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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4829
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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Just paid my membership. Have a Brake Question: PutRode in

Customer Question

Hi, just paid my membership.Have a Brake Question: Put*****Rode in Storage. Got it out 1 to 1.5 years later. Now the situation!!Backed out of garage, stopped, pulled back into garage, HERE IT COMES. The power brake peddle went right to the floor.
The car went right thought the back wall of garage.
I had just did a complete tune up on the C3, and a new Edelbrock 750 CFM Carburetor on the , already installed High Rise Manifold that was installed 6 years ago. Old Edelbrock carburetor was gummed up from sitting.First checked for vacuum leaks, found none. However my total Vacuum off the manifold was around 9 to 10 CFM.
I have a high lift, long duration roller Comp Cam. New Carb, new lines. Still very very low peddle. Hade new Boster and new Master Cylinder installed also.Tried an Electric Vacuum Pump that gave me minimum Peddle but not safe on the road but at least I can move it around the garage now. Went to my last try, a Hydro Boost system that uses Hydraulic from the Power Steering Pump and a Hydraulic unit to replace the Vacuum Booster. Just opened the box and will start replacement Monday. Now, why I contacting you.I've been told buy friends that I trust and all said, "...That system will stop you on a dime and give you 9 cents change...".
What is your recommendation on this option. It's a $1200.00 option and don't want to spend that much money on a guess. The unit look top notch.Thanks, Johnny
Submitted: 1 year ago.
Category: Chevy
Expert:  Eric replied 1 year ago.


Ok, before we get into the hydraulic unit, I want to make sure you have done the proper checks with it having sat so long.

So, I need to know if you have done a brake hose clamp test yet to isolate the low pedal.

Customer: replied 1 year ago.
No, I have not. The shop that replaced the Vac Booster and Master Cylinder said they went over the total system. May Wheel Cylinder's are 2.5 years and the hoses were replaced with stainless steel at the same time. No loss of flooded, just a supper Hard peddle you must stand on to get ant response. Every thing they did points to vacuum loss. Remember I only have about 10 worth of vacuum coming from Intake Manifold. Also the elect assist Vacuum gives very poor assist but is better then the Manifold feed. But not by much. plus it is to dam load for everyday use. All of the symptoms' seem to point to Low Vacuum.The biggest change to the Intake System from "before storage" was that brand new 750 CFM Carb, a complete Tune up, plug wires, and distributer. And the engine is running better and smoother then it ever did in the past, "...the bitch just won't STOP now...". Could it be the new Carb is allowing the Cam/Intake system run so much better that that is where the Vacuum went?
Expert:  Eric replied 1 year ago.


Ok, a bit confused as you stated that you had minimum pedal after electric vacuum pump, which means a low pedal, but now you state the pedal is a hard pedal

Customer: replied 1 year ago.
Both, feels very hard and is nothing close to the brake system before storage. Push on the hard peddle long enough and it does go to floor. Nothing that is safe to take out on the road. Moving around the drive, ok but not good by any amount.
New Master Cylinder, new Vacuum Booster, very low vacuum even with the electric pump running. No vacuum leaks. I don't trust the electric Vacuum pump. To say nothing of the load nose from it's discharge.
Expert:  Eric replied 1 year ago.


Ok, gotta say I am stumped on the symptoms. I have not encountered one that had both a hard pedal and still going to the floor. I will opt out and see if another expert may know

Customer: replied 1 year ago.
It feels like the old Mechanical Brake systems they used on Tanks. Any where from no assist to just a little. This car brake system was working perfect when it was stored, a nice peddle you expect from a Corvette. After new Booster, new Master Cylinder, new Vacuum hoses, Electric Vacuum, and still hard to stop. Vacuum still to low based on Corvette Specs.. I have heard from other people that had to go to the Hydro Boost to get a peddle due to Long Duration High Left Comp Cams.Maybe some one that has used a Hydro Boost on other Street Rod Cars might have an idea.
Expert:  Jerry Newton replied 1 year ago.

Let's separate the two issues: a hard pedal, and a pedal that goes to the floor.

If the pedal is going to the floor, then there is a brake hydraulic issue that MUST be addressed. That fluid is going somewhere, it's either leaking externally (onto the ground) or internally (past the master cylinder pistons). That has to be rectified.

HARD pedal is something else. If you put a vacuum gauge onto the hose going to the brake booster, and tee it in so you can watch it as the car is running and you're using the brakes, what is the vacuum reading doing?

Customer: replied 1 year ago.
The Auto repair center said the original Cylinder was seeping around the Cylinder allowing peddle to be pushed to floor. they also Replaced the Vacuum Booster for the hard peddle. See March 27th text, after they did this work what I had was a peddle that was so hard that you had to stand on in to get any brake response at all. After adding the Electric Vacuum Pump directly to the booster and removing the Manifolds Vacuum Line to the Booster the peddle was still very hard and not anything near the original feel before storage. With the Electric Vacuum Pump, the Vacuum went from around 8 to 9 down to about 11 to 12. GM wants around 16 for proper operation.I've got the Hydro-Vac Power Brake Buster kit and will start the replacement of the factory Vacuum Boost Power Brake System with the Hydro-Vac system today. I'm doing this because I know a Long Duration High Left Cam will decrees the factory 16 Vacuum specification to a much lower number, like I'm getting, there for making the peddle feel like a mechanical system with far less stopping power.With everything having been checked as stated above, please reading the whole book here from my first posting to here, does it sound like the Hydro-Boost System sound like a good idea at this point? Thanks.
Expert:  Jerry Newton replied 1 year ago.

I have read your previous notes, and I agree with you that some of this is possibly due to the camshaft you have installed. 12" of vacuum should still be sufficient to make this booster work, that's where I'm hung up. A new booster is not equal to a good booster, if you're putting 12" of vacuum to it and it's not boosting, then it's no good.

I'm not familiar with the aftermarket hydroboost kit, that sounds interesting and would definitely solve the issue once and for all. But having extra hydraulic hoses in an already cramped engine bay isn't ideal, if this were me, I'd be looking for ways to make the vacuum system work. I think your engine is producing enough vacuum (when driven, not just at idle) to make these brakes work with perhaps just the addition of a vacuum canister, or the vacuum pump that you have added.

If you deadhead the vacuum setup (remove the hose from the booster and put your finger over the end of the hose), does the vacuum increase dramatically?

Customer: replied 1 year ago.
I can agree with the 12", I've seen it work on other mussel cars. I miss named the Kit, it is called Hydratech, they have a fairly good web site. Space for the Hydratech is not as bad as with the use of the additional electric Vacuum Pump along with it's additional hoses and control circuit, and the nose is unbearable. Plus you also remove the Vacuum Booster from the firewall. The Hydratech unit bolts up where the Vacuum Booster was using the same configuration, the Accumulator that replaces the Vacuum Booster is 1/2 the Vacuum Booster size. All and all considered the Hydratech allows you more space under the hood then the stuck configuration or the electric pump.and no load discharge from a Pump. The Auto center that replaced the booster and master cylinder said the tested the new booster and master cylinder. I know what your saying and agree, but the said the parts they used for replacements were 100% "good", and I've already paid out over $1500.00 for the labor and parts they have used. If you would, take a look at the Hydratech web site and evaluate, your opium the worthiness of their product is and tell me what you think please. It sound good but so did the new booster that lead to a new master cylinder to the use of a after market electric system. Here is their URL = ; like I said I have seen them used, for the same thing I'm having. I would love to have a good feeling I've done everything to date before Installing the Hydratech System.Everything in the 79 Vette is Vacuum driven from Head Light doors to all heating and A/C controls and God knows what else.Thanks for your prospective on this situation I'm in.
Expert:  Jerry Newton replied 1 year ago.

I looked at Hydratech's website, and that looks pretty slick with their installs. It definitely solves your brake boosting issues, I think.

But as you note, you still need engine vacuum. Late model GM cars and trucks sometimes come with a supplemental vacuum boost pump that attaches right to the booster. It's big, I'm not advocating that you use it this way, but my point is that I never hear these vacuum pumps run.... they're quiet, and it might be worth looking into finding one of these to see if you can adapt it to your car to run the other vacuum-necessary gadgets.