Steering System

[rwstevens59]

BillCobb,

I believe the YouTube video, while a gross exaggeration of the variable velocity effect, does show your reference of 'lumpy steering'. I hope that is correct and it does demonstrate why it would be hard to detect given only partial revolution of the steering wheel and a much lower angular velocity.

Ralph

[DougMilliken]

https://www.youtube.com/watch?v=gmV4qwLfOMY

Good find, nice demonstration with the driveshaft.

Claude -- we had ancient Snap-On Weaver plates. I had to flush the dirt out of them and re-lube with a bit
of light oil. Then they worked fine, we could go a few cycles left and right to "settle" the hysteresis and after
that the data repeated quite well. I don't remember (was a long time ago), but I think we made our own
steer angle measurement device that was better than the crude pointers built into the plates.

Bill -- of course the method I described is fast and cheap. It's not going to find small Cardan joint angle errors but the angles shown in the sketch at the start of this thread were pretty big. A fish scale on the steering wheel isn't going to set any records for steering torque accuracy either, but it was plenty good enough to show that a certain fancy sports car had asymmetric boost -- iirc, the peak steering force at the rim was ~7 lbs in one direction and ~11 lbs the other. I only had about 15 minutes with that car (part of a magazine test), and no instrumentation budget.

If we are going to model a car in detail we go to a K&C rig and get good data, and then we write a big check.

[rwstevens59]

Poor mans turn plates.
http://www.arkansaspontiacs.org/tech...urnplates.html

[DougMilliken]

I don't like these plexi turn plates, they have a fixed axis of rotation -- which is hard (impossible) to align with the kingpin. Weaver plates I'm familiar with are free to rotate and also translate (X & Y motion).

[rwstevens59]

DougMilliken,

Agreed. But, with some thought they might be improved to allow some lateral movement. Good Weaver plates or equivalent are quite expensive for the amateur or occasional use.

Ralph

[Claude Rouelle]

Ralph,

EXCELLENT VIDEO! Thank you!!!

Not related at all but this also an excellent video, this one about differential. Wish I had youtube when I was trying to understand vehicle dynamics and vehicle components...

https://www.youtube.com/watch?v=yYAw79386WI

I DO like this kind of video that demystifies apparently incredibly complex systems.

Claude

[rwstevens59]

Claude Rouelle,

Ok, I'm hooked. Found several more good videos of the same vintage listed after watching the one you posted.

Being an old tool & model maker you will appreciate my affection for old school hard models. Oh, I have embraced our digital tools but there is still a lot to be said for something you can hold and feel the forces and motions.

Thanks for sharing.

Ralph