[TR] Brake fluid for Triumph

[DAVID MASSEY]

 I have heard several anecdotes about folks making the change by just bleeding and experiencing some sort of brake system failure soon there-after.  Makes me wonder if they would have suffered the same failure regardless.  I think DOT5 gets a bum wrap in these situations even if the seals are marginal to begin.  There is little indication that a seal is about to go so when it does fail one tends to blame the last thing one did to it.  But correlation does not prove causality.  Seals fail when nothing is done (especially if nothing is done).
I have converted three cars to DOT 5 and every time it was part of a total rebuild of the system.  I converted my TR6 in 1996 and it performed flawlessly for 12 -15 years.  I replaced the master cylinder several years back and more recently replaced all the lines (part of the frame repair this past year) but the calipers and wheel cylinders are still working just fine.  I converted the TR8 in 2000 and had no issues up until I wrecked the car in 2009 (over 50,000 miles).

I guess the upshot is if your braking system has been performing well for the last 15 - 20 years, you're running on borrowed time.  Start making plans to overhaul it soon.  Regardless of what fluid you are using.
 
Dave 

 
 
-----Original Message-----
From: Randall <TR3driver at ca.rr.com>
To: 'Sujit Roy' <triumphstag at gmail.com>
Cc: 'Triumphs' <triumphs at autox.team.net>
Sent: Wed, Nov 28, 2018 11:40 pm
Subject: Re: [TR] Brake fluid for Triumph


> Can I use DOT 5 in the Stag? Do I need to flush out the 
> current DOT 3/ 4?

Both of my Stags have DOT 5 in them.  LE1473 was converted just by bleeding
through at each corner until clean purple fluid appeared.  The other one
(dubbed Frankenstag because it appears to be parts from at least 3 different
cars) had a failed MC and stuck rear wheel cylinders when I got it, so those
were repaired at the same time.

However, LE1473 already had what seemed to be a minor master cylinder
problem before the conversion (pedal would sometimes drop towards floor
while sitting at a stop light), and it suddenly got a whole lot worse not
long after the conversion (no hydraulic brakes at all).  (I also learned
that the back brakes on a Stag are more prone to fade than a TR3.)
Post-mortem showed both MC piston seals torn, and approximately the
consistency of Gummi Bears.

So I'd have to say that "best practice" is probably to replace the seals at
the same time.

Randall

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