Re: brake runout specs

["jtrealtywebspannet" <jtrealty@xxxx>]

I got the specs I quoted out of a Chrysler manual. I also checked with 
a brake shop that I deal with. In general when they don't have 
something to reference these #'s are what they aim for. In general the 
lower the spec the smoother the brakes. Some systems are more tolerant 
of runout so the pulsation isn't transmitted as directly in which case 
you don't have to be as fussy. It is also a function of how good the 
brake lath is at holding tolerances and how well the rotors stay in 
shape. Non ventilated rotors as we have in the Delorean hold shape 
well until they get severly overheated. If that happens then they 
usually do not return to their normal shape and instead become 
distorted. I used english measurements as in America most brake lathes 
are calibrated in this system. Use a dial indicater to measure 
run-out. Use a micrometer to measure thickness variation. In many 
cases you can get by after measuring everything by just doing the one 
rotor that is the worst. It is usually the worst by far as the other 
three are close to each other. Remember ANY ONE rotor can cause pedal 
pulsation but if the steering is affected it is most likely a front 
rotor.
David Teitelbaum
vin 10757


--- In dmcnews@xxxx, Jan van de Wouw <jvdwouw@xxxx> wrote:
> David Teitelbaum wrote:
> 
> > There are no published specs for the runout of the rotors. There 
is
> > also no published spec on parellelism. In general the runout 
should be
> > kept below .0025" and parelleism .0005". (Parden my speeling).
> 
> I wrote:
> 
> > But I happen to have the WorkShop Manual for my Escort too!
> > For my Escort the maximum allowable runout/wobble is 0,15mm.
> 
> Then Walter Coe wrote:
> 
> >> I'm going to have to convert
> >> David T's specs to metric before I can understand them (yep, I 
hate
> >> the old system! I can't even put those numbers into perspective
> >> without converting.) The specs that Jan gave don't make much 
sense
> >> either. You are only supposed to use commas every three digits,
> >> so 0,15mm makes no sense. Do you mean 0.15mm? I think I have a
> >> lot more run-out than that. I'll get back later with some real
> >> numbers once I get the car up on jacks again.
> 
> .0025" = 0.0635mm
> .0005" = 0.0127mm
> 
> Yes I DID mean 0.15, but on our side of the big pond the use for
> commas and points is just the reverse of the USA, so one thousand
> in the USA is 1,000.00 and in Europe we write it down as 1.000,00
> Sorry for the confusion...
> 
> What does strike me as surprising is that Davids' specs are less
> than half of the ones I found. I guess the difference in performance
> would be a good explanation?
> 
> Hope this helps,
> 
> JAN van de Wouw
> Thinking Different... Using a Mac...
> Living the Dream... Driving a DeLorean...
> 
> #05141 "Dagger" since Sept. 2000
> 
> ------------------------------