Low Brake Pedal, hard to stop

[67Vette427]

Just put a rebuilt Hemi booster on the Challenger and I've bled the brakes about 10 times but the pedal is real close to the floor before the brakes start to apply. I had all the lines off the car and put a new M/C. IS there a way to adjust the pedal higher or maybe the brakes need more bleeding? I was thinking of using a pressure bleeder. The booster is getting vacuum.

I know the is an adjuster on the rod between the booster and the M/C but I don't want it out too far...

[OUTLAW]

first off BEFORE bleeding adjust the rear shoes (i assume you have front discs) this should raise the pedal some low pedal is usually too much shoe travel and spongy is usually air in system
ps always adjust the shoes BEFORE the e brake or else that to will screw up the pedal feedback

[Chryco Psycho]

I wouldl extend the push rod between the booser & M/C some more to raise the pedal 

[67Vette427]

Thanks for the input.

I adjusted the rear brakes shoes before bleeding the brakes and I thought they were pretty good. I'll check them again.

I think I'll try the adjuster out first to see how that helps.

[AprilsPink72Cuda]

this may sound like a stupid question but, did you bleed the master cylinder?  a friend of mine had the same problem. he had the m/c replaced at a shop once and they didn't bench bleed the m/c.  they tried blaming the booster for the problem hoping to suck more money out of him.

just a thought
april's hubby

[67Vette427]

lol... the only stupid question is the one tht isn't asked ... right?  I adjusted out the rod and that brought the pedal up but you still have push the pedal hard to stop good. This is the second M/C on the car. I bled both but I think I'm going to do it again. The first cylinder started leaking out the piston seal and I removed it. I'm going to remove the lines and blow them all out too.  Thanks for the input... I want to make sure I can stop that Hemi  :driving:

[67Vette427]

Here is the latest picture. I drove to the exhaust shop today... Varoom!! :fire:

[kowalski]

 :thumbs:   looking good!!!

[Chryco Psycho]

Lokks Great
 What is the manifold vacuum reading ?

[67Vette427]

LOL I was just coming on here to post about the vacuum.... :laughup:

Its got the 472 Crate Hemi and I do believe the vacuum is low on that motor at idle but I'm going to throw the vacuum gauge on it tomorrow. I wouldn't be surprised if its 6" or so.


Thanks

[Chryco Psycho]

Probably not enough vacuum to make the booster work efficiently , you could go to standard disc brakes by eliminating the booster or try to get a vacuum pump or vacuum reservoir

[67Vette427]

I was thinking the vacuum pump too. I saw one at Summit Racing. I think I can hide under the battery tray and mig weld a cover in case of acid drips and some studs to mount the pump. That way it won't be seen. What is the usual vacuum, around 10"  ?


Thanks

[Grancoupe]

I'm idling at around 6" to 7" and really have no problem stopping the car. Have you checked to see if all the brakes are in fact being applied? I believe if a proportioning valve fails it can cut off the rear brakes from being applied. It happened to my Charger and fixed it with a proportioning valve off a Diplomat. If your stopping on your front brakes only it can make things difficult on the brake system.

[Popeye]

Where did you get your brake booster? I know Hemispherical Products sells them....they are mostly junk.

[Grancoupe]

Im not sure if your asking me where I got my booster from but if you are I did in fact have it rebuilt in a shop that was local in Long Island NY. They've moved since them but I have seen their ads in some of the Mopar Mags. I think the name was Brake Specialties or something like that. I'm going to get a few of the mags out of the atic and get back to you on the name and address. Its not the first time I've herd of booster problems and can say I've never really had any reason to complain with my car. I am running a higher than stock cam with a good amount of overlap, and the thing still has good grab in the brakes at idle.