After I installed a roller idler in my 67, I did notice a little bit of reduction in the return-to-center function of the steering, especially at lower speeds. You can compensate for most of it with increased caster (I run 4.2*), but it's still there in my car. At 15mph, I can crank the wheel 1/4 turn and it will stay put. At freeway speed, slight road variations are more likely to result in changes in direction without a grip on the wheel. If you have slop in the steering, this effect will be increased.

The tradeoff is vastly improved steering feedback, especially at higher speeds. I feel much more connected with the tires now. Steering effort is also slightly reduced.

I wouldn't put a roller idler on a car for my gf, but I like it in mine. I honestly don't notice it anymore after driving it for a few months. It's one of those things your mind automatically compensates for after a while. Keep your hands on the wheel and it's not a problem.

 

Pooty,

So that you know. The main benefit of the aftermarket control arms isn't the roller bushing or spherical heim joint, it's the negative roll that aids handling the most.

 

You do not have to use the roller lower arm with the adjustable strut rods though it is a good idea. The reason why is if you pull the lower arm forward a lot, it puts bind on the inside bushing. That can over stress the bushing in the lower arm, cause premature wear and can crack the mounting point in the chassis. The spherical bearing does allowe the arm to move freely in any direction.

It is far better to move the upper ball joint backwards to get more caster. You can do that by offsetting the upper arm shaft kits and by adding washers/spacers under the front bolt of the arm, even if you use the lower arm camber kits. Also, pulling the lower arm forward brings the tire closer to the front of the front fender causing a rub issue. Most of the adjustable strut rods are a bolt in deal. No frame mods are required.

What you feel as bump steer might be from the alignment settings. If any early Mustang is set to factory settings, it won't drive well. They didn't put enough caster in the cars and that makes them wonder over bumps. The return to center is done by the caster angle more than the idler arm. The factory settings had up to 1deg. of positive caster. We put 2deg. or more of positive caster in all of our cars. That gives the cars stability at speed and return to center around corners. We use these alignment settings on all of our street cars.

0 - Camber

2deg. positive caster

1/8" toe-in

The camber and caster should be the same on both sides. We do not set the cars for road crown.

The 1" upper arm drop is a good idea if you don't mind drilling holes in the car. The upper arm drop changes the camber curve to give the car more grip. It can also give you better tire wear if you like going around corners.

 

Are these alignment specs applicable to 71-73 stangs?

 

Sure are. We have used them on several 71-73 Mustangs. I used them on our 68 Ranchero and it drives great. My 64 Falcon Sprint has the same settings.

Sometimes on the power steering cars we will go with 3deg. of positive caster. Using that much caster on a manual steer car can make them hard to steer at low speeds. It helps with the feel of the cars at speed with power steering.

With the camber, we start at 0 so the tire sits flat to the ground. If we start seeing outer edge wear from hard cornering, we'll add some negative camber ( top of tire inward ) to the cars. You don't ever want any positive camber ( top of tire outward ).