# Brake Pulsation Warped Rotors ?



## VW_NUT (Mar 16, 2000)

I am trying to find the cause of a pulsation when braking in my sister's Jetta 2.0 I just put new rear calipers, rear pads and rotors. The front pads and rotors have 10k on them. The drivers side front rotor has .003" runout. Is that enough to feel in the steering wheel? The pulsation is worse under light/moderate braking and almost goes away if you brake hard.

Any ideas? Should I change that rotor?


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## OddJobb (Nov 6, 2004)

Did the pulsation exist before you replaced the rears?


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## flood514 (Jun 3, 2011)

did you bed them in? try bedding them in again (if you didn't already)
I also had a similar problem from sized carrier slider...


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## VW_NUT (Mar 16, 2000)

Update, yes pulsing existed before rears were changed. I changed the front rotor and 80% of the problem went away. I have changed the rubber slider boots in the caliper carrier and the slides move freely. I don't know why vw changed the carriers as I find the older MKIII style works much better.

There is still some pulsation in the wheel which is probably the front control arm bushings. I hope to change those over the weekend.


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## EngTech1 (Nov 30, 2008)

_*Usually this is because the Brake Jobber - didn't Clean the Hubs well enough !*_ :beer:

Further more everyone Over Tq.'s their Wheels !

Everyone recommends Greasing everything , so You don't get Stud Pull out frozen Bolts
Corroded Rims etc. 

No One Mentions : that there is a Big Difference in - _*Torqued Dry & Torqued Wet *_

read: ( Oil or Greased ) :facepalm:


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## GTijoejoe (Oct 6, 2001)

EngTech1 said:


> _*Usually this is because the Brake Jobber - didn't Clean the Hubs well enough !*_ :beer:
> 
> Further more everyone Over Tq.'s their Wheels !
> 
> ...


Since we're throwing out info, I should ask/state, did you measure runout of the disk with the wheel unmounted?
When measuring runout it is important to understand the condition of the individual parts and the assembled condition. The wheel mounting diameter vs hub diameter and clamp load can have a huge impact on the overall runout of the disk. 
0.003" = 0.076mm this is a little high (IMO but no uncommon) for disk/hub assembled condition. Normally you would like to see 0.030mm or less than 0.05 .... because when you bolt the wheel on its not uncommon to see over 0.1mm of runout and this poses a huge concern for judder/vibration.

Also, runout measurement doesn't always correlate to judder serverity, it is true that more is worse but every car is different, different suspension geometry, bushings, steering rack position, electric vs. hydro power steering, steering wheel weight, diamter etc.... etc... contribute to judder and the harshness seen by the driver. 

... and in closing be aware that the actual runout measurement doesn't always mean you'll instantly have judder based on what I just stated above, BUT can indicate as you get corrosion building up, pad debree, disk/pad wear etc etc.... the judder has more propensity to come
In addition, runout isn't the only thing that causes judder technically


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