Hi , Until you know why, what really happened on the F , not sure it makes any sense to blame silicone fluid? And yes there will be many opinions on this , and that is ok . Either way can work .. I do not agree with Jeff that some mysterious malady causes some rubber parts to not hold silicone . I do not doubt his experience but I submit those same parts would not have held glycol either . Replacement parts today are often low quality in terms of say scratches in bore, poorly made rubber seals etc . Rubber loves silicone . There is no doubt about that from the engineering aspect . . Further every military vehicle has it . They know what they are doing . Last , I know the typical long term failure caused by glycol in an old car is a pit in the wheel cylinder that causes or can cause sudden loss of brakes. I do not know the history of any given car and I cannot rely on myself or others to change glycol in many cars or keep track of that .. to what benefit ? No benefit st all, to my view . In fact the opposite . But to each his own , that is fine — but first person experience with this stuff really matters . And details of failures ? Maybe when you find out why the F lost its fluid with no floor puddle you can tell us . Look under the floor mat .. pits in master ? Pits from glycol? Best , John Sent from my iPhone not by choice I have both a 1957 300C and a 1962 Chrysler 300H that both have been running with silicone fluid for over twenty years now with now issues, except that since I had repeated failures of the brake light switch on the C, I eliminated it and to a mechanical switch mounted next to the brake pedal to activate the brakes lights such as was used in 1962 Chrysler models.. Since then, no issues at all.
Hoever, after a brake job on my 1960 300F about 10 years ago also using silicone and redoing the brake switch to match the H, I recently went out to my garage to take the F out for a spin and found to my dismay that there was no braking available at all. I have not had the opportunity to investigate the matter yet, but I have been concerned about this since it happened recently. All I know is that the master cylinder was completely empty and was unable to trace any fluid on the garage floor.
Recently I went to Karp's Brake service near where I live here in California and asked the proprieter Jeff what he recommends using in older cars, silicone or regular brake fluid (Dot 3 for example)? Keep in mind that Jeff is one of the few persons that gets 1955 Chrysler brake systems to work again when most cant and he repairs all kinds of brake systems from the past and has been doing this for decades now on all makes and models. He said his conclusion over the years is that there are some seals in replacement parts that will not maintain their integrity using silicone fluid, and it is hard to know going in which replacement parts will ulimately fail using this fluid. just as some fluid brake switches as in pre 1962 models use and also fail. After many years of people asking him this question, he maintains that he recommends using converntional brake fluid in the systems of our old cars for this reason - just be sure to flush the brake system every few years to keep moisture out of the system. Here in California, the climate is generally very dry, so flushing may not be needed quite as often as in more humid areas of the country/world. My cars are kept in a sealed, climate controlled garage so the change intervals can be extended some. But Jeff at least was pretty firm on his conclusion about this use of conventional fluid being the best option. Before my experience with my F, I would have probably still be using silicone fluid - but that was an eye opener for me and a bit scary and very unexpected. I personally will rely on experts such as Jeff for what I will do. I was lucky for some time with my C and H, but on my F I was not. .
Steve Albu
Most 61’s still had a pressure switch. I had silicone fluid in my old G,
and always had a good pedal. I had the car for 75,000 miles, so I did change a
few brake light pressure switches. Good switches last, cheap ones don’t. My 66
Imperial has had silicone in it since 1987. Still the same wheel cylinders and
master. II t also has a good pedal.
Don
Sent: Tuesday, March 24, 2020 3:59 PM
Subject: Re: [Chrysler300] Brake Fluid for a 300F
I have a G that I put silicone fluid in it about 40 years ago and
never had a leak in a wheel cylinder or the pressure brake switch until after it
was in a body shop getting rust repaired for 4 years. At that point a wheel
cylinder failed. I don't recommend going 35 years without changing the fluid, as
had I changed it every 10 years or so, that cylinder would likely not have
failed. I am replacing the master and wheel cylinders and will use silicone
fluid again. I use Dot 3 or 4 in my drivers and change the fluid when I replace
brake pads. If I put Dot 3 in my G I would change it every year or 2 max. I will
probably never wear out the shoes on my G as I doubt I will drive it that much.
I will change the silicone after 10 years if the virus doesn't get me first... I
mentioned that silicone had not affected my pressure brake light switch before
on here and someone wrote me back saying that G's didn't have a pressure switch.
My car was delivered in November 1960 and is equipped with a pressure
switch.
Loren Nelson 300G in spring blooming N Georgia
Moisture cannot mysteriously get to brake line in first place
with silicone , but glycol carries it just as you say and once saturated it
settles out in wheel cylinder bottoms .
So if you change it often you are ok . But it also absorbs it from
air as air pressure changes at master over a long time , then you push
it into system . Silicone does not . Army does not have soft pedals. It is
difficult to install right — really .
Cars were made for ten years life, we are 60 now . Water is in the glycol
. And I admit to not tracking this on so many cars . Silicone does not have
the problem at all . I like that . To each his own.
Often soft pedal has in fact nothing to do with fluids . Often
mismatched diameter shoes and new drums or shoes . Why people give up on
brake designs that won at nascar 55 and 56 .. add in skill of guy
doing it . My first attempt on an F was a disaster , all new stuff back
in 67
Sent from my
iPhone not by choice
John -
The way
I understand it, moisture gets trapped in the brake lines. Having a brake
fluid that absorbs moisture is a good thing, since otherwise it has no place
to go and settles either between the fluid and the inner line, or by the
line-to-wheel cylinder connection, which will cause rust to form. Since DOT
5 does not absorb moisture, that may lead to the condition just described.
DOT 3/4 starts out as a golden color, but turns darker as it reaches a
moisture saturation level. So I would change out DOT 3/4 every five years or
so and your brakes will be happy. Having a soft pedal, IMHO, is a worse
alternative to this. Very scary.
There is
also something called DOT 5.1, which I haven't researched. Anyone want to
chime in ?
Ron
FYI — Soft pedal with silicone is because you got air entrained
in it . Takes months to get out , If ever , if in a car . Must pour very
carefully from undisturbed container sitting on a shelf , still for a year ,
imho. And extremely smoothly , slowly ideally down a paper ramp into master
. Anything to avoid aerating it . Just dumping it in makes tiny
bubbles . Micro bubbles stay suspended. Soft pedal. I would avoid
pressure bleeders . Obviously if you shake can once you are done for .
It is standard in military ( where I got mine surplus —some large cans
on eBay ) . Rubber loves silicone , —silicone seals rubber and
preserves it twenty years or more . Critically, it does not
absorb water .I really believe “sealed for life” .. like a
stored military truck. But if you do not know about the easy aeration it
will not work .
All glycol absorbs water ; on our cars it ends up over many years in
the bottom of wheel cylinders and makes a rust pit as it is heavier than
glycol.. One day you get a very big sudden surprise .
On several of my cars I added a micro switch to pedal mount to get rid
of problematic and in the way hydraulic switches. See 70’s dodge
trucks for idea /switch , or make bracket yourself for a real 15 amp
large body micro switch . Pedal up holds it open. Helps with dual master
room and plumbing too . Although not absolutely sure on any given pressure
switch, silicone is more chemically innocuous than glycol (?) so
switch failure is most likely due to lousy switch — not silicone
,— plus, and a biggy , a spilled or sprayed drop of glycol , and your paint
is absolutely trashed due to the chemical aggressiveness. A leaking master
gasket took all the paint off my firewall , under master .
MBenz requires new brake glycol fluid every two years . I did not do
that, result was $ 2000 in bills as rubber in ABS system valves fell apart
and seals in rear axle disc brakes too, brakes failed after 5-6 years.
... ...personally I think due to crappy German rubber , but it happened .
Temp differences in glycol DOT rankings mean little on drum brakes ,
but critical on discs . Might as well use best , however.
I would not use the stuff on a rebuild. I have
seen those pits on 4- 5 300F, enough for me -/ — and once had the sudden
brake failure they imply . As shoes wear , or are replaced , seal moves to
new place in wheel cylinder can uncover pit, your brake fluid squirts
right out around seal lip .
Just info , your mileage may vary . Most of above info learned the hard
way ..... If you go glycol , change it every few years .. keep record..
John
Ps , glycol probably ok in a car driven a lot , gets warm under hood
frequently water vapor probably leaves due to higher vapor pressure etc .
But a sitting car must soak it up .. military does not have “
soft pedal ”
Sent from my
iPhone not by choice
Do not use synthetic if you’re still using the original
brake light switch. Supposedly it will cause it to leak and fail. I just
use regular brake fluid.
Ready to fill up the master cylinder after replacing all lines. Which
brake fluid is most recommended for our cars? Used silcone in other
classic cars and have had soft pedal. Tempted to use the original
dot 3? Never had a problem with the stuff.
Sent from
Yahoo Mail for iPhone
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