Leveling the Playing Field for a Wheel Alignment

When you align the front end of a vehicle, you align the camber first, caster and then fiddle with them cause both affect the other. Finally, when both are within specs, you adjust toe-in. I've used +1 deg for Camber and caster and 1/16" toe-in. The steering axis inclination is a fixed value of 7 deg and was part of the machining of the front spindle and mount.

Most if not all alignment shops, for the past 20 years, use some form of laser and computer alignment equipment. The old bubble style gauges and turntables are ideal for home garages and race tracks and provide pretty accurate adjustments. I borrowed a caster/camber gauge and a set of turntables from the local tech institute's automotive department. None of the instructor's had ever used them and weren't sure how to do an alignment with them. It's not difficult at all as I found out.


Setting up for alignment

Check that your frame is square within 1/4" from corner to corner (diagonals). I chose the front leaf spring mount on the driver's side and measured to the passenger's side front bumper mounting hole. I used a measuring tape because it doesn't stretch like string does. I then measured the same points on the opposite sides and compared the measurements

Check that your rear axle is square to the frame. I measured from the driver's side front leaf spring mounting hole to the center of the differential's axle. Then compared it to the passenger's side. I tried a few different measurement points on the rear axle until I found a point that I was confident in. Because the differential is sandwiched mounted between a rubber pad and the springs, there can be quite a bit of offset from driver's to passenger's side.

Adjust the rear axle so that it is square to the frame. If it isn't square you will end up doglegging it down the highway. The car's rear end will be off to one side when driving straight down the road.

The floor must be measured to make sure that the front wheels are level. The front wheels are placed on the turntables and a spacer is placed underneath (not necessarily in this order) to level the front end. This is required because we are using bubble gauges as measuring devices. Since our goal is less than 1 deg of accuracy, even minor "unlevelness" can create errors.

floor level

Making sure the front end is level

I used a 5 foot long carpenters level to determine that the floor at the front of the car was out by 1/4". I placed a 1/4" piece of masonite which I happened to have around under the passenger side turntable to level everything out.

rear wheels

Blocks placed under the rear wheels to achieve same height as turntables.

The rear end of the car must be the same level as the front so I placed a block of wood under each of the rear wheels so that they were the same height as the turntable. I put the caster/camber gauge on one of the rear wheels and it indicated 0 deg of camber which means that the rear of the car was level.

IMPORTANT: The brakes must be locked otherwise the front wheels will roll on the turntables giving incorrect measurements. I jammed the brakes on by using a piece of wood between the front seat mount and the brake pedal.

The steering wheel should be centered. This means turn the steering wheel completely to the right then turn the wheel completely to the left and count the number of turns. Mine was 3 1/2 turns end to end. I then turned the steering wheel half of 3 1/2 turns which is 1 3/4 turns. This places the steering gear (rack n pinion in my case) in the center of its travel. The steering wheel should be straight ahead. If it is not, you should remount the steering wheel so it's positioned straight ahead.

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Copyright Jan 16, 2011 Eugene Blanchard