Single Seat SolidWorks Design Review

[IronSpade]

Anyone who has competed on an SAE Mini Baja team would have had to have at least one Mechanical Engineering major on the team to qualify. Every Mech Engineer will tell you that a triangle will always be structurally stronger than a simple square or rectangle. All box shapes should be triangulated for strength! There are many different arguments and just as many examples of what design is better between a dual A-arm and a single trailing arm rear suspension. Back in 1995-1999 I competed in 4 consecutive Mini-Baja competitions while completing my degree in Industrial Design at Metro State College in Denver CO. We tried them all. Almost all failed under the most strenuous of circumstances. We found that in a real world scenario of offroad racing a good proven trailing arm design with Type IV or 930 CV's worked best in most all conditions. Trust me I know how tempting it can be to try to reinvent the wheel, but hey don't fix it if it works so well!

I believe that the reason it works so well is the natural rotational travel of the arm in response to an impacting force. A dual A-Arm system must be able to transfer the forward to rear acting forces and torque into a vertical reaction. A lot of stress is placed onto the mounting points at the frame in this condition. The longer an A-Arm, or in this design an H-Arm, is the more rotational force is placed on the mount points of the arms. If you can spread the mount points as far apart as possible you will in turn spread the reactive shearing forces imposed on the mounts.

I hope that I've explained this in as simple terms as I could without sounding too technical. If further explanation is needed I will try to explain more. I have seen so many amateur buggy builders who have experience with 1/10 and 1/8 scale RC cars design there buggies like what they have seen in the model designs. I don't think most of the RC buggy manufacturers would still be in business if it weren't for the spare parts sales. The number one part replaced on RC cars is suspension arms! They fail, period! Almost like they were designed to fail. But that being said I would much rather have a suspension design for my full scale buggy that would flex or bend or be so overly engineered to take all abuse than fail in the middle of nowhere and then try to push or drag my 1000lbs broken buggy back to camp. LOL.

I like a lot of the ideas you have for this buggy but some items just need a little refinement. And again don't forget the KISS method. (Keep It Simple Stupid).

Later Travis

[chuckorlando]

Yea I see what you mean. Thanks

[NorCalBuggy]

When designing the rear end, I am currently limited due to the chassis design. I too am not happy having such a boxy rear a-arm. I think I am going to try and integrate the engine into the frame more (Making it a integral component to the frame structure), in so, it should allow me to widen the rear frame structure giving me more room to widen the rear mounting locations. Ideally I would want about 20 inches spacing between mounts to give it as much torsional stability as possible.

ed

[mvash]

I’m designing one similar….slowly!

I am at the rear suspension.

Big picture concept wise…Why A-arms vs Trailing arms.
I love Yoshi’s designs. Maybe it’s the shiny finished product, which appeals.

I find I can get the travel I want with the trailing arms and stay out of the engine space.

I intend to step up the lateral tube (not unlike a VW). No torsion bar though.

Currently my arms are just over 25inch in length.
Need to do stress study for tube size and all.

I am looking for specs for allowable motion with axle (stretch, angles of swing, etc…)