Larry,
Despite having spent a considerable number of hours working on the
adjustment of these Fiat calipers, I have not been able to figure out how
they are supposed to work. I had first noticed that one of them took quite
a bit more motion of the EB lever than the other to lock the rotor. I
wanted them the same and to lock with a minimum of motion of the cockpit
handle. I tried everything I could think of to try and get the offending
one to have less free motion - all to no avail. When you replace brake pads
or for other reasons need to remove the caliper, you screw in the piston
using the slot in its face. Any attempt to force it directly in is futile.
Some calipers have a notch on one edge of the slot that, I believe, is
supposed to be installed pointing up. I spoke with the local Fiat repair
guy and he said that if the caliper has a lot of motion to engage the EB,
then there's nothing you can do to fix it, short of buying a new one -
which I wound up doing. Incidentally, the caliper I bought from him looked
a whole lot nicer than the one it replaced, and worked better in terms of
the EB action too.
I'm still not certain there's not a way to adjust the free lever action on
these units. Also, I'm not sure, but I assume there's some kind of
automatic adjustment that takes up the slack as the pads wear - but I'm not
sure of that either. Sometime when I have some spare time I'd like to
completely disassemble the piston assembly - if that's possible - to find
out just how that tricky one-way piston works.
As far as the amount of friction with the pads, I wouldn't worry about that
as it will probably loosen up as soon as you drive it a little, due to end
play, run-out, etc. You might try prying the pads back a little to see if
they loosen up. Although, as I said, you can't compress the pistons without
screwing them in, I would think they would move enough to quite riding on
the disc.
Larry, if you find out how these calipers are supposed to work, or if
anyone else on the List has the answer, I'd sure like to hear about it too.
One other thing: When you get the GQ on the road, try and rein in your
enthusiasm and stay close to home for awhile until you are pretty sure
everything is working OK. And take the time to inspect things carefully
after each test run. Usually, in spite of being as meticulous as possible,
a few things usually still need "sorting out". It took me several months to
sort things out completely after my restoration, but I expect yours won't
take that long.
Have fun,
Bob
At 08:11 AM 10/27/99 -0400, Wright, Larry wrote:
> I got _really_ close to finishing the GQ last night. I was
>checking out the handbrake, and wondered if any of you who've installed
>rear discs have any recollection of the handbrake mechanism on the
>calipers. The cable seems to move freely enough, and pulling up a couple
>of 'clicks' actuates the handbrake. However, the lever arm on the
>caliper, in the "released" position, is forward a good 1/2" from what is
>would be when the cable is disconnected altogether. Also, there's a fair
>bit of friction resisting motion of the wheel -- but that's also true
>when the cable is disconnected -- more than on the front wheels. Any
>thoughts or observations?
snip, snip, snip, . . . . .
>Lawrence R. Wright, Purchasing Analyst
>U S Office Products, Mid-Atlantic District
>Formerly Andrews Office Products
>larry.wright@usop.com (new)
>Ph. 301.386.7923 Fx. 301.386.5333
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