anyone know what would cause the brake peddle to go to floor before it can stop the truck. it stops but it seems weak and the brakes are not spongy the master cylinder is full and there is no leaks.
either air in the lines of a messed up master cylinder wouldn't suprise me the least. it still stops decently i might have the local ford dealership look at it because i really dont feel like messing with it.
Check the mounting plate that the master cylinder bolts to, they have a seam that will split from the firewall and make you loose brake and clutch pressure.
I am having the same problem on my 88 F350. The whole system has been changed an I meen the whole thing. Master cyl. vac. boost, calipers, the lot. A mech told me it could be the pads are not sittng in the calipers properly and not pushing them in flush. This is a total rebuild truck and it is the only thing not working. Any help would be appreciated
The pads being suspect, from maybe from Princess Auto have given you the correct part? Maybe the surface area where the pads slide on the rebuilt calipers have slag from casting and a die grinding applied to lightly touch up the surface to smooth it out? Hi temp caliper grease on the areas where the pads touch the caliper to permit free movement, doesn't take much. If the rubber caliper hoses are still the original ones, expansion can occur in the old rubber causing a spongy pedal.
I just got my problem fixed. I had the master cyl. replaced in Nov. but that did not solve the problem. After changing the vac booster twice due to a faulty new part it just made things worse.
As a long shot I took the truck into Fountian Tire and they discovered the new master cyl was faulty. There were no leaks but the fluid was bypassing the seal internally. Frustrating to say the least but finally fixed
Glad you finally figured it out. Never think new part was the problem but it was. Sent from my SM-G930P using Tapatalk