juddering when braking

[Gary Waugh]

I have a 2008 Ford expedition limited (extended/max), it has 225,000 miles and runs great, doesn't use any oil or make any strange noises, however whenever I apply the brakes, the car judders badly, I thought I must have a warped disk, so I replaced the 2 frond disks (i guessed after 225,000 miles they would be worn) but they were within spec, but I changed them anyway , the car still judders. I assumed it must therefore be the rear disks that are warped, so I replaced both rears, but I still have juddering everytime I apply the brakes. If I apply the brakes very gently, then the juddering is very light or not there at all, but under normal usage they judder as soon as I start braking.. Any idea what might cause this? I am thinking maybe bad wheel bearings? I am not hearing any strange noises when I jack the car up and rotate each of the wheels, could it be bad track rod ends or ball joints? as its all under compression, I will probably have to take it to a garage and get them to pull the fornt end apart and find the cause, but wanted to ask if anyone had any suggestions? I replaced the brake pads at the same time I changed the disks so all brake pads are new (that was both the parking brake pads and the disk pads at the rear!).

Regards Gary

 

[DeafBringer]

Did you replace the metal clips when you changed the pads? grease the metal clips?

Did you inspect the caliper pistons and ensure they were moving within the housing smoothly and evenly? Inspect the brake pads to see if you're getting uneven wear. At 225k if they are the original calipers, they are long overdue for a rebuild.

 

[Gary Waugh]

I removed the pads (obviously to change them out), I checked the pistons retracted into the calipres and moved freely, I did fit new metal clips and cleaned the calipers with brake cleaner, everything looked good and even the rubber parts looked fine. I then flushed the brake fluid as it hadn't been done in a long while!! I did not rebuild the calipers, but I can't see how they could cause the juddering, the calipers are solidly bolted to the suspension arm with 2 bolts (the bolts where checked for torque and were okay), the brake pistons (all 4) did not seem to have any movement/play and moved in and out smoothly when I pushed them in with a screwdriver and pumped them out with the brake pedal. I can certainly rebuild them but can't see how they would cause juddering? nothing (brake pads, caliper pistons, etc) showed abnormal or non-symetrical wear.

Gary

 

[Retiredusps]

On our 2006 it did the same thing, It turned out to be the front calipers and brake hoses from the frame to the caliper. it was most notable going down hill with light pedal pressure.

 

[Trainmaster]

These aren't those $ 17 China rotors, are they? If you want a project, try switching them side for side or check them with a dial indicator. The quality of import rotors are very inconsistent and some are really bad.

This year had a problem with brake hoses. Most have been replaced by now. Check your lower ball joints, which is easy with a jack and bar, and check your tie rod ends. It could be a bearing, but you'd check that too when the truck's jacked up to check the ball joints.

As was suggested, it's possible a caliper piston is hanging up and the pad's chattering, though that would show on the pad rather quickly and you did say you checked these.

I never heard the verb "juddering," but I know exactly what you mean. Good luck with this one.

 

[bodabdan]

Do you feel anything in the steering wheel or brake pedal?
Do you have a pull to one side when braking?
Things like a worn control arm bushing can deform under braking load and change your steering geometry, causing weird stuff to happen.

 

[Gary Waugh]

Thanks everyone, to answer some of the question, no they where not cheap Chinese brake rotors and I have put a dial gauge on all 4 rotors and there was no noticable warp, I forget the measurment but they were all good. I don understand how a brake hose can cause judder, the lines look okay externally (no cracking, etc), and the pads all look good (nice flat area as where they contact the rotors and no gouges, etc). When braking I really don’t feel anything through the steering wheel and the car doesn’t pull to either side, I just feel the whole car speeding up and slowing down as the brakes are applied (the deceleration is not linear but jerky), it is more noticable with light braking. Will check the bearings and track rod ends, but **** been 106+ for the last few weeks here in Texas and I am too lazy to work outside, need it to cool down a bit.. thanks for all the suggestions.

 

[bodabdan]

I wonder if your torque converter is engaging/disengaging properly? Might see if it acts different in tow/haul or throw it in neutral and brake it, maybe hold it in a lower gear and feel it there also.
If any of this makes a difference in symptoms it might help find the issue.

If a caliper gets hot enough, any moisture in the brake fluid can turn to steam and cause havoc. Maybe pull a little fluid out at the caliper and take a look at it.

Sounds like you have all the basics covered, something weird is going on. Like everything else, it's always something simple, it's just a matter of finding it.

I'm definitely interested in knowing how this turns out.

 

[GlennSullivan]

To confirm, you did replace the pads at the same time you replaced the rotors, and you did perform the pad / rotor seating procedure after installing right?

 

[Fastcar]

Bedding the pads properly should be done right after installation.

Could be a collapse of a flexible line.

Did you set the proportioning valve?