[quickvicbrown]

I've reviewed previous forums, but didn't find anything specific to the 68 Ford Mustang. Anyway, I have a v8 with a 289 engine. Suddenly the brakes went all the way to the floor and I replaced the Master Cylinder this morning. After replacing the master cylinder there is a little bit of pressure from the brakes, but their basically still going all the way to the floor.

Does anyone know of what else could be wrong with the brakes? Any suggestions, ideas? Please help......Vic

[darom]

Any leaks around? Did you check your brake fluid reservoir? Is it full?

[poncho62]

When you changed the master cylinder, did you bleed the system? Sometimes you have to bleed it a number of times to get all the air out.
Also, did you "Bench bleed" the master before you put it on?

[adtkart]

You probably won't find much specific to that car, as they are basically all the same from that era. It sounds like you either have a serious leak, or need to properly bleed the system. You could also have gotten a bad master cylinder.

[RustBucketChevy]

bench bleeding is the most ovelooked procedure in the world I found out the hard way. Help me out if I miss a step here guys, but in order to bleed a master cylender you
plug the line connector inlets
push the accuater in the cylender with the handle of a screw driver (or other blunt object) until you build pressue
then release the plug
repeating until brake fluid fairly sprays out as you loosen the plug
Sound right to you guys? My last master cylender change netted the same results as quickvic's and led to a trip to the shop where they explained the procedure to me. I tried to remember everything they said but its been a while.

[poncho62]

I made up some fittings that I put on the outlet of the master which puts the fluid back into the resivoir. You pump it untl it builds up pressure and gets all the air out.

[adtkart]

Almost all rebuilt master cyls come with fittings and hoses for bench bleeding them. You have to force the air out of the unit before installing it. Then bleed the entire brake system.

[crazy larry]

Have You replaced the wheel cylinders? forgive my lack of knowledge, but front disc or drum? what condition is the caliper in? parked, make sure the MC is full of fluid,depress the brake pedal, if it goes to the floor, pump the brake pedal, till you get the slightest pressure, then let it hold for a few secs.... hop out and look at the inside of each tire, if you see a wet trail, you've got a blown wheel cylinder. i've not known of a caliper leaking, but i guess it could happen, my exp. with them is they usually just freeze up. what shape are the hoses in? i guess i may be typing stuff you've all ready done, but i don't know what you've done to the stang or not........ but with <30 year old brakes, you really oughtta look into replacing anything NOT new..... IMO of course....

[k2mooch]

I have no idea how this works or if it will for that car, but I just replaced rotors and pads on my girlfriend's '95 olds this weekend and when I bled the lines, I had no pressure on the pedal either. I got frustrated and pushed the pedal all the way down as far as I could with the engine running in park and the car dropped its idle so low it almost cut out.

I have no idea of the mechanics of what happened when I did this, but I got a little bit more pressure in the pedal and the pedal didn't have to travel as far to grip either. So I tapped and held the gas at about 2000rpm and forced the pedal all the way down a few times and pumped it. Pressure is back to normal.

Like I said, I have no idea what is different between cars, but it might be worth a try. Does anyone know what is happening to brake components when I did this? I am curious as to how it worked.


MoocH

[Darkman270]

I think you just need to do a proper bleed and after that I feel it should be OK. I worked on one car (early 60's Dodge SW) where you could pump up the brakes and they would work fine but if you let the pressure bleed down you would have to pump them back up. The problem was that the previous mechanic (he told her it would take another $200) had replaced the rear shoes and failed to adjust them. When you pumped the first two to three times you were just taking up slack between the rear shoes and drum. Adjusting the rear shoes was all it took. Does your 68 have a power booster?