Installing a brake booster..

[Joe Kriston]

Ok,After I get a new vacuum hose to go from the manifold to the new brake booster,I'll have everything I need to have power assisted drum brakes,which should at least be an improvement...What are the correct steps to adding a brake booster?...Don't want to sound like a dummy,but my concerns are:1)Proper bleeding of the brake system after installation...I'm also eliminating a trailer brake line that's tied into the master cylinder.2)What about making sure that proportioning valve light doesn't go on when I'm done with everything?...I figgered I'd ask here first to avoid any snafus that usually accompany my own repair work....Thanks...

[FORDification]

Well, normally you don't even have to disconnect the brake lines....you can just unbolt the master cylinder from the firewall and the brake pedal from the master cylinder, and then gently pull the master cylinder away from the firewall. Then you can remove the retaining ring which holds the MC pushrod and remove the pushrod, since it's no longer needed. (The booster has it's own.) Then bolt up the booster, push the MC back to bolt it up to the booster, run a vacuum line to the intake manifold. And you're done.

However, since you're going to be removing the trailer brake setup, that does mean you're going to have to open the brake circuit and remove the 'tee', which in turn means bleeding the brakes. About the only way you're going to be able to avoid tripping the warning light switch is to just bleed a little bit at a time out of each corner, doing your best to not upset the front-to-rear balance. You might get lucky, but I wouldn't hold your breath. However, I would suggest your checking that light after every purging, so that if it does come on, you'll know exactly which end (front or rear) tripped the switch, and you can reset it much easier than randomly re-bleeding and hoping for the best.

[Joe Kriston]

Thanks,Keith...So the idea of bleeding the master cylinder doesn't work,right?...I'm still going to end up with air in the lines and the only way to get it out is at the wheels?...

[FORDification]

Well, you need to bleed the master cylinder as well, that's always the last thing to bleed though. But yeah, I'd be willing to bet the air will find it's way into the lower brake lines instead of making it easy on you and staying on top. Isn't that the way it always goes?

[flyboy2610]

Yup!

[QC]

I would recommend bench bleeding the master cylinder before you hook it up so you don't pump all that air into the lines. Then open the bleeders and let it gravity bleed for a little while. Keep the m/c full. Close the bleeder valves and bleed conventionally. You shouldn't have to pump much at all.

[71 LONG BED]

I don't mean to interrupt, but since we're on the subject... Does anyone have a assembly diagram for a booster? I took mine apart awhile ago and should have taken before pics. live and learn. Just want to make sure I put it back together correctly. Thanks

[Joe Kriston]

Well,longbed,if it takes two of you using both feet to stop it,you probably didn't reassemble it correctly...Otherwise,I don't know...QC,what do you mean 'gravity bleed'?....Loosen all four bleed screws to release the vacuum,put no pressure on the brake and let the air work itself to the top?...Don't want too seem overly careful,but I've always seemed to have trouble bleeding brakes...Thanks again,you all...

[QC]

To gravity bleed you just open the bleeder valves and let the brake fluid run out. It usually just drips. You might want to put a pan or rag down to catch the fluid. Make sure the m/cyl doesn't go empty. When the fluid is coming out clear (no bubbles) tighten the screws, top off the m/cyl and check the pedal. You might have to do a little more bleeding but most of the air will be gone. It's easier than pumping the pedal 50 times.

[Joe Kriston]

QC: Thanks,man...I may try to get this done this weekend...I'll let you know how it works out...

[Joe Kriston]

QC...I did like you said....I let it gravity bleed for about an hour,but I really didn't lose a lot of fluid....Then I bled each wheel,starting from the furthest,until no longer air,but solid fluid came out...The good news is,the old lady in the walker got out of the way just in time...No--seriously,I got a nice,easy pedal,but there is some travel and they feel somewhat spongy...Now,it looks like the 'eyerod' connecting the booster to the padal is threaded so I can adjust it to get rid of the pedal travel...But,should I bleed them again to get the sponginess out?...The only thing I can compare it to is the old rock hard pedal before I installed the booster.....Thanks...

[68F250]

There could be some air still in the system. Try this, with the engine off pump the brakes around 5 times to get all the vacuum out of the booster. Now push on the brakes and see if they are spongy, should feel like manual brakes. If so, bleed some more. Power brakes feel a little softer but not spongy.

[Joe Kriston]

Muchos Gracias,Senor Barry...

[capeclassics]

Hey Joe..........did you work on my brakes?????????

[Joe Kriston]

No,Cape,...your's came with power brakes....Although when you told me you were flying out and driving it back to NE,I had a garage check 'em out and repack the bearings and such so I wouldn't have to worry about you being stuck somewhere outside of Tucumcari with your thumb out

Turns out,I got my brakes bled right the first time...I just wasn't used to how power drum brakes felt on a bumpside since I sold my last one to Cape....I'll say this,though,..I can certainly tell when one of my drums is a little out of adjustment....Does anybody know if that old trick works on these where you back up as fast as you can and jam on the brakes to get the self-adjustment ball rolling?..