Designing the Satchell Link

[g-roadster]

Norm: Interesting discussion on the Satchell Link. Thanks for your input. A couple of points about the Satchell Link: The roll center is determined by the intersection of the two lower links, If you want to minimize roll center migration relative to the frame bring these inner pivots as close together as possible. Making a large A frame with a ball joint would be a solution for minimum roll center migration but would increase stress on the single ball joint rather than two and reduce your alignment adjustment possibilities. Roll steer is controlled by the upper links, adjusting the length and inclination affects roll steer. You hinted at this in your discussion.

I am designing the g-roadster with a Satchell link rear suspension. So far I have only laid this out graphically. I feel comfortable doing this as I have designed everything from large space craft to small optical systems from the drafting board. But I do realize the limitations of graphical only design. What program are you using for your suspension analysis? I will need to get a program, or access to one, to refine my front and rear suspension designs. Recommendations appreciated.

Norm, if it wouldn't be too much trouble could you do computer run for my Satchell link design?

Not sure what: RideHeightChange, LCAchassisZchange, LCAaxleZChange are in your inputs.

[Norm Peterson]

RideHeightChange allows you to input a ride height change due to a change in vehicle loading or a spring height change for a quick ,if slightly dirty, set of results.

LCAchassisZchange is simply a lowering (or raising) of the chassis side LCA pivots relative to some baseline value, and perhaps useful if you have multi-hole or otherwise adjustable chassis side pivot pickups. It's just another way of modifying the LCAchassisZ data that could provide a hint about what you were thinking when you look at the sheet in a year or whenever. Also slightly approximate.

Ditto for LCAaxleZChange, which is where one would enter changes in LCA attachment elevation at the axle brackets. AKA relocation or anti-squat brackets.

P.S. One can perform moderately sophisticated geometry and engineering analyses using Excel or similar spreadsheet software once the necessary equations have been worked out.

P.P.S It's not much trouble at all to run a few of these every so often. After all, there are less than 20 separate inputs (symmetry has been assumed). But I'd rather handle this sort of consulting via e-mail, as the amount of allotted attachment space is limited.


Norm