Which brake fluid...
Tony Bennett
Should I stick to the old type which needs regular changing, or go for the
newer silicon based fluid. 1972 Type 1 front disc rear drum.
TIA
Tony
Wolfgang
hence longer stops! Stick to the old stuff.
"Tony Bennett" <tony.b...@tbcomputing.com> wrote in message
news:pan.2005.09.09...@tbcomputing.com...
Lorem Ipsum
news:YRqUe.12480$Cc5.7870@lakeread06...
> Silicone based takes more pressure on the pedal to compress the fluid ---
> hence longer stops! Stick to the old stuff.
What? That's crazy. You can't compress any of the brake fluids.
Anywho, unless seals have changed, the ACVW should use DOT 4.
Jim Adney
<tony.b...@tbcomputing.com> wrote:
>...to use in a restoration where all of the brake parts are brand new.
>Should I stick to the old type which needs regular changing, or go for the
>newer silicon based fluid. 1972 Type 1 front disc rear drum.
Either will work. Your other brake parts will last longer if you
switch to the silicone, but you have to flush it thru vigorously in
order to remove as much of the old stuff as possible.
There is some chance that the brake light switches won't last long
with the silicone, but I'm not convinced that this is the fault of the
silicone rather than the poor quality of current switches.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
Randall Post
> ...to use in a restoration where all of the brake parts are brand new.
> Should I stick to the old type which needs regular changing, or go for the
> newer silicon based fluid. 1972 Type 1 front disc rear drum.
>
> TIA
>
> Tony
>
>
I've used silicone fluid in my VW for 25 years with no complaints. I used to
have to buy new wheel cylinders when water, which is attracted by the old style
ethylene glycol based brake fluid, corroded the metal and leaked fluid past the
seals. Since I switched, I've never had to buy replacement wheel cylinders.
Randall
Tony Bennett
So thats one reply that says it requires more effort, a couple for the
silicon, and one for the old stuff it was designed for.
Question - if silicon fluid was widely available in 1972 would VW have
specified it.
Comment - I did stress it was a completely new braking systen - every
hydraulic part has been replaced.
Any more wisdom - I am inclining to Jim Adney's 25 year experience and my
gut feel that I'd give the silicon a try unless there was a convincing
argument to the contrary.
TIA
Tony
Joey Tribiani
"Tony Bennett" <tony.b...@tbcomputing.com> wrote in message
> Question - if silicon fluid was widely available in 1972 would VW have
> specified it.
>
nope...manufacturers don't spec it now for your run of the mill dialy
driver...
Randall Post
>
> So thats one reply that says it requires more effort, a couple for the
> silicon, and one for the old stuff it was designed for.
>
> Question - if silicon fluid was widely available in 1972 would VW have
> specified it.
>
> Comment - I did stress it was a completely new braking systen - every
> hydraulic part has been replaced.
>
> Any more wisdom - I am inclining to Jim Adney's 25 year experience and my
> gut feel that I'd give the silicon a try unless there was a convincing
> argument to the contrary.
>
> TIA
>
> Tony
>
>
This link explains the pros and cons of glycol based and silicone based fluids.
http://superchevy.com/technical/chassis/brakes/0509sc_fluid/
Randall
Tony Bennett
Thanks, and I did you a disservice - its you that has the 25 years
experience.
Tony
Jim Adney
<NOwolfgang...@cox.net> wrote:
>Silicone based takes more pressure on the pedal to compress the fluid ---
>hence longer stops! Stick to the old stuff.
Not true, and I think even Wolfgang would agree that this doesn't make
sense. The PRESSURE is the same in all parts of a hydraulic system,
this is the fundamental principle of hydraulics. So more pressure in
the master cylinder automatically translates into more pressure
elsewhere, like in the wheel cylinders. More pressure in the wheel
cylinders would mean more braking (assuming the same brake shoe
material.)
There IS the possibility of more pedal TRAVEL with silicone, if the
stuff is not installed properly and allowed to absorb air, but this is
different from pressure.
I've used it exclusively in all my VWs since 1978 and my experience is
that it actually reduces pedal force (and consequent system pressure)
simply because it is a much better lubricant between the seals and the
wall in the MC and wheel cylinders. IOW, it is slippery, and this
means that less pedal force is consumed in overcoming brake component
friction. The reduction in MC friction has made a HUGE reduction in
the wear that my brake component seals sustain in use.
Jim Adney
wrote:
>Anywho, unless seals have changed, the ACVW should use DOT 4.
The "rubber" seals used in all brake systems since about 1962 are all
compatable with DOT 3, 4, and 5 brake fluids.
Dot 4 has a higher dry boiling point than Dot 3, but I've had bad luck
with Girling LMA Dot 4. It just didn't lubricate well and my seals all
wore out in a very few years.
Both Dot 3 and 4 are hydroscopic, which means that they will absorb
water out of the air, bringing their boiling points slowly downward.
This means that they should both be flushed with clean, dry fluid
every few years.
The boiling point of DoT 5 is higher than either DOT 3 or 4, plus it
is non-hydroscopic, so it does not need to be periodically flushed.
Yes, I know that no one out there actually flushes their brake fluid.
Instead you just wait for something to fail and then replace it.
Flushing is a lot easier and cheaper. Replacement with DoT 5 is
expenive up front, but if you actually keep your car for a long time
it's well worth it, because of all the trouble and replacement parts
you'll save yourself.
If you're interested in DoT 5 silicone brake fluid, I have a FAQ that
I'd be happy to forward to anyone who emails me directly.
Jim Adney
wrote:
>I've used silicone fluid in my VW for 25 years with no complaints. I used to
>have to buy new wheel cylinders when water, which is attracted by the old style
>ethylene glycol based brake fluid, corroded the metal and leaked fluid past the
>seals. Since I switched, I've never had to buy replacement wheel cylinders.
Nice to hear from another convert. Your experience is the same as
mine.
I used to have to rebuild MCs about every 4 years and calipers every 2
years. When I got to about 4 ACVWs this got to be quite a work load. I
switched to DoT 5 in 1978 and have never regretted it.
Since then I've had to rebuild very few of my brake components. My
daily driver developed a bit of a leak in the MC a couple of years
ago. That car was a '73 that I bought in '90. I put in Dot 5 and
rebuilt the calipers and rear cylinders at that time, but I didn't
touch the (original) MC at that time.
When I recently removed the MC to fix the leak, it turned out that the
MC had developed some rust in the rear opening. The rust was holding
the seal slightly away from the MC wall, so the fluid could leak by
slowly. All I did was hone that rust down smooth, and clean around the
opening. I inspected the seals, and they were still fine, pliable and
with good sealing edges. I put those (original) seals back in, and
they've continued to serve well for 2 more years. I don't expect any
trouble from them unless the rust builds up again.
Jim Adney
<tony.b...@tbcomputing.com> wrote:
>So thats one reply that says it requires more effort, a couple for the
>silicon, and one for the old stuff it was designed for.
>
>Question - if silicon fluid was widely available in 1972 would VW have
>specified it.
They could not have done so. The fluid was available even before that,
but it did not get DOT approval until the late '70s. It was still
installed by some individuals, however, but some changes in the
formulation were made between '71, when a friend of mine installed it
in his Super Beetle, and '77 when I finally got serious about looking
for it. (It WAS hard to find in those years.)
We don't find it installed by OEMs because it is more expensive than
the polyglycol fluids. GM and Ford could not tolerate the extra $3 per
car that it would cost.
Harley and some other small makers DO install it at the factory,
however.
You may note that all the Bentley manuals for water cooled VWs
specifically state that silicone brake fluid should NOT be used in
those cars. I can not see any reason why this should be true. The
components in those cars are all the same as in ours. Dow-Corning, in
their testing, has installed silicone in hundreds of those cars, and
I've done it in dozens. I've never had a problem that was related to
the fluid itself in any car that I've put DoT 5 in.
There IS a legitimate question about whether it is appropriate for use
in modern cars with ABS systems. The automakers don't recommend it,
and I've not heard anything definitive on this. The concern is whether
it is a suitable lubricant for the ABS pump, which apparently has
metal to metal sliding surfaces. I don't know anything personally
about the inner workings of ABS systems, so I've shied away from
installing it there.
Randall Post
< snipped
>
> There IS a legitimate question about whether it is appropriate for use
> in modern cars with ABS systems. The automakers don't recommend it,
> and I've not heard anything definitive on this. The concern is whether
> it is a suitable lubricant for the ABS pump, which apparently has
> metal to metal sliding surfaces. I don't know anything personally
> about the inner workings of ABS systems, so I've shied away from
> installing it there.
>
> -
> -----------------------------------------------
> Jim Adney jad...@vwtype3.org
> Madison, WI 53711 USA
> -----------------------------------------------
>
The following link:
http://superchevy.com/technical/chassis/brakes/0509sc_fluid/
which I cited previously in this thread, makes mention of the incompatibility
of ABS and silicone under "Drawbacks #7".
Randall