front end and steering wheel shake violently under braking

[blues14]

like the topic says, under very light and very hard braking, there is no problem, but under normal braking pressure, the front end and the steering wheel shake violently back and forth. it doesnt pull to either side more than the other. I just had my engine replaced, did they forget to tighten something?

[navysnail]

your front brake rotors are "warped", you need to replace them, then follow the bed in procedure outlined on the stoptech website

[Fenvy]

if they are thick enough, you can resurface them and keep on driving.

I am under the impression that most rotors can be surfaced UP TO 5 times, depending on the amount of damage sustained.

go get them resurfaced, if thick enough to do this, for about 20 to 40$

If it is cracked, you should replace them, though.

[blues14]

heres the thing though, the pads and rotors only have about 3,000 miles on them. they were rusty when i bought the car since it had a blown motor and sat for like 5 months.

[Fenvy]

you must brake like a ***** jk

same thing happened to me before, just tone down the hard braking a bit

[navysnail]

if you read on the stop tech website, you will find that a "warped" rotor is really the product of not bedding in your pads properly, which causes uneven pad deposits and therefore, raised areas on the rotor.

here is the article http://www.crush007.com/love.cgi?id=1119063821maa

[NISTECH]

I have read stop techs article but there is more to it then what they mention there. There are a few things about setting up new rotors that need to be taken into account especially with aftermarkket rotors. 1) you need to index the rotor for the least amount of runout during installation. If you can not obtain at least half of maximum acceptable runout you should have the rotors machined ON THE CAR. This will give you the best opportunity to prevent brake judder.2) Then perform the Bedding procedure as mentioned on stop tech cause yes that is as important as the indexing. I have a set of after market replacements just put on my 240 and I did none of the above mentioned proceedures[why you ask? because I am a tech and love to short cut things on my own cars,call it ummm R&D..lol Really cause I plan to do the 300Zx 5lug and brake conversion soon and just need it to get thorugh a state brake inspection] Any how my brakes judder even with new rotors ,aftermarket BTW. So just because you have new rotors dont mean they wont "dance".

Also BTW loveless you usually get about 3 cuts out of the rotors when a judder is being resolved.

[Q45tech]

1.0mm = 0.0254"........a perfectionists [using brand new bit each time] being extremely slow and methodical would remove 0.003" per [every 6-9,000 mile retrueing] yielding 6-7 possible retrues.............roughly 40,000-60,000 mile rotor life.

Few techs [and almost now brake shops] are perfectionists.

Failure to index and shim [after a complete cleaning sanding of all mounting surfaces] to an error of less than 0.001" just means you are installing a perfect rotor on a warped surface MAKING the rotor conform to a WARP at the first heat cycle.

A PERFECT Brake job takes 3 times the hours normally spent!1 in 100,000 get a decent brake job.

[NISTECH]

Dennis makes a good point If you dont clean the hub when doing a machining or rotor replacement you are suseptable to yet another warpage. Also once the hub is clean you need to check its runout as well, if it is excessive then deeper diging is needed to find the source of the excessive runout. Although it is near impossible to eliminate all runout in a "reasonable" amount of time, nor do typical car owners wish to spend the money to make thier cars perfect. They like the good enough price better. Granted most shops especially the ones with "brake" in their name dont do the job correctly and achive no where near perfectionism. That is a problem usually related to lack of available, affordable techs for the shop to hire and another thread entirely.