Re: brake runout specs (revisited)

["jtrealtywebspannet" <jtrealty@xxxx>]

If you aren't getting any pedal pulsation, pulling when you apply 
brakes, or shimmy in the steering wheel when using the brakes, or 
brake squeal, leave the brakes alone. Do inspect the pads for 
thickness and the rotors for any gouges but runnout is only checked if 
there is a complaint of pulsation in either the pedal or the steering 
wheel on braking. Runnout cannot be eliminated so the pins that hold 
the rotors will take up a small amount allowing the calipers to 
"float" absorbing minor amounts of runout. Runnout and parellelism is 
best checked off the car to eliminate measuring any play in the 
bearings of the car. Cutting the rotors is done way too casually by 
too many shops. Not only does it reduce the life of the rotor by 
cutting it unnessaceraly but it can introduce stresses which can cause 
the rotor to warp. When changing pads on disk brakes it is not 
required to "cut" the rotors. What is required is to present a fresh 
surface to the new pads so they can "seat in". That is done with a 
drill and a small disk attachment using #80 paper and using a circular 
motion so there is no tendancy to "thread" or have the pads move like 
the needle on a record player where they move up and down causing a 
clicking noise.
Some things are best left alone. I heard of someone who used to check 
every bolt on his motorcycle once a week. After a couple of months 
they all started breaking off. It seems he gave each one just a little 
bit of a turn to make sure it was tight. Instead of working on the 
brakes I would concentrate on finding the clunking noise, check the 
trailing arm bolts and spacers again.
David Teitelbaum
vin 10757



--- In dmcnews@xxxx, "Walter Coe" <Whalt@xxxx> wrote:
> I've heard some bad clunking noises long enough under my car, so I 
did a
> complete inspection of every suspension component and found no 
problems. I
> suppose I have some loose body bolts, but I'm not ready to take the 
rear
> fascia off to tighten them. Anyway, while I had the car up in the 
air with
> the wheels off, I decided to check my rotor runout since I told 
y'all that
> I'd eventually get back to you about it. My front cross-drilled 
rotors had
> no runout that I could measure, but the rear ones are a different 
story.