Date: Sat, 4 Jul 2020 00:32:24 -0500
Reply-To: Tom Hargrave <thargrav@HIWAAY.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Tom Hargrave <thargrav@HIWAAY.NET>
Subject: Re: FW: Brake reservoir
In-Reply-To: <CACvdLxM9TwZkeje_v9P_kH8UeW9sfbgftA49f_ZwYuAq4Rz0Eg@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
DOT 5 is silicone based and it's not compatible with DOT 3 or 4.
DOT 3 is glycol ether and it's hygroscopic.
It absorbs water from the air like a liquid sponge, and will cause internal brake parts corrosion if not changed annually.
DOT 4 is a mixture of glycol ether and borate ester, and it's much less hygroscopic than DOT 3.
It still absorbs water from the air but not near as much as DOT 3, and internal brake parts corrosion will be much slower with DOT 4.
I put DOT 4 in everything marked DOT 3.
DOT 5, being silicone based, will not mix with or absorb water. You will never have a corrosion problem with DOT 5 but DOT 5 is not compatible with DOT 3 or 4.
Also DOT 5 has some nasty properties. The brake fluid can trap micro-bubbles that will cause a spongy brake pedal that's almost impossible to bleed out. Plus any moisture that may be in the system, being heavier than the brake fluid, can migrate down to the lowest point in the system - the brake shoe cylinders or calipers - where the moisture can cause your brake pedal to go to the floor when you need brakes the most. This can happen if water is present and your brakes get hot enough to turn that little bit of water into steam. Then you have this steam bubble in your wheel cylinder that works the same way un-bled brakes work - you have no brakes until the steam condenses back to water!
Then some 'smart people', came out with DOT 5.1.
DOT 5.1 is borate ester with some glycol ether. It's even less hygroscopic than DOT 4 and should help even more with internal brake system corrosion.
But why they called this stuff DOT 5.1 and not DOT 4.5 or DOT 6, I don't have a clue!
My 92 Harley-Davidson shipped from the factory with DOT 5. I went down to Auto Zone to buy DOT 5 and the sales person said 'Oh, you mean DOT 5.1, here's some.' I said 'No, I need DOT 5' and he responded with 'But DOT 5.1 is better.'
Oh, and I need to do more research on DOT 5.1. If it is really is compatible with DOT 3 and 4 then I'm switching my DOT 3 and 4 vehicles to DOT 5.1 because less corrosion is always a good thing.
Thanks, Tom Hargrave
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-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of David McNeely
Sent: Friday, July 3, 2020 8:51 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: FW: Brake reservoir
Larry, you understanding is the same as mine. But the older designation fluids are still available. I do understand that the newer types (Type 5 for example) will stand up to higher temperatures. But, I continue to use the one specified, which for my camper is Type 3, iirc. Interestingly, that is also specified for the power steering, rather than a dedicated power steering fluid. Perhaps someone more expert can enlighten me as to why that is. mcneely
On Fri, Jul 3, 2020 at 4:09 PM Larry Alofs <lalofs@gmail.com> wrote:
> Once, a long time ago, I believe that I learned that DOT 5 was not
> compatible with brake systems designed for DOT 3 and 4.
> Have I been operating under the wrong misconception?
>
> Larry A.
>
>
> On Fri, Jul 3, 2020 at 3:00 PM Stacy Schneider <vwcrewman@gmail.com>
> wrote:
>
> > I’ve always put it in with my waste oil.
> >
> > On Fri, Jul 3, 2020 at 11:50 AM Robert Clemmer <n51219@comcast.net>
> wrote:
> >
> > > With all this discussion about brake fluid, what is the proper way
> > > to dispose of brake fluid?
> > >
> > > BobC
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
> Behalf
> > > Of Dennis Haynes
> > > Sent: Friday, July 03, 2020 10:34 AM
> > > To: vanagon@GERRY.VANAGON.COM
> > > Subject: Re: Brake reservoir
> > >
> > > Looks like I didn’t put the fluid on the bill. Ravenol DOT 5.1.
> > > There is an arrow on the left side of the reservoir indication the
> > > fill line.
> > >
> > > Dennis
> > >
> > >
> > > From: ddbjorkman@verizon.net <ddbjorkman@verizon.net>
> > > Sent: Friday, July 3, 2020 8:52 AM
> > > To: d23haynes57@hotmail.com; ddbjorkman@VERIZON.NET;
> > > vanagon@GERRY.VANAGON.COM
> > > Subject: Re: Brake reservoir
> > >
> > > Thanks Dennis. I was wondering if anyone got my post. I wondered
> > > if there was a fill line I couldn't see. Topping off has been
> > > what I have done in the past. How about any way to check brake
> > > fluid that's been
> in
> > > it's container for a year or so. BTW, which DOT fluid was used
> > > when
> you
> > > last worked on the system?
> > >
> > > Dave B.
> > >
> > > Also BTW, Dennis located and fixed significant errors done on a
> bearing
> > > and brake job done on my vehicle just prior to my bring my Westie
> > > to
> him
> > > for transaxle work, which turned into suspension work, which
> > > probably
> > saved
> > > us a few times on our 3 month trip out to the Grand Circle of NP's
> > > and
> > lots
> > > more around them.
> > >
> > > -----Original Message-----
> > > From: Dennis Haynes <d23haynes57@hotmail.com<mailto:
> > > d23haynes57@hotmail.com>>
> > > To: ddbjorkman@verizon.net<mailto:ddbjorkman@verizon.net> <
> > > ddbjorkman@VERIZON.NET<mailto:ddbjorkman@VERIZON.NET>>;
> > > vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM> <
> > > vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>>
> > > Sent: Thu, Jul 2, 2020 7:03 pm
> > > Subject: RE: Brake reservoir
> > > Brake fluid is something that should be checked regularly. As the
> > > front pads wear and the pistons move out the fluid level will
> > > drop. If the
> > system
> > > is kept topped off it is very important that during brake service
> > > the bleeders are opened as the pistons get pushed back or the
> > > fluid will
> get
> > > pushed up and over flow the reservoir.
> > >
> > > As the fluid is inside the vehicle is does not get contaminated
> > > that easily although it is an open vent design. Some set ups use a
> > > diaphragm
> > to
> > > keep air off the fluid and allow for the level to change as needed.
> Still
> > > it is a good idea to purge and replace the fluid every 2-3 years.
> > > If nothing else frequently opening the bleeders will help prevent
> > > them freezing in place.
> > >
> > > Dennis
> > >
> > > -----Original Message-----
> > > From: Vanagon Mailing List <vanagon@gerry.vanagon.com<mailto:
> > > vanagon@gerry.vanagon.com>> On Behalf Of ddbjorkman@verizon.net
> <mailto:
> > > ddbjorkman@verizon.net>
> > > Sent: Thursday, July 2, 2020 10:42 AM
> > > To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
> > > Subject: Brake reservoir
> > >
> > > Switching out a broken antenna. Fine time to check brake fluid.
> > > I noticed my brake reservoir was not filled to the top. Should it be?
> > Brake
> > > work done last year. My brake fluid is somewhat old, how do I
> > > make
> sure
> > it
> > > has not absorbed moisture etc. while sitting?
> > > Dave B.
> > >
> > --
> > 1989 Swedish Tristar with Aluminum gates and Atiwe 16" Wheels.
> > Oldest son is an Eagle scout.
> >
>
-----
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