Thanks Pete and all the replied. Yes the simple thing to do is replace the
shock, but I do not have $120+shipping in my budget at this time to just
toss at the situation. (I am VERY tapped out with the V8 conversion on the
car.) Plus I have the time and energy, so if I can spend a day emptying,
cleaning, refilling and mounting the shock to completely rule out the
possibility of air in it I want to go that route.
I guess I see it as your engine loses oil, so just replace the engine, and I
don't jive with that scenario, call me stubborn, but if you can find out why
it happens, you can possibly correct the situation. However, I do
appreciate all of your folks input, I really do, I guess I am just a little
shocked that 95% of us never even think about working on thier own shocks or
even diagnoses what is wrong, they just replace them. If it was a $20 item
sure why bother, but these are a $100+/ea item and have agreat deal of
affect on the car's performance, so why not understand how they function so
that we can better tune our cars handling?
The poppet valve does sound plausible, in terms of what I felt from the
shock, so I will get some of the shock oil from my local moss distrib and
give it a go, once I mount it back on the car I will easily be able to tell
if new fluid fixed the problem. Can't you buy new poppet valve assemblies?
I know I have seen heavy duty versions in the catalogs.. Worst case it is
just bad and I use one of my backup shocks, if they are also bad I will have
to kill the V8 project and buy new ones.
Larry
----- Original Message -----
From: "Peter C." <nosimport@mailbag.com>
To: "Larry" <larry@larryembrey.com>; <mgb-v8@autox.team.net>;
<mgs@autox.team.net>
Sent: Monday, February 19, 2001 8:14 AM
Subject: Re: Shock help
> 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
> -
> 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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