Brake Lock

[Mikes91]

Would a vacuum pump issue cause brakes to lock?

Reason I ask is this...

In the morning, after the truck's been sitting overnight, the brake pedal often is very firm the first time or two I apply the brakes.

If I apply the brakes more than just a touch, the brakes will lock.

Tonight I tried and tried to get the brakes to lock (truck had been driven earlier in the day), and the problem was much less apparent.

As a matter of fact, I'm thinking this: when Ford replaced the A/C compressor last week, they may have torqued the vacuum belt a little tighter when they installed a new A/C compressor belt. If that is the case--if the vacuum pump is able to deliver more power to do its job--perhaps this is why the brake lock issue seems less later in the day.

Of course, that doesn't fix the firm pedal in the mornings.

Does that sound like a bad vacuum pump? Does the locking brakes sound like something related to a weak vacuum pump?

In the mornings, it is no kidding feather touch on the brakes or the wheels will lock.

Thank you,

Mike

 

[L.Wilkinson]

A hard pedal may be another issue, but your locking (rear?) wheels sounds a lot like leaking wheel seals. Easy enough to inspect for that.

 

[Mikes91]

A hard pedal may be another issue, but your locking (rear?) wheels sounds a lot like leaking wheel seals. Easy enough to inspect for that.

Thank you, but have already been down that road, seals are fine.

 

[argve]

The Enterprise was like that - never did figure it out - just lived with it... I figured it had to have something to do with the system heating up.

 

[Mikes91]

The Enterprise was like that - never did figure it out - just lived with it... I figured it had to have something to do with the system heating up.

Brakes heating up? I'm confused. (easy to do)

Seems to me, first thing in the morning when the pedal is firm/touchy, things'd be at their coldest.

 

[argve]

No problem...

When brakes heat up they loose some of their effectiveness (sp?) meaning they don't put as much braking power (less WHOA there big fella). Happens to big trucks as they decend the mountains if the driver rides the brakes - hence the reason for the runaway truck ramps.

I just assumed that because the brakes were nice and chilled (first thing in the morning) that they were working extra good and then once I stopped a couple times they had lost that nice coolness and so I was back to my old slow long drawn out stopping. Which The E would in a panic situation slide the fronts when needed - like when some idiot pulled out in front of me.