How to fix an improper alignment?

[Por_sha911]

I just got the car back from the shop with some major front end work:"frame" straightened, new A-arm, Turbo tie rods, front crossbar, new ball joint. Had a 4 wheel alignment done. It pulls to the right and the steering wheel is a hair off center. On the interstate it with the hands off the wheel it takes about 2-3 seconds till it is on the right line from the center of the lane. It is not the crown of the road. The shop said bring it in and they'll adjust the toe so that it doesn't pull but they don't want to put it back on the alignment machine. Is this reasonable? I was thinking that we should check all the measurement. What do you think?

[BoogieOnSkis]

Did you replace the tires? If not, it could be a tire pull.

[Por_sha911]

What is a tire pull? RF tire was removed and put on a new Fuch.

[Tyson Schmidt]

Get it corner-balanced. Especially since the chassis was straightened.

If the CB is is off significantly, it can pull harder than any bad alignment would.

[Por_sha911]

Tyson-thanks for the idea. Is it normal for a shop to not want to put the car back on the machine to make sure there isn't a problem? Will adjusting the toe fix the car driving down the road but affect the wear of that tire?

[Tyson Schmidt]

Toe does not cause the car to pull. It will cause the steering wheel to be off-center though.

But the total toe can be fine, yet still have an off-center steering wheel.

Camber and caster discrepancies between left and right cause a pull. But it takes a fair amount of difference, and in fact usually is built-in to compensate for road crown.

As I said, if the car is off in corner weights, it wall have a far greater effect on pull than if the alignment tech is off a few tenths on the camber or caster.


EDIT: just wanted to add that aligning the car with used tires can have a great effect on pull, since there is a wear patter on the tires, and that can actually cause a proper alignment to make the car pull.

[stormmaster]

if you only replaced one tire that may be a major part of your problem

[Por_sha911]

Tires were not replaced. I replaced the wheel (same size) and put the old tire on the new wheel (the wheel was balanced).

[76911]

If the tires aren't directional switch the two front tires side to side and
see if there is a change first. If there is then it's a tire pull

[Quicksilver]

If they had to straighten the frame and replace an A-arm and they didn't automatically do a corner balance then they don't know enough to be working on a Porsche. You can't look at it and guess. You have to measure it.

Ask them if they did a corner balance. If not it needs it. If they did (or even if they didn't) look carefully at the wear on the tires to see if the tires are wearing symmetrically. If they aren't at the same tread depth it will effect the accuracy of the corner balance. If you end up getting it corner balanced it wouldn't hurt to see if a friend will let you borrow a set of fresh tires with consistent sizes. (That is probably over kill though...)

[Por_sha911]

The tires are directional but I'm still not sure what "tire pull" is. Maybe I understand the physics but I'm just am not familiar with the term. Can someone please explain?
I asked if they did a corner balance and they said no, just a four wheel alignment. The tires have miles on them so I'm thinking that it would be wiser to do a corner balance when I put new tires on the car.

[scottbooth]

I am also interested in learning the science behind a "tire pull".

Last summer I bought a used BMW 325XI out of state and was hit by a tractor trailer while driving it back from the dealer (and shortly afterward, commenced drinking heavily).

After the body shop was done with the car (besides the body work, they replaced front right tie rod, strut and wheel) my coworker in VA (where I bought the car) drove it and noticed a pull roughly similar to what you describe.

The body shop claimed it was a "tire pull" and swapped the front tires. I was suspicious but when I went to pick up the car it tracked straight and has continued to do so ever since.

So there must be something to it, I just don't know what it is.

Cheers,
Scott

[Tom '74 911]

I will second (or third or fourth) the vote for a corner balance. Your car could be aligned nuts on as far as the alignment rack and computer is concerned and still pull severely if the corner balance is not correct - Ask me how I know! If you had the car re-bent and some of the suspension replaced (A-Arm) - get it corner balanced!

JMO! Tom

[Por_sha911]

Thanks for the help. I'm bringing it in the end of this wk. Now back to a question: What is "TIRE PULL"?

[Jessie7188]

Tire pull is when the belts in a tire get loose.It will have a higher rolling resistance.Mostly felt as a pull when this happens on a front tire but can be a problem if bad enugh on a rear tire.By switching tires from one side to the other sometimes will correct a pull do to the crown in the road if switched from right to left.Thats what I was told enyways:-}Cheers

[BoogieOnSkis]

Put 'radial tire pull' into a google search -- you should find plenty of reading material.

[lespaul]

Forgive me, but what does it mean to straighten the frame? How is it done? How would one know that the frame needs to be straightened? Sounds serious.

[Elombard]

As the former owner of an alignment establishment I will agree with Tyson 100%. I also had this experience with my 911. The Corner weighting corrected a significant pull.

As a side note the shop does not want to put stuff back on the rack because there is rarely a reason too. Unless a sensor slips or something else really weird happens the alignment rack wont help. Any remaining problems are the result of worn parts, tires, bent chassis etc. We used to get people coming in with massive vibrations thinking an alignment would fix it.....Usually we would jack up one front wheel and shake the tire. Amazing what 2 inches of slop in a broken ball joint will do :-)

A big part of an alignment is to check for worn parts, unfortunately by the time most owners decide they need an alignment its because something big is worn out. Then they want the $49.99 alignment not the $499.99 parts and labor to make an alignment even possible. Its a fine line, I found most cars did not need an alignment unless parts were worn out, unscrupulous owners when they sense resistance to repairs or an unprofitable repair will sell an alignment on a car that will absolutely not hold an alignment. Its like pointing a spaghetti noodle north. By the time it rolls off the rack its pointing a completely different direction.

Another note: "street" cars have soft rubber bushings that allow the suspension to not be jarring ..blah blah. Why align cars to within a nats hair when as soon as you back it off the rack everytithing is moving around. It just needs to be pretty close on a street car. I think the manufactures design in so that everything sort of pulls into a straight line when you are going down the road. You may be able to see why alignment on race cars is so critical based on these comments. When you add spherical bearings etc. and there is no movement any where except in the specified planes you are really losing time dragging that tire if its not pointed straight ahead because the bushings cant flex and allow it to go straight ahead.

Also, its pretty easy to pull the steering wheel off on these cars and re-clock it. Vs. messing aruond with tie rod ends and screwing something else up.

[Jessie7188]

I was stating the loose belt problem may be a cause of the hit the poster indecated he had. If the tire was switched on a rim that needed replaced the tire is the first to take a hit before the rim.:-} Cheers

[Por_sha911]

Elombard: you may be right on all that you say but if you read my original post, you will see that I had a valid shop do a lot of repair/replacement work. I am not trying to get a $500 repair from a $50 alignment. Apparently you've had many problems with customers quite a bit on that but this is not the case.