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RE: more TR6 brake issues

To: <triumphs@autox.team.net>
Subject: RE: more TR6 brake issues
From: "Randall" <tr3driver@comcast.net>
Date: Tue, 21 Jun 2005 13:38:12 -0700
> I can rebuild the m/c easily enough; what about the
> booster?  Rebuildable?

The parts are almost impossible to find retail, and it takes some special
tools & techniques to rebuild it.  Makes more sense, IMO, to have it
commercially rebuilt.  Ashford already recommended PartCo ... I'd probably
enquire at my local independant parts store first since they seem to be able
to send out a lot of stuff to be rebuilt at very reasonable prices.

>   The next issue is fluif conversion.  Should I go dot 5?

You'll get lots of opinions there.  Seems like people either love it or hate
it.  Personally, I'm in the former category (along with everyone I know who
has tried it), wouldn't have anything else in my LBCs.  It lasts essentially
forever (unlike glycol which should be changed every few years), makes the
other brake components last longer, doesn't corrode the system from the
inside out (glycol can actually absorb not only water but salt, directly
through the brake hoses !), and won't harm paint if spilled.  Resists
boiling better than DOT 3/4 too, although that's not usually an issue for
Triumphs driven on the street.

>  Is it better?

Yes, in almost every way.  See below for some caveats.

> Is there anything involved besides draining the
> lines?

Again, opinions will vary.  To get the maximum benefit from switching, you
need to disassemble the slave cylinders/calipers and clean out all the old
glycol.  But IMO, most of the benefit of DOT 5 can be had by simply bleeding
each wheel until you get clean purple fluid out the bleed screw.  There will
be some glycol left in each slave that will appear as black gunk if you ever
do replace the slave seals.  But I've converted several cars this way, and
the gunk has never been a problem.

There are a couple of issues with DOT 5, one is that it supposedly 'foams'
more than glycol when agitated with air.  I don't know if that's true, but I
always wait a few minutes after adding to the MC, before continuing to bleed
the brakes, so any air bubbles formed by adding fluid have time to rise to
the top.

Another is that it is very slightly more compressible than glycol.  This
could result in a slightly lower pedal under heavy braking, although ISTR
Nelson Riedel analyzed it and said the difference during a panic stop would
be less than 1/2 inch at the pedal.  In any case, I've never noticed a
difference.  If it bothers you, you can "firm up" the pedal by converting to
Teflon/SS braided brake hoses, as they balloon less than the originals.

The last is that you can't just walk into any auto parts store and buy it.
I mail order mine from TRF by the quart ... fortunately unlike DOT 3/4 it is
safe to store DOT 5 after the container has been opened.  DOT 3/4 has a
definite shelf life once it's been opened, as it starts absorbing water from
the air immediately.

I wouldn't recommend DOT 5 for racing ... there are racing brake fluids that
handle heat better than DOT 5 and heat is a big issue for a race car.
However, they need to be changed several times a year to maintain their
effectiveness.

Randall




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