Brake problem has me stumped!!

[72RS]

My 72 Camaro had a stock , disc/drum,booster,master, metering block setup. A member here on the board had a Wilwood tandem master, proportioning valve and D52 calipers all new in the box so I purchased them. I also bought a set of Right Stuff drilled and slotted rotors.

My brakes worked fine but wanted to up grade to the Wilwood setup, I bench bleed the master and installed everything and and bleed the system. I have NO brakes!! pedal goes to the floor. I call Wilwood and say sounds like I got a bad master ...so i reinstall my old master...no brakes!

So I remove all the brand new parts i just installed and put on my old metering block. At this point everything is the same as it was BEFORE I touched anything 4 days ago...no brakes!! pedal just goes to the floor with minimal. I drove the car around my cul de sac and you push the pedal to the floor and the car will just "slow dow" but wont stop.

I am clueless......

[juggernaut]

Is the bore size the same on the willwood master as the original master? The wilwood master may not be displacing enough fluid. I experienced that converting my car to disc. I used the drum master just to move the car in the garage and the brakes were next to nothing.

[72RS]

1 1/8 bore on the Wilwood,not sure on the stock.I put my old setup back on the car and still nothing...

[a67]

Need to pressure bleed the system, there is still air in there someplace.

Bob.

[72RS]

Need to pressure bleed the system, there is still air in there someplace.

Bob.

we used a vacuum system on it yesterday...I agree it seems like air in the system...

[1966longroof]

Gotta be air.

Couple years back when I put D52's on the front of my car, Wilwood sold me the 7/8 mc for disc/drum set up. Never any issues. Last fall I put D154's on the back to replace the drums. They said keep the same mc. Still no issues.

[TheJDMan]

You may need to use several methods for bleeding the brakes. I had to pressure, vacuum and pump to finally get the brakes on Dust Off working right. It also took nearly 3qt of brake fluid to finally get all the air out.

[RobNoLimit]

Just for comparison, the Wilwood D-52 with 2" bore pistons (the standard large bore fronts)has 6.26" of piston area. The OE large GM single has 6.61" of piston area. With an estimate 6-1 pedal ratio, I worked out a few things. Your stock master was probably a 1" bore, with a booster amp of 1.8 (I use 60 lbs of pedal input as a standard) will build appx 720 psi of line pressure. - more if you push harder, but again, I use 60 lbs foot load as a standard. A 7/8" bore master with no booster, same set up, will build appx 609 psi, only 13% less. If a 1 1/8" bore master is used, without a booster, 6-1 ratio pedal, this will only build 367 psi at 60 lbs of foot load. - Not enough to stop. This info is just to help you sort out the parts choices. If the 1 1/8" bore is used with a booster, it's OK. As far as the "no brakes" situation, I agree with the others, you have air in the line. A new system will take 12 oz. per corner, or more to bleed i tout. The last 4 oz. should be bled out the old way, pump and bleed. Best of luck.

[bryant]

check to see if the bleeder screw on the calipers is at the top of the piston bore. i recently had a disk brake kit that mounted the caliper higher than it was designed. this moved the bleeder screw port below the top of the piston bore. it required the caliper to unbolted and lifted up till the bleeder was correctly orientated.

[MCB Matt]

What does your prop valve look like? If its the aftermarket brass style valve you must pressure or vacuum bleed them before you
TOUCH the pedal once!

If you don't, the pin inside the valve will "pop" which will close off fluid flow to the front or rear, which will usually cause little to no pedal!

Confirm which valve and we can go from there.

Matt

[72RS]

Thanks for all the replies...

Her is where I am at this point..found out I did indeed have a bad master cylinder. Wilwood said to put the master on the car and block off the out ports and pump the pedal, pedal should be hard because nothing is escaping anywhere. I did that and the pedal had no resistance at all. So I put my stock master, Tuff Stuff Prop valve I had laying around and bled the crap out of them..I now have brakes but, not good ones. I recently had the motor done over and am now only pulling 8" of vacuum! I put a canister on there to see if it helps and will try that out tonight. If that does not work I will have to go manual brakes or Hydraboost I suppose.

[72RS]

What does your prop valve look like? If its the aftermarket brass style valve you must pressure or vacuum bleed them before you
TOUCH the pedal once!

If you don't, the pin inside the valve will "pop" which will close off fluid flow to the front or rear, which will usually cause little to no pedal!

Confirm which valve and we can go from there.

Matt

Matt,

I did have one of the stock style non adjustable brass valves on there from Right Stuff.Thought there have may have been an issue with it so I put on a similar chrome one I had here.

[MCB Matt]

Matt,

I did have one of the stock style non adjustable brass valves on there from Right Stuff.Thought there have may have been an issue with it so I put on a similar chrome one I had here.

You can test to see if the valve is "popped" by checking for an open or closed circuit from the pin in the middle of the white plastic switch on top of the valve to the body of the valve.

An open circuit is what you want, if its a closed loop the valve needs to be reset.

Matt

[72RS]

just drove the car with the canister attached, no real improvement.I think it is a vacuum issue at this point. So manual or hydrobooost?

[MCB Matt]

If its a low vacuum issue typically it will give a rock hard pedal where you fell like no matter how hard you push the car won't stop, but you should have a high pedal..

The canisters and pumps are usually good for one or two applications, after that they can't keep up in surface street driving...

Hydroboost will for sure fix the low vacuum problem, from there as long as everything else in the system is good and bled properly you will have a nice brake system with very very low pedal effort thanks to the hydroboost.

Matt

[72RS]

Pedal is not rock hard...actually feels about right just lacking some stopping power. Maybe I will bleed tham again. I did check the vacuum again..8" at idle.

[MCB Matt]

Pedal is not rock hard...actually feels about right just lacking some stopping power. Maybe I will bleed tham again. I did check the vacuum again..8" at idle.

With 8" at Idle your only option is to go manual or Hydroboost, Vacuum needs about 15" steady at Idle.

Matt

[72RS]

With 8" at Idle your only option is to go manual or Hydroboost, Vacuum needs about 15" steady at Idle.

Matt

I agree MAtt...which route would you suggest?Car is a weekend cruiser/show car. I don't race it and it see probably less than 1500 miles a year.

[MCB Matt]

I agree MAtt...which route would you suggest?Car is a weekend cruiser/show car. I don't race it and it see probably less than 1500 miles a year.

Honestly, at this point its your personal choice. Manual will obviously mean more pedal (leg) effort to stop, especially in panic situations, that's the true worry for me... Too many idiot, distracted drivers we share the road with! If they aren't paying attention and have to panic brake and you are following, you will have to panic brake too, if you can't stop in time, bam... You are at fault, or worse someone gets hurt.

If you feel confident you can lock all 4 with manual brakes and don't mind the effort when cruising go manual, otherwise, make the investment in hydroboost and never look back, they work, WELL and you will have less pedal travel.



Let me know if you need parts or any assistance.
Matt