View Single Post
Old 04-22-2009, 12:35 PM   #221
1_2Many

 
1_2Many's Avatar
 
Drives: 2008 Suzuki SX4
Join Date: Oct 2008
Location: SoCal
Posts: 785
Quote:
Originally Posted by UCF w00t View Post
I don't understand how people are saying this is harmonic related. That doesn't make sense to me. The breaks barely move. In order to have a harmonic issue, they need to be moving in a constant fashion (e.g. spinning) causing an imbalance which creates noise at a frequency. Breaks don't move at any sort of frequency! It's not like these are on the rotor or something. Squealing breaks isn't caused by some sort of harmonic imbalance it's caused by friction. That's why break pads aren't made out of some plain ol metal as they would squeal like a mofo every time you tapped the breaks. Obviously this is a bandaid for something but a harmonic imbalance, I think not.

You are incorrect. Let me explain:

This has nothing to do with "harmonic imbalance". Something doesn't have to be spinning to have a resonant frequency...and everything has a natural resonant frequency. If the brake calipers have a natural frequency in the range of the vibration caused by the friction of the rotor against the pads then they will "squeal".

Brake calipers must be an engineering nightmare because not only are they very light compared to the massive rotor...they are actually shaped like a tuning fork which is exactly what you don't want when trying to control vibration.

I should know...I'm a vibration test engineer! I've worked here for the last 8 years and my whole job is to control resonant frequencies. http://www.baughneng.com

Using lead weights to control noise is a very feasable idea. Lead is very dense and relatively soft which is great for noise dampening. We use what we call "Q-Damp" to dampen vibration and although I'm not at liberty to tell you what it is made of I can tell you that it basically does the same job as the lead weights appear to be doing.

In my opinion, GM should not replace these calipers. They do not need to spend anymore wasted money, but instead they should have a solid painted lead weight to replace the generic wheel weights.
__________________
We are the early orderers...we are GM's voluntary guinea pigs and their free source of feedback. How will we be thanked?
1_2Many is offline   Reply With Quote