ALIGNMENT ?? - 2003 Impala 3.4V6

I recently upgraded to H-rated tires of OEM size for my Impala and had 4whl alignment done as a package at a local Town Fair.
The improvement from S-rated to H-rated was noticeable, particularly in
steering response. No more squeal in turns, and a firmer ride. Unfortunately, the car "seemed" to exhibit some pull to the left, which
I brought the car back for the next week.
My sales rep reviewed the alignment printout which showed everything to
be pretty much within manufacturer's spec window, but proceeded to rack
up my car for an adjustment. And actually, the conditions that would contribute to a left-pull: more positive camber on the left, less positive caster on the left, were not the case!
Afterwards, I was handed a new print out, which showed my caster to be just outside the manufacturer's window, but all other measurements within spec. Caster for the '03 Impala should be +2.7 <> +3.7 deg, but
mine was +2.5L/+2.6R. I asked how the caster got to be so out of spec and will it effect my driveablity, the sales guy said, the other adjustments affect caster, and, no, it shouldn't effect driveablity.
Once back on the road, the left pull was gone, but now the car exhibits
little or no "center" feel to it. Steering wheel return after a turn is not nearly as nimble, and I often must correct slightly one I'm on the road I turned on to. And even at highway speeds, I have to guide the car to keep it in the lane I'm in.
If what the sales rep said is true, what other adjustments can have an effect on the Impala caster, which itself is not adjustable? And what should I have them do to get the caster closer to GM's +3.2 suggested spec?
Thanks in advance,
-ChrisCoaster
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Unless you were expieriencing extreme tire wear or some pulling to one side, WHY did you have a 4 wheel alignment done on a car that's barely two year old?
I never had one done till the front struts were replaced when the car was 9 years old.
========Harryface ======== 1991 Pontiac Bonneville LE 3800 V6 ( C ), Black/Slate Grey _~_~_~300,079 miles_~_~_
~_~_~_~_U.S.A._~_~_~_~_~_
~~~The Former Fleet ~~~ 89 Cavalier Z 24 convertible 78 Holiday 88 coupe 68 LeSabre convertible 73 Impala sedan
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Harry Face wrote:

I guess i just operated under the assumption that when you get new tires, you get an alignment. But you are right, and this Impala's ride was ok until Town Fair f^$%d with it!
The caster after the second alignment is now +2.5 deg(GM calls for +3.2, plus or - 1/2 a degree), and I'm always having to correct the car, even at highway speeds. Not to mention I have to cancel the turn signals manually more often than not.
Can a good alignment shop "crack" the tops of the front strut towers and straighten out this mess?
Also what other alignment ajdustments can impact caster?
thanks,
Frustrated
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ChrisCoaster wrote:

I seriously doubt that they actually changed anything to do with the caster. There are no adjustments to the caster on that car. The only possible way to move the caster a little bit is to move the entire subframe on the body. You can get a little bit of adjustment this way, but not much. I can't really see why any alignment shop would waste their time trying to do this.

Is the steering wheel centered properly?

No, and the fact that you are at 2.5 instead of 2.7 should really make little difference. What are the camber and toe readings?

None, you start by adjusting caster/camber and then move to adjusting the toe. On a truck, ride height changes will affect caster, but this will not affect your car.
Ian
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shiden_kai wrote:

simply is not positive enough. The steering feels so damn vague. The camber and toe readings were in spec as I recall, as were the caster before I had this alignment done.

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ChrisCoaster wrote:

Oh, well then what are you asking us on here for? You seem to be the alignment expert now. How many alignments have you done lately, if ever? You know next to nothing about it, you have to ask questions, and then you are going to tell me that you will feel the difference between 2.5 and 2.7? You are full of it! How do you know what the caster was before you had this alignment....you have a readout from a previous alignment, or do you foolishly believe that because GM says the specs are such and such, all vehicles come from the factory at exactly those specs? If so, you are sadly mistaken.
Go ahead and see if you can get some mechanic to hack your strut towers up to get the caster where "you" think it should be. Good luck! You don't understand much about FWD front end geometry if you think that caster will affect much on a FWD car. Why do you think there is no provision for adjustment? It's because it's not that "critical" on FWD car. Don't believe me though, I've only been a licensed tech for 24+ years, with a number of those years doing front end alignments on GM vehicles, be they cars or trucks.
Ian
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