excursion brake "shuddering"

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#1
My first "post" didn’t seem to go through.
Does anyone have experience w/ "shuddering " brakes, I pulled them apart and every thing looks okay. Cleaned and put back together, shuddering still happens and might even be worse now. When I was checking out all the steering linkage to see if I can see a possible cause, I pulled on a long bar that is on the rear side of the front axle(I think its a stabilizer bar, can someone please confirm), the bar is about 1 3/4" to 2" in diameter, its straight section is about 3 feet long and its bent about 90(+) degrees at each end and the ends are about 1 foot long after the bend, the bar ends are attached to the bottom end of a connecting rod(?) on each side and the connecting rods are bolted through the frame at the top end. The straight section of the stabilizing bar is attached with 2 brackets that are on the back side of the leaf spring/axle brackets, there are bushings in the stabilizer bar brackets that I think may need replacing. I can move the bar back and forth by hand a little(1/4 - 1/2"+) and the bar moves up and down in the passenger side bushing(about 1/16"+/-) if you bounce the vehicle up and down by hand. Could this be causing the "shuddering"? and is it a stabilizer bar? and should the bar move like that? Vehicle is 2000 Limited,4 wd,V-10, gas engine. Thanks for your help in advance.
 
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#2
When you say shuddering do you mean it feels like the pedal kicks back on you ?

Ford_Dude
 

Gus

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#3
Say you are driving on the highway and are entering an off ramp...at 65 mph you "lightly" apply the brakes.....does the steering wheel shake(front brakes), or do you feel a shudder in the seat(rear brakes), or both? If this is the only time you feel the shudder, when you apply the brakes, then you have a pulsation.....you can't generally "see" a pulsation problem when you take the brakes apart, unless it is very obvious, like a rust spot in the rotor, pads worn at an angle, frozen pins, etc. Everything can look ok, but if you check thickness variation or rotor runout, we are only talking thousands of an inch that can cause this problem.....once the pulsation has happened, the rotors(or drums), have to be turned, or if needed, replaced.....new pads/shoes and new hardware(if necessary)and proper installation techniques have to be used....
 
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#4
daddy,
The part you describe has been called a stabilizer bar, sway bar or anti-sway bar. It will not cause shuddering brakes. If it is loose it might cause a thunka-thunka noise.

Brake shudder is usually warped rotors or drums.

Wild card is a problem with the antilock brakes, if it is equipted with them.
 
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#5
I do have that "thunka thunka" noise, I just was not sure if the stabilizer(?) bar could be affecting the brake "shuddering" problem, so thank you VERY much for all your replies so far,I'll have to replace those bushings and hopefully that noise will go away. As for the brakes, I believe they are anti-lock (in the front at least), it doesn't seem to matter how fast you're going when they're applied is when they "shudder" and yes the steering wheel and column shudder(at least thats what I call it) it feels like the front end might just fall off sometimes, I think this problem has got to be causing other things to loosen up because it shudders really bad most of the time, and if it was just warped rotors I would think it would mainly result in the pedal "pulsing " which is referred to in another reply and the pulsing would slow down as the vehicle slows down. One thing I forgot to mention, I replaced the pads last year and we had the rotors turned, but when I took off the caliper, the caliper mounting bracket (which has the bushings(?) for the guide/glide pins which the caliper attaches to, had a problem. Each side had 1 pin that was frozen, on one I was able to free up the pin, on the other the pin snapped off and I had to drill out the piece that was still stuck, so I put new pins in the bracket, this time I checked for side play in the pins and there may have been a little but not much, but if that is causing the problem why didn't the problem happen when I first did this last year, it started about 1 1/2 - 2 months ago ?? Thanks again for all your help.
 
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#6
Sorry,I forgot to reply to individual postings, Ford Dude- Wife says "pedal does not pulse or shudder", Gus - shuddering seems to be only in the front, not in the seat or towards the rear of the vehicle, Danica - should the stabilizer bar move back and forth like that ?? Thanks in advance for your replies I greatly appreciate the help, Just an FYI- I was looking at some new rotors from "Brake Performance" that are slotted and dimpled and thought (with all the bad things I've heard regarding excursion brake parts having a very short life span) maybe these would last awhile and not warp at all or as soon. Any input ???
 
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#7
Once again, its just me. A little more input, when the vehicle is traveling at slower speeds like 20-30 mph (I just drove it myself) and the brakes are applied(only happens when brakes are applied),the shuddering is not as severe as when you're going 35 - 50 mph, but it doesn't always shudder(at least at slower speeds).
Regarding the new rotors(slotted & dimpled- see above message), I was also thinking about just putting new caliper mounting brackets( $80 + per each from dealer) on so that the guide pin bushings are new and will be nice and tight. The caliper pistons are fine(not frozen) and both pistons in each side seem to work fine. I have 1 more question, when I cleaned and remounted brakes(2 days ago), I applied some brake grease to the spring clips that hold the pads in the bracket, the pads did not move as freely as I thought they should, there are 2 clips(1 for each end of pad) that go on each side of bracket, I only put the grease where the pad(s) make contact, is that a normal practice for a mechanic to do, was I not supposed to do that, can that cause any harm?? This has nothing to do with the shuddering(that started almost 2 months ago),I was just wondering. Thanks again !!!
 
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#8
Sounds like you need new rotors. I have no valid opinion about the performance rotors, I have never used or installed them.

If you can slide the sway bar with your hand, the bushings that fasten to the frame are worn.
 
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#9
I have opinions on rotors.
First I don't like drilled rotors. The cheap ones they do not chamfer the holes and they are likely to crack. If you are likely going to spend a lot more money than stock rotors. Second is few places are set up to machine these rotors. Third, if drilled/slotted rotors were needed they would put them on the truck stock.
Bottom line clean the hub before putting the rotors on. Have the tire guys use torque sticks, and torque the wheels when done.

Good luck,
Ford_Dude
 
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#10
Ford Dude - I went back to "brakeperformance. com" and checked out the dimple-drilled/slotted rotors, cannot tell if holes are chamfered from picture and it doesn't mention that, didn't even think about "having them turned(cut), so thanks much for your input. As for stock rotors, Ford(dealer) wants $149. 48(+ tax) for 1 rotor, I know the china junk is out there cheaper but I'm trying to find something OEM grade for less than $150, same place that has slotted, has stock rotors for $91. 50 ea. (with free shipping) and they say they're "premium quality solid casting, TUV approved steel" and that rotors "meet and exceed Federal safety standards required for new vehicles", I live in Illinois and I think this place is in another state so I don't think I'd have to pay taxes either, so I could get 2 rotors for $183, instead of $320(+) and that matters alot,(I'm unemployed right now so I'm watching every penny), any input on that??
 
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#11
Thanks Danica, I'll definitely be replacing the sway bar bushings, dealer probably wants $75 or some ridiculous amount for those. (and I sure hope that noise goes away) I always try to insert one of those different smiley things in here and it never works, only get text.