1969 F-100 Pickup.

On occassion and getting more frequent, the brake pedal is 'rock hard' for lack of a better description. It's like the breaks "FREEZE" or something. The break pedal is extremely hard to push, maybe 1/2 inch at most. However, the breaks seem like they are fully engaged.

Anyone have any insight on what this might be?

 

does your truck have power brakes? if so the booster may be bad, if it does not have power brakes check the master cylinder. How is the actual stopping ability? brakes applied is it stopping quick or long could be the wheel cylinders or brake hoses in any event all brake parts are pretty darn cheap

 

Where the brakes working fine before this happened? If so your wheel cylinders are seized if not the adjustment rod between the booster and master cylinder is not adjusted right.

 

If your booster is not working It will feel like manual brakes which means you,ll be standing on the pedal to get it to stop. Brake hoses break internally sometimes causing a flap of the inner rubber to peel back and act like a one way valve.If wheel cylinders are stuck on truck will have a hard time moving and u probably won't be able to even push truck in neutral by hand

 

Thanks for all the feedback. It's so strange to me. In the mornings, the break actually has some push to it. Once I go 7-10 miles, the break gets very hard and I would have to say that the breaks feel 'locked'. Because at times, when I start moving forward in the truck, it is as though the breaks are fully engaged.

So, I'll start working on it this upcoming weekend and see where it takes me. Again, I appreciate all the feedback.

 

cdowden it really sounds like the brake hoses are bad, because when sitting overnight the pressure in the lines has a chance to bleed back off until u apply them again. So to me it does sound like an internal break in the hoses

 

Have you made any changes to the brake system or did this come about on its own. You can have the wrong residule check valve so its holding to much pressure and not allowing them to bleed back. or you can have a blocked line which would do the same thing after you apply the brakes the fluid is not draining back to the resevoir.

Usually a bad booster will feel like the motor stopped running say your on a hill and the engine is off and you let it coast backwards and brake, its much harder to brake and requires more effort then normal, so I would rule this as not your problem since you said it feels like its dragging and holding pressure.

I would overhaul the brakes including the wheel cylinders and shoes, check the drums for wear and if you can mic them to see if they are over worn, pump some fluid through it then bleed it. Remember to bleed the master first then start with the wheel farthest from the master cylinder. It wouldn't hurt to isolate the master and flush it out, the holes are very small and can get debrit caught in them

And dont use silicone brake fluid (purplish stuff) Its always caused trouble for me, USE ONLY STANDARD OR SYNTHETIC Dot 3/4

I have also seen when a drum has been turned to much and then worn, this allows the cylinder to expand out to far and it will come apart and not release back together.

After you have done all these maintenace issues and have a fresh system see if the problem pursists and maybe pull the master and take it to be tested.