Nobody needs an explanation of why having a proper alignment is important, so I’ll try to keep the focus on my plans for doing my own alignment.
Inspiration and Setup: For those needing a visual reference or a quick refresher on alignment settings, watch these three videos put together by Robbie Nelson from the now defunct RacetrackDB.com. I plan on setting up my alignment “rack” much like his:
I really like his method of establishing a level working surface – cheap, easy, and effective. Also as he mentioned about having the same track width, I will be using my 17×9+20 wheels since they are all the same size and offset as well as have the same size tires (less variables the better).
Another good read for setup and measurements is this write-up by SELOC (a Lotus enthusiast group). While the chassis is different, the concept and setup are applicable to any car. This write-up demonstrates the second manner of toe measurement; I’ll explain below (different from the videos’). They also give some Excel formulas to covert your measurements.
My plan: After reading enough do-it-yourself alignment write-ups to make me feel comfortable, or crazy enough, to actually do it myself, I have devised a plan. The three base measurements of an alignment are toe, camber, and caster. On any car, once you get “too low,” you exceed the adjustment range of the stock components. At that point, an alignment is futile. When I go lower, I’ll correct camber and toe by buying the necessary adjustment arms front and rear. Caster is the more difficult adjustment and will take more investigation. On the JZX100 like the S13/S14/S15, caster is adjusted through the tension/caster rod. However, on the JZX100, the most “steering lock” (good for drifting) can be achieved on OEM Toyota JZX110 caster rods which lack aftermarket adjustment – a catch-22.
Ride Height: Before beginning, I’ll double check and adjust my ride height as necessary to get it the same all the way around. Changing ride height affects camber and toe setting so it’s important to get it set before proceeding with any other measurements or adjustments.
Toe: To measure toe, there seems to be two ways to go about it; each involving strings. By the first method, you “string box” your car. Essentially, you set up two equal length bars horizonally at the front and rear of the car and run a string front to rear on each side. The taut string should intersect the hubs’ mid-line. With the steering wheel centered, you adjust the string line on each side until the distances from the hubs to the string are the same for each side of the rear and each side of the front (all four distances will not be the same in cases of different track widths). With that setup, you can measure the distance between the string and the front and back of each wheel. If your car already has zero toe, they should be equidistant. If not, you can make adjustments until you reach the desired toe. This is the method demonstrated in the Lotus club’s Wiki write-up I linked to above.
The second method follows the same principals but achieves it in a different manner. The string is strung between two stationary objects (jack stands) at a equal distance from the front and rear wheels. Measuring from the front and rear hubs to the string and adjusting the jack stands accordingly will allow you to get the string equidistant. Extend the jack stands wider than the wheels so you can measure from the front of the front wheel and the back of the back wheel to the string. Again as above, you measure from the front and back of each wheel to the string and take your measurements to determine toe. Zero toe means they are the same distance.
Toe can be measured in degrees, inches, or millimeters. Since I want zero toe, I will measure in milimeters to keep my life simple and avoid any unnecessary conversions. Also, in either method, the body cannot interfere with the string.
Camber: There are a lot of track-side/garage camber gauge alignment kits that range from pretty cheap to rather expensive. I will be going a different route and using “free technology” a.k.a. my iPod Touch. This will be for verification as well as experimentation. There are multiple “level” apps for download many of which are free. They measure in degrees while also showing a digital version of a traditional bubble level. After a simple calibration (put the iPod on a level surface), they are ready to rock. I have downloaded a few of the free ones so I’ll review which worked/worked best.
As a comparison to my iPod reading, there are two “old fashioned” methods to determine camber – one using a bubble level and the other using string. Each of which have been proven to work so it will be a good baseline. But instead of a handy-dandy calculated digital readout, it requires some basic trigonometry to get the results.
The bubble level method is as demonstrated in the video above. Using a straight edge vertically across the surface of the wheel, you can pivot at the bottom and find plum by adjusting the level-straight edge combo at the top (in the case of negative camber). Then, measure the gap from the wheel face to the plum position. To find the degree equivalent, the measurements can be put into the formula:
Degree = (inverse sin) (opposite/hypotenuse)
The “inverse sin” is the “sin-1” button on your calculator. “Opposite” equals your measured top length. “Hypotenuse” equals your wheel face diameter. Make sure both are measured in same units; which unit – mm, cm, inch – does not matter.
The string method uses the same concept but goes about it in a different manner. First, you drop a plumb-bob vertically through the horizontal mid-line of the wheel. From the plumb string, you measure the distance to the top and bottom of the wheel. The string acts as the “plumb” level. Subtract the bottom distance from the top distance (for negative camber) to find the same measurement as the previous method. Again, plug this measurement into the formula to find the degree equivalent.
Caster: As I said above, I am still looking for caster adjustment possibilities for the JZX100.
That’s a lot of drivel and should be much easier to follow with some pics. Check back for Part 2 when I put all that in motion…my brain hurts just thinking about it.
To add a “scientific” nature and prove the validity of my method, I may pay a shop to check my alignment after I have it completed. Compare the alignment racks measurements to mine.