RE: [Chrysler300] Pros and cons of silicon brake fluid...HELP!!

["Owen Grigg" <ram300@xxxxxxxxxx>]

Hi, this current discussion on silicon fluid has become very relevant to me
as of today! I have just rebuilt all my brakes and primed the system with
silicon fluid thinking that was the right thing to do ,the car does a fair
bit of sitting around in between runs. I sent the power booster off to Karps
for a rebuild and have just received it back. Now I find out this concerning
the booster rebuild...

 "You can use Dot 3 or Dot 4 not silicon as the rubber parts are made of
E.P.D.M for standard brake fluid."

Since the rest of the system is primed and ready to go with silicon I'm not
sure whether to start again and flush out the system, m/c, brake lines,
w/c's OR run the silicon fluid anyway , would I be risking the life of the
booster? If I flush the system what should I use, everything is new in the
system, all lines and rubber seals replaced. How successful is flushing?

Any advice much appreciated.

Thanks
Owen    
 
-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of Warren Anderson
Sent: Friday, 23 May 2008 11:22 a.m.
To: chrysler300@xxxxxxxxxxxxxxx; Narve Nordanger
Subject: Re: [Chrysler300] Pros and cons of silicon brake fluid


  Really nice post. 

  Adding only, the boiling point of DOT 4 is higher than DOT 3 which is what
drum brake cars use. DOT 4 I consider to be necessary for European, high
performance disc brake applications. I really doubt any normal use old
Chrysler with drum brakes will ever boil DOT 3. Moisture migration is
greater with DOT 4 than with DOT 3. 

  The DOT 3 & 4 synthetic fluids I have seen but have no in use information
on. As with so many things, the possible non compatibility of old rubber
compounds and this stuff would concern me. The published boiling point is
once again so high I really wonder why old drum brake cars would need it. 

  If you accidently put DOT 4 fluid intended for your BMW in your 300 with
DOT 3 in it, that is not a problem. DOT 3 or 4 in a DOT 5 system and there
is no idea what that mess might be. 

  Maybe there is a member that has seen something about DOT 5.1 in old car
applications. That stuff is very high boiling point with lower viscosity,
which I find interesting, and has some moisture migration advantages also.
It is not silicone; not related to DOT 5 at all.   

  Warren Anderson
  Sedona,AZ


  Having almost 20 years experience with using silicon fluid on my C-300 and
a
  few Type 1 VW products, some lessons learned can be identified.

  Compared to DOT 3 and 4 the silicon brakes do not seize up, especially
disc
  brakes which otherwise frequently get stuck (VW discs which needed freeing
  up every 3 months of standstill with mineral, performed faultlessly for
the
  next 10 years with silicon), there is less risk of rust in the cylinders
as
  it is not hydroscopic and you will have less fading by hot brake fluid
  (higher boiling point). It does neither attack your paint.

  The downsides are sticking brake light switches (every 12 months on the
VWs,
  also frequently on the C-300) rendering the switch either permanently on
or
  off, it is actually compressible as John L has recognized (I once bottomed
  the pedal on one VW during panic braking, and there was no air in the
  system), and if you spill any it is really hard to later repaint the spot
  without silicon fish eyes. When introduced, the silicon fluid also gained
a
  reputation for destroying old rubber gaskets/cups, so everything renewed
is
  recommended. Blending silicon (DOT 5) with mineral fluid creates
"porridge",
  so a total clean-out (spirit) is essential before changing back and forth.
  As I have recently learned, the engine runs very poorly (not at all) if
you
  get DOT 5 into the intake.

  Bottom line: Unless you are racing, silicon brake fluid is beneficial for
  cars with external brake light switch as Tony Rinaldi recommends. For cars
  with pressurized brake switches, stick to mineral and change it every 2-3
  years to avoid sticking and rust.

  Narve Nordanger

  (out to fix my C-300 brakes this week-end)

  [Non-text portions of this message have been removed]



   

[Non-text portions of this message have been removed]


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