164 technical opinion-vibration

[Alfa Romeo Search and Rescue Society <alfabill@xxxxxxxxxxxxx>]

Birkett, Graham wrote:
> 
> Bill 'one-lap' and Doug S make some good points about this problem in
> V7/230, the cars are very sensitive to out of balance forces (being fwd
> there's more to wobble I suppose) and there may be more than one unbalanced
> component causing wobble at different speeds.
> In my case, the new rotors (discs) have now eliminated the 60/70mph (worst)
> wobble leaving a slight and probably acceptable wobble at 80/90mph ( because
> I never travel that fast obviously!). Although I've swapped the wheels
> around without apparent effect it's now time to have a careful check for
> bent rims.

I have spent many hours trying to find the one step solution to this
problem and as much as I resisted, physics is what it is . I have solved
the problem in mine.

4 general, but different issues cause problems on the 164 front end:
	1) Wheel trueness, if such a word exists.  My alloys were pothole
dinged. Balance was perfect. This was a mechanical vibration from non
round wheels. Solution is to repair or replace the bad wheel(s). Even a
minor flaw causes a vibration, exagerated by 4 if they are all bent.
Mine would get in harmony and drive me nuts, hence 4 new wheels in the
middle of my One Lap.
	2) Warped brake rotors cause an "out of balance feel" but is also a
mechanical disturbance. Usually the rotors are beyond spec, so the
solution is to replace the rotors. I also had this problem, mainly
caused by Sebring usage.
	3) Worn front end parts, namely a-arm bushings and strut rotation
bearings.
The a-arm bushings wear and tolerances allow movement. My front end is
much more secure with the soft urethane bushings. Strut bearings,
according to Tony Wood in past postings can cause odd vibrations.
	4) Obvious but overlooked often is the quality of the balance job you
get. It is as good as the operator. Most standard spin balancers should
be adequate even for high speed operation. 

Summary:
If it is shaking, something is wrong, don't rule out the actual tire,
but today, it is seldom the real culprit.
	


Bill Harkell
Tampa Florida
http://pw2.netcom.com/~alfabill/enter.htm

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