Alignment vs mpg
 

Ive always had a pull in my car to the right, not super bad (would take about4 seconds to steer off the road at highway speed)but definitely noticeable. Has anyone checked their MPG before and after a good alignment?

My alignment was way off, but getting it re-aligned did not make a difference in FE. One reason could be the fact that my camber was also bad and the front tires were riding on the inner edges making a smaller contact patch with the road.

Here in the Netherlands all cars have by default a pull to the right. That's because when you're driving and go knockout the car will slowly go to re rights and leave the road. But 4 sec is indeed a bit to much.

how is your tread wear? if your tires are wearing pretty even in the front, then i don't see it making much of a difference. if your front tires are "cupping" (especially the right-front), then they are dragging to one side when the steering wheel is straight. i can see this hurting mpg if its bad enough.

The farther away from 0 degrees toe in you get, the more your tires are scrubbing (and the more force it takes to move the car).

Right at 0 can translate to a bit of toe out, and any amount of toe out means it will be work just to keep the car on the road ;)

Tires wear pretty bad on the inside after a few thousands km's far more then normal. Thanks for the inputs, ill post my change in mpg after I got an alignment done

Radial tires are wound in such a way that they creep to the right by default. Woulen't want them going to the left now would we? Roads are also crowned to help with drainage - and suspensions (depending on the caster) can be sensitive to side-slope.

I had a right front wheel bearing problem with my Celica, that caused the car to pull right, and the alignment to be out enough to see odd tire wear (prematurely wearing of the inside edge)... after I fixed it, FE got better by about 2-3 mpg.

My thinking is this: If there's worse than normal tire wear, you are scrubbing the tire(s) and therefore wasting energy.

Alignment can effect fuel economy due to the "scrub" effect from improperly aligned tires.

How can this be? Youve got both sides of the car, and also youve got the choice to have them mounted whitewall in or out. Only a handful of tires are directional tires.

If you take a wheel from the right, and put it on the left, it's now spinning backwards - thus, it still has the same directional creep. If you mount it whitewhall in, it's now spinning backwards - thus, preserving directional creep. It has to do with how the non-radial, non-belting plies are laid, and how even the radial and belting plies are seamed. The only way they'd creep left is if you drove in reverse. Only then, reverse would be the new forward, and left would be the new right.

So even if you take a directional radial and spin it backwards, it still maintains creep. Directional tires are only directional because of tread design. Some performance tires are built with a stiffer sidewall to go outside - thus, they're not directional, but inside/outside specific.

There are some tires that are spiral wound, but the gyroscopic effect of how the tire is constructed is offset by the balancing. No tire on your car should cause a pull in any direction, given proper mounting and balancing. That being said, the best FE alignment is zero toe (see dcb's post above). Once the car starts moving, any suspension dive will result in toe-out, and the accompanying loss of directional stability. If you have the proper front geometry, this can be negligible, but unnerving. I recommend 1/16th toe-in as a minimum for experienced drivers, 1/8th toe-in for less experienced drivers.

FTR, I run my car with zero toe...

Bull. Balancing accounts for nothing except for uneven weight distribution of the tire wheel combination. Balance has nothing to do with how a tire, deforms, twists, squashes, and otherwise interacts with the pavement.

A tire's behavior while in contact with the road, and thus under forced deformation, may not entirely be as simple as we imagine for a perfectly balanced, perfectly round tire. As a simple example, the part of the tire where cords overlap (commonly seen as radial lines in the sidewall of cheap tires) indicates a part of the tire that is stiffer. Even if perfectly round and perfectly balanced, such tires may "roll" as if that stiff spot were a "high" spot on the tire. IE, they don't roll round, but they are round. That is why certan manufacturers test their production for balance and rolling dynamics while spinning them under load against a rotating drum.

This very deformation of the tire as it rotates into and out of the contact patch is the reason that tires with diagonally laid layers will tend to have a desire to walk one direction or another under load. While radials have far less diagonal character compared to bias-ply counterparts, there are still diagonal features, such as joints in belts and cords banded at low angles.

Tire rolling dynamics are far more of a complicated subject than anybody has business getting into on this forum. Certain people, and certain people I know in the business make honest livings employing technology to explore the subject in manufacturing enviornments. Certain companies hold patents on large sections of the territory. Ever notice what tires come stock on a Honda? Cadillac? Yup, they pay extra to get those, and they have to, because certain companies put extra time and money into monitoring these things. Certain auto manufacturers are now demading that their OE tire suppliers give them tires that DO NOT REQUIRE wheel weights. However...

I was simply trying to suggest that just because your car tends to go to the right when you let go of the wheel does not necessarily mean that you need to run to the alignment shop. It may actually be designed into the equation. Certain patterns of "uneven" tire wear are actually quite normal, which is why we will always be told to rotate our tires. Every corner of the car will tend to wear differently. If you can do it every oil change, you're off to a great start. Once you can see uneven wear, it's too late.

Of course, maybe none of this applies on ecomodder. Since everyone runs infinite air pressure, infinitesimal contact patches take loaded behavior out of the question. Oh, but wait, even if the air doesn't flex, the rubber still will.

My truck calls for zero toe.

Im not sure if that was a rant or what, but my car is 19 years old, and pulls hard to the right, steering wheel when traveling straight is crooked and the only time it drives straight is on the wrong side of the road, Ive driving enough cars to know my alignment is off + the insides of the tires are going bald with after like 7000k, not normal. Cops run the PSI at 50 in the training cars, rising about the factory spec isn't necessarily a bad thing.

Wasn't a rant. I agree, poor tire wear indicates a tire being scrubbed. Scrubbing a tire is a waste of energy and an indication that something is causing higher rolling resistance. If you say it pulls hard, I believe you. I tend to wonder why cars go out of alignment over time. I got one airborne one time on a dirt road (dukes of hazard style) and changed my upper mcpherson pivot plate locations once, but that's pretty non typical. It's not like your a-arms or frame are bending, are they?

My theory is that lots of cars will tend to sag on their suspensions over time, which may very well be your case at 19 years. IME, sagging tends to cause excessive wear on inside edges due to camber issues typical of suspension geometry on every car I can imagine, even independent rear suspensions. Short upper arms or McPherson setups tend to go "top in" as they sag. I've seen this on most of the cars I've worked on. I don't know if coil springs tend to sag (I know leafs will) or if it's just the rubber spring seats that compress over time. Sagging will also cause your tie-rod end geometry to change, so toe will be out also.

You'll see in most of my posts - here or elsewhere - I tend to ask more questions or think of other contributors more often than I jump to the typically accepted conclusion. For instance, I know plenty of people say they need an alignment when their steering wheel is off centered. Some people (on s10forums, for instance) confuse this with "pull." While a good alignment tech will fix this, you can be perfectly aligned with a steering wheel off center. If you experience straight tracking on the left crown of the road, then I agree. You needs an alignment. I was simply throwing a word of caution and more factors into the equation before suggesting an alignment. Why? I had to have one recently on my truck and the best price in town $60 for a two wheel only - on one of the easiest to adjust setups ever. It was saw-toothing the inside edges - typically an indication of combined caster/toe issues.

I think we're all on the same page here. The first step in ecomoding is to wisely spend money on maintenance issues - but avoid spending money on things that may not help in reality.

Speaking of money and alignment...

I should mention that it is pretty simple to check toe and camber on all 4 wheels with a plumb bob, a small block of wood, a clean garage floor, a pencil, a tape measure and a calculator (and some basic trig).

It'll get you in the ballpark if you're out. Could be a good plan for Meph. Whole degrees are pretty reasonable, but tenths of a degree are pretty hard to come up with. Add also - make sure to scribe lines on your tread. You can't really trust that the tread blocks on your tires are axially even.

I put the block on the rim (assuming it isn't bent) and transfer marks from 3, 6, 9, and 12 oclock to the floor on each wheel. Bring the bob to a halt right above the floor and take care with the tape measure and your interpretation of the last digit and you can probably get close to 1/10 of a degree.

0.1 deg on my 16 inch rim is a shade under 1/32th of an inch. That's why they use lasers to project that bad boy out there.

I get more like 1/72 of an inch. My tape measure has 1/32 markings on it (0.225 degrees) Lasers not required to get accuracy below one degree though :) It just makes it a lot easier to do quickly in a shop.

Um, math check on aisle three. Top to bottom of a 16" rim is just under 1/32nd at a tenth.

Another barrier to doing it on the garage floor is that jacking the car up and down to make adjustments will tend to bind up the suspension - preloading a-arm bushings. You can walk most of it out of there, but those roller plates on alignment racks are there for a reason. I've tried toe measurements and found that this alone made it difficult to get repeatable results. Alignment shop said I got within 0.2 degrees, but I felt I was further off than that based on difficulty repeating measurements. If you're multiple degrees out, just dropped your truck, or replaced suspension parts, you can get close enough to get to the alignment shop. However, long, term, I think it's worthwhile to pay the guy with the lasers.

Plus - scribing lines on your tires for toe as opposed to measuring from the rim actually accounts for bent rims that would throw off rim-centric techniques. So, actually better than a lazer alignment in this regard if it turns out well.

0.2 is pretty good, and you are supposed to bounce the car before measuring, and I avoid letting other people touch my fleet like the plague, you have to factor in the number of times they goof something up into the results ;)

Bouncing, rolling, turning the wheels doesn't quite equal those roller plates.

Yup. I think they actually set mine up to 0.0 caster. Mine has the sport steering box and needs some caster to help it out. Back I'll go to ask questions. Alignments are pretty much the only regular item that gets contracted. We know a great guy back home, but that's the cost of moving away from your resources.

re: math check

a 16 inch diameter rim would scribe a circle of 50.27 inches if rotated around a fore-aft or verticle axis (i.e. toe-in or camber).

50.27 / 3600 = 0.01396 inches per 1/10 degree, or roughly 1/72 of an inch

Yes, only if you're measuring edge position relative to the center of your rim. However, I think most of us would measure edge vs. edge. So your 8 inch radius gets doubled.

I showed my work, rim to rim, 2x8xpi=50.27. Where's your work?

16" * sin(0.1 deg)

Ah, thx, interesting. I was looking at it geometrically, if you consider the pivot for toe adjustment is located near the center of the wheel, then the basis for making a degree comparison would be the radius (8 inches), even though the tire toe measurements themselves are about 16 inches apart.