DIY Alignment Question - Toe Plates

So I'm working on making some adjustments to my alignment.  My aim is for just a little bit of toe out in the front.  I have some toe plates.  Right now the measurement in front of the wheels is 70".  The measurement behind the wheels is 69-3/4".  Does this indicate I have 1/4" of toe out (the combination of deviation on both sides) or do I have 1/8" of toe out (the difference measured at just one side)? 

Also a bit confusing - the toe plates do extend a few inches past the rim, both front and back.  If I were using strings and measuring the deviations at the rim edge, I would be getting smaller differences in measurement front vs rear.  Can anybody help me understand better?

Yes, your car has 1/4" toe out. That's more than I run on my race car but ymmv. 
No, when using strings, you measure to the rim of the wheel at the front and rear edges. Same concept as toe plates but without the plates

The way I understand it you would have 1/4" total toe out in the front, but that doesn't necessarily mean it is a symmetrical 1/8" toe out per side. This is one of the challenges with toe plates...you are assuming the previous alignment is symmetrical and lines up with the rear of the car. 

The spacing of the toe plate from the edge of the wheel shouldn't matter so long as it's the same difference between the front and rear of the wheel. A lot of alignment specs are in degrees. I usually measure at the edge of each side of the wheel and convert it to compare to the service manual. 

thanks. 

But do you see my point about the toe plate vs the string?  The place where you measure on the toe plate is exaggerated a bit compared to the lip of the rim. 

In reply to Lof8 - Andy :

You have a point, but its probably not that great of an exaggeration. 

With a little bit of trig you can find the angle the toe in is.  If you post the width of the toe plates (from where the measurements were taken, not from edge to edge) then we can figure it out. 

In reply to Lof8 - Andy :

It's a rather small enough difference in length comparing the measurement at the wheel to the measurement at the toe plate that you shouldn't notice much of a difference. 
 I havent noticed a difference in measurement on my car comparing string to toe plate. 
ymmv 

In reply to Lof8 - Andy :

Its a great question and one no one has been able to answer to my satisfaction. I tried to align my car with the string method but never to my satisfaction. 

Let's take a common size tire/wheel. 225/45-17. Overall diamter is around 25" and lets say the wheel is right around 17". Based on yout numbers, you would measure front to back

70" (right at tire edge front)
69.96" (rim edge)
69.79" (rim edge)
69.75" (tire edge back)

The difference would be greater as the toe plates extend further from the tire. You have 1/4" at tire edge and .17" at the rim. So you go from 1/4" to less than 3/16". 

Even worse when I go by degrees, its impossible to measure with a tape accurately. I have no idea how people do it at home, I am probably missing something but I was never able to understand it. 

When you are using toe plates, you have a few errors to observe.  The toe is measured at the outside circumference of the tire, if measuring in inches.  Your toe plates, if longer than the outside dimension of the tire, will be give you a larger number. It probably isn't as significant an error as the difficulty of holding both plates in place properly, and the fact that you are measuring from the surface of the tire which may be erratic, and there is no way of compensating for the runout of the tire and wheel, or the sidewall variation on the tire.  Having raised letters under the front of the plate, but not under the rear will give you error.

That's why a real aligner makes you do runout compensation, and specs are often stated in degrees instead of inches or millimeters. 

Set the toe, run the thing, watch tire wear, check lap times, and guess it into place.

And as to string toe adjustment, make sure you have the same offset and track width front to rear, or you can have errors there, too.

I'm not dismissing the utility of strings and toe plates, either.  I use a digital carpenters level for camber.  Just remember that you are coming up with a number which may be repeatable, but may not be real.

because when you're dealing with street cars, even one with uber solid bushings or heim joints, there is enough play in it all that you're getting it within 1/16" at the best.

Pure race cars are a little better, but you generally have better access and rarely have to make huge adjustments after most services.

One more thing to remember is that the numbers don't matter, except in reference to the same number from the past.

Assuming you're adjusting things correctly (same amount on both sides relative to the centerline of the car), whether you have 1/8" of toe or 1/4" is meaningless, as what you're trying to do is optimize handling vs tire wear as StreetWiseGuy says..  Run it, and then say "Yep, 1/4 was too much" so, measuring the exact same way, you now set it to 1/8.

Unless you have a laser setup that's calculating the distance between their own measurement devices, your specific numbers won't apply to someone else, nor will their numbers really mean anything to you.

Timely thread. I picked up a set of toe plates a few weeks back to attempt my first home alignment. 

Re: front wheels being parallel to the long axis of the car, I chewed on it for a while and this is what occured to me:

I was going to start by using two pieces of string tied to each side of one of the plates, then strung diagonally to the same location on the opposite toe plate. If the wheel is centered and held there well, by adjusting toe such that each diagonal string is equal in length, it should mean you're centered and starting @ zero toe, right? I THINK you can do that and clear the edges of the tire, unless you've got small diameter, wide tires. I haven't checked clearances yet.

I just finished replacing every bushing and wearable suspension component on my e46, so planning to attempt this over the long weekend. Figured I'd need to do the same in the rear of the vehicle.

I hold about a 4' length of 1x1" square tubing on the top of my toe plates, and measure the distance from the square tube to the rocker panel, and make it equal on both sides.  Then as I adjust the toe, I adjust each tie rod equally (one turn, one flat, half a turn, three flats, whatever) until I get the toe I want.

I do the same with the rear as well, to make sure the rear wheels are pointing straight before I adjust things.

The last thing I do is test drive and adjust the steering wheel position if need be, by lengthening one tie rod and shortening the other.

Toe plates are pretty crap IMO. I can consistently repeat and measure down to 1/64" of an inch of toe on my setup. You'll never get anywhere near that with toe plates, there's just way too many potential points of error.

Also inches of toe is a very ambiguous way of expressing amounts of toe. My alignment spreadsheet automatically converts my measurements to degrees.

In reply to freetors :

sounds like you have it all figured out.  Care to share what your using?  Instead of just coming in with hot takes 

WonkoTheSane said:

One more thing to remember is that the numbers don't matter, except in reference to the same number from the past.

This x10.

It doesn't matter whether you have 1/4 inch toe out or 4 inches toe out. What matters is what is fastest on your car and if you can set it repeatably. 

In reply to 79rex :

I've posted about it on here before but I'll take a run through it again. I've developed this process through dozens of alignments on my cars and friends'. I'm still constantly dreaming up new tools and thing that might make it easier or faster but for now this what I do. It's not a fast or easy job, heck just getting everything setup can take hours. But the results are impeccable and I don't need to do it often so I've accepted that. This will be a long series of posts.

I always start with a good clean garage floor, sweep out all the dust and pebbles and crap. Next you'll need to figure out how to get your car leveled on your floor. I doubt many people have a perfectly flat garage floor and mine is no exception, it actually slopes several inches from front to back. If I need to bang out a quick and dirty, toe only alignment then I'll use linoleum floor tiles to raise the wheelprints where they need to be. I would recommend buying an eight foot level and a digital camber gauge for this. Eight feet barely gets the job down for leveling front to back. Some nice rigid and straight box tubing of the appropriate length would also work really well. Also a machinists level would be great but I find the 0.1 resolution of the camber gauge on to top of the level to be "good enough".

When I'm doing the whole shebang I'll use corner weight scales on top of a set of longacre scale leveling pads so I can get everything leveled better (but way more tedious). The leveling pads have the because added benefit of getting the car a few more inches off the ground too. Setting these up deserves a paragraph of it's own. 

If you're going to use scale leveling pads you need to plan ahead a bit. You need to lay out on your floor where you want the car to be and by extension where all of you leveling pads will go. Lay out pads out on the floor where they need to go and get them all paralleled and squared up with each other. Now if you ever plan on aligning your car again mark each foot position on your floor with paint or something. Now you need to get each scale leveled to itself and to each other scale. I will pick the scale pad on the lowest part of the floor and raise it all the way up and level it. This becomes my "key" scale to level an the other to. Leveling a scale is good conceptual practice for corner weighting if you want to do that. My pads have six feet which are all adjustable. Shorten the two middle feet all the way or they will fight you. Go ahead and level the scale either other four feet. It's worth noting that tightening the nut in the foot will take up the slop in the threads and will raise that corner an amount equal to the thread pitch. Once it's leveled you can lower the middle feet being careful not extend them so much that they are preloaded. Now you get to repeat this on all the other pads, just make sure to constantly check it back to the key scale.

Stay tuned for part 2.

So now that you've done all that you can get your car up on whatever you've used to level the car. For ease of making adjustments you'll want to cut out friction underneath your tires. There's plenty of documented ways to do this so just use your imagination.

From here, my strategy depends on what I'm planning on doing or how off I think the current alignment might be. In a perfect world there would be no crosstalk between different adjusters but that's almost never the case. In some applications I've seen adjusting the camber to have an almost one to one effect on the toe and vice versa. In case like these you'll generally have to sneak up on both adjusters simultaneously. But because camber usually has a big effect on toe it's generally the first thing I'll adjust. Just bear in mind that a really good alignment is an iterative process. You will likely need to go back and forth a couple times. Adjusting camber before setting up your strings also has practical benefits too. For one it's easier to do without all the stuff in the way, and camber adjustments on strut cars generally requires jacking the car and taking the wheel off which would decalibrate your string setup. Don't forget to bounce the car after each adjustment to settle everything.

Stay tuned for part 3: setting up the strings.

So, to answer 79Rex's question: you're using a string alignment.

So now we're ready to setup the strings. This, IMO is what really separates the men from the boys. There are many ways you can mess this up. I've read so many diy alignment guides of people who get this wrong by taking giant assumptions. Once you get this setup you will also need to frequently double check that your car is still centered between the strings, it WILL move around. After you've set up your strings to be perfectly parallel do not touch them! Walk around them very carefully!

There are many ways you can setup strings from basic and janky to pretty advanced. When I first started doing alignments I just set up a piece of conduit and clamped it to a pair of jack stands and stretched out the string from front to back. I got tired of all the slop in this setup though. Now I'm using some scaffold jacks bolted to some old brake rotors. On each jack post I have a t-piece welded up from different size conduits. The largest tube slips over the screw jack. Then there's a medium sized conduit welded on as a t. The main conduit passes through it and some thumb screws hold it all together and allow for width adjustments. The scaffold jacks allow me to easily raise and lower the string to hub height on every corner. For string I use bright green mono filament fishing line.

Now that you have your strings stretched out along the car, move the ends so that each string is the same distance from every where center cap. This will NOT be their final resting place, only a starting point. Always measure perpendicular to the srting and use a machinists scale for better accuracy.

Nowtake your 8 foot level, a tape measure, and a large carpenter's square to measure how parallel the strings are. There's a bit of a technique to this. Set the level across the floor perpendicular underneath the strings. Don't forget to level your level with floor tiles too! Stretch your tape measure out on top of the level. Set one leg of the square on the top of the level and gently slide it up to the string. You want to just barely touch it, enough that you can't see any air between. Slide the end up the tape measure up to the square. Take your square over to the other side and slide it up the the sting. Take a note of this measurement. Repeat this process on the other end of the car. Now you'll see just how un-parallel your strings are. Now is the long and tedious process of moving the string ends in to slowly converge on having both perfectly parallel strings and also equidistant left to right.

Next is part 4: measuring and adjusting toe.

SkinnyG said:

So, to answer 79Rex's question: you're using a string alignment.

Yes.

This is the easy part now. All you have to do is measure the distance from the wheel rim to the strings. And adjust to where desired. Remember that any adjustment you make will both move the car around and minutely affect the track width. You will need to keep checking your distances to the hubs and gently shoving the car back centered between the strings. If you don't do this you will get some wonky results.

After that it's just repetition and iteration until you're satisfied or exhausted! 

In reply to freetors :

This is great! But to make sure the strings are parallel you just need to make sure they are the same distance apart on the front and back bars, and the length of each string is the same. 

Then you'll either have a rectangle or a parallelogram, but both function I'm that the strings are parallel.

You can make this easy by cutting slots in two pieces of conduit the same width, and then also making a mark on each of your two strings that is equidistant. 

Robbie said:

In reply to freetors :

This is great! But to make sure the strings are parallel you just need to make sure they are the same distance apart on the front and back bars, and the length of each string is the same. 

Then you'll either have a rectangle or a parallelogram, but both function I'm that the strings are parallel.

You can make this easy by cutting slots in two pieces of conduit the same width, and then also making a mark on each of your two strings that is equidistant. 

In this theory yes that is true! But my setup doesn't really allow for that. For one thing, the fishing line will stretch out quite a bit, meaning getting it both taught and the same length is pretty much impossible.

In a perfect world I would have a frame of steel around the car that is verified square, with the same lengths side to side, and front to back, a true rectangle, and very rigid. This would be so much easier to set up and you could even get rid of the strings entirely if you wanted and just measure to the beams. I've never gotten around to building something like this though as getting it perfect would be tricky.