# Wheel Alignment Tool - "BUILD a TOOL" Contest

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With the wear of the joints and shocks, the wheel alignment of your vehicle begins wrong.
This can cause a pulling (left or right), premature tire wear, and loss of grip.

The mechanic proceeds to a cure and adjustment with a specific professional device, this operation can be expensive.

To reduce the bill, I suggest you make your own inexpensive and accurate tool. You will find similar tools in the trade like Gunson.

But you will gain to do it yourself.

## Step 1: Prerequisites Knowledges

On most popular vehicles, the only adjustment we can make is front wheel alignment.

The constructor gives us positive or negative angular values expressed in degrees.

Example:
Manufacturer's face value for each front wheel of my Austin Mini = - 0.22 °.

This means that each front wheel must be inclined by 0.22 ° with respect to the axis that the vehicle follows while driving (different from the median plane of the vehicle).

• The sign "+" means that the wheel is getting closer to the vehicle, we speak of "pinching".
• The sign "-" means that the wheel moves away from the vehicle, we speak of "opening".

On a classic car, you should know that:

• The rear wheels direct the vehicle => fixed alignment.
• The front wheels adjusts the direction of the vehicle => variable alignment (thanks to the steering wheel).

## Step 2: Principle of Tool Operation

The tool made will measure deviation angle, through the lateral displacement of a plate.
Steeringwheel stayed right, the vehicle runs on a free movable plate which can only move laterally.

Important : You have to remove your foot of the throttle pedal and let the vehicle runs free across the plate, otherwise the the measurement may be wrong by the torque of the wheel.

• If the vehicle has "open", the plate will get closer to the vehicle.
• If the vehicle is "pinched", the plate will move away from the vehicle.

After we have just to amplify this displacement (for accuracy), and to transform the translation into rotation (for the angular reading).

## Step 3: The Mechanical Study

The measurement accuracy is important, that is why the movements of the parts were studied on a mechanical design software.

I put you here the full drawing folder (PDF and DWG) you need to make your flow.

## Step 4: The Main Part

After cutting all the elements, I proceeded to assemble the fixed part.

Due to lack of material, I had to make a bolted subassembly to have the correct plate width.

The inclined parts are folded in the vice, which explains the marks and the irregularity of the fold.

Fixing screws may vary depending on what you have available, if necessary you cut them to the necessary length.

## Step 5: The Roller Cage

I made a rolling tray on the principle of a needle bearing.

The upper mobile plate is supported on free rollers (recovered threaded rods).

They are held by a "cage" made in a plastic sheet plate.

Cutting the notches is not very accurate but at this level no need for precision, the goal is to keep the rollers in place.

## Step 6: The Reading Arrow

The axis of the boom is a countersunk screw which is tightened from below the base.

The end is adjusted to the length so as not to rub on the underside of the movable platen.

It takes the minimum operating clearance to ensure the most accuracy :

• The hole of the axis of the needle is a diameter of 4 mm for an M4 screw.
• The groove of the needle is 3 mm for the sliding of a screw M3.

Adjust the operating clearance with a file.

## Step 7: The Mobile Plate

This plate is the part on which the tire will come into contact.

It is very simple, you just have to make a tapping to place the M3 screw that will guide the reading arrow.

We just slide this tray on the fixed part and on the roller cage.

We end up placing the M3 screw that will guide the arrow.

This small screw will be shortened to not rub on the fixed part.

At the end of assembly, we check that the mechanism works perfectly, and that the functional games are correct.

## Step 8: The Angular Rule

I made a series of measurements on the 3D model, according to the displacement of the moving plate.

I considered that the tire was in contact on 300 mm during the movement of the vehicle.

I calculated the angle of inclination with respect to the lateral displacement of the plate:

angle = ATan (lateral displacement / contact length)

Thanks to the kinematics, I reported the positions of the arrow on the angular rule.

## Step 9: Tests and Finishes

Once the tool is assembled, proceed to the tests.

I put here a video made by testing the tool with my Austin Mini.

The tests are conclusive, the repeatability is surprisingly accurate.

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## 17 Discussions

I like it but I can't download it for some reason (yes I'm logged in). I get the following error: {"error": "Sorry, we couldn't find that one!"}

3 replies

Hi Mike,

The ability for users to download instructables in pdf format is currently not working correctly, and the site's engineers are aware and working to resolve this issue.

Sam (seamster)
Instructables Community Manager

I am sorry to say that your design for a mechanism is neat as to how you are able to make the pointer move with small movement of the bearing plate above. Your design is well documented. However, this device will have no bearing in reality as to measurement of the parameter you seek to measure. Here are some points to consider:
-- your device Must be calibrated to the car body itself and mountable onto, referenced to, and consistent with it.
-- Consider the existing design of the very expensive wheel alignment systems you hope to emulate: they DO this. Any statement of accuracy must be related and based upon comparison to state-of-the-art devices and you show no data for comparison but you do state it is "accurate".
-- You have no ability to control your angle of approach to the device and then, do not even verify after you have driven over the unit to calibrate / reference it to the wheel or body. Note that your own diagram references the angle of the wheel with regard to the centerline of the car chassis. YOU must accommodate this in your design, but you do not.
-- Toe in/out is only one of three measurements necessary for measuring wheel alignment. Also, camber, caster.
-- The money and time spent of this device could have gone to paying a pro to do the job and knowing it is done correctly and diagnosing the source of joint wear.
-- The concept you base this on is predicated by a need to know that shocks and suspension joints are worn. One does not tweak the alignment to accommodate deficiencies in other worn parts. Good maintenance of suspensions is based upon replacing the worn joints( not usually the shocks) which cause degeneration in the angles and THEN professionally adjusting the angles of alignment. With your "system" one would be continuously measuring the joints for wear(not easy without special tools) and the spending time using your device to adjust and then, not accurately. Your alignment will end up hunting back and forth and never finding true "alignment".

I suggest you re-think your entire protocol and basis for this device.

5 replies

I note that you say the rear wheel alignment cannot be adjusted but on many vehicles particularly those with trailing arm suspension the wheels can be aligned to the body. Then the front wheels can be aligned. 3 ways as Brian says not just toe in. If the rear wheels are out the vehicle will end up"crabbing", driving slightly sideways and no front wheel alignment will fix that. Like you I like fix things myself but given the complexity and accuracy needed I leave this to the pros. It's amazing to watch too well worth the money just for the entertainment value.

Hello,
I didn't tell rear wheels can't be adjusted, I wrote "on most popular cars"

Hello Brian,
Thank you for your comment, I understand what you describe.
For your information professional brand Gunson made a tool like mine which named Trakrite, and it works well, check it on the web.

I did not have to explain correctly what is the main goal of my tool here.
It measures the lateral displacement of the tire, one of the origin of tire wear.
Watch how "old men" make to adjust their vintage car geometry with a ruler (search on Google ...) by measuring the gaps on the edges of the wheels ...
Excessive toe out or toe in will prematurely wear your tires. The tool is mainly used to reduce this angle.
I was mechanic so I never wait a failure to replace parts. I always check the different parts which can affect the measurement.
Of course, a professional tool measures many other angles, such as caster or camber, and even the offset between the median plane of the vehicle and the rolling plan.
You say Brian that I refer to the middle plane of the body, which is wrong: I refer to the plan of rolling (which can be different if the vehicle rolls like a "crab").
As you can see, I use it on my vintage vehicle, and it plays its role perfectly.
I also personally find that doing a dynamic measurement is much more interesting than static.

In a perfect world, yes. To a prepper fantasizing about what he'd do with just some sheet metal and a vise, with his survivor Hilux driving cockeyed, it's mental candy.

The video in particular was mesmerizing.

Well, it's a wonderfully documented project, at least. I can see a use for it with trepidation-- finding differences in toe at each wheel lock. But there's a lot of things that can go wrong because of deflection of the tire as camber changes and vehicle load spreads across the torsion bar.

I think this would be a better project for an Oculus Rift owner.

edit: And I've never seen a shop that's done a "professional" alignment-- I'd imagine that's a luxury for enthusiasts. They have guys turn wrenches as dictated by the terminal and end up just ignoring numbers that can't be adjusted rather than watching all the numbers to identify bent, worn, modified, etc. suspension components that "suggested toe" on toe-adjustable-only cars won't fix. That, and and overloading the rack and constantly being off on one side.

Great idea. I have a few concerns and doubts, but for what it is these can be addressed somehow, but this "tool" can offer a very reasonable rough-in.

I would imagine the needle bearings would need to slip longitudinally relative to their cage-end. Is this stress/friction affecting these fine adjustments? I wonder if two plates, greased, would do a good job as well.

Awesome

The plate move very well on the "needles" (longitudinal), I don't thing that the ends affect the movement, so the adjustments.
I tried again this evening on my Mini, I found again the same measurements.

One of the best and most elegant instructables that I have ever seen. Merci Beaucoup!

WOW Incredible!!!!
So nice to see such intricate interesting concepts. So Very Cool! Great Job!!!