[TR] Spit: 2 dumb discoveries, 1 to go?

Randall tr3driver at ca.rr.com
Sat May 30 20:19:44 MDT 2009


> Despite blowing out a piston earlier, the brake light comes 
> on only at startup and goes off after that. 

IMO that means the PDWA is not working, in addition to your other problems.
The shuttle should have gone to one extreme when you blow out a caliper
piston, and then stayed there.  While it is possible to move it back to
center by carefully bleeding just a bit of fluid from the other side while
both sides are under pressure, it's most unlikely IMO that you would have
done that by accident.  Normally you have to remove the switch and
mechanically push the shuttle back to center after an 'incident'; and the
light stays permanently on until you do that (or disconnect it).

> Does anybody have any ideas?

All I can make out is that you must still have a big lump of air in the
system, possibly in the MC itself.  I would start by bleeding right at the
MC fitting : Have your wife depress and hold the brake pedal while you
loosen and tighten the fitting; then release the pedal and try again.
Continue this until you get no more bubbles.  Then bleed each wheel using
the same method (pedal down first, then open valve, then close valve, then
release pedal).

IMO the pulling probably indicated something wrong in the suspension, rather
than the brakes.  If a brake was dragging that badly, you should be able to
tell easily by trying to turn the wheel with it jacked up.  It takes a bunch
of drag to introduce much pull, if the suspension is in good shape.
However, a bad bushing or whatever can cause the alignment (either front or
rear) to change significantly when the brakes are applied.

On my TR3A with the horrible pull, it turned out that one of the suspension
mounting points was pulled out of the frame.  Two different alignment shops
failed to notice that ...

Randall


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