LR thrust

[shadowj38]

With the car up on the bars, accelerating off the corner… Are both LR bars “thrusting” into the chassis or is one trying to thrust into the chassis and one trying to pull away? If the second is true, which bar is thrusting and which is pulling?

[MasterSbilt_Racer]

If your chain is tight, and the wheel no longer separating from the body, the forces in all directions cancel out. So, you need to have a bunch of measurements and calculate.

The sum of the forces on the axle will be zero. The sum of the rotational moments on the cage will also be zero.

The lower bar is going to definitely have more compression on it.

Lifting thrust is really only helping you that brief instant the car is raising from the height it fell to on entry to the point your chain goes tight. A lot of people think they are doing much more with bar angle, that isn't really taking place. You are not tightening late exit by moving your top bar higher on the frame. You have added dynamic steer and initial throttle tightness, but it's gone in an instant.

[shadowj38]

So if you could some how find a way to put more force into the lower bar (chassis pushing bar into birdcage) would you gain more forward traction?

[MasterSbilt_Racer]

So if you could some how find a way to put more force into the lower bar (chassis pushing bar into birdcage) would you gain more forward traction?

No. Ultimately you gain forward traction (ability to drag race) from more load on the rear tires, equal balance between the rear tires, and less stagger between the rear tires.

To make the car tighter during the transition from less than full hike to full hike, you need more load in the bar with more angle. To get more load, you move a bar closer to the axle. That's why people used to drop the lr top bar on the cage, back in the wheelie off the corner, slam down on entry days of the 1990s.

[shadowj38]

Makes sense. Definitely changes my way of thinking. Thank you.

[ZERO25]

Some good asphalt racers I used to hang around with, have always suggested that we are hurting out lr contact patch by allowing it to move so much, forward and backward. That has always stuck in the back of my mind.

[7uptruckracer]

Yup I run asphalt still and we don't like the tire to go through any transition or minimal if possible. A tire that is already at optimum attack posture is ready to turn immediately it doesn't have to get there first!

Some good asphalt racers I used to hang around with, have always suggested that we are hurting out lr contact patch by allowing it to move so much, forward and backward. That has always stuck in the back of my mind.

[FlatTire]

What kind of load values are typical for the Left Rear 4-bar links?

[billetbirdcage]

What kind of load values are typical for the Left Rear 4-bar links?

Not many will give you an answer after having to spend 4 to 5K for load sensor for the bars. But it varies greatly at different parts of the track, can be anywhere from negative to 4 digit numbers

[ZERO25]

How does that translate to tire loading? Do they have a magic number that maximizes tire traction?