Hey guys,

I've been searching for two hours now and still haven't found a thread quite like the problem I've been having.

I have a 2002 F150 with 118000 miles on it. I just bought it in May and ever since then, I've been experiencing this weird thing below 15mph when I come to a complete, controlled stop. It happens EVERY time I brake normally to a stop, so it's consistent and I know that there are NO vibrations/noises at any other speed or braking situation. If I brake very hard to a stop, this rarely occurs.

Ok, so the sound.

At first it sounds like there's an electric motor, but I think this noise could be the master cylinder.

weeeeEEEEEEEEEn-DUh duh du du

Duh being the shuddering. It's a fast shuddering.

The pedal fades and the shuddering is felt in the pedal and steering wheel. Then below 10mph, the wheel suddenly jerks to the right so I have to force it left to keep my wheels straight.

I've just been dealing with this ever since I got the truck because braking at any other time (i.e. getting off the highway, in town) the brakes are normal.

Also... if I just roll to a low speed, like, with downshifting into 2 or 1, I still hear that motor noise, just no brake shuddering as brakes are not being applied.

This leaves me to believe it's something electronic, such as ABS. But honestly I have no idea where to start.

I guess I'll take the front wheels off tonight and take a look...

Please, if there's any more info you need, let me know. I appreciate your help.

-Ian

2002 F150 4x4 XLT Reg cab Long bed
4.6L V8 Automagic

 

Go ahead and take the front wheels off and let us know what you see. Look for excessive brake dust on one side vs. the other, etc. I know every so often my caliper will lock up or not release fully and my left side's shoes are still brand-new but my passenger side shoes are almost to the point of being replaced. Ford has had some issues with their brake systems. But I have no idea what that whine could be. You might want to take it to a Ford dealership if you can afford it/think the truck is worth it.

 

Sounds like a majorly warped rotor(s) to me....That's why you feel the shuttering, just imagine a warped CD spinning in a CD drive....same issue.

Try some new rotors, pads, and bearings. If it still does it after that, have a mechanic/dealership troubleshoot.

 

i had the same thing, except my vibration occured between 55-65 as well. New hubs fixed this issue.

 

Well, so far I've been able to take the wheels and calipers off to inspect them.

There's not any excessive brake dust. The hubs spin smooth as silk when I turn them (with calipers on and off). Pads look fine, rotors don't look worn except for some light grooving. I've had a wheel bearing go before in my other f150 and this just doesn't have the same symptoms. There's no play in the hubs, which was noticeable in that situation. However, I can't eliminate it because I haven't put new parts in.

One of the things I didn't have time to check was the caliper/piston motion, maybe I have stuck or sticky pistons?

Thanks for the help guys.

-Ian

 

Discovered something interesting yesterday.

First of all, I must correct something. All this business happens below 5 mph.

Now...

If I COAST to a low speed (downshifting into first) the truck will make the same noise as it slows to a stop. Right around 5 mph is where it starts and as I said before, it sounds like an electric motor running.

If you've ever ran an electric drill at a REAL low RPM where the electric motor is whining and hardly rotating, that is what it sounds like in the cab and feels like through the pedal.

SO. If the truck makes this noise by itself with the brakes only complementing it, it leads me to believe it's not rotor, pad, or hub related. To me it's unlikely those physical parts would be so digital, on/off like this is. This happens every time at the exact speed and has NEVER changed since I got the truck. It's always been the same. Never worse. Maybe it's abs sensor or master cylinder related. But again, I really don't know.

Maybe I should move this thread to brakes?...Is that possible?

Thanks guys,

-Ian
__________________
Ian Duckett

Mechanical Engineer
RPI Class of 2009

2002 F150 4x4 XLT Reg cab Long bed
4.6L V8 Automagic

1997 F150 4x4 Reg cab Long bed
4.2L V6 5spd

 

your 4wd isnt engaged is it?

 

Does it do it if you throw it into neutral?

 

Wonder if your Caliper(s) aren't square anymore and your pads aren't hitting flat to the rotor? I had a friend tell me that the I didn't get my bearings tight enough and the rotors being loose make it vibrate, rattle, and make all kinds of strange noises at low speeds and normal pedal stopping. He said it doesn't take much to make it do it either. Ck it out!

 

Nope not in 4 wheel and it did do it in neutral.

However I just installed my rough country 4" lift this weekend - bought new hubs to go with it and so far no noise! (poking round the house, haven't been out on the road)

Also, my pads might not be square like you're saying GeoEak, I got an up close and personal view of them this weekend.

I'll let you guys know how it turns out soon!

 

Well, the shudder went away with the new hubs I put in. Expensive as hell but worth it in the end. My guess would be the sensors as the bearings in my other hubs felt fine... But now the ABS light is on. Mixed blessing I guess...

First drive on my rough country lift though!! It was a ton of work with many holdups. At LEAST 25 hours total...



(See my profile for more pics of the truck and install!)

Still a couple more inches I can get out of the front with the torsion bars, the CV shafts are horizontal right now!

Thanks guys so much. Take care!

 

Glad you got it going Ian and I forgot it was a 4wd, that does have differences.
I'm going to lower mine in the future since It's a city ride and I don't run it anywhere I'd need the height, just 6ply tires for the debri.