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My brake pedal doesnt seem to pump up...low pedal #376148
07/15/09 12:43 PM 07/15/09 12:43 PM
Joined: Jan 2003
Posts: 2,410
Wichita,KS
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Blakcharger440 Offline OP
top fuel
Blakcharger440  Offline OP
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Joined: Jan 2003
Posts: 2,410
Wichita,KS
My 70 Charger RT 4speed car came with power drum brakes. The engine (512ci)has a Hughes cam 587 lift with 260 duration with 10.5 compression.

For the front I have installed Cordoba disc brakes with E body calipers.

On the rear I have installed a TSM disc brake kit which has Ford Explorer discs and calipers from a 77 GM vehicle.....I know

I purchased a remanufactured power brake booster and master cylinder for a 70 Charger with disc brakes.

I am trying to fix a slight leak coming from the bottom of the brake junction block that is mounted on the frame at the front of the car and from the brake line at the passenger side rear caliper.

I have bled the brakes twice and the pedal only comes of the floor about 3 inches and I feel the pedal pressure could also be firmer.

What could be causing the pedal to only come off the floor a couple of inches?
Re: My brake pedal doesnt seem to pump up...low pedal [Re: Blakcharger440] #376149
07/15/09 01:37 PM 07/15/09 01:37 PM
Joined: Sep 2005
Posts: 6,516
Santa Cruz, California
L
Lefty Offline
master
Lefty  Offline
master
L

Joined: Sep 2005
Posts: 6,516
Santa Cruz, California
Quote:

My 70 Charger RT 4speed car came with power drum brakes. The engine (512ci)has a Hughes cam 587 lift with 260 duration with 10.5 compression.

For the front I have installed Cordoba disc brakes with E body calipers.

On the rear I have installed a TSM disc brake kit which has Ford Explorer discs and calipers from a 77 GM vehicle.....I know

I purchased a remanufactured power brake booster and master cylinder for a 70 Charger with disc brakes.

I am trying to fix a slight leak coming from the bottom of the brake junction block that is mounted on the frame at the front of the car and from the brake line at the passenger side rear caliper.

I have bled the brakes twice and the pedal only comes of the floor about 3 inches and I feel the pedal pressure could also be firmer.

What could be causing the pedal to only come off the floor a couple of inches?




For the leak, loosen and re tighten the fitting several times. If that does not fix it. check for wear in the block and fitting. Replace either/both if you see wear.

Does the pedal come up off the floor further if you try and pull it up?
Re: My brake pedal doesnt seem to pump up...low pedal [Re: Blakcharger440] #376150
07/15/09 04:24 PM 07/15/09 04:24 PM
Joined: May 2009
Posts: 18
California
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brake tech 73 Offline
member
brake tech 73  Offline
member
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Joined: May 2009
Posts: 18
California
Although the leaks are probably attributing to the soft pedal, that isn't the cause of the low pedal. It sounds to me like the pushrod from the master to the pedal may be the short one.

Re: My brake pedal doesnt seem to pump up...low pedal [Re: Blakcharger440] #376151
07/15/09 08:07 PM 07/15/09 08:07 PM
Joined: Jan 2006
Posts: 957
Heart of Ohio
4boxers4 Offline
super stock
4boxers4  Offline
super stock

Joined: Jan 2006
Posts: 957
Heart of Ohio
Possibly the pushrod length between the 2 M/C's is slightly different and you need more length to bring the pedal up.Double check the length maybe?
I have concern with the "slight leak" on a pressurized system as it can draw air in some rare cases.Tough fix but probably has some impact.

Good luck!

Persistance is omnipotent Durability Engineer, Chair and Couch division...
Re: My brake pedal doesnt seem to pump up...low pedal [Re: 4boxers4] #376152
07/15/09 08:23 PM 07/15/09 08:23 PM
Joined: Jan 2003
Posts: 2,410
Wichita,KS
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Blakcharger440 Offline OP
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Blakcharger440  Offline OP
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Joined: Jan 2003
Posts: 2,410
Wichita,KS
Hey I can lift up on the pedal about 1 inch! It will not go any higher because then it hits the brake light switch and bottoms out.

Is there any adjustment to the rod inside of the master cylinder or somewhere else that may be causing the problem?
Re: My brake pedal doesnt seem to pump up...low pedal [Re: Blakcharger440] #376153
07/16/09 08:24 AM 07/16/09 08:24 AM
Joined: Apr 2008
Posts: 203
florida
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74fldart Offline
enthusiast
74fldart  Offline
enthusiast
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Joined: Apr 2008
Posts: 203
florida
check and see if you have an adjustable push rod.
just loosen the nuts holding the master cyl. to the booster and move everything forward enough to pull out the rod and make it longer if it can be .
Re: My brake pedal doesnt seem to pump up...low pedal [Re: 74fldart] #376154
07/16/09 06:24 PM 07/16/09 06:24 PM
Joined: Jan 2003
Posts: 2,410
Wichita,KS
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Blakcharger440 Offline OP
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Blakcharger440  Offline OP
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Joined: Jan 2003
Posts: 2,410
Wichita,KS
I will remove the master cylinder to see if the push rod is adjustable...hopefully it is adjustable and will solve the low pedal problem.

I have the power brake booster vacuum hose hooked up to the back of the carburetor (950CFM). Is that a good enough source for vacuum?
Re: My brake pedal doesnt seem to pump up...low pedal [Re: Blakcharger440] #376155
07/16/09 06:49 PM 07/16/09 06:49 PM
Joined: Jan 2003
Posts: 21,129
Niles , Ohio
T
therocks Offline
oh wait.but hey.lets see.oh yeah.
therocks  Offline
oh wait.but hey.lets see.oh yeah.
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Joined: Jan 2003
Posts: 21,129
Niles , Ohio
The PBs on them did sit low.Just look at a 4 speed car sometimes.The manual brake pedal sits probally 3 inches higher than a PB car.Rocky

Chrysler Firepower
Re: My brake pedal doesnt seem to pump up...low pedal [Re: Blakcharger440] #376156
07/16/09 07:30 PM 07/16/09 07:30 PM
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383 Offline
Too Many Posts
70Cuda383  Offline
Too Many Posts

Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
Quote:

I will remove the master cylinder to see if the push rod is adjustable...hopefully it is adjustable and will solve the low pedal problem.

I have the power brake booster vacuum hose hooked up to the back of the carburetor (950CFM). Is that a good enough source for vacuum?



as long as that port sees manifold vacuum and not ported vacuum, you'll be ok. you want something that gets vacuum ALL the time, not just when the throttle blades are opened up. I always hooked mine directly into the back of the manifold

**Photobucket sucks**
Re: My brake pedal doesnt seem to pump up...low pedal [Re: 70Cuda383] #376157
07/16/09 07:43 PM 07/16/09 07:43 PM
Joined: Jan 2003
Posts: 2,410
Wichita,KS
B
Blakcharger440 Offline OP
top fuel
Blakcharger440  Offline OP
top fuel
B

Joined: Jan 2003
Posts: 2,410
Wichita,KS
Quote:

Quote:

I will remove the master cylinder to see if the push rod is adjustable...hopefully it is adjustable and will solve the low pedal problem.

I have the power brake booster vacuum hose hooked up to the back of the carburetor (950CFM). Is that a good enough source for vacuum?



as long as that port sees manifold vacuum and not ported vacuum, you'll be ok. you want something that gets vacuum ALL the time, not just when the throttle blades are opened up. I always hooked mine directly into the back of the manifold



I wonder if the lower back part of the carb where the outlet is located on a Proform 950 carb is ported vacuum?

I noticed on my RPM intake that there is a plug on top of one of the back intake runners...maybe that would be a better location


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