[DeTomaso] Wilwood Brakes WTF????

[Al Chelini]

Hi, Mike,

I bought a set of Wilwood brakes from one of our local vendors back in the
1990s. and when checking the runout ("wobble") of the installed rotors,
several were found to be in excess of 0.050", over 10 times the usual
working range.  This will produce the juddering you spoke of.

Thanks again to S O Bill for the help, we spent a lot of time on his lathe
correcting the misgivings.  It seems that although the kit was stamped
"Wilwood", the rotors were actually cloned by a pacific rim company, not
sourced from Wilwood.

Also, get rid of the 2 psi residual pressure valves ASAP, they belong on a
car that has the master cylinder physically lower than the calipers, as in
the 'ol T-bucket street rods. They will typically drop the master brake
assy below the floor so as to hide it and present an uncluttered firewall.

Hope this is of some help.

Congrats on the upcoming nuptials, BTW,

Al
==================================================

On Sun, Apr 14, 2013 at 2:07 PM, <MikeLDrew at aol.com> wrote:

> Hi guys,
>
> So, you may recall my description of me beating the snot out of my Pantera
> at Laguna Seca a couple of weeks ago.   I had a super, super time!
>
> Partway through the second session, I started to get some juddering in the
> steering, from the brakes.   I presumed that the cheapo rotors had warped
> slightly, but I was able to drive through it, and then unwarped when the
> car
> cooled off.   I noted with some surprise that the front pads had worn down
> 50% in just two 30-minute sessions while the rears looked perfect.   The
> wear
> was perfectly even.
>
> I then had an uneventful three-hour drive home.   During one of my stops, I
> took the time to feel the wheels for any excess heat that might be caused
> by brake issues, and didn't feel anything untoward.
>
> The next time I drove the car, I noted that the brakes were definitely
> sticking (or at least, SOMETHING was sticking).   I could drive down a
> gentle
> slope, put it in neutral and the car would gently come to a stop.
> Obviously
> not right.
>
> Today I jacked up the car and pulled the wheels, and was shocked at what I
> found:
>
> http://www.poca.com/index.php/gallery/?g2_itemId=39244
>
> http://www.poca.com/index.php/gallery/?g2_itemId=39260
>
> Both brakes were clearly stuck on, with the pads badly tapered and worn
> within microns of bare metal on the bottom sides.
>
> Since I have 2 psi residual pressure valves in the system, I thought that
> perhaps the front one had failed and stuck on.   If that was true, then it
> would act almost as if somebody was stepping on the pedal.   To test that
> theory, I cracked a bleeder on each caliper, expecting brake fluid to jet
> out.
>
> Nothing.
>
> So the problem is more mechanical in nature, rather than hydraulic.   I bit
> the bullet, pulled the pads and then removed the passenger side caliper.
> The pistons were very, very difficult to move within the caliper; I managed
> to compress one almost all the way before wising up to the fact that it
> would be almost impossible to remove if it was flush.   The other three
> came out
> with some work, that first one came out after a LOT of work.
>
> The rubber seals inside the calipers look and feel just fine--having said
> that, I don't exactly know how they are supposed to feel, but they are soft
> and pliable.   The pistons were covered with brake dust, but a few minutes
> spent with brake cleaner and a rag, and some emory cloth, and everything
> cleaned up perfectly.
>
> http://www.poca.com/index.php/gallery/?g2_itemId=39251
>
> So, the question is, what caused this?   Could excessive heat have caused
> the pistons to expand and swell and jam in the caliper?   Not what I would
> expect from 'racing brakes', and the pedal never went even slightly soft,
> so
> it's not as if the fluid was boiling.
>
> Does anybody have any other theories as to the cause?
>
> And more to the point, what should I do now?   I suppose since they are 20
> years old, and apart already, I should probably buy new seals (or new seals
> and pistons?) and swap them out before reassembling everything.   But this
> still begs the question--why did this happen????
>
> Looking forward to words of wisdom (along with inspired wild-ass guesses!)
>
> Mike
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> DeTomaso mailing list
> DeTomaso at poca.com
> http://poca.com/mailman/listinfo/detomaso
>