I converted a 79 Spitfire and a 59 Sprite to silicon fluid in both the
brakes and the clutch.
This was done as part of a brake rebuild process. My main motivation was to
avoid future paint and metal corrosion problems. Interestingly, the DOT 3 or
4 (all the normal stuff), does not really harm the metal itself. It's just a
great paint stripper over time. It is also volitile AND moisture absorbing,
so it leaves the metal surface doublely vulnerable to the ravages of
moisture. This is why so many spitfire firewall shelves and sprite pedal
boxes are so rotted out. This is my non-scientific observation. Hopefully
some chemical engineer can be more exact with what's going on, as the topic
has been discussed many times on this list.
I am very happy with the results. I used original lines and hoses. Just
cleaned and rebuilt all cylinders on both ends of each system. I used
alcohol and lots of compressed air to clean and purge the lines.
The only problems I have run into are poor quality rebuild parts which
possibly work fine in DOT 3 or 4, but were a little balky in DOT 5. Go for
the best quality cylinders and rubber parts. Inspect for defects. Yes, some
rebuilt cylinders test fine, but are made up so tight they don't really work
right. This, IMHO, was to overcome some manufacturing shortcuts, i.e. not
carefully honing the bores.
But my complaints are minimal compared to the benefits. I highly recommend
the switch to silicon. Maintenace is a breeze. Performance is still great.
In theory, they say silicon absorbs more air, so it can feel spongier. I
think other factors contribute to sponginess as much and on a short run
system like a MGB, you would be hard pressed to note the difference,
especially on the clutch line.
Let us know how it goes for you.
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