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Get Yourself in Alignment - Part I

By Jim Lunson, tech committee

 

I get lots of questions asked about getting the MG cars front end aligned properly. Questions range from what is the proper setting, how to make the measurements, how to align the steering wheel, and who has a good shop to do a proper electronic alignment. All are valid questions and I will try to answer them here.

For any MG, there are only two things that we need to be concerned with on the front alignment: the proper toe-in setting for the two front wheels, and secondly, their proper positioning with the steering wheel. Contrary to most modern cars that have adjustments for the camber (tilt inward of the front wheels when viewed from the front) and castor (tilt of the king pin from vertical when viewed from the side) as well as the standard toe-in/toe-out setting, MGs are completely rigidly fixed for all but the toe-in adjustment. There is nothing else to adjust. And most modern cars, especially those with front wheel and all-wheel drive, require alignment adjustment of the rear wheels as well, including a tie in to the front end alignment to provide the correct "thrust angle" so all four wheels are pointed in the exact same direction. Again, the MGs, with a fixed rigid rear end assembly, have no adjustment on the back wheels.

The last time I bought tires for my MG, the salesman tried hard to twist my arm to purchase the "all wheel alignment" package. He used the old adage that it would make the tires wear much better, improve gas mileage, make handling easier, and absolutely had to be done every year at a bare minimum. I politely refused the service, and held my ground. Then, while in the service bay getting the tires mounted, the alignment technician came over to give me another dose of sales pitch; at least until he looked closely at the MG's suspension and then exclaimed There is no way to adjust anything here. It's all fixed. So the answer to where is a good place to get a good modern electronic four-wheel alignment is "nowhere." You can do it yourself.

The proper toe-in is all that can be set on an MG. This needs to be set so the distance across the car for the front face of the tires is approximately 1/16" shorter than the same spot on the rear side. This creates the "tow-in" effect required for the car. The theory is that when the car is moving forward, there is a friction drag from the tires on the road surface. This drag pulls the entire suspension system back slightly. While this pulling is happening, the wheels are then in perfect straight-ahead alignment allowing the car to role perfectly. This exact measurement is not critical and varies slightly from each MG model and also changes with wear and tear on the suspension over the miles. The ideal is to maintain about 1/16" difference when the car is still.

This adjustment is made on the tie rods ends protruding from the steering rack. Each tie rod end coming out from the steering rack is threaded on the outboard end and screws into a short piece which attaches to each wheel hub. Adjustment is made by threading this tie rod either more into or out of the short end, with the threads on the end either going into or out of the short end, changing the length between the tires. There is also a jamb nut on these threads which is tightened against the short end after the adjustment is made to lock the length and prevent any unwanted movement.

The problem is that in trying to set the 1/16" difference, it is easy to measure the front of the tires level with the center of the wheel, but difficult on the rear side because the body of the car gets in the way of taking a straight across measurement. To take this rear measurement, you need to overcome the problem by using either of two methods. One is to build a wide rigid U-shaped frame of wood or metal that will span between the tires below the car body and yet allow a comparison of the dimensions between the front and rear higher up on the tires. This frame can then be set at both on the front of the tires and on the rear and the measurements compared to obtain the 1/16". A second method is to get two blocks of wood, preferably 4x4 and make them exactly the same length, preferably the exact outside diameter of the tire. Then set them on the ground against the outside of the front tires, making sure they are exactly centered with the center of each wheel and the tires are at the same pressure. Then simply measure on the floor the distance between the boards at the front and back ends and set the toe-in accordingly. Either way, take the measurement and adjust the tie rods lengths to get the 1/16" difference. Each complete turn of a tie rod equates to about 1/32", so if the measurements are exactly equal at the front and rear of the wheel, each rod needs about a one-half rotation inward to get the 1/16" difference. Get the dimension set and then tighten up the jam nuts to hold everything in place and you should be all set.

There is a third way to set the alignment which I use. This involves the feel of the steering wheel. I start by reducing the toe-in about 1 full turn of the tie rod on each side of the car to insure there is plenty of toe-in. Then drive the car a short distance at 20-30 mph. If the toe-in is too great, there is strong tendency for the car to want to move straight ahead, with any turn of the steering wheel to either side taking a lot of effort. You can feel it in the steering wheel. Second step is to increase the spread of the front tires by a full turn on both sides. Drive the car again and feel if the steering is easier. The method is to continue this process until the steering is easy and the car rolls well. You can tell when you go too far as the front of the tires will then be wider than the rear (toe-out). This will cause the steering wheel to float or skate as you drive, requiring more turning of the steering to affect any turn of the car. It is a pronounced unmistakable feel. When this occurs, readjust the tie rods inward again, probably about 1/2 a turn of each. This pulls the front of the tires back toward each other slightly, soon giving a perfect alignment. Then tighten the jam nuts and you are set with a perfectly aligned MG. This method takes a little longer, but by using the steering wheel feel, you can get a very good alignment setting for your particular MG.

This is how to set the alignment for any MG. Not a hard job, but does require getting slightly under the front of the car, using a wrench and vise grips to loosen the jam nuts, and make the necessary rotations of the tie rods, but with a little practice, it is not hard and will yield as good an alignment as any shop can accomplish. Just count your rotations of the tie rods and don't forget to retighten the jamb nuts when everything is set.

The final step is to align the steering wheel so that when it points exactly straight ahead, that is where the car is going. This is not critical, but makes for much more pleasant driving when going straight ahead on a road and feeling the steering wheel correspond precisely to the direction of the car and not having it cocked off to one side. I go into how to accomplish this task next month.

 

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