Just a quick follow up on the recent question
about silicone brake fluid. I recall
you mentioning packing calipers and wheel
cylinders with silicone grease as well, do
you have a recommendation on which to
use? I use the Permatex lubes in my shop,
the purple stuff on metal to metal contacts
and the green for metal to rubber. Is either
of these OK or is there something different/
better? I’m getting ready for a brake redo
on my truck and want something that will
help keep these parts from going bad since
it’s a major pain to pull drums and hubs to
replace wheel cylinders. Also, any thoughts
on CuNi brake line?
Depending on my mood, I use either
Dow‑Corning silicone grease (thicker than
Vaseline), or some very old GE heavy silicone
fluid (barely pourable). I think the grease
does a better job long‑term, but probably
increases retraction time by a very small
amount. What I have never checked, and
have meant to for 40 years, is whether the
grease dissolves in the BFS—I suspect it
does, they should be miscible. If I’m correct,
the grease or fluid is really just an assembly
aid, although I’m betting it will offer some
corrosion protection in the caliper’s seal and
boot grooves for years to come. For external
rubbing/sliding parts, any good lube will do,
although I think the silicone is less likely to be
I have almost zero experience with
Permatex products so I can’t offer an opinion.
I am happy that they are again American
owned (they were part of Germany’s Loctite/
Henkel conglomerate for many years). Just be
100% sure that you use no petroleum-based
products in the brake hydraulic system.
With today’s phenolic caliper pistons, all
of these shenanigans become almost moot.
But phenolic isn’t really the hot ticket for
HD or race use (pun intended), and that still
doesn’t help with drums, where the concentrated
loads generated at the pushrod tip
seems to keep plastics out of the picture.
(Guys with a lathe and some stainless rod,
are you listening?).
From what I have read, Cupronickel
(Cunifer) brake tubing is excellent. I still
have tons of the ternecoated steel stuff, but,
when that’s depleted, I will be investigating
the CuNiFe alloy. It is said to be even easier
to work with and flare than steel, and will
obviously be much easier than stainless.
Many high‑end European manufacturers
now use it as standard equipment. The 3⁄16˝
size is rated for over 3000 PSI, and meets all
SAE and federal specs, so no worries there.
The only reason, as near as I can tell, why it
hasn’t made inroads in the US market is that
it, being softer, is more susceptible to roadhazard
damage—most new US cars use
unarmored brake tubing, unlike our classic
Mopars which had heavy steel spiral armor
in vulnerable areas. As far as I know, it is still
strictly made in Europe only, but can be had
here if you look around.