Brake booster/master cylinder upgrade

[B-Co Kid]

I'm considering doing this upgrade on my brake booster/master cylinder:

http://www.fordtruckclub.net/forum/showthread.php?t=6078

Basically, swapping out my brake booster/master cylinder with one from an f350 of the same year. Oh by the way, I have 1987 b-co, 351w, c6 trans. According to the thread above, it should be a direct swap. Has any one done this modification on a b-co?? Seems like a good upgrade, if it is a direct swap.. Any input would be greatly appreciated

 

[Rons beast]

The Bronco and F150 should be the same. A direct swap should be as shown in your supplied link. The question is why?

 

[B-Co Kid]

Ive been having issues with the brakes. as of lately, the brakes are spongy and the pedal sinks a little further to the floor than normal, and when driving it pulls to the left when braking. doesnt feel safe if i were in a emergency situation and had to brake hard. pretty much everything has been replaced, pads, calipers, axle seals, drum, etc. the only thing that has not been replaced is the booster and master cylinder. this may or may not be the problem, but since it is the original brake/master cylinder, im sure it time to be replaced. and since i was considering replacing it, i figured why not try this upgrade, rather than switching to all new system, ie. hydraulic brakes. just wanted to know if it would work.

 

[Rons beast]

Spongy pedal is an indicator that there is air in the system. Changing the booster and master will not cure the problem, unless you get the air out of the system by bleading everything.

Under no circumstances would I install a used master cylinder. When you bleed the system the seals inside will be forced into the portion of the bore that is rusted and gummed up. This is a sure failure.

Ultimately it's your vehicle, but I don't see the advantage of changing to the F350 booster, unless you have added weight, or pull a trailer with your Bronc.

Good Luck

 

[B-Co Kid]

Thanks for the quick responses ron..i was actually either going to get a new (remanufactured booster/master cylinder) for my year/model b-co,

or get a new f350 (remanufactured booster/master cylinder), not any junk parts. either way, i was getting a new booster/master cylinder. just seemed like the new f350 setup would have more stopping power. as far as added weight, i have 35" mud terrain tires.

 

[Rons beast]

Ok, thanks for the additional info. Just to be safe I would all the flexable hoses, to be sure they can handle the extra preasure of the 350 set up.

I would turn both drums and rotors, and probably replace the pads and shoes as well. Since you said you have a pull.

Bench bleed the master then gravity bleed the entire system, to be sure to get all the air out.

Good Luck

 

[B-Co Kid]

Finished the F350 MC/Vacuum booster swap today, and the brakes feel better, but still kinda odd. hard to explain. Further research, online, seems to point in the direction that i need to upgrade my wheel cylinders, and calipers also to match to mc/booster upgrade. the rear wheel cylinders and drums have been replaced (stock). front calipers arent new (still stock). all break pads are new (stock). from what i have researched, thunderbird calipers and/or wheel cylinder perform great without any mods. my question is, if i want to complete this brake upgrade using thunderbird calipers and/or wheel cylinders, what year thunderbird calipers and/or wheel cylinders do i need??

on a side note.. i will be posting pics of the upgrade for all of the 87'ers. we seem to be the minority.

 

[Rons beast]

I can't comment on the T-bird brake hardware. I would think the calipers to a truck would be better suited.

maybe from an F250, or 350.

Truth is it can be very touchy when messing with swapping brake components. The entire system has to be in balance in order to prevent problems. What you have done is increase brake preasure assist, by enlarging the power booster.

Before spending time and money in swapping parts, try to explain your problem.

It could be a matter of adjustment, bleeding, etc. Have you changed the flex hoses?

 

[B-Co Kid]

By flex hose, do you mean the vacuum hose to the manifold?? if so, yes that has been replaced. The problem i seem to be having is that it requires a little more effort to stop than i was anticipating, however i am able to lock the wheels with enough effort. I was not able to do this at all before the swap. the b-co still pulls to the left when breaking at higher speeds (40+), but not really noticeable at lower speeds. also, after the swap, once i make a complete stop, such as at a red light, i feel the pedal pushing back. I have brand new wheels and tires, new drums, new axle seals, new rear calipers, new rear pads, stainless steel brake lines, new front brake pads, of course remanufac f350 booster, and brand new (not remanufac) f350 master cylinder. i did bench bleed the master cylinder before install, and bled the entire system with someone pumping the brakes as i bled, starting with the rear. also bled the abs hydraulic unit mounted on the driver frame rail. the only thing that has not been replaced is the front calipers, which i am assuming may be part of my problem.

**i think i made a mistake . With the new booster, there was, what appeared to be, a metal spacer on the front side of the booster. it was left in place, and installed in between the mc and the booster. see photo below. I think this is a test shim, to gauge if the rod needs adjustment.

 

[Rons beast]

The Flex lines I'm speaking of are the flexable lines running from the frame to each caliper and from the frame to the "T" coupling at the rear end. Are you running 4Whl disc? You said you had new rear capliers. Did you mean wheel clyinders? Did you have the rotors/ drums turned when you replaced the pads/ shoes?

I forgot about the ABS. With that I would Gravity bleed the system. Open the bleeder at eash wheel. Attach a piece of rubber or vinyl hose and run them to an old plastic bottel. Take the cap off the master. Allow gravity to do it's job, and let the fluid run out. This could take some time, but it will flush any air bubbles out from the master through the calipers/wheel cylinders. Watch the fluid in the master and don't let it run out.

There is also the possibility that mounting hardware for the calipers is worn, or there is a wheel speed sensor going bad.

BUT!!! you have to replace the flex lines, if not already done.

The kickback seems like it has to be from misadjustment of the booster rod.

Good Luck..let us know.

 

[B-Co Kid]

Rear brakes are still drums, I meant rear cylinders not calipers. and rotors were turned, drums are brand spanking new. Anyway, i pulled the master cylinder today, bench bled it again..adjusted the brake booster rod. turns out, the metal spacer that i thought was a test shim, has to be necessary..bcuz even with the rod adjusted all the way in, the master cylinder wouldnt fit flush against the booster. i re-adjusted the booster rod, and i was careful when i adjusted, making sure that there was adequate space to allow the master cylinder to engage/disengage. didnt get the chance to gravity bleed everything though. however, i took the b-co for a short test drive. brakes work considerably better. not as much effort to stop, and i dont feel the pedal pushing back like before. next on the list, gravity bleed the brakes, may or may not upgrade to f350 rear cylinders. after that, slotted front rotors with new front calipers. after the test drive, i dont think i'll need anything other than what i just listed. thanks for your help ron

 

[Rons beast]

Glad it's comming together for you.

Good luck with the project.