Jim, what generally wears alum brake parts, is contamination. Dirt,
water, and corrosion.
Most people don't change brake fluid that often, and as a result the
above starts it work.
If you bleed the MC for example, and the piston has only traveled
through the normal distance, then when you change fluid, it goes into
that area where all that crud is, the the seal is denigrated, cut, and
leaks can start.
While Tiger Tom did some studies several years ago, on swelling of seals
with DOT 3 or 4 vs Silicon DOT 5, the studies showed, if I remember
correctly, that DOT 3 and 4 had a slightly larger swelling ability.
So wear is not because of the fluid, but contamination in the system.
How do you solve that?
First with DOT 3 or 4 change fluid every 2 years.
Second, if bleeding an older system, you will damage the seals if they
pass that crud, corrosion, dirt, etc., so you Power Bleed.
There are several power bleeders on the market, EZBleeder for around $40
is what I use, but you can go higher, and it is a one man operation, and
fairly easy.
I personally don't like Silicone DOT 5 (and yes there is non Silicone
DOT 5, very expensive race fluid), because as someone said if you change
you have to disassemble the entire braking system, flush to get all of
the old fluid out as they are not compatible, and generally replace all
seals as you are going to disassemble all the parts anyway.
Silicone does not absorb water, as DOT 3 and 4, but water, moisture,
does enter the system, and some antique cars owners have had the brake
lines rust from the inside out, as the water accumulates at the low
point in the lines. But it will not hurt paint. Of course, if you race
the car, don't use silicone.
BTW, what do your brake lines look like? Shinny, and not rusty, I hope.
But not 35 years old.
DOT 3 or 4 is cheap, and with a power bleeder it is simple to change
fluid, without hurting the seals.
Initial investment in a power bleeder, and a $3 can of DOT 4 every 2
years and you are all set.
Larry
Jim Blackwood wrote:
> So I guess nobody can answer my question then. I would have hoped that
> some wear studies would have been done, but apparently if so the info is
> not available. I'm familiar with all the other characteristics,
> problems, attributes etc and would be using silicone exclusively, but
> when a slave cylinder costs over $350 you think twice about wear.
>
> Jim
>
> -----Original Message-----
> From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net]
> On Behalf Of Gary Moore
> Sent: Tuesday, April 08, 2003 9:53 AM
> To: Theo Smit; tigers@autox.team.net
> Subject: Re: Hydraulic fluids - getting your DOTs lined up.
>
> Very interesting piece of disinformation. Dot 5 is silicone in the
> United
> States. The advantage of Dot 5 is it's permanence. To install into an
> existing system you must strip and thoroughly remove any vestige of
> Dot3/4.
> Once done it will not deteriorate under normal conditions. You can pour
> on
> your hood and all it does is to shine the paint. It does not attack or
> swell
> seals including the rubber ones in old English cars and bikes from the
> pre
> sixties. I find Dot 5 performance quite acceptable but then I am not
> racing
> down Pikes peak which is the example nay sayers like to use."Altitude
> change" if there are air bubbles in system gives soft pedal. The fluid
> knocks the hell out of master cylinder, wheel cylinder, brake hose and
> fluid
> sales. Now you know why it's unpopular. Regards, Gary
> ----- Original Message -----
> From: "Theo Smit" <tsmit@shaw.ca>
> To: <tigers@autox.team.net>
> Sent: Monday, April 07, 2003 8:01 PM
> Subject: Hydraulic fluids - getting your DOTs lined up.
>
>
>
>>Hey gang,
>>I've found this FAQ from the Bel-Ray site to be great for putting to
>>rest the what-is-compatible-with-what and where-should-I-use-silicone
>>debates.
>>
>>http://www.belray.com/consumer/Q&A%20pages/q&abf.html
>>
>>Bel-Ray is a well-known supplier of high performance fluids in the
>>motorcycle world which is why most of the FAQ mentions bikes rather
>
> than
>
>>cars, but I think the basic information is most useful: Silicone
>
> fluids
>
>>are not compatible with glycol fluids, and DOT 5 does not imply
>
> silicone
>
>>everywhere in the world.
>>
>>Theo
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