Camber measurement: it really works!
I have a set of camber adjustment bolts waiting to be installed. I bought my anti-sway bar from RedShift Motorsports, which has quite a bit of info about Civic suspensions. While browsing the site, I saw the camber bolts listed, for not much money, with the description that they will help improve handling over the stock setup. So, I bought them. As I make preparations to install them, I wanted to know what the current camber settings were. I *thought* I didn't have the tools to measure camber reliably, but it turns out that it is fairly easy to do, with simple tools. Sure, you can spend $1,000 for a set of Hubstands, but I'm saving up for my coilovers.
I stumbled across this information on bimmerworld.com, which gives a link to the Youtube video called "DIY Alignment, Part 1". There's also a part 2 and 3. Look them up if you like, but I'll describe the procedure here:
First step: prepare a level spot for your car. Most people will be using their garage, and the floor *seems* pretty level. However, it isn't. But it's easy to fix.
Park your car where you want to have it when you work on it. Use a Sharpie marker to put a spot on the floor next to the spot where each tire contacts the floor. Back your car out of the garage. Measure the width of your tires. For an Si with 215/45R17 tires, they will be about 9" wide. You are now going to draw a 12" square for each tire, centered at the contact patch. Subtract tire width from 12, and divide by 2. Go that many inches out from the spot you marked, to find the outside edge of the box. Measure 6" fore and aft to get the front and rear edge. Do that for each contact patch.
Head down to your local home improvement store with about $30 in your pocket, and buy about 12-16 cheap, vinyl flooring tiles (they are 12" square). You'll also need about 10 feet of 1/4" vinyl tubing, a level and a yardstick, if you don't already have them. You will also want to buy a aluminum square "rod". It's a 3 foot long piece of aluminum with a square cross section. When you get it home, cut it so that it is just long enough to span your wheel rims. I was somewhat surprised to find that my 17" rims are actually 18 1/2" across.
Use the tiles to draw a square for each tire patch. Then put one tile on each square. Pour some table salt on the square, and lay another square on top. That way, if you need to turn the wheels for adjusting toe, the salt acts like tiny ball bearings, that let the upper tile turn over the lower one. With our salt-and-tile sandwich at each corner, it's time to do some leveling!
If you have a really long, really accurate level, you could just use that. Or, you can fill a bucket with water, set it on a low stool in the center of the work area, and stick one end of the vinyl tube in. The other end of the tube, you will tape to a straight edge, so the tube sits next to the graduations. Suck on the end of the tube to draw the water out of the bucket, into the tube, until it gets to the straight edge. Now, put the straight edge on each tile in turn, and look where the water level is. Find which square is the highest point. It is the one where the water is *lowest* in the tube. Then, go to each of the other squares, measure how far off it is from the reference square, and add tiles until it measures the same. Each tile is about 1/8 inch thick. Write down, on the floor next to each square, how many tiles are needed to make it level. That way, you won't have to do the water manometer thing every time. Now, drive your car onto the tiles, and you have a level car to work with.
Measuring camber
Now that we know the car is level, all you need is a carpenter's level and a ruler to measure the camber for each wheel. You can just use the tire sidewall, or, use your aluminium square straight edge to use the wheel rims as reference. Unfortunately, the wheels on the Si have spokes that stick up a little above the plane of the rim, so you may have to work around that. The *right* way to do it would be to jack up the car, turn the wheel so the spokes are out of the way, and set it back down again.
If the wheel has negative camber (the top leans in), you will have to lean the level outward to get the bubble to center. Measure how far the straight edge is from the top of the rim. Now, it's time for some trigonometry. As I said earlier, my wheel is 18.5 inches, but I find it easier to work in millimeters. There's 25.4 mm/in, so 18.5 " is 470 mm. However many mm you had to rock the level out, divide that number by 470, and take the "atan" of the result. My front wheels had 0 camber, and my back wheels needed 12 mm to get the bubble centered. atan(12/470) = 1.5 degrees. Both right and left were the same. As the top of the wheel is leaning in, it is -1.5 degrees.
So, results in hand, I went back to redshiftmotorsports.com, and looked up the factory spec for camber on the 8th gen Si (they didn't have numbers for the 9th gen, but no reason to think they will be different). Lo and behold, the factory settings are zero in the front, and -1.5 deg in the rear! Amazing.
My next task will be to measure the "toe" for each wheel, and to install the camber bolts to put a little negative camber on the front. Stay tuned!
