vibration/shudder at 70 - possible alternatives (other thanwheel balance?)

[scirocco81@vwmail.net (Eric S)]

Let me chime in with a "me too" on this.  The mk2 has done this since I got it, and it bugs the crap outta me.

And, patrick, I *just* put new a-arms with poly bushings in....no difference.  

Its done it with 13s with 175/70s and now with 15s with 205/50s, it already has new shocks, I was going to change the rear wheel bearings next and get a *true* 4-wheel alignment (shim the rear backing plates).  I have new half-shafts that I thought about trying...but now from hearing from you guys that it made no difference, for some reason, I think its coming from the rear....don't ask me why, just a gut feeling.  I will let you all know how it goes with the 4 wheel alignment.

--
Eric
Northglenn, CO

79 VW Iltis
81 Scirocco S (*TDI* swap and complete restoration in holding pattern)
81 Rabbit Truck LX Diesel (Waiting for BAE Turbo Install)
83 Scirocco Wolfsburg
91 Cabriolet (2.0 Crossflow 8v swap and mechanical rebuild in progress)


--- Patrick Bureau <txrocco@sbcglobal.net> wrote:
>Nope it did this with spider wv 13" , with Konig;s
>15x7 with new rubber, and still doing it with
>speedline 14" with new rubber as well... 
>
>it is not a tire/rim related issue I am pretty sure of
>it, Oh yeah add change bearings, cv joint, shocks and
>springs, ball joint and tied rods...
>
>I am thinking that it could be the sway bar bushings
>or the a-arms bushings that need to be changed (small
>bumps would cause because of deterioration of the
>bushing a "loose" vibration....
>
>I have the same problem on the prowler and I will know
>soon anought as I change the bushings for poly's on
>a-arms, and new sway bar bushings (oem)...
>
>
>
>--- Rhett Farnum <rocco_crossing@hotmail.com> wrote:
>> HOw about flat spots? I have at least one tire with
>> a flat spot on my Cut' 
>> and she likes to shake between 76-80mph. Just a
>> thought.
>> 
>> 
>> 
>> Peace Out,
>> Rhett
>> Rocco_crossing
>> '83 Rocco (autocross ready, tune up, harness bar,
>> rear wheel bearings, and 
>> finally I may get to makeing it look better!!)
>> 
>> 
>> 
>> 
>> 
>> >From: "Allyn" <amalventano@sc.rr.com>
>> >To: "scirocco list" <scirocco-l@scirocco.org>
>> >Subject: vibration/shudder at 70 - possible
>> alternatives (other than wheel 
>> >balance?)
>> >Date: Mon, 21 Apr 2003 20:28:24 -0400
>> >
>> >ok, the rieger has had the same shudder at 70ish
>> for the longest time.
>> >
>> >things changed:
>> >a-arms, bushings (all), bearings (all), half shafts
>> (replaced with a
>> >questionable set), engine/tranny, engine mounts,
>> and a totally different 
>> >set
>> >of wheels. not to mention rotors and hubs (i think
>> this covers just about
>> >every moving part).
>> >
>> >...and yet i still get the shudder...
>> >
>> >exact symptoms:
>> >
>> >- 0 vibration felt in wheel, even with the shudder
>> at its worst.
>> >- alignment is close enough such that it couldnt
>> cause a problem like this
>> >- shudder is not constant, the vibration is
>> consistent with wheel rotation
>> >at 70 mph, but it comes/goes at a 1 second cycle
>> (kinda like its amplitude
>> >modulated).
>> >- shudder seems proportional to throttle
>> application. the other day i did
>> >several runs on the highway, coasting from 90-60 in
>> neutral, and the 
>> >shudder
>> >seemed to go away. shudder returns when holding
>> speed at 70, and gets worse
>> >under acceleration.
>> >- feels like an out of balance wheel, but i've also
>> felt the same feeling
>> >when i had a bad inner cv (however the bad inner cv
>> had a constant
>> >vibration).
>> >- also seems like bad inner cv in that its almost a
>> side-to-side vibration,
>> >felt in the floor under the center console.
>> >
>> >possibilities:
>> >1. other set of half shafts (rebuilds from
>> potterman) had the exact same
>> >problem with the inner cv.
>> >2. frame/engine is misaligned such that one of the
>> half shafts is at its
>> >compressed limit when installed / car on ground.
>> possibly forcing tranny
>> >over as it rotates, causing the vibration.
>> >3. both sets of wheels/tires have had the exact
>> same imbalance, after being
>> >balanced several times between both sets
>> (doubtfull).
>> >
>> >suggestions???
>> >
>> >(thx in advance for info)
>> >Al
>> >
>> >
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>> 
>> 
>>
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