<VV> front end shimmy
O.b. Stewart
obstew at bellsouth.net
Wed Sep 2 20:31:05 EDT 2015
I have a '65 vert that doesn' shimmy now, it drove me nuts trying to determine what was causing this shake at 45 mph, what was so annoying was/is the speed limit on the main road here is 45 mph, anyway, found some 14 in wheels with tires mounted and balanced, same problem, balanced them again, same thing, then on a whim I rotated the tires front to back, problem gone, It does not shimmy now at any speed......
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On Wed, 9/2/15, virtualvairs-request at corvair.org <virtualvairs-request at corvair.org> wrote:
Subject: VirtualVairs Digest, Vol 128, Issue 4
To: virtualvairs at corvair.org
Date: Wednesday, September 2, 2015, 11:00 AM
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Today's Topics:
1. Deleted comment (Jack Pinard)
2. Front End Shimmy - Not (Ray Davis)
3. Re: Front end shimmy (Jim Simpson)
4. Re: Deleted comment (George Jones)
5. Re: Deleted comment (Frank DuVal)
6. Re: Front End Shimmy (jbailey at daytonwa.net)
----------------------------------------------------------------------
Message: 1
Date: Tue, 1 Sep 2015 16:11:55 +0000 (UTC)
From: Jack Pinard <corvairjack at yahoo.com>
To: Virtual Vairs <virtualvairs at corvair.org>
Subject: <VV> Deleted comment
Message-ID:
<291952795.4166333.1441123915683.JavaMail.yahoo at mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8
Why was my comment Re: "Server upgrade" deleted from my
message?
"In interest of transparency, please publish list of all
contributors, with or without amounts."
Jack PinardContributor
?John W. "Jack" Pinard
116 E Garden Green Port Hueneme CA 93041
805-340-6533
------------------------------
Message: 2
Date: Tue, 1 Sep 2015 13:13:07 -0400
From: Ray Davis <scout1977 at hotmail.com>
To: Bryan Blackwell <bryan at skiblack.com>,
Virtual Vairs
<virtualvairs at corvair.org>
Subject: <VV> Front End Shimmy - Not
Message-ID: <BLU168-W600840CF78C23813889558B96A0 at phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
During the late 50s and 60s dance craze, the gals did what
they called the shimmy. It was not a front end thing
but a top end event! Miss those daze.
Ray
> Date: Tue, 1 Sep 2015 11:42:46 -0400
> To: virtualvairs at corvair.org
> Subject: Re: <VV> Front end shimmy Pt 2
> From: virtualvairs at corvair.org
>
> I believe there is a torque value in the shop manual,
and then you back the nut off and install the cotter
pin. Like Joel, I just snug them down then back off to
the cotter pin hole. The torque value is just there so
somebody doesn't crank down on them to get the tighter hole
to line up.
>
> --Bryan
>
> > On Sep 1, 2015, at 9:18 AM, Joel McGregor via
VirtualVairs <virtualvairs at corvair.org>
wrote:
> >
> > No. You tighten the nut to zero play with
your fingers and then back off until you can install the
cotter pin. Greased bearings have to have a little
play in them or they will fail quickly.
> > Joel McGregor
> >
> > -----Original Message-----
> > From: VirtualVairs [mailto:virtualvairs-bounces at corvair.org]
On Behalf Of Ralphsebrell via VirtualVairs
> > Subject: <VV> Front end shimmy Pt 2
> >
> >
> > So IF it is the bearings, is there a torque value
to achieve before the castle nut/cotter pin?
> > Part 3 soon, I hope
> > Ralph
>
> _______________________________________________
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> _______________________________________________
------------------------------
Message: 3
Date: Tue, 1 Sep 2015 13:57:22 -0400
From: Jim Simpson <simpsonj at verizon.net>
To: Virtual Vairs <virtualvairs at corvair.org>
Subject: Re: <VV> Front end shimmy
Message-ID:
<CAAeLaHt6yxw3r46=Qhff9L-5xyFfFR5piV_5Oo1CenLM2pe1Ng at mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
There are a couple of things people think of as front end
shimmy.
One is more accurately called cowl shake. Usually it's
visible as vertical
motion of the front hood. That's a body flexure issue
and Corvair
convertibles -- particularly late models -- are susceptible
to that.
Without the structural support of the top, a convertible can
bend in the
middle. Think of what happens as a car goes over
something like a railroad
track. First the front is pushed up and then drops
down again followed by
the rear doing the same. The car's body is somewhat
flexible and tends to
bend a bit. But it's also "springy" so if undamped, it
will tend to keep
on flexing up and down somewhat like a ruler if you hold one
end down on
desk and "twang" it. The "cocktail shakers" installed
in the front and
rear of the late Corvair are intended to counter that.
They're basically
just weights suspended in oil that act as vertical vibration
dampers. When
the car body flexes vertically, they absorb the energy and
damp that
vibration.
Front end shimmy is normally a front
wheel/suspension/steering issue where
things tend to vibrate horizontally. It mostly shows
up in the steering
wheel although if severe enough can shake the entire
body. There are many
causes as the earlier posts have noted. Usually it's a
combination of
problems/issues any one of which might be the trigger but
usually indicates
that there are several things you probably ought to take
care of .
In diagnosing and fixing front end shimmy, keep in mind that
the entire
front suspension and steering system -- including the body
structure -- is
a combination of springs. All of those steel and
rubber components are
flexible to some degree and will act as a spring.
Shimmy results when you
hit a resonance point in that spring system that amplifies
and maintains a
severe vibration.
Normally the shimmy is triggered by the tires and
wheels. It may be a road
irregularity or perhaps an inherent issue with the tire or
wheel such as
balance, broken belt, out-of-round condition, etc. But once
the initial
impulse is given then it's other components that sustain the
vibration.
Alignment: When a car is moving, there's a certain
amount of drag from the
wheels. If there is ANY flexure or play in the front
suspension (and there
is!), then the wheels will tend to splay outward from that
drag. Toe-in
compensates for that drag. In a perfect situation, the
wheels would be
perfectly straight and parallel, but given the suspension
and steering
flexure, it's best to have the wheels pointing slightly
inward (toe-in) so
that under normal conditions the front wheels are hunting
back and forth
over dead straight ahead. That hunting can cause
shimmy.
Wheel bearings: If the wheels start "hunting" back and
forth over straight
ahead, significant looseness in the bearings will allow them
to move
farther back and forth, accentuating the movement.
Steering components: Tie rod ends, pitman arm bushing
and loose steering
box (including the mounting bolts and rusted frame) all
contribute to
allowing the front wheels to wobble in something other than
a straight
path. Keep in mind that the steering components are
all designed to allow
motion (normally some kind of twisting), but because of
that, they have to
have some play. But as they wear, the allow more and
more play. So if
something triggers that initial wobble (shimmy), any loose
or worn
component in the steering will accentuate the problem.
Suspension: These are normally the most rigid
components in the front end,
but if there are seriously worn ball joints or bushings,
they can
contribute as well.
My recommended approach is this:
First rotate the tires. Poor quality, old worn, or
damaged tires are
frequently the trigger to shimmy.
Second check the alignment, particularly the toe-in.
Sometimes just
increasing the toe-in will eliminate the problem. But
that usually is just
a band-aid to a more fundamental problem -- something loose
or worn in the
steering.
Then check all the steering components, paying particular
attention to the
tie rods and pitman arm bushing. Play in these will
allow a sudden jolt on
one of the tires be amplified into a continued vibration
(shimmy).
Finally check the basic suspension -- ball joints and such.
Sometimes it can be hard to pinpoint a single item. As
I pointed out
above, the entire front end is a spring system with many
components all
working together.
Jim Simpson
Group Corvair
------------------------------
Message: 4
Date: Tue, 1 Sep 2015 19:13:46 -0400
From: George Jones <65crownv8 at gmail.com>
To: JackPinard <corvairjack at yahoo.com>
Cc: Virtual Vairs <virtualvairs at corvair.org>
Subject: Re: <VV> Deleted comment
Message-ID:
<CADXh+cetomgv6HVT_yRMPjkY2Ez8oOSXB1iBNzMUY7EgUtYokg at mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Jack,
Why would what I do (or anyone else, for that matter) with
my money be of
anyone's concern but my own? I'm not donating it to CORSA,
I'm giving it to
a friend (Bryan).
On Sep 1, 2015 12:12 PM, "Jack Pinard via VirtualVairs"
<
virtualvairs at corvair.org>
wrote:
> Why was my comment Re: "Server upgrade" deleted from my
message?
> "In interest of transparency, please publish list of
all contributors,
> with or without amounts."
> Jack PinardContributor
>
>
> John W. "Jack" Pinard
> 116 E Garden Green Port Hueneme CA 93041
> 805-340-6533
> _______________________________________________
> This message was sent by the VirtualVairs mailing list,
all copyrights are
> the property
> of the writer, please attribute properly. For help,
mailto:
> vv-help at corvair.org
> This list sponsored by the Corvair Society of America,
> http://www.corvair.org/
> Post messages to: VirtualVairs at corvair.org
> Change your options:
> http://www.vv.corvair.org/mailman/options/virtualvairs
> _______________________________________________
------------------------------
Message: 5
Date: Tue, 1 Sep 2015 22:13:59 -0400
From: Frank DuVal <corvairduval at cox.net>
To: virtualvairs at corvair.org
Subject: Re: <VV> Deleted comment
Message-ID: <55E65B67.9000801 at cox.net>
Content-Type: text/plain; charset=windows-1252;
format=flowed
I agree with both! A lot of organizations publish a donor
list with or
without amounts. So, when donating, note if you want your
name mentioned
or anonymous. Or just keep them all anonymous and be an
organization
that does not publish. But, since people have already given
without
permission yay or nay, err on the side of caution and do not
publish if
no permission was given. Have I gone full circle with this
thought?
Frank DuVal
On 9/1/2015 7:13 PM, George Jones via VirtualVairs wrote:
> Jack,
>
> Why would what I do (or anyone else, for that matter)
with my money be of
> anyone's concern but my own? I'm not donating it to
CORSA, I'm giving it to
> a friend (Bryan).
> On Sep 1, 2015 12:12 PM, "Jack Pinard via VirtualVairs"
<
> virtualvairs at corvair.org>
wrote:
>
>> Why was my comment Re: "Server upgrade" deleted
from my message?
>> "In interest of transparency, please publish list
of all contributors,
>> with or without amounts."
>> Jack PinardContributor
------------------------------
Message: 6
Date: Tue, 01 Sep 2015 19:27:53 -0700
From: jbailey at daytonwa.net
To: Virtual Vairs <virtualvairs at corvair.org>
Subject: Re: <VV> Front End Shimmy
Message-ID: <c1255626f176d28450767b10fbc1e20b at daytonwa.net>
Content-Type: text/plain
I have to agree with Shaun. My very first car, a 1965 Monza
Convertible
was purchased in 1974 with 35,000 miles on it. The car
always had that
shimmy at 35 - 45 mph as described below. A year or so
later, my father
bought a '66 Monza Convertible and it had the same problem.
No matter
what we did with either car, the shimmy always remained.
Both cars had
the "cocktail shakers" in place.
John B.
------------------------------
Date: Mon, 31 Aug 2015 23:06:52 -0700 From: Jay Maechtlen
<jaysplace at laserpubs.com>
To: S M <shaun_mcgarvey at shaw.ca>
Cc: virtualvairs at corvair.org
Subject: Re: <VV> Front end shimmy Message-ID:
<55E5407C.8060906 at laserpubs.com>
Content-Type: text/plain;
charset=windows-1252; format=flowed
On 8/31/2015 10:58 PM, S M via VirtualVairs wrote:
> I've driven 5 or 6 Corvair convertibles, all of them
did this... I've driven dozens of coupes and sedans, none of
them did this. Does anyone have a convertible that doesn't
shimmy at least a little in the 35-45 mph range? It's the
reason the "cocktail shakers" were implemented. Are yours
intact? yea, Vairily ... Shaun
------------------------------
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