Random single "pop" while braking

[lgmagone]

My 2004 Ford Explorer has started "popping" in the brake pedal while braking. It does this about 5% of the time. What are the possible causes of this, and what should I look at to try to troubleshoot?

I suspect it is the transmission as I never had the problem until the transmission was rebuilt. However, the transmission shop has replaced both the valve body as well as the solenoid pack since and it hasn't gone away. I'd like to check over anything else possible before taking it back to them a third time.

 

[caspian65]

Do you feel it in the steering wheel also? Could be something like suspension or a sway bar mount/bushing.

 

[lgmagone]

No, brake pedal only.

 

[lgmagone]

Some more information:

I had my wife drive the car today with me in the passenger seat. I can feel a slight vibration in the floorboard of the passenger seat when it pops. It popped 4 times on the way into work today.

Each time is at slow speeds - always under 20 mph. Usually the car needs to be traveling above 20 mph before it happens. Always forward, never happens in reverse.

I do have a rear wheel bearing that is failing, and will try to get that swapped out. Could this be related to the popping? I don't think so.

 

[05XLimited]

Have them check the torque converter, as it sounds like it may not be operating properly.

 

[pet575]

Are we talking about a hard downshift, maybe?