[T3] Battery Install, Oil Change & Brake Fluid Reservoir

[Gary Forsmo]

I read your lengthy email ... three times ... to try to embed all of your
50+ years of knowledge, experiences and learning about the similarities &
differences of the DoT Brake Fluids.  And just as important; how the brake
systems on our aging cars function.

Your follow-up email made complete sense, too.  E-Brake adjustment in a
certain order is important & what to expect is understandable, also.

I think we get so accustomed to stopping our modern cars with power brakes
that when I drive my '69 Square the "feel" is totally different.

Thanks again for your tutorial.

BTW ... H.B.

On Tue, May 14, 2024, 12:24 PM Jim Adney <jadney at vwtype3.org> wrote:

> When my '68 Square was just a few years old, I started to have problems
> with the calipers sticking, so I decided to learn how to rebuild calipers.
> That's
> when I discovered that the OE brake fluid was blue, later determined to be
> ATe Blue, a DoT-4 brake fluid. ATe Blue is still available, but it was too
> expensive and too hard for me to get at that time in my life, so I
> switched to
> domestic DoT 3 or 4. As brake fluids, those worked just fine.
>
> Eventually, however, as I acquired a wife and a second Square, I started
> having more trouble than I liked, trying to keep the calipers and master
> cylinders on two cars all in good running condition. Seemed like something
> always needed rebuilding every couple of years.
>
> In the meantime, a good friend of mine bought a '71 Super Beetle and had
> his dealer install STP Silicone Brake Fluid in it. This was before there
> was a
> DoT-5 standard, so this did not have any DoT listing. I'd never heard of
> the
> stuff, but the memory stuck in my mind. Eventually, this led to a phone
> call to
> Dow-Corning, where I found a fellow by the name of Chip Nelson who had
> run the D-C test program for silicone brake fluid, which D-C had developed
> for the military. We had a couple of hour-long phone calls where Chip
> shared huge amounts of useful information. That was in 1977. I still have
> my
> notes from those conversations.
>
> For their testing, D-C offered to put their brake fluid in any employee
> car, as
> long as the employee agreed to let them do all the brake service on that
> car
> for free and to inspect and replace parts as necessary. They did this for
> several years, on as broad a spectrum of auto makes as possible. Chip
> explained that, for some reason, the only systematic problem they
> encountered was with Corvettes, where they found that the factory flare
> connections tended to be not quite as perfectly sealed as one would hope.
> They did not leak normal fluid, nor did they leak the silicon fluid, but
> they
> sometimes sucked in air on the pedal upstrokes.
>
> Every year, Chip and his team would replace brake parts on a number of
> those cars, to be cut apart to look for wear and rust. There must have
> also
> been a control group, because they published photos of cut apart cylinders
> that had been used with both silicone and normal brake fluid. The silicone
> bores were always shiny while the normal ones showed rust.
>
> Chip sent me a sample bottle of their brake fluid, which by that time had
> been qualified as DoT-5. I cleaned out the brake system in my beige '71
> Square and managed to fill the system from that small sample bottle. From
> that time on, that system never needed any new hydraulic work.
>
> Why is DoT-5 better? It's better for two reasons. First, it does not
> absorb
> water, so rusting of internal hydraulic surfaces in hugely reduced.
> Second,
> it's a MUCH better rubber to metal lubricant, so the rubber seals that
> have to
> slide along a metal bore tend to almost never wear out. I had found seal
> wear in master cylinder bores to be a big problem with DoT-4 and rust in
> caliper bores to be even more annoying. DoT-5 fixed both of those problems.
>
> Around 1980 I found a supplier for DoT-5 and started to install DoT-5 in
> various customer cars, all old cars, all daily drivers. I stopped keeping
> records of this after that list got past 50 cars. In that time, I believe
> I only had
> two "failures." One was with a Volvo master which stopped working. I
> rebuilt
> that master and found that one of the pistons was badly corroded and a
> chunk of that crusty white oxide had fallen off and worn a groove in one
> of
> the rubber seals. So I can't blame the DoT-5 for that.
>
> The second "failure" was some sort of British sports car where the owner
> wanted to do the work himself. He was never able to get the system bled
> and
> finally took the car to a different shop, where they replaced EVERYTHING
> and bled the brakes with their usual DoT-3 or 4. I never got to see any of
> that, so I have no way of knowing what the actual problem was, but I'm
> guessing it was user error.
>
> Over the years, I've heard many people tell me things about DoT-5 that
> simply aren't true. I've heard that if you allow it to mix with DoT-3 or 4
> it will
> turn to jell, but I have a little bottle of DoT 4 plus 5 that's been mixed
> since
> 1977. They're still there. You can shake it up and mix them as much as you
> like, but they will slowly separate and they're still perfectly fluid.
>
> I've been told that DoT-5 isn't compatable with some of the rubber
> compounds used in brake systems, but I've never seen a problem, and Chip
> explained the 4 (yes, only 4) different elastomer families EVER used in
> hydraulic brakes, and DoT-5 is compatable with all of them, even natural
> rubber, which was last used, even in rebuild kits, sometime around 1966.
>
> (Some of you may know that old British cars were known to use natural
> rubber brake seals, which required special brake fluid. Now they can use
> DoT-5. OTOH, this is no longer a problem, because those old cars have
> surely had all their seals replaced with seals made later than 1966.)
>
> I've also been told that DoT-5 is more compressible. That's true, but the
> difference is insignificant and imperceptable. This complaint often comes
> from the 914/4 crowd, where there's a huge problem getting all the air out
> of
> the proportioning valve. Yes, I've been there and done that, but once you
> get
> the last of the air out, the brakes are fine.
>
> Okay, how about downsides? There are three. First, it's expensive. Second,
> it's lighter than the glycol based DoT-3 & 4 (and 5.1.) Since the silicone
> is
> lighter, there are places where normal bleeding won't expell the old
> fluid;
> you'll just keep bleeding silicon fluid off the top. You can overcome this
> problem by mixing the fluids using turbulance, which is easy to create in
> master cylinders and wheel cylinders, but not possible in all parts of our
> front
> brake calipers. To bleed our front calipers, just unbolt them and bleed
> them
> slowly while they are upside down, with the bleed valves on the bottom.
>
> The late Type 3 calipers, with two bleed valves, make this easy: Just
> bleed
> the air off the top and the old brake fluid off the bottom. I like to go
> back and
> bleed a tiny bit off the bottom after a few weeks of daily driving, just
> to get
> any remaining old fluid out, and to give me an idea of how good a job I
> did of
> getting all the old fluid out in the first place.
>
> The third downside is that DoT-3 is probably not suitable for use with ABS
> systems in modern cars. This is apparently because there's lots of metal
> to
> metal contact in the ABS pumps, and silicone is not a good metal to metal
> lubricant. You may wonder about metal to metal contact in a standard brake
> system, but the side pressure on those pistons is minimal and no cause for
> a
> problem there.
>
> So, not a problem in our Type 3s.
>
> Since 1977, ALL my air cooled VW have had DoT-5 installed in them. I've
> had to do almost no maintenance on the hydraulics of those cars. The
> largest benefit may be with old cars in storage. When I got my '69 out of
> being stored for over 10 years, the brakes were still perfect. OTOH, I've
> got
> a '73 in storage for about 30 years. It's pedal now goes to the floor, so
> I
> know that master is going to need work.
>
> For anyone who's interested, I have a FAQ I wrote on how to install DoT-5.
> I'll gladly email a copy to anyone who requests it.
>
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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