Where do I want it and what do I need to consider, how does this effect my front suspension redesign???

Oddly enough between my stock link configuration and my new link designs the roll axis hasn't moved too much (My LCAs have stayed in almost the same vertical plane).

Is this something I need to be watching cause I am not or at least have not been.

I have spent all of my time dealing with instant center and mounting locations and have kinda left this alone, UNTIL NOW!. I do feel good about the significant drop in my instant center but I am still playing numbers games so if this is going to bite me in the ass I wanna know.

Okay we had the god of suspension thread
We had the 200% anti squat thread


Does this subject deserve to go down in history as well?

Those in the know help me out.

PS. I have yet to make a cut and I HAVE to be rolling and in Disney by the 19th of September. Anyone think I can do it?

I'm pretty sure you want the roll axis to about the same area as the center of gravity from side to side. Does that make sense. That way your rig doesn't act all top heavy, but it might just be best to get the roll axis up as high as possible.

Originally posted by jesselt
I'm pretty sure you want the roll axis to about the same area as the center of gravity from side to side. Does that make sense. That way your rig doesn't act all top heavy, but it might just be best to get the roll axis up as high as possible.

Pick one man, side to side or up and down...

Also this will be a three link so it more or less makes a V pointing rearward while looking at it from above, the only way I can think to point it side to side is to put my single wishbone mount at the chassis and offset it to one side, that doesn't sound like a good idea to me.

So first vote is shaky with a make your roll axis point at the COG or higher.

This sound good?

I dunno if making the roll axis higher then the COG is possible unless I run alot more anti-squat then I desire or have the CAs cross close to the chassis which is not an option IMHO.

you won't be able to get it as high as the COG, but like stated, try to get it as high as possible. The configuration you are using will lend itself to that goal, because the main articulation point will be the tip of the 3 link at the fram side.

Sorry, I didn't explain it very well. I basically just meant you should have the axis as high as possible, i wasn't trying to contradict myself.

Like elf_cruiser said, your wishbone 3-link will lend itself nicely to a high roll axis, you should be just fine.

Too bad this is a holiday weekend and none is posting.

Oh well BTT and I'll do it once again tomorrow if no more info comes in.

Originally posted by elf_cruiser
you won't be able to get it as high as the COG, but like stated, try to get it as high as possible. The configuration you are using will lend itself to that goal, because the main articulation point will be the tip of the 3 link at the fram side.

OK there is no way to get everything perfect. It is a give and take with every aspect of a link suspension.

Now for the topic at hand. Yes ELF, once again is on the money. There is gonna be no way to get it the roll axis in the same plane as the CG plane but the closer the better. TJ FREAK, you said point the RA @ the CG point. I think you just tried to say what Elf and Jesselt were trying to say. However, if you didn't DO NOT try and point the RA at the CG this will result in a FUCT RA. Does that make sense? Keep the RA as parallel as possible to the ground while being as close to the CG as possible.

Originally posted by PIG


OK there is no way to get everything perfect. It is a give and take with every aspect of a link suspension.

I am planning to leave some adjustments in the chassis brackets to allow me to reposition the control arms slightly but I can't do much. Being under-(or un)educated makes the compromise system even worse. :(


Now for the topic at hand. Yes ELF, once again is on the money. There is gonna be no way to get it the roll axis in the same plane as the CG plane but the closer the better. TJ FREAK, you said point the RA @ the CG point. I think you just tried to say what Elf and Jesselt were trying to say. However, if you didn't DO NOT try and point the RA at the CG this will result in a FUCT RA. Does that make sense?

K, I think I got that, I run some sketches of what it would take to get RA to target the COG and that isn't going to work for many reasons. ;)


Keep the RA as parallel as possible to the ground while being as close to the CG as possible.

That is some really good news to me!!!

My RA should be about 60% of the height of the COG which is I guess okay at best BUT it is almost totally parallel (< 5* off) to the ground which I just learned is what I want.

Is there any concern over the forward to rearward location of the instant center?

Mine is about where the ashtray is located on a TJ. I don't see how I can move it any closer to the center of the rig without either stretching my wheelbase or shortening my arms.