upside down brake booster

i know im going to get blasted but iam crosseyed from reading all these posts but none seem to answer my problem . i have an after market set up with a gm type double resevoir .i mounted my booster upside down for clearance . i cant seem to get any pedal .

 

Stranger things have happened.

 

I'm quite sure the Booster direction is not going to be the problem. How can rotating the Booster give you more room? Where did you mount this thing?
The Wizzard

 

The booster only assists the application of the brakes. If you have no pedal I'd start looking at the hydraulic system. Try bleeding the system and make sure the master cylinder is working. You might also want to check the push rod for correct length and free play to make sure that something didn't change when you turned the booster upside down.

 

it is firewall mounted. i get fluid at all 4 wheels but no air . it is a f100 and the support rods going to the fenders are interfering .

 

Drums will need to be adjusted.
Pedal ratio, stroke, and rod need to work properly.

I can't see upside down making a difference unless it puts the master at some weird angle.

 

it came as a unit ,so i would think they would work together . it is a normal mounting. it does not have the normal rod setup it has a swiveling two sided arm .

 

I can't imagine a scenario that makes a power servo/booster not work in any position.

Master cylinder, yes. They cannot be mounted upside down... of course we know you didn't do that.

Vacuum is omni-directional, the valves in the booster are inline with the pushrod and not gravity dependent. The rest is a big canister with a rubber diaphragm in it. Search is on to find your brake issue.

 

what is a "swiveling two sided arm"?

 

did you bench bleed the master cylinder/

 

adjusted rod to booster?

 

I've experienced this a few times with power and non power brake installs.
It has always turned out to be the length of the rod going into the master
cylinder being too short. It doesn't have to be by much. If its not pushing
the piston in far enough you will not have a pedal or you will have poor
brakes. You don't want the rod too long or your brakes will bind and over
heat. Just my experience.


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Did you unbolt the booster from the bracket or did you just unbolt the master cylinder from the booster and flip the complete booster assembly?

 

Had you checked it out for operation, before "flipping" it over, or did you just install it inverted ? I'm with the above post, it shouldn't matter.....

Let us know what you find.......that fixes the problem, Tnx.

4TTRUK

 

I think he's talking about the clevis.

 

First make sure you have a power master cylinder with the short bore or a manual with the correct plug in the rod bore hole. Check the pushrod length from the pedal to the back of the booster.

First make sure you have a positive stop for the brake pedal so that you can adjust the rod length. I usually jack the left front up so I can spin the tire. Then adjust the rod length longer by a half to a full turn at a time. When there becomes drag on the tire when spinning it, back it off a half to a full turn. You may still have to back it off a little after driving it because it tends to build heat and pressure going down the road.

This should get your pedal in the ballpark for adjustment , granted there's no hydraulic problem

 

I prefer a small dot of Modeling Clay in the push rod dimple of the brake piston. Then tighten the 2 together. Take it back apart and check the Clay thickness. Now you know what you have and that should never change. Zero contact and about 1/32nd of Clay at the push rod tip.
The Wizzard

 

i have moved my vacuum source from the carb to the intake and i think that was the problem . king size thanks to all who helped .

 

now i have front brakes but no rears. lots of fluid but no brakes

 

Do you have drums front and rear?

 

disc front drums rear . all lines are new master and booster are new ,prop valve is used.

 

Rear brakes adjusted correctly?

And I am going to believe this goes right back to push rod length and travel. The pushrod may not be traveling far enough to effectively put enough pressure on the rear brakes to have them work right. It will bleed the fluid and air out of the system but won't build up enough pressure to push the shoes out against the springs to the drums tightly.

The cause could be push rod length, a stop that isn't adjusted right on the pedal or a flaw created when it was installed in this particular vehicle. The old "had to change this to make it fit here now it doesn't work right" thing. The guys may have hit on something with the possibility of the hole for the pushrod in the piston of the master cylinder not matching up with the pushrod length of the rod in the booster too. If both came off a donor car as a unit and it was one you hadn't driven yourself they may have been mismatched before it became a donor car. Or if you bought a replacement Mastercylinder after buying the booster and pedal assembly (you did use the pedal assembly that matches the booster?) it may not match the booster's push rod.
OOPs, they caught me in middle of typing for a Hamb pitstop.

 

Check the drum brake adjustment, and also the return on the pushrod or freeplay on the pedal. Too much freeplay will mean it might not get full travel. Too little (or none) might mean the pedal wont fully return and it wont ever get enough pressure to the brakes.
If you spin the rear tires with the car jacked up, you should just hear the shoes touching the drums slightly. If you can slip the drums off, I'd adjust the shoes until you can just get the drums on. If they go on without touching the shoes, they're backed off too far.

 

the booster and master are after market are new and came as a unit brakes are adjusted as u say can just get the drums off and on with a a little tugging and tapping. there is about a 1/4 inch freeplay in the pedal . i am baffeled. thanks everyone for the help.

 

How about some pictures ?
Maybe someone can spot something.

It's time to stop taking stuff for granted and begin the elimination process. New parts or not you need some methodical troubleshooting.

It's really not to difficult to get brake fluid to do what you tell it to do.
You dont even have to out smart it.

Lets say you got a bad master cylinder that's brand new, you wouldn't be the first on that.

Lets say your pushrod is all set up from the supplier but fucked up right out of the box, again not the first.

Maybe you got something wrong, happens to all of us at some point. Sometimes we catch it sometimes we go nuts for a while.

I'd start by eliminating the master cylinder. Remove the lines and plug the ports, you should have a "Rock hard" pedal. If anything else try a re bleed of the master and see what you have with it plugged. If its not rock hard you have a problematic master cylinder.

Try to bleed them again if your master is now confirmed good. Follow all the routine procedures and don't let the master go dry.

Still messed up?
Check your pushrod , the stroke and pedal travel and pedal ratio.

 

well i found my problem and i dont believe anyone mentioned it . i had a frozen wheel cylinder . with the open rear it would just spin the wheel with the frozen cylinder . the other brake was actually working but i didnt know it . thanks to everyone for all the help.