What about the toe change when you hit a bump? I'll bet the toe changes more than a 1/4". That could be your handling problem at speed.
In order for a R&P to work correctly on a straight axle the rack would have to be mounted to the axle. So it would move up and down with the axle. Then you would have to have u joints and a slip connection in the steering shaft.
Nope Ron, that is completely wrong. I have posted on this subject many times. And I have went to a real steering pro for answers (as in a friend of a friend that designs steering systems for the oem, and has written several SAE tech papers on steering designs, and holds many us patents for steering box and pump designs). To bad that other T bucket website doesnt have a decent search function. Because this topic has been Beaten to death over there.
A rack can work just fine on a straight axle car. The theory that the axle moves straight up and down, and the ends of the rack move in an arc, causing toe change, sounds good in theory. But in reality, the axle does not move straight up and down. For the axle to move straight up and down, you have to hit a bump with both front wheels, at the same time. Highly unlikely. In reality, you will have one front wheel hit a bump, or one front wheel fall in a pot hole. And in that instance, the axle is not going straight up. It is pivoting around the center of the transverse front leaf spring. And moving in an arc... Just as the end of the rack is doing.
Back around 1999-2000 Me and my father built his first T. It was my first T bucket build. He had an idea of a tube frame car, torsion front suspension, and rack and pinion steering. So off we went building it. As I posted pics on that other T website, people stated telling me it wouldnt work, it was dangerous... one guy even accused me of trying to kill my father. So we went into this very carefully. And we were having no effects the others warned about. The car worked beautifully. We hauled the car half way across the country to the NTBA nats in omaha. All the shit talkers were totally silent when the car was there, Done, and I had the keys in my hand offering rides. Hmmmmmmmmm. strange how that went. But I refused to believe that I was a genius that could do what no other could, And that Is how I ended up in touch with a steering engineer at Visteon. I sent pics, we emailed a lot, learned alot about the real world design dynamics. And how the pros do it.
But it was with my fateher that we found the real reason people have problems with racks. remember the car we built had torsion bar front suspension. No transverse spring. The problem isnt with toe change... it is with the deflection of the shackles. The rack pushes one side, and pulls on the other, shifting the whole axle over. Put on a panhard bar, and the issue is solved.