Have a nice 28 Ford Roadster with a flathead v8. Steering is horrible at 45 miles an hour once to try to kill me. Changed out a couple of things fixed a couple of things still tries to kill me at 45 miles an hour. Notice the ch***is twisting when I move the steering wheel when the vehicle is stationary near the steering box. Frame was in great shape doesn't look like it should need to be boxed but any help is appreciated have checked everything else toe in toe out kingpins, steering box, steering column,. It has a brand new Vegas steering box. Any help is appreciated
Open drive line you need to box the frame / Closed driveline the torque tube takes car of the twist, Also needs some type of K member. I used a 32 complete crossmember and that in itself strengthens the frame and helps with twist.
I'm ***uming that the Vega is a cross steer system? If so, The reason you're seeing flex is the force applied on the relatively flexible frame pushing and pulling left to right across the frame rather than the force being forward and aft like on the original steering system. The frame was originally designed to twist in the poor roads of the day. And because of this flexibility, it isn't really stiff enough for a cross steer system without boxing.
The cross steering is forcing the rails apart, so you need cross members to keep them together. Boxing will help, but only a limited amount. Also make sure there are no cracks in the existing front or middle cross members. Put the car on a four-post lift and have someone turn the steering wheel lock-to-lock so you can see what's going on. Good luck!
As stated Stock model A frames, or C channel in general for a better visual is really strong for lateral loads but was designed to twist in a non critical way when tied together with crossmembers and torque tube and side steer to keep the all the Loads within the strengths of the frame. Once us dang hot rodders start messing with it like side steer your introducing a twist in one rail it wasn’t designed for. Unfortunately that twist is with the steering box, a component that needs to be very rigidly mounted. Kinda the same way unsplit bones and torque tube articulate really well on road conditions, once you split the bones your axle needs to twist and with open driveline you need a torque arm. Henry had it all figured out, may not seem like it at a glance but a stock model A is really well engineered, once you start modifying without understanding why it was built like it was you get into problems. With your problem the least intrusive fix on you completed car would be maybe a bolt on tube crossmember that drops bellow the motor and ties the two rails together if you have the room.
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