sometimes when i brake, my car shakes pretty ugly, in the front. it happens most of the time, usually after i drive it an hour or so. i noticed it happens it hot weather the most. but maybe that isnt important. my dad changed the rotors on it already, but its still happening. anyone with similar problems? its an automatic 94 LS btw.

 

make sure the rotor is sitting flush on the hub of the axle so that no rust is sitting below ur rotor. also make sure he bled the old fluid out to.

did your new rotors always do this even after they were new? or did it just start a while after he put them on for u?

 

your rotor might be deeply scratched

 

you probably need to resurface it or replace it

 

How are your tires?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pinkspider &raquo;</TD></TR><TR><TD CLASS="quote">sometimes when i brake, my car shakes pretty ugly, in the front. it happens most of the time, usually after i drive it an hour or so. i noticed it happens it hot weather the most. but maybe that isnt important. my dad changed the rotors on it already, but its still happening. anyone with similar problems? its an automatic 94 LS btw.</TD></TR></TABLE>


Your rotors have excessive lateral runout. In easy terms, they are warped.

If you were to put a Dial Indicator on the face of the rotor and turn them in a circle you would be able to see how out they are, and compare that with the factory specifications.

But obviously, If you can fell pullsation while you are brakeing, then you need to have the rotors machined. Only 10-15/each at a local shop.. So about 30 max.

When you said you put new rotors on It doesnt necessairly mean the new rotors are good. I See this almost daily in my shop. When these rotors are shipped and stocked, the rotors are stacked on top of each other. Think about how much a stack of rotors weigh. We Believe, the stack of heavy rotors combined with time sitting on a shelf, can warp brand new rotors.

We have had to machine New rotors right out of the box. So My money is on the warped rotors, and its a cheap repair to have them machined.

 

Brake rotors do not "warp". I know what you are thinking "yea, right!" While it is common knowledge that the surface of the rotor is supposed to be flat or "true" you can measure the "run out" on it to see the damage. But this does not mean they "warped". This has become the layman’s term (and most mechanics too) for a condition they don't understand.

This is a condition you can prevent and often times a turned rotor will develop the same problem soon after it was done due to the fact that the damage does not alway get cut out when you turn them. The prevention involves properly bedding in any set of new pads and rotors, AND ensuring that the new set of rotors you just installed are 100% clean. That means all of those nasty finger prints you just put all over them need to be cleaned off with brake cleaner. Rotor also ship from the manufacture with a coating on them that is also required to be cleaned off.

The function of your brake pads is to deposit material on the surface of the rotor so "effective" friction can occur. When that deposit layer is uneven it causes hot spots on the rotor surface. These hot spots cause more pad material to be left at that spot. Over a short amount of time you will start to feel this as a pulsation in the pedal. The worse news is the temps from those hot spots will change the iron in the rotor on a molecular level to a hard brittle deposit of cementite .

For further info and a better explanation please read these:
http://www.stoptech.com/faq/data/faq25.htm
http://www.stoptech.com/whitep...h.htm
And if you check around, most brake parts have instructions for proper break-in/bedding; the problem is nobody reads them.



Modified by Wraith_G2IC at 11:10 AM 8/11/2005

 

my tires are practically new. thanks for the info guys, im gonna check out everything on the weekend

 

get new rotors and pads will fix the problem

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94rs-turbo &raquo;</TD></TR><TR><TD CLASS="quote">get new rotors and pads will fix the problem</TD></TR></TABLE>

That is how I fixed mine. My Axxxis Ultimates dust like crazy tho.