DIY Wheel Alignment

[brandon.mol]

So I have been contemplating different measurement processes for doing my own wheel alignments, or at least measuring my current wheel alignment. #1 goal is to do this for less money than 1 [professional] wheel alignment the first time, and effectively for free on subsequent times.

 

#2 goal is to be accurate to +/- 0.2 degrees for each of camber, total toe, individual toe, and thrust angle.

 

So I think I have come up with a few methods that used in conjunction will work well and I will do all these and follow up with a pro wheel alignment to validate (once).

 

First method:

To measure thrust angle, individual toe, total toe, and camber: I bought a self-levelling cross-line horizontally projecting laser level. Set it on the floor near either end of the car with the vertical line/plane running down the side of the car, roughly 3 - 6 inches away from the car, as parallel as you can get it (OK if its not exact - it won't be, don't try). Using a good quality metric ruler, measure the offset from the center of the laser to the lip of your rim at the 12, 3, 6, and 9 o'clock. Do the same at the rear wheel. Now move the laser to the opposite end of the car and repeat from the other direction. This roughly cancels out any systematic miscalibration in the laser.

 

Repeat on the other side of the car.

 

Some of the calculations (for total toe and for thrust angle) using this method require knowing the difference in track front to rear. Based on previous alignments I've had done on my car, that is only 0.03" on my car, so I will ignore it.

 

With these measurements we can calculate all these angles with a root-mean square error of about +/-0.15 degrees based on my calculations.

 

I will be putting together a spreadsheet that does all the math and will share it.

 

Second Method:

 

Total Toe obtained by measuring the the difference in distance between the front and back of each pair of wheels. I am building a pair of jigs each out of a couple cheap 2-foot levels and an aluminum straight edge and some hardware that I can mount to each wheel and then use a digital level (inclinometer) to measure the camber directly to 0.2degrees and measure the toe-in/out by measuring distance front and back of the wheel between the two jigs. Measuring the cross dimensions will tell you if the wheels are perpendicular to the effective-axel or not.

 

However...you can't measure thrust angle unless we assume the wheelbase is identical on both sides of the car, which it isn't, but I guess thats not hard to measure either.

 

I've read about people using a pin in your tire or a line, etc, but that doesn't work well when you only have 3 inches under the car to pull a tape. You need something that extends out from the wheel and down near the floor.

 

Once I have this all figured out, I'll post pictures, if anyone cares.

 

What d'y'all think?

[9thwonder]

I don't understand how #1 would work... It sounds like you're measuring the distance from the lip of the wheel to some line "approximately" parallel with the car. What does that tell you? I just don't see how you would keep things consistent between both sides of the car.

 

I'm trying to understand, maybe I'm missing something.

[brandon.mol]

Doesn't matter if the line is parallel. The average of the 12 and 6 positions on the front minus the same on the rear is the constant used to correct the 3 and 9 position measurements. Since wheel diameter is small compared to wheelbase, the error create by that is proportionally small... Fractions of a mm.

[brandon.mol]

Alright, here is the spreadsheet that will do all the calcs for the laser-based alignment check:

 

Laser-Based 4-Wheel Alignment Calculation Spreadsheet

 

Feel free to make a copy of it for your own purposes. It is free (as in beer) and free (as in speech) and comes without warranty of any kind, expressed or implied.

 

You need a Cross-Line laser level, preferably self-levelling, and a good quality metric light-coloured ruler/scale. I am using a survey-grade measurement rod, and may get a laser target for improved accuracy. Up to you.

 

Here is the measurement procedure to follow:

 

1. Park the car on a flat surface, and make sure the car is level side to side (front to back doesn't matter). Try to minimize twists in the car - use your laser level to find the differences left to right and shim the wheels up if there are variances of more than 1/4 inch.
    
   
2. Place the laser level on the ground near the front of the car on the left side and project the vertical line rearward, roughly parallel to the car. By roughly I mean within a few inches is fine. The angle between the car and the laser is irrelevant, as long as it doesn't exceed about 30 degrees, which would be several feet out, so you're fine as long as it looks close.
    
   
3. Measure offsets from the line to the rim surface at the 12, 3, 6, and 9 o'clock positions on the rim. Doesn't hurt to measure each a couple times. Always take the smallest reading, which means the ruler is perpendicular to the laser beam. Wave the ruler around a bit to find that spot. Record your measurements. Do this for each of the front and rear wheels on the left side.
    
   
4. Move the laser to the rear of the car and project it forward. Again it doesn't matter if its parallel or even parallel to the last set. Repeat the above for both wheels. Its important to take the measurements with the laser at each end. This will cancel out any systematic errors in the self leveling mechanism in the laser level or any misalignment in the level vial on a manually levelling one. For anyone with a surveying background, this is probably obvious. Its like face-left and face-right on a transit/total-station.
    
   
5. Repeat this procedure on the other side of the car.
    
   
6. Enter everything into that spreadsheet.
   

 

The whole measurement process should take maybe 20 - 30 minutes, tops.

 

 

You get individual toe at each wheel, toe-in front and rear, camber at each wheel, Cross-camber, and thrust angle. You can't get caster...I don't think. maybe you can, if someone knows how to calc it.. but I am guessing its not so simple.

 

I have developed this process using techniques derived from my background in industrial metrology and precision surveying. Obviously, the instruments being used here are not survey grade, and certainly not metrology grade, but we also don't need thousandths of an inch here. +/- 0.15 degrees per wheel toe/camber is near as good as any alignment rack out there anyway. The procedure is developed to not require anything other than a straight plane laser beam, which is easy to achieve with low-cost lasers, especially indoors.

 

I would definitely be interested in seeing some comparisons between professional alignment results and this method from several people.

 

I've also got the on-wheel jig setup with inclinometer and direct toe measurements coming soon. I'll make sure to use both methods and compare results.

 

Shortly I will fill in my own numbers and you can all see them.

 

To me, the purpose of this is mostly for checking your own alignment or for tweaking adjustable parts like coil-overs, lower control arms, toe-arms, etc.

Edited January 13, 2015 by brandon.mol
typos

[Unsp0kn]

LOL Someone actually thanked you for this nonsense.

 

Cool story bro. Do you ever offer any constructive input or are your posts just filled with judgement and disdain all the time? Possibly suggest a way to improve the OPs process or kindly point out why it may not work instead of just being rude and a waste of bandwidth.

[Perscitus]

StevesH6 is our new resident thread troll, he's cute and special like that.

 

Steve - how about a build or at least a golden thoughts of the day thread?

You can quote and multi-quote yourself, and criticize each reply.

[brandon.mol]

Update. I have made all the measurements on my car and the results look good. Built into the process is a way to detect errors/blunders, etc. I can reliably measure the offsets to +/- 0.5mm with the laser I have.

 

Check out the spreadsheet link above to see the results, here is a summary:

 

http://legacygt.com/forums/attachment.php?attachmentid=200483&stc=1&d=1421050569

 

Which seem right based on how the car is driving, and also compared to my last alignment report + knowing that my Blacksteins would have settled a bit more. Once I get my lower control arms and toe arms installed and adjusted, I will get another set of measurements and then take it for a professional alignment and report back the differences.

 

 

 

Oh and Steve buddy.. I happen to be quite qualified to develop something like this. I have a degree in Geomatics Engineering and have deep understanding of measurement system design and error control/estimation, and the geometric accumulation of error though spatial measurement systems, etc. Particularly when it comes to precise-positioning and dimensional-control.

 

What makes you qualified to call any of this nonsense?

 

You "sir"... are nonsensical.

 

Hopefully this thread is helpful to others. Especially those who make alignment changes and need a way to measure the results.

Edited January 12, 2015 by brandon.mol
Updated screenshot. Corrected an error in the thrust angle calculation.

[Unsp0kn]

Nicely done Brandon. Oh and he doesn't deserve a "sir."

[GTEASER]

What do you do for a profession Brandon, Land Surveying?

[tdelker]

Cool! Suggestions on a laser? This one seems like good value: http://www.harborfreight.com/self-leveling-laser-level-kit-69243.html

[brandon.mol]

What do you do for a profession Brandon, Land Surveying?

 

Sort of, but mostly in the past. I was in the land surveying business, as well as sub-sea surveying down in the gulf o' Mexico recovering rigs after Katrina. Done a lot of work in construction surveys for precision stuff, like ultra-flat hospital floor concrete layout, ground subsistence and building deformation monitoring, and control surveys. Also things like positioning system alignments on large ships, offshore rigs etc to calibrate subsea sonar gear. Kind of a mixed bag of stuff. I generally avoided legal "land" surveys because I found it boring.

 

That was a number of years ago. More recently I am working in IT setting up enterprise geospatial information systems which doesn't involve freezing my nuts off in Alberta winters nor being cooped up sea-sick on ships offshore.

[brandon.mol]

Cool! Suggestions on a laser? This one seems like good value: http://www.harborfreight.com/self-leveling-laser-level-kit-69243.html

 

I can't tell if that is a cross-line laser versus a point-beam. You need at least a vertical line beam (i.e. forms a vertical plane of laser light). These are usually referred to as cross-line lasers, as they usually have both a horizontal and vertical beam and form one, the other, or both.

 

I have a Black and Decker BDL310S, which I got on Amazon for $75 with free shipping. Looks like there are more (and possibly better) options on the US Amazon store. They are also very useful for many reno and household tasks.

 

Be careful not to buy a laser "line level" that shoots a line in one direction only along a wall. Those won't work. it needs to fire a line-beam out to the side. Mine goes up and down about 45 degrees so I only have to have it around the bumper to get the beam to the top of the wheel. The dewalt and Bosch ones are very good, but more money.

 

If the one you mention is in fact a line laser and not a dot-beam, then it looks great. If it just shoots a dot-beam, it won't work.

 

 

Here is a graphic that makes it clear what I am talking about:

 

http://www.homedepot.com/catalog/productImages/1000/ee/ee89cc52-7f50-4da4-b6e5-9df8687cb88e_1000.jpg

[RailKill]

LOL Someone actually thanked you for this nonsense.

 

C'mon, are you guys blind? "Steve" has all of the signs of being BobGee. If you look at all of his other posts, their all written in typical BobGee format.

 

.....Sigh......oh Bob

 

 

[brandon.mol]

I got my digital inclinometer today. It claims to be accurate to +/0.1 degrees near horizontal and vertical and +/-0.2 degrees everywhere else. It appears to be precise to better than that as I can repeatedly measure the same value over and over.

 

I put together a jig with some 3/4" angle aluminum and nylon bolts as feet. I calibrated the inclinometer while mounted to include any variation in the length of the nylon bolts. I measured camber directly from the top and bottom of the rim and got -1.4 degrees for both of the fronts and -1.9 for both of the rears.

 

Both of those are within the error of either my laser-based measurements or the inclinometer measurements alone, and well within the combined error of the two. This leaves me feeling very confident with my results, so far.

 

If all you care about is camber, this is definitely simpler (and faster) than the laser method, however it won't get you toe and it is less accurate unless you get an inclinometer that can do +/- 0.1 in any orientation (hard to find for reasonable $$$).

[Glack]

I'd like to see some pics of your jigs

[brandon.mol]

I'd like to see some pics of your jigs

http://tapatalk.imageshack.com/v2/15/01/15/0d1f9fa1e2610edf8507283a7181b36a.jpg

 

Thats the one for camber. I abandoned building one for toe because I feel the laser meathod is better and easier.

 

I have a carpenter's level strapped to the back to make sure the jig is vertical when measuring camber.

[1stick3pedals]

I think I'll be giving your method a shot brandon for measuring.

 

It looks like this thread is in the 5th gen section and hence why it got buried a year ago. Maybe it would have had more activity in the suspension section.

 

I'm curious to see if you have any further information, did you ever end up comparing your data to a professional alignment machine?

[brandon.mol]

I have, yes.

 

What I found was that steering wheel angle matters a lot. Not only does I severely impact total toe but camber also. Overall it was very close.

 

Also, it's important to have the car close to level with very little twist in the chassis. Using thin plywood to shim up wheels to get it planar helps a lot.

 

Accuracy could be improved by using a laser level that has two beams to the sides as well that could be used to align the laser at fixed 90 degrees using alignment marks on the walls.

 

Have you looked at the latest version of my alignment calculator spreadsheet?

 

The main problem with the process is how long it takes and how careful you have to be to not introduce blunders.

 

 

It's certainly good for roughing it in.

 

For just camber the digital level is splendid.

[rhino6303]

This is a big time thread revival.

 

On your spreadsheet, what do the values in Floor Height (F-L), etc represent?

 

Thanks.

[boxkita]

interesting approach. Kudos on working through the math and setup.

 

a common solution for avoiding going to a shop is using the smartstrings system. I've seen racecar teams change a setup in minutes using it.

https://www.smartracingproducts.com/smartstrings

 

They also sell a camber tool : https://www.smartracingproducts.com/smartcamber