warped rotors?? I doubt it

[bullpeters]

hey
my front end brakes, act like they are warped. I took of the tire and put a dial indicator on them. Its like .03mm on drivers and .08 on passengers. no oblivious bind spots.
the rotors just sit on the axle and are held tight by the wheel nuts, Right?
I dont think the rotors are warped, i reckon its got to do with the way the rotors seat.
my third commodore. all shuddered under brakes. I find it hard to believe that the rotors would have zero runout if they are help flush by 5 randomly torqued someone smarter, please educate me

 

[Dayvo]

I had similar problem with my vx , used to shudder like crazy . Turned out to be the rear rotors that were warped .

 

[Immortality]

I see your problem,

I find it hard to believe that the rotors would have zero runout if they are help flush by 5 randomly torqued someone smarter, please educate me

Wheel nuts are not randomly torqued! There is a specific pattern to follow and specific torque for the nuts. Do this correctly and warped rotors become much less of a problem.

 

[bullpeters]

ok took of the wheel. judicious smack of rotor body with hammer in proper spots, using a dial indicator. the warp is about 95% gone. i dont have a torque wrench so i used my body weight to tighten lug nuts. tommorow i will remove rotors and inspect the way it seats. it seems a bit random. I machine stuff and runout on parts is a tough task.

 

[bullpeters]

ok. please tell me the way to tighten the nuts.

 

[bullpeters]

"Wheel nuts are not randomly torqued! There is a specific pattern to follow and specific torque for the nuts. Do this correctly and warped rotors become much less of a problem."
i belive that this would be news to any tire shop. unless there is some torque setting on an air wrench.

 

[Immortality]

The correct method is to tighten the nuts in a star pattern. Any shop that only uses a rattle gun doesn't deserve your business, go elsewhere. Torque to 120 Nm.

The mating surfaces also need to be clean, new rotors on old hubs without cleaning is a recipe for disaster.

 

[chrisp]

Since you have a dial gauge and seem to know how the measure the runout, try measuring the runout of the rotor in each of the five different stud alignments. The one with the lowest runout is the correct alignment.

 

[rambunctious]

"Wheel nuts are not randomly torqued! There is a specific pattern to follow and specific torque for the nuts. Do this correctly and warped rotors become much less of a problem."
i belive that this would be news to any tire shop. unless there is some torque setting on an air wrench.

Firstly tyre shops DO have torque sockets to suit the different cars, or they should have, and if they don't have, or they don't use them, then you tell them you won't be back and why you won't be back.
Secondly, rotors can run out of true simply if the hub is dirty when the rotor is fitted.
Rotors can also warp if they are hot and you run the car through water on the road.
To understand this, you have to understand how steel expands/contracts when hot or cold.

Now, to doing up wheel nuts.
DO NOT tighten the nuts in a circular pattern.

Start by doing one nut up to touching the wheel, then do the opposite nut(either one of two) the same.
Then go back again to the opposite nut, and so on, until all nuts are touching the wheel.
Now comes the interesting part, repeat the process giving the first nut(any nut) a half turn with the wheel brace, then follow this on the opposite nut, and so on until all nuts have been tightened half a turn.
Repeat the process until you are happy with the tighteness of the nuts.

 

[bullpeters]

wow.
googled it!
never knew that. i am not a mechanic but i am at least able to fix most stuff and I Did Not Know That!
going out tomorrow and take of rotors, clean up the faces and correctly tighten and torque.