There was a discussion not too long ago of brake fluids which I read
out of intellectual curiousity rather than any idea that it might
apply to me. As such, of course, when I pulled the front suspension
this weekend, I discovered a nick in one of the flexible hoses (and
later found what would have become a hole very soon in the rear
flexible hose). As such, I've pulled all 3 hoses and thus have
emptied most of my brake lines. As such, I'm thinking about
switching to DOT-5 brake fluid. My impression is that the advantage
to this is that it won't attack my point in the event of clumsiness
on my part and that it doesn't have to be bled as often since it
isn't hygroscopic. The disadvantage is that I have to get rid of all
the old DOT-4 already in there or the new stuff will be "impaired".
Thus my questions:
- What does "impaired" mean in this context? How will I know if I
haven't properly flushed the system?
- How do I properly flush the system? I've seen some people say that
I should run iso-propyl alcohol through it and other say that I
should just run DOT-5 through it.
- I'm confused about its abilities under hard braking. Roger
Garnett's list of vital fluids (which I save on 1 Aug) says that DOT5
"may be more prone to boiling in heavy braking usage" whereas Moss
promotes it in part because "Silicone fluids has a higher boiling
point". I thought I'd heard the problems under hard braking stuff
before, but if Moss wrote it in their catalog... :-)
- Someone had mentioned the procedure they use for initially filling
the system to help prevent the introduction of air. I don't remember
the details so would be interested in any information on this.
A quick update on the state of the car. The engine is running pretty
well now, although the mixture should probably be tweaked again at
some point to give a slightly smoother idle. To fix the suspension
and braking problems, I decided to rebuild the front suspension and
to replace the disk rotors and pads. The left side kingpin was in
pretty good shape. The right side was a mess. At least one of the
A-arms was bent. Both A-arms had developed almost an entirely new
bolt hole next to the original as the trunion pin ate it was down.
Apparently something (the kingpin I think) was rotating on the
trunion pin instead of a bushing so there's a nice .25" to .5" area
worn down into the threads of the pin. I still can't get that pin
out of the A-arm despite my best efforts with a hammer. (Mostly I'm
just curious to see exactly how bad off the A-arm and pin are. I
guess that's my answer. Now I've got a nice piece of memorabilia to
put next to the Lucas box in the office.)
After work, I'll head down to the mechanic (who sold me the car and
gives me advice) to use his solvent tank to try to clean everything
up before a coat of paint. Then, with a major suspension rebuild
kit, a tube shock kit (all 4 shocks were bad), new flexible brakes
hoses, new disk rotors and pads, and new A-arms, I should be set.
Thanks,
Scott
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