[TR] Brake Fluid

[Randall]

> Also, if anyone has any information on any

> requirements or issues in converting to DOT 5 silicone I would appreciate

> them.

 

Here's a nice write-up of the pros & cons of DOT 5 silicone

http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm

 

That article references two other papers presented to the Society of
Automotive Engineers, which you can find here

https://drive.google.com/drive/folders/0B2H2NJt34OffdnhWS19scjlNUU0?usp=shar
ing

 

I've been using DOT 5 for some 30 years; and IMO the advantages far outweigh
the disadvantages on the street.  (Racing is quite another matter, though, I
wouldn't use it in a race-only car.)

 

IMO, there is something to be said for doing the whole megillah when
converting: completely disassemble the system, replace all rubber
components, clean all the lines, cylinders etc.  However, I've converted
several times now by just bleeding through until only clean silicone fluid
comes out; and it still works out OK.  It just seems to take awhile before
you get the full advantage of the DOT 5.  It's almost like exposure to DOT
3/4 starts a slow deterioration process that doesn't stop (or may even
accelerate in some cases) after converting to DOT 5.  If you don't change
the seals now, they'll be leaking eventually and you can change them then.
By way of contrast, I am still using the brake calipers I rebuilt some 30
years ago and have never seen DOT 3/4.  Got to be well over 200,000 miles on
them; and the bleed screws aren't even stuck!

 

I also (eventually) switched to the "braided SS" soft lines and copper alloy
(aka Cunifer) hard lines.

 

As far as DOT 3 vs DOT 4; I don't think it makes much difference.  DOT 4 is
just like DOT 3 in that it will eat paint, absorb water (and salt!), turn
corrosive over time and so on.  This is an extreme example, but seems
typical to me of the kind of damage you can expect from DOT 3 or 4 if it
doesn't get changed.

http://s258.photobucket.com/user/TR3driver/media/DSCF0002_cropped.jpg.html

(Of course, what usually happens is that something starts to leak and then
the fluid gets changed while fixing the leak.)

 

There was a time when which brand was important (British brake seals didn't
like American brake fluid); but that doesn't appear to be a problem these
days.  

 

-- Randall

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