High Speed Brake Pull

[Trainmaster]

Basic stuff, but I need some advice. Just installed Motorcraft pads and new hardware. Bled the system and replaced the fluid. Breaks work great. Except at high speed. Up around 80 MPH, hitting brake hard causes the front right to dip and slightly pull on the initial application. After that shot, they pull evenly. No problem if hitting just the parking brakes.

Nobody here turns rotors but they look very good.

I'm figuring perhaps air in that side or maybe a caliper piston hanging up. I'm going to take the thing apart, measure both rotors and bleed the front brakes.

Anyone have anything to offer here?

 

[08T1]

Bleed both sides and throw some grease on the slide pins after cleaning them.

 

[Trainmaster]

Thanks, 08. That's the plan. I'll check for binding, etc.

 

[JExpedition07]

Mine does the same, pulls to drivers side for a second under hard braking then corrects itself

 

[Plati]

Whatever it is ... I'd fix it.
I'm sure you'll dog it down.

New rotors aren't that expensive.
I used to just do pads now I do rotors and pads together.

I had a problem like that (not the high speed part) and it was the flexible hose collapsed inside. New hose fixed it.

 

[bobmbx]

Sounds like an air bubble. Bleed the "delayed" side again.

 

[1955moose]

If he had air in the lines, he'd have a spongy pedal. I'd also do the obvious first, the caliper slides, check tightness of both calipers, torque and tire pressure of both wheels. And hoses last.

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[bobmbx]

If he had air in the lines, he'd have a spongy pedal. I'd also do the obvious first, the caliper slides, check tightness of both calipers, torque and tire pressure of both wheels. And hoses last.

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Doesn't take much air to cause the delay the OP relates. A larger bubble would certainly cause a spongy pedal, and even then "pumping" the pedal hardens it up.

 

[1955moose]

That's true. I've had cars that I worked on, bled thoroughly, and still had a tad bit of spongy, that went away driving for about 10 minutes or so. You might try lightly tapping on each caliper with a rubber mallet, while bleeding. Sometimes a pocket of air gets trapped. Motorcycles were the worst to get right, especially after rebuilding a master cylinder. Even reverse bleeding forcing fluid from caliper bleeder back up to the master didn't always work.

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[JExpedition07]

I’ve read most of the time it’s a partially collapsing line like Mr. Sticker said. Mine pulls to the drivers side just enough to be noticeable under hard braking for a split second and corrects itself, been doing so for a while now. Doesn’t do it for moderate braking. As far as replacing the line, no thanks. I’ll wait until it gets worse....not going to rip into it for a tiny inconvenience the internal liner of the hose is causing.