 inches Hg vacuum, that's exceptionally poor and would definitely not allow the booster to function near as effectively as it should. I usually consider 12-14 inches Hg marginally acceptable, but with some potential pedal inconsistency, 16 inches Hg plus would be ideal.

Describe your pedal feel for us. Is it high or low? Hard or soft? Any sponginess? Does it pump up with multiple applications or not? How much does the pedal drop when you pump the pedal multiple times, apply and hold the brakes, and start the engine?

Tobin

 

[broncnaz]

Yeah you have a vacuum issue most boosters need to be in the 14in and up range to work well. Although you should be pulling that when you are off the gas pedal and braking anyhow. but again the vacuum booster only makes the pedal easier to push it doesnt really increase braking ability. A correctly setup brake system should stop well with no boosters.
You may be a canidate for hboost as its is commonly used to get better braking since it provides a lot more power than a vacuum setup or your leg.
It almost sounds like your MC may have to large of a bore which could result in a hard pedal with less actual PSI applied to the brakes but if its the stock ford MC then it should be the correct size.

 

[74broncodude]

High pedal feel but very hard soon as I touch it the pedal is hard enough
To feel like the brakes should completely lock up.. If I pump several times
They stop better but still not good at all. And I hate to go hboost bein as I
Have about 700 dollars in new brakes that stopped better when they were stock
Manual

 

[broncnaz]

Id check your old MC's bore against the new MC bore. See if there is any differance. Still your vacuum is to low for a vacuum booster to work correctly. But You shoud still see the same braking as you had before. Only thing I can say it to recheck the booster rod to MC adjustment as was suggested earlier.

 

[broncodriver99]

I wouldn't hop on the Hboost wagon just yet. May not be necessary. A properly setup vacuum system should perform pretty well. Definitely sounds like you have a low vacuum issue. How about some engine details? I have a pretty stock Bronco 302 and have 20-22" vacuum. The vacuum booster can only exert as much assist as the engine vacuum will allow. If you have a big cam or a worn out engine then there is only so much a vacuum system can do. You may just need a tune up.

 

[savage]

I'm with the low vacuum, the peddle should have less effort with the help of the vacuum booster. You said if you pump it ,it helps a little, so it still may be air trapped in the system. When I put my system on it was a bear to get all the air out, it took many tries to get all the air out, when you bleed the brakes did you crack the line at the proportion valve, air can get trapped in the valve.

 

[74broncodude]

Savage what do you mean crack the line at porportion value ?
I bench bleed the cylinder and bleed lines twice . Thinking about
Taken every back off and goin over It again and re bleeding