jcb100 said:
Triple...tell me your theroy on why you think it could be the sterring pump? Is there some type of damper inthe sterring pump that mught be going bad and letting something come thru to the steering wheel..please expound on your theory
Process of elimination...
Balancing problems usually come in at a certain speed, usually fairly high and usually circa 55 mph or slightly higher. This is when the imbalance sets up a resonance within the whole car as a system... you've got weights distributed at various places, with various 'springy' connections (tire sidewall 'squish', suspension springs, bushing tolerances, etc.), and several damping items (shock absorbers, soft bushings,...). One of my engineering courses in University involved modelling physical systems like this, using electrical components (weight/mass = capacitance, springs = inductance, damping = resistance). You can work out the resulting big-azz equations to determine how your overall system will behave under different excitations (harsh impact, simple displacement, varying inputs, etc...).
That being said, it's rare (not impossible) to have similar reactions like this shimmy at more than one range of speeds.
What's even MORE disturbing is that I have felt something like this shimmy through my steering wheel at speeds as low 25-35 mph... not as noticeable as what I feel at 60 mph, but enough to say "Hey, I
swear that vibration is similar to what I feel at higher speeds!". Also, at speed, I can somewhat control the intensity of the shimmy by nudging the wheel against the steering resistance... it either becomes more noticeable or sometimes completely disappears.
Now, do keep in mind that this 'shimmy' I get is not the type that is liable to get Marge Simpson's hairdo to come crashing about her. It's a subtle something... slightly noticeable through the steering, slight enough to have me wondering if it isn't just the road surface that is irregular (it sometimes is). But I know some roads like the back of my hand, and at those points I am sure it's something in my car, not the road.
I gotta add that my '98 WS6 seems more apt to react adversely to high frequency irregular pavement in a similar manner (ie. I start wondering if my balance is off, or my tires flat-spotted). The common item here is a Rack-and-pinion steering system. Say what you want, but I've always liked the feel of a recirculating ball type (I have this on my GTA and '78 T/A, and had it on my Parisienne and ever other American car I've ever driven).
But I do think there is something up with the MM's power steering system... it's the only car I've ever experienced that low speed *distant* shimmy.
(one more thing... the low speed thing I barely feel, is at the SAME frequency as what I feel at highway speeds... another giveaway that it might not be wheel-related).
(yet another thing... my MM's steering system is, in my opinion, noisy. At speed, if I nudge the wheel left or right, I can hear the low hiss of the system under load. Starting from a complete stop while turning, it's downright hellacious raspy... I used to think my diff was faulty!).
