A arms and a 3rd link

[Engineer]

Thanks engineer.I'm at home on dialup today.I'll watch it at work tomorrow.

It's a picture..........

[Engineer]

The real solution to the bushing wear issue would be to make the end of the A-arm wider, along with the mounts on the carrier.  Just from the pictures it seems that the ends of the A-arms are only 2.5" wide, (front to rear).  This 2.5" is controlling all of the toe of the rear tire from acceleration and braking loads.  The center of the tire where the acceleration and braking forces are coming from are 8" away from the a-arm end.  The Tire has a lot of leverage on the pivots.

If the end of the A-arm were made 6" wide, it would significantly reduce the load on the bushings.  The rod helps, but it is only mounted 1/3 of the way to where the load is produced.  However, apparently it is enough to keep the bushings from being overloaded.

IMO on a new design, I would make the A-arms wider (front to rear), with the mounts on the carrier as wide (front to rear) as possible.

[Rick S.]

We all make certain compromises when we build our buggies.
I agree the carrier pivots would be better if they were wider. This was my fix to a preexisting problem with the plans I chose to build from. The fix obviously eliminated the bushing wear and proved to serve as added protection for the arms. Here is a photo of a wider design that I'm working on for another build. This build is completely my own design. I did double the width of my upper mount and increased the lower only slightly.
I run the link low to help the bushings on the lower arm and because I really do like the link.
And all of the criticism it brings.

[Engineer]

You do nice work Rick.  I think most of the discussion is not critical as much as people trying to get their understanding of how others do things and the many variables that need to be juggled for every build.

I am working on some designs of my own.  I am sure the criticisms will follow the unveiling shortly. 

[fabr]

Discussion is not criticism.

[Yummi]

Discussion is not criticism.

  - No seriously: I agree 100%.  Discussion = good.  Bitter attacking petty = bad.

[Rick S.]

Here's a sketch of the torsion bar idea.
The bar attaches to yokes at each end, so that the trussed links are free to fan in and out as the suspension cycles. of course the bar clamps would need to be mounted out closer to the yokes.
This is just a sketch. Critique away.

[fabr]

Hmmmmm, I gotta think about that.Ouch !!!!,thinking hurts!

[SPEC]

No critiquing here,
I was just talking with Fabr on the phone about that ,well really similar set-up on the phone yesterday, I was working on a similar set up with 2 short torsion rods a while back...when my spine took a dump I abandoned it and started working on thing/builds to make my life easier...Tractors and stuff to take my back and arms out of the equation

[Admin]

This 3rd link is pretty slick, got to check it out in person yesterday, the jig is as cool as it looks as well... Great meeting ya to Rick..

[Rick S.]

Great meeting you too. Not often I get anyone over here that's interested in any of this stuff. Hey, I do have another set of laser's for the same rear end that's in this Piranha. I have all of the cad for the modified frame too. Maybe you should build one. I could probably help you out on the other waterjet stuff too.     

[Admin]

Great meeting you too. Not often I get anyone over here that's interested in any of this stuff. Hey, I do have another set of laser's for the same rear end that's in this Piranha. I have all of the cad for the modified frame too. Maybe you should build one. I could probably help you out on the other waterjet stuff too.   

Hmmmm...

[Engineer]

Here's a sketch of the torsion bar idea.
The bar attaches to yokes at each end, so that the trussed links are free to fan in and out as the suspension cycles. of course the bar clamps would need to be mounted out closer to the yokes.
This is just a sketch. Critique away.

It would work!!  Your sketch is worth a thousand words.

So how "tight" would you want a torsion bar to control body roll, vs the freedom of the benefits of IRS.  I believe the trophy trucks use torsion bars, I have just never come to grips with the benefits of IRS, that you throw a torsion bar in on.  I guess it comes down to individual use.  If you prefer corner railing, a torsion bar is good.  For straight lines through the rough stuff it's not as good?

[Rick S.]

It was just a thought I'd had. Not that I will ever try it, or even thought I would need it.
But it would be interesting to see how it might help or hinder.

[artie on edge]

Hi Rick, just read your post re torsion bars. Its a topic that has been around for quite a very long while. Question, "how much body roll are you experiencing?" The reason behind torsion bars linked from wheel to wheel is to control body roll. In buggies the size we are using, this usually isnt a problem. Larger machines (trophy trucks et al) are a different matter.

In a nutshell, wheel to wheel torsion bars bind individual suspension movement. When you are dealing with large amounts of mass, this isnt too big a problem. When dealing with small mass (us!) it can really inhibit independant free suspension action.

You may notice I use the term wheel to wheel, what about two small torsion bars which anchor to the chassis and one controls each wheel? This will allow each wheel to operate individually.

Damn, its been done! This is simply what we used to run years ago before coil overs became common. The down side is the amount of twist (or wind up) each bar could tolerate and they limited the amount of wheel movement you could achieve.

Have fun.