Larry,
Interestingly, the "dead zone" that you are feeling is likely not
from there being air in the shock, but rather some dirt or possibly a
weakened poppet spring, or a scored bore. When there is air, the shock
actually locks up as the air isn't sufficient to open the metering valves.
(that large nut perpendicular to the 2 piston chambers.) The shock is meant
to be almost completely full of oil. When the pistons move the oil through
the valves, the displaced oil in the non-pressurized bore is allowed to
pass through the non-pressuring piston. It sometimes happens that one of
the 3 types of poppet valve in the piston hangs open so that at the time
when the motion is reversed, the poppet valve is open on the pressurizing
piston no allowing oil to pressurize and open the metering valve. This is
usually determined when the dead spot is felt at any point in the arm swing
when it is reversed. (NB. this poppet valve is why it is not recommended to
use a very heavy oil like STP or such, as while it will indeed flow with
more resistance through the metering valve, it will also flow too slowly
through the poppet valve. The poppet valve spring is quite light.)
A scored bore occurs when a piston wrist pin works loose and cuts
a groove in the bore. The dead spot is felt only in one direction and for
only about 30 degrees of arc.
Bleeding instructions, which might help with changing out the oil
to clean the poppet valve, should still be in the archives. I can repeat
them if necessary and requested.
HTH Peter C
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At 10:21 PM 2/18/2001, Larry wrote:
>Hello all.
>
>Last summer I had a couple instances where I almost lost control of my B
>during "chatterbump" type road conditions. The car would just drift to the
>left during these episodes, then as soon as I was off the rough surface all
>was fine. My gut instinct told me shocks, but I had no way of checking as the
>car was being my emergency transportation while another vehicle was down. I
>also had a clunk up front so thought it might be a bad bushing.
>
>Well, finally this weekend while tearing the front end down for an engine swap
>I found the culprit. the shock has what I will call a "dead" zone in it. The
>shock arm will move a good 1"+ without any resistance. then it will get thick
>like it should. this tells me there is air in the system.
>
>What do I do to get rid of this?? Drain the entire shock, then refill it?
>are there any "tricks" or procedures you folks could recommend? My haynes
>manual tells me nothing..
>
>Larry
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