That's not showing the center of gravity is at 24mm. When you raise the car up, the center of gravity goes up too, so that's a bit chicken/egg. I believe what you have encountered is you raised your ride height such that you raised your roll center above ground and now jacking force has reversed. What you have demonstrated was raising the front roll center above ground and its affect on jacking forces.

A more accurate jacking force demonstration of jacking force would be to press at the base of the tires near the contact patch.

Jacking forces are the upward or downward force placed against the chassis due to roll action and chassis geometry. If the roll center is above ground, the jacking forces will raise the chassis. If the roll center is below ground, the jacking forces will suck the car toward the ground.

The b44 platform places the roll center really low due to its nominal ride height, If you try this on a b4 rear, it will actually raise at 24mm ride height, but the center of gravity is well above 24mm on the b4.

Jacking forces are one of those things you rarely consider outside of the initial design of the car. Front roll centers are frequently found below ground and tend to suck the front down and add steering on hard corners. Rear roll centers are frequently found slightly above ground, allowing making the rear suck down on hard corner exit when weight transfer lowers the rear and reverses the jacking forces, while still allowing the rear to unload easily in corner entry. The relative GENERAL location of roll centers are part of the car's design. The final fine tuning position achieved with camber link positions and ball stud washers is just playing in that area.

This is yet another reason one does not vary ride height much from the factory settings -- it jacks up the jacking forces and general location the roll centers should be for the car to behave right in all situations.

Wayne

I know better than to heads up with that war wagon... But I can if I can A in....

Okay I did get some of that. You know how I am. But Is that not the elusive Imaginary line/center...?

Hey that's good info. Never looked at it like that. Rounding the edges and digging that is.

I'm not sure what you mean. There's a lot of imaginary lines in the whole SAE roll center world.

If I did that with four hands and picked the car up would it be the jacking forces that would hold it center.

Really having trouble understanding what you mean. It's not jacking forces keeping it from raising or lowering, it's how close your roll centers are to ground level, I *believe*. In your video, I think you raised the roll center WELL above the ground.

I think the answer is it is the lack of jacking forces with the roll centers so close to ground (ground = line connecting bottoms of tires) that would cause it to stay put when squeezed.

if any one is interested or knows anybody im going to sale my b44.2

Okay so to make it easy did I explain it right? The center of gravity starts at the center of the roll center right? The center working from the out side in. Seems how there is no way to find it from the inside out. (Well with out a computer). I was Able to show the center of where the roll is. By pushing in, forcing the imaginary center of that set up to show itself. "For lack of better or more scientific words". If I changed the set up it could be 23mm/25mm depending on where I want the roll center to be high or low.

Above 24mm I raised it. Below 24mm I lowered it. If that's not where the center of gravity starts with this set up. Where is it? Or where does it start.?

Ehhh... I'm so lost. LOL. You're really not showing anything about center of gravity. Honest. The only thing you're showing is where the roll center is in relation to the ground. Center of gravity of the unsprung weight is not changed, just its relation to the ground, and the roll center's relation to the ground does change. The "moment arm" does connect the roll center and center of gravity, and both of them move when you move the ride height. Only the roll center will move if you change only the setup.

It is possible to change the setup in such a way that the car squishes up at 21mm ride height. Just put enough washers/spacers (like what I did in my vid showing roll center) and push together at the tire base and that will be the effect due to raising the roll center so high above ground. In that case, the center of gravity didn't move at all, so the test is not really showing anything about the center of gravity if you think about it.

You should just call me before somebody complains we're too off topic

Actually I don't even care about it. Above 24mm the tires are on top of dirt. Below 24mm gets the tires more in the dirt. Easier for me and most to understand. You can go to high or low. COG/weight keep it low...

Hey guys looking to trade my TLR 22 for a b44.2 let me know if anyone is interested http://www.rctech.net/forum/r-c-item...dex410-v3.html

-Tim

It's a great technical discussion Raz and UN4 are having but what most racers need to take away from this ride height discussion is:

For 99.9% of tracks the whole 44 series cars like a front height of 22-21 and a rear height of 20-21.... Set it and be done.

100% true. I always tell folks to never deviate far from the team/book/standard ride heights on any car or you will find yourself outside the range where the suspension works as designed.

One time I accidentally set my front ride height to 24mm on my b44. It was the strangest thing. It wouldn't hardly at all... then if you hit a corner hard enough, it would just pole vault / traction roll in the front. I was like WTF. No steering, but then traction rolls. I pulled the car in and noticed the front was high. Amazing how bad the car can act just being 2mm over a normal setting of 22. Impressive.

That's why I usually wont go into this technical stuff. But its a way to find where your roll center is. And you can then actually learn more about roll centers. If it was locked in at 22mm you would most likely be running a lower roll center or racing hard bite surface. 25mm would be higher or a very soft surface. A true genius would probably say just the opposite. I have never even had to ask anyone to do that to try to find out where there at.
The good thing is we are pretty much going to be in the same area as far as the kit and suspension. I never change my ball stud shim setting from the stock set up. RAZ will vouch for that. I don't go there. I would have to be desprit. You can't pay me to change it.
On my set up its pretty much in layman terms middle. I cant get to scientific cause I'm not that educated at it. If my kit was locked in at 25mm I would be traction rolling. Then I would be all into limiters, oils dampeners, and well the point and scenarios are endless.
It just gets to deep.
The thing is on the track if your running 24mm on my kit the suspension is not working and the kit feels like its not even touching the ground. Its all just gravity driving or a good example is hovering around the track. Running weight to get it to handle would make the kit traction roll. But I could land it off a sky scraper and not chassis slap.
The surface we are running on commonly is and should never get over 21mm in the rear and 22 in the front. IMO Oh wait where have I read that.

At any rate I bet the guy that was having a goofy handling kit at 24mm knows not to or maybe why not to now. Or hes got a real bad head ache from trying read why..