When you lower the panhard bar the rear roll center drops. Originally posted by Goran Malmberg Anyone having an opinion about this Q:s.Let us say that we do have a 1” front and 3” rear Rc, all in order for a good turn in balance. Originally posted by Goran Malmberg If building a new car we are not tied up by as much limitation as that of a rebuild. 2. A narrow instant center width creates a more radical change and also makes the roll center height move up and down radically during body roll, which effects front tyre loading during corner entry and mid turn. Finding the roll center for a live rear axle is very different from finding it on an IRS car. Roll Center Understood is correct. The roll center height is the vertical distance from the ground to roll center An important point to note that the roll center will move when the suspension is compressed or lifted, that's why it's actually an instantaneous roll center. 3D SoundBack Beta 0.1 (Realtek 3D SoundBack restores audio effects, including surround sound, reverberation, and spatial effects, for legacy game titles when running on Windows Vista.) The roll center height has two effects on vehicle dynamics. Goran Malmberg-It is commonly accepted (often without being questioned) that the rear Rc height is to be higher than that of the front. Originally posted by Goran Malmberg If the car makes a clean roll, whats sort of difference would it make if the bar is welded solid to the chassis or not?Goran. They all have software that lets them play around with suspension points. As Bill states,” Keep them both about the same height above the ground, make them both move about the same amount & direction vertically - it's less important laterally but common sense applies” is not a bad idea for a neutral build philosophy that might call for less harsh ”anti figures”.If some more anti should be looking for, a slight adjustability could easily be built in to the A-arm chassis mounts. Depending on the type of suspension, the roll center can be an actual pivot point or a virtual point in space and they don’t necessarily lie along the center line of the vehicle. In going to the GT2 they lowered the front roll center and raised the rear; before these changes the GT2 was said to be nearly un-drivable in testing. By doing these two things, you also reduced the roll couple at the rear which would make it act similar to having a stiffer sway bar. The roll center is an imaginary point around which the rear of the race car rolls. A high roll center has much the same effect. With the roll centre below ground height more weight is transferred via the springs (likewise raising the roll centre reduces weight transfer through the springs and increases weight transfer through sprung mass). This video will help to explain the relationship of a vehicle's center of gravity to it's roll center. First, it determines the change in tread with wheel stroke. Originally posted by jeremy durward my understanding is that would create a weight jacking effect... i could be wrong, please tell me if i am but everything i've read and experienced tells me that is the case. With the roll center below ground height more weight is transferred via the springs (likewise raising the roll center reduces weight transfer through the springs and increases weight transfer through sprung mass). Changing the roll center height or sway bar settings on the front or rear changes the roll stiffness. A low roll center has more of a rolling moment for the springs to react. ... same load distribution with different levels of anti-roll / roll centre height isn't the issue so much as what other effects those different geometries have other than on the "steady state" loads. The Effects of Rear Roll Centre Height Can someone please explain what effect the raising and lowering of the rear roll centre of a V8 Super Taxi has on the car? For each option we did indeed calculate a geometric roll centre height (to please management) but more importantly calculated the vertical force distributions per g at the contact patches (we call it roll couple distribution or mechanical balance). However, they raised the inner attachment point 10mm on the 930 which must be what made it viable for a street car. You currently have javascript disabled. As with the other variables affecting the rear roll center height, moving the roll center up will increase rear roll stiffness and thus loosens the car up. Goran. Some race cars with extreme amounts of lateral grip can move closer to the centre of gravity position but these figures are a good starting point to set your car up to and tune from. In my book I therefore start of with tires, wheel position and aero. Perhaps it was a parts-sharing compromise, but the fact is they were able to work around it. If you want to quantify the suspension dynamics that you're describing, my recommendation is to get the either or preferably both of the following books. For example: perhaps the major change between the 997 GT3 and 997 GT2 suspension was roll center height. Please re-enable javascript to access full functionality. Same as around the RC, if the RC isn't perfectly in the middle sway bar then the swar bar won't just twist from the center. You can adjust roll center by changing the angle of the suspension arms. Originally posted by mariner Simialarly the latest F1 cars appaer to throw al suspension geometry out eh window in order to get the front links to slope up out of the airflow. However, a sufficiently stiff anti-sway bar can cover up bad roll center placement and achieve the desired lateral load transfer rate. John von Neumann University, Hungary, 6000 Kecskem ét, … Roll Center Understood is correct. What we found was that the geometries made little difference once the roll couple distribution was equalised. Several functions may not work. The ideal roll centre position range that can be used to begin your set up is between 15% and 30% of the height of your centre of gravity height. Really, roll center is often found at about 1.5” off the ground to 2.5” off the ground for most cars – give or take an inch. 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