RE: E30 highway vibrations

[alex.fadeev@xxxxxxxxxxx]

Nicolas.Roman@domain.elided [mailto:Nicolas.Roman@domain.elided] wrote:
> 
> that is what i was suspecting... my 94 e36 has the original sports
> suspension and i have brand new tires which balanced to zero...  
> yet i get a little vibration at 45 but not at 90.... normally, if
> it is a balancing problem the vibration will repeat at double the
> speed.... (as they fall in the same frequency range....)

FWIW,
When I put 2" dents into my driver side wheels on DFW road-titties (don't
ask), I would get vibration at around 85-95mph. Could never verify the 2x
speed theory - the car barely goes to 165 ... -)

> my question is, since i am here.....  i already noticed my tires
> getting worn on the inside (all around, worse in the back) 

That's normal - rear tires wear mostly on the inside while fronts wear
primarily on the outsides (depends on how aggressive your turns are),
assuming the suspension geometry is stock. Thus the incentive to rotate the
tires front<->rear.

> i have 17,235,40 my car came originally equiped with 15,225,50

Is that miles or dollars?

> would i be able to correct this camber problem with alignment alone? 

Rear - yes.
Front - no, unless you install aftermarket camber plates (very good idea if
you autoX - the cost of camber plates will be made up with the increased
front tire life).

> I understand my car probably handles a little better with the 
> camber as is.. but heck i paid 750 for those dunlops 9000
> any input would be great... thanks

Nicolas, 
First of all don't even look at how much S03-PPs cost.
Second - assuming your wheels are not staggered ('94 should not be), rotate
the tires. 
Third - high performance E36 wheels rarely last past 20K miles. That's the
price you pay for great grip. 

alex f

> Nicolas Roman
> Senior Engineering Consultant
> North Miami Beach, FL.
>
> On Wed, 19 Sep 2001 alex.fadeev@domain.elided wrote:
> 
> > Adam Lazur [mailto:adam@domain.elided] wrote:
> > >
> > > I begin to feel mild vibrations around 45 or 50 in both 
> > > the steering wheel, shift knob, and a little in the gas
> > > pedal when the vibrations get worse. If I increase speed 
> > > to 60 it gets worse and I get a more serious vibration and
> > > a slight hum. The vibration then varies in severity all 
> > > the way up to 80.
> >
> > Adam,
> > 55-65 mph vibration are frequently either out of balance 
> > tires or bent wheels.
> > Just for kicks, swap your front/rear wheels and see if the 
> > vibration gets better/moves to the back of the car.
> 
>  Nobody has brought up the possibility of worn suspension
> bushings.  These can cause vibrations too.  Have 'em checked!

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