Bad Pull

With the crap winter we had I just got back to driving my 2002 C4S again. Anyway, I had the car lowered (H&R 1") and realigned at an indy alignment shop a year or so ago. When I picked it up the tech said it was the best he could do but and I'd have to live with a slight pull to the right. It wasn't too bad and I almost never noticed it. Fast forward and I've been driving it for a month or so. The pull is much more noticeable now, or I'm over sensitive to it.... I took it to the Porsche dealership the other day and they aligned it to GT3 non-aggressive to match the rise height. Didn't help. What could be causing the right pull with an assumed proper alignement?

It was hard for me to accept at the time, 1986, but tires can cause that effect.

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Previous accident would do it, bent control arms or tie rod and tires inflated to different temperatures. Also if you have gt3 spec alignment, they probably put essentially no toe-in on it, so the car will tend to wanna follow the slope of the road.

A consistent pull in one direction on a variety of roads with zero to a lot of crown and in different directions is not the behavior of a properly aligned car. Do you have a print out of the alignment values the car actually has? (BTW, I followed a thread on another forum about some issues with a Porsche and the consensus was the car was not properly aligned. The owner went back to a dealer several times and each time the car was checked and he was told everything was ok. Finally he took the car to another shop and the was put on the alignment rack and found to be out of alignment. It appeared the first dealer had been stringing him along all the time.) BTW, a "proper" alignment can contribute to a puling car. In some cases a bit of extra camber or caster is dialed in on one side at the front to counter the common road crown orientation. When used on a crowned road the car doesn't have as much pull due to the crown of the road. However, in some areas though the roads are not crowned and the car has a pull. You need a before and after printout of the car's alignment numbers. 'course, I'm assuming tire pressures are ok and all the tires are the same brand, and are identical in size, tread hardness, speed rating, and if unidirectional mounted in the right direction.

Yes, pressure and tires are all good. I may not have been clear in my description of the problem; the car seems to pull the same now as it did before meaning after the alignment there was no improvement. So as Macster implied, it may be properly aligned, but something else may be "off". I don have the before and after spec sheet on the alignment. Of course none of it makes sense to me, what should I be looking for?

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You need to see the actual alignment numbers taken from the car on an alignment rack. I am having a hard time imagining a properly aligned car -- with no tire pressure issues and with properly sized tires mounted correctly -- having any reason to pull. The alignment numbers should point the finger. Incorrect toe in or caster are the two settings that most have an affect on a car's tendency to pull. With incorrect toe you can feel the tire tread and perhaps detect some signs of scuffing/feathering of the tread this arising from a tire or tires that are properly aligned. Have to add I have so much confidence in good alignment numbers resulting in a well behaved car that frankly if the numbers do not indicate an alignment problem I would seriously doubt the veracity of the numbers.

I'm having trouble posting a pic of the spec sheet from my phone. I can type the before and actual numbers for caster and camber in if that helps. I know when a car is pulling from crown, and that certainly adds to the issue, but my car will change lanes in a couple hundred feet at about 50mph.

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I agree. Any competent shop would have noticed accident damage preventing alignment. Even more so true if you've taken it two places. There's a slight chance you can't visually see a bad tire, but I'm skeptical.

FR Camber = -1.0 before -1.0 actual caster = 8.6 before 8.6 actual Toe = 0.06 before 0.06 actual FL Camber = -0.3 before -0.9 actual Caster = 8.3 before 8.3 actual Toe = 0.18 before 0.06 actual RR Toe = 0.31 before 0.24 actual Camber = -2.4 before -2.5 actual RL Toe =0.33 before 0.24 actual Camber = -2.2 before -2.6 actual Again, the car has pulled since it was lowered. This alignment and the previous alignment made no noticeable difference. The car ran true before being lowered 1". Can lowering a car have that kind of effect? I sincerely doubt both places are doing poor alignments. I'm pretty tight with the sales mgr at the dealership so I don't think the service mgr would brush off my alignment. Tires were replaced between alignments so it's not tires, or highly doubtful. No history of any accidents.

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Looking at those numbers the car should drive pretty straight. Your camber numbers are quite a bit more negative than a factory ride height car but they're even from side to side. Ideally adding negative camber to the passenger side should help counteract road crown. Also your caster (which is not adjustable in factory trim) looks good. You have slightly more on the passenger side, which again will help counteract road crown. I would look at those numbers and say that car should drive pretty straight. Just for giggles I would try swapping your tires from side to side. Would take about 15 minutes in your driveway and I've seen that correct pulling issues.

Fwiw. I'm dealing with same thing Just dropped my Boxster down Took to race shop to get aligned I'm at Front -3.1/2.9 camber 8.1/8.2 caster .05/.04 toe Rear -2.7/-2.6 .18/.17 toe I now have pull to right at almost any appreciable speed. Had alignment double checked and it's basically identical to when it was aligned post suspension change a week ago All components look fine, as do tires. I have not swapped front wheels yet. Apparently on castor plates it would flop right on its own. Race shop is confused as well. Suggested maybe swap wheels to see. Mike

Well, my WAG is in both your case and the OP's case the extra negative camber is the cause. While the camber is the same per side, negative front camber reportedly makes a street car more "darty". This could be considered pull without stretching things. Found this note in the factory manual in the alignment section: The toe−difference angle value is also influenced by the vehicle height! For this reason the measured result must be evaluated accordingly! No action is necessary in the case of small deviations from the toe−difference angle required value, as long as the value to the right and the left is almost the same! What this means is not clear to me but I note both cars in question have been lowered. I could read the above as some alignment values are more critical when the car's ride height differs from stock.

In my case the alignment was done to GT3 specs (non-aggressive) which is lower than a stock C4S. My car is lowered 1", not sure how much lower a GT3 is than a stock C4S.

While your car may not be any lower than a GT3 it does not have the GT3 suspension and steering and as a result the alignment may *not* be compatible with your car's suspension/steering. I do not have the GT3 numbers but the GT2 height at the front with 18" wheel is 118mm to 123mm. At the rear it is 133mm to 138mm. Oh, wait I found on my notebook the GT3 and Carrera numbers� The Carrera 2/4 USA height is 158mm +/- 10mm and 163mm +/- 10mm. The GT2 height is 112mm to 102mm front and 125mm to 135mm rear. (The numbers are for 18" wheels.) Car is with a full fuel tank, and vehicle spare wheel (not the GT3) and tools, but with no driver or additional weights.

I swapped the front wheels this morning and it seems considerably better. The drive to work doesn't give me much opportunity to test. I'll report back once I can get some open road.

Straight as an arrow. No noticeable pull at all after the wheel swap. Props to PTEC!!! Thanks all!

Great to hear! We have a nice batch of knowledgable folks on this forum!

Are your front wheels directional? When you said swap, you mean just swap the whole wheel/tire without remounting the tires in the right direction?

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Correct. Simple wheel w/tire mounted swap. No, the tires are not directional.