Pulsating sensation felt through brake pedal

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  #1  
Old 05-06-13, 07:13 AM
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Pulsating sensation felt through brake pedal

Hello,

I have a 92' Ford Ranger XLT with 2.9 V6. Disc brakes in front and drums in the back. I am feeling a pulsating sensation when depressing the brake pedal at higher speeds. It's almost as if the brake pedal is making tiny little up and down oscillating motions. The brakes still do their job well. The front and rear brakes look ok visually with tires removed. I was hoping I could narrow down the problem area to control labor costs. Could it be something besides the brakes?
 

Last edited by bluesbreaker; 05-06-13 at 07:51 AM.
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  #2  
Old 05-06-13, 07:29 AM
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Uneven wear on the disk would be my first guess.
You would need a vernier or micrometer to check them.
 
  #3  
Old 05-06-13, 07:33 PM
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its either the rotors or drums out of round. to figure out which let go of the wheel next time this happens if the wheel shakes its in the front for sure. if it dont it still could be, next try to slightly apply the e-brake, this will work just the rear drums. if you get a shake then, you know its in the rear.
 
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Old 05-07-13, 11:08 AM
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Thanks Iceman,

When you say 'let go of the wheel and see if it shakes' you mean the steering wheel correct?

And I should let go of the steering wheel for both disc and drum tests.........correct?

Can the drums or rotors be measured while still on the vehicle?
 

Last edited by bluesbreaker; 05-07-13 at 11:31 AM.
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Old 05-07-13, 07:32 PM
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the steering wheel part will just test the front. if it shakes then it is for sure in the front.the e brake test is for the rear, sorry i should have said this will shake the car not the wheel if its just the rears. only the rotors can be done on the car. but the drums should slide off(might need a hammer) once the wheels are off.
 
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Old 05-08-13, 04:27 AM
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Old 05-08-13, 08:14 AM
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Ok, I think I undestand Iceman. Thank you Amy and Joe for you input also. I was not able to view the video. But I will read up on Amy's subject.

I did Iceman's test while driving on the freeway. I did not notice any steering wheel shaking other than the brake pedal pulsating. However when I depressed emergency brake alone, theere was no shaking, vibrating, or pulsating at all.

I also carefully checked all my brake repair invoices going back years. It seems I have had the same rotors since 2004 and these have been resurfaced four times.

I guess the cause would not be front end alignment or bad wheel balancing, since the shuttering happens when I press brake pedal? Tires are in good shape.

Also, it just occurred to me that the word 'shuttering' might be a better word to describe what happens when I press the brake pedal at speed. Although 'pulsating' could apply as well.
 

Last edited by bluesbreaker; 05-08-13 at 08:30 AM.
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Old 05-08-13, 08:28 AM
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Rotors resurfaced 4 times? Hard to believe they had enough meat to do it that much.

You might try doing it at a slower speed (like 20 mph) on a smooth road...mine was more noticeable then. Light application at higher speeds I think it oscillated so rapidly that it was hard to tell apart from regular road vibration.
 
  #9  
Old 05-08-13, 08:34 AM
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Yes. Four times according to my repair records. It definitely won't do it at 20 mph.
 
  #10  
Old 05-08-13, 10:42 AM
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bluesbreaker,

Your last posting changes everything. Originally you never posted that you had the rotors resurfaced four times. Stamped on the inside of your rotors is the thickness at which the rotor can be resurfaced to for minimal thickness and brake safety. The individual doing the resurfacing should have the proper micrometer to measure the rotor and be able to mic it after the final cut and know if your rotor meets the factory minimal thickness for brake safety. For your particular vehicle the rotors should not have been resurfaced more than twice. With all this being said (and I feel) that the pulsation you are currently feeling is because the rotors are too thin, and itís time to replace them.

Thank You
Amy
 
  #11  
Old 05-08-13, 12:03 PM
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I didn't check my repair receipts till last night. But with the age of the rotors and the number of times resurfaced, I agree these rotors are highly suspect.

I've learned that it is very useful to save repair invoices for different reasons.
 
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Old 05-08-13, 12:24 PM
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bluesbreaker,

Itís no problem, and Iím not criticizing you or anything like that. All Iím saying here is that the fact that the rotors were resurfaced four times sheds a whole light on your pulsation issue.

Thank You
Amy
 
  #13  
Old 05-08-13, 12:29 PM
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And lets not forget the possibility you were charged for something that wasn't done. Like I said...hard to believe they could be re-surfaced (turned down) 4 times w/o going out of spec. I'd be interested in if this was a local garage or a chain store. No names though! No competent, principled mechanic would turn rotors below spec.
 
  #14  
Old 05-08-13, 12:55 PM
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This is true.

Maybe these were only resurfaced three times. Or maybe I misread one of the invoices.
I would never go to any chain store for repairs.
 
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