Ken,
I did a fair amount of research on this topic before I elected to put DOT5 in
my TR6 post-restoration. Here are my thoughts:
Firstly, you mean DOT4 (e.g. Castrol LMA), not DOT3. DOT3 is universally
opined to destroy the rubber in the system and retains a lot of water. So,
the choice is DOT4 or DOT5. Also, do not confuse DOT5 with DOT5A. The latter
is NOT silicone; it is an improved DOT3, so it is unsuitable.
Secondly, the MC is steel, not aluminum, as are all of the front caliper parts
and lines. The rear cylinders, I believe, are aluminum. Conversely, the
clutch MC is aluminum, while the slave is steel. Go figure. So, your risk is
limited to the clutch MC and the rear cyls.
Thirdly, what I learned is that all of the "warnings" about DOT5 seem to come
from non DOT5 users. I could find nothing from anyone who actually uses it
who had any complaints, other than it is somewhat difficult to bleed when you
start with a dry system (I had this problem, but it just takes patience and an
extra quart of fluid to resolve). To me, the main advantage of DOT5 is that
it does not damage paint, a problem that virtually everyone has had since
these components all leak eventually.
Lastly, my bottom line is that I'd rather replace the aluminum bits
periodically than repaint the firewall (inside and out) and the servo. I will
be changing over my TR8 this winter, as well. But, the decision is yours.
BTW, I believe that the Buckeye Triumphs web site has a superb article on this
topic. Also, try searching this list's archive -- you'll find more info than
you really want!
Good luck.
Paul E.
Annandale, VA
71 TR6 Damson CC67060
80 TR8 Aqua TPVDV8AT210430
*****
Date: Fri, 5 Dec 2003 07:36:57 -0500
From: "Ken Owens" <kenowens@mchsi.com>
Subject: DOT 3 vs DOT 5
Hello Listees,
I have just purchased all new parts relating to the clutch hydralics and am
now receiving some conflicting advise on which fluid to use after installing
the parts. After talking with some who use silicone I thought this would be
the way to go. However, when ordering parts from BPNW Greg suggested I not
use silcone fluid as Girling parts (both brake and clutch) contain aluminum.
Apparently silicone does not get into the more porus aluminum material
(compared to steel) and the part is not protected as well. Consequently over
time the part wears away prematurely. They go so far as to say that the fluid
will begin to turn dark as the aluminum erodes. Since I am using new parts
for the long haul I want to make the best decision from the start and need
some help from the collective wisdom of the list. What saith ye all ?
Ken Owens
71 TR6
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