The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

**robnolimit** · 11-21-2010, 06:10 PM

Lets get back to the main topic, HANDLING. One of the best upgrades you can do is swaybars. Swaybars, or Anti-roll bars, work by adding traction (downforce) to the outside tire. To do this, the swaybar has to take downforce away from the inside tire. So if you think about it, you can go 'too big' on the bars. If you went so stiff that the inside tire lifts off the ground, then that tire isn't helping at all. The balance between the front and rear bars is called "roll couple", and here's where a truck layout changes normal thought. In a normal performance car, with say 52% front weight and a low CG, the roll couple needs to be up around 80% (calc for this is really complex, so think of this as a comparison number), but in a truck, with 58% front weight and a higher CG, you aqctually need to move the roll couple BACK, maybe to 65%. This means that in comparison to a Camaro that would run a 1 1/4" front and a 7/8" rear, the truck would tend to 'need' a more evenly matched bar set. Say 1 1/4" front and 1 1/8" rear. Most retailers/manufacturers are missing this and selling bar sets in 'car' sizing, so be carefull.
From the set-up you have now, you can use the following rules for tuning.

A larger FRONT bar will "tighten" the chassis, making the truck tend to push, or not want to turn into a corner, also the rear of the truck will seam a bit stickier. A smaller front bar will do the opposite.

A larger REAR bar will "loosen" the chassis, the truck will turn into a corner easier, but the rear may want to slide around.

Last weekend in Pleasonton, I was explaining this to a few people and most believed that a smaller rear bar would help the truck turn, do to the added cross weight from the inside rear to the outside front - as the truck leans over. So, I pulled one of the rear swaybar links on our 55, effectively it had no rear bar. The truck pushed like crazy, and on the second lap, I spun out trying to throttle steer it through a corner. Bad outcome, but it was a good demonstration of swaybar tuning.

How you mount and connect swaybars is equally important, we'll get to that later. Think out this and ask away. Oh yeah, We won our class in P-town, even with the demo run!!!

11-21-2010, 06:10 PM	#203
robnolimit Senior Member Join Date: Jul 2010 Location: Dandridge, Tn. USA Posts: 2,226	Re: Make it handle Lets get back to the main topic, HANDLING. One of the best upgrades you can do is swaybars. Swaybars, or Anti-roll bars, work by adding traction (downforce) to the outside tire. To do this, the swaybar has to take downforce away from the inside tire. So if you think about it, you can go 'too big' on the bars. If you went so stiff that the inside tire lifts off the ground, then that tire isn't helping at all. The balance between the front and rear bars is called "roll couple", and here's where a truck layout changes normal thought. In a normal performance car, with say 52% front weight and a low CG, the roll couple needs to be up around 80% (calc for this is really complex, so think of this as a comparison number), but in a truck, with 58% front weight and a higher CG, you aqctually need to move the roll couple BACK, maybe to 65%. This means that in comparison to a Camaro that would run a 1 1/4" front and a 7/8" rear, the truck would tend to 'need' a more evenly matched bar set. Say 1 1/4" front and 1 1/8" rear. Most retailers/manufacturers are missing this and selling bar sets in 'car' sizing, so be carefull. From the set-up you have now, you can use the following rules for tuning. A larger FRONT bar will "tighten" the chassis, making the truck tend to push, or not want to turn into a corner, also the rear of the truck will seam a bit stickier. A smaller front bar will do the opposite. A larger REAR bar will "loosen" the chassis, the truck will turn into a corner easier, but the rear may want to slide around. Last weekend in Pleasonton, I was explaining this to a few people and most believed that a smaller rear bar would help the truck turn, do to the added cross weight from the inside rear to the outside front - as the truck leans over. So, I pulled one of the rear swaybar links on our 55, effectively it had no rear bar. The truck pushed like crazy, and on the second lap, I spun out trying to throttle steer it through a corner. Bad outcome, but it was a good demonstration of swaybar tuning. How you mount and connect swaybars is equally important, we'll get to that later. Think out this and ask away. Oh yeah, We won our class in P-town, even with the demo run!!!