brake problem

Took the nova for a test drive and the brakes don't feel right. It feels like the brake booster is doing nothing but when I test the booster it seems to work but I'm not sure if it is a accurate test. this is what I did. I unbolted the master from the booster started the nova up and hit the brake pedal it seemed to assist it was easier than with the motor off. but with the master bolted up it feels exactly like the motor is off (no vacuum) It requires allot of pedal pressure to stop the nova there is no way I could stop short if I had to. This was a kit master, booster,valve. So am I chasing my tail or could it be something else? Sorry for the long post just wanted to get the info on the table. here is a pic

http://i102.photobucket.com/albums/m85/383vette/Novaresto390.jpg

first check vacuum to the booster check valve. once youve established that you have vacuum. take the valve and try to suck threw both ends. you should only be able to suck threw one way.
reinstall the valve the correct way.and depress the brake pedal 5 times till the pedal feels real hard. then start the car. the brake pedal should go down quite a bit from the vacuum boost. if it does not the booster is faulty.
also you should not hear any hissing inside the car. that would be a vacuum leak.

obviously when you bleed the system there was good fluid transfer?

valve is good did that already. You say the pedal should drop a bit I assume that is with the master UN bolted from the booster right? If so I doesn't drop at all It only feels like a slight bit of assist when I step on it.

no the master should be bolted up to the booster. the pedal should drop to at least the height of the gas pedal. maybe even a bit lower.

It don't drop at all with or with out the master. But it dose hold vacuum.

then its a defective booster .

the car does stop and the brakes are not dragging correct.? i had the thought of the push rod being WAY over adjusted . but the car most likely would not move.

ok i gotta go get dinner for the boys .

thanks Necro

anyone have any suggestions on a master cylinder. I think I will upgrade and get something better what do you guys think?

anyone have any suggestions on a master cylinder. I think I will upgrade and get something better what do you guys think?

yo i just came back to re read and i meant to say defective booster. not master.

thats what i get for rushing.

yo where on the island are you?


im in n babylon by dpa.


looks like the island is becoming popular for novas in thi site.

gotcha I started thinking about you answer and I kind of figured that's what you meant no big deal. So that booster should suck the brake pedal to the floor with no master in place am I correct?

all the tests are with the master on the booster.

if the brake pedal doesnt go down softly with the engine running that is a booster problem if the check valve is working good.

the only other thing to address is the size of the cam on your motor. is the motor stock or do you have a lumpy cam.

low engine vacuum will give you a 1 time shot on the brake pedal being soft and then it will be firm again . until you drive and build up enough vacuum.

WOW cool your local I'm in wantagh.

OK I had it both ways anyway and the pedal don't move either way. but it did hold vacuum witch I found funny

well it can hold vacuum . it may be low vacuum. you need around 20in/vac to really have soft power brakes.

do you know how much vacuum you have at idle.?

is this a new setup or has it been driven on the car a while.

14 in of vac but the booster has been in the nova for several years and always worked with the same vac. The thing is I changed the master and added the proportioning valve that you see in the pic. So I figured it was the master but it looked like a booster problem. this is the first time that I drove the car in about 8 months. had the whole thing apart did a back half and a million other things.

14 inches of vacuum may not be enough. Check this out:

http://www.hotrodheaven.com/tech/brakes/brakes5_index.htm

is it the same master cylinder as before or a different model?

the next question is what brake set up do you have, you said you put in aprop valve. why? did you put in disc brakes anywhere in the zillions of stuff.

before I had the original master with the front brakes hooked up to a t then into the front of the master with the rear hooked up to a adjustable proportioning valve. Now I have separate lines in the front going to a gm style valve and the rear lines hooked up to valve as well. just look at the pic. So its like a gm factory disk brake car. its front disk rear drum.

Shane 65 it worked before with the other master and wilwood valve so I'm pretty sure its enough. But I'm not sure if the new master requires more assist. so you maybe right after all. I guess I'm going to have to take it all apart and check the master and valve.

i still say you have a bad booster. i was only questioning on the rest of the system to see if you changed out to some aftermarket brake set. but you still would have power assist. i thought maybe you have some hose clamped off if you used hose clamps. but you would have noticed it when you bleed the brakes.

im going with bad booster. if it doesnt drop on start up its bad.

1. Go to a large empty parking lot.
2. Do a couple test braking tries at 25 to 30 mph
3. Disconnect the vacuum line to the booster and try the same

If thier is no difference than you know:
A. the booster is bad
B. The booster is not getting enough vacuum

If thier is a big difference then it is something else.

Note: Be ready on the emergency brake during this testing! Also when you disconnect the vacuum line for testing make sure you plug it or any other vacuum controlled devices might stop functioning correctly.

Not gonna be able to get there till this weekend.

You have a very small booster. It will only offer a small amount of assist. You need to use a manual brake master cylinder, it should be a 1 inch bore. The bigger the booster more assist you will get. The factory used a 11 inch booster and a 1-1/8 inch master. Big blocks work well with a 9 inch daul booster, but you must be carefull that the booster does not interfere with the valve covers. This web link shows each boosters performance.

http://www.classicperform.com/PDFs/BoosterBrakePressureChart.pdf

Hope that this helps you.
Danny Nix CPP

looks like you have the 60s corvette style master.

There is a 1 1/8 bore for power brakes and a 1 inch bore for manual. Maybe your booster is to small for the 1 1/8 bore?

I don't think you have gotten this far but I think you might need a residual valve for the rears as the 60s corvette master is made for disc disc, unless that combo valve there has teh residual in it.

arndog

I bought the whole mess together as a kit. valve,master,booster. it is a disk drum setup. I installed the booster about a year ago with the original master and a wilwood valve it had plenty assist.

Looks like mine I am running a 194 six 4whl dick I had the same problem. I did several bleeds and finally started getting good fluid transfer and allot of air out the back. They work better now, but I think its a vaccume issue at least in mine. Bench bleed was great 3 power bleeds and 2 manual ones later I am ok. try it it couldn't hurt http://www.atg-music.biz/images/eng1.jpg

more thoughts ... I realize you bought it as a kit but in any case confirm your bore diameters ... the old master may have had a smaller bore and hence working. Also from what I have read on the "intanet" IF it is a vette master then the rear port (closest to the firewall) is for the front lines and the front port is for the rear. There are couple of rules of thumb both of which I have had flaws in when determining which port is for which: 1) Largest port is for the front (flaw, Im pretty sure the factory used different fittings so you couldn't hook them up wrong) 2) Largest resorvoir for the front (seen a couple that appeared to have the same size)

Note that all things being equal (in my experience) the front and rear port thing doesn't seem to matter.

arndog

It came plumed into the valve and there is no way to hook it up back wards.

THE_330.... I think I am going to bleed it some more just to be safe since it is the easiest thing I can do. Is the assist adequate on your setup? or dose the booster feel like it is struggling? I think the booster is small for this master and I cant fit a bigger one:(

I had very little power assist on my '66 SS. Master Power sold me a kit. It worked terrible and left me with dangerous brakes! It was a tiny 7'' booster with a 1 1/8'' master. I fought with this for a while. Finally I bought a 9'' booster (CPP has there own made and work well) and a 1'' master from CPP and the brakes work.

Scott

the the assist is not quite adequate, but with the engine size it my be vacuum, but no surg at all I feel safe driving, but it does not feel just right yet

I might buy a 8" double disk master But I need to check valve cover clearance first. anyone have a double disk 8?

changed the bracket that mounts the booster and relocated the rod to the top hole in the pedal 90% difference. but it is clear know that the booster cant handle the new bigger master. So I might pick up a dual disk 7'. hate to spend the money if its not going to work.

any one here have a duel 7" booster in there nova? I would like some input on the performance. I'm loosing faith on the hole 7' booster thing.