droop load

[racer-15]

why do guys take droop load out of left rear for slick track? I would think it would take bite out and traction away?

[MasterSbilt_Racer]

why do guys take droop load out of left rear for slick track? I would think it would take bite out and traction away?

The ultimate load up the straight comes from how high that corner is lifted. Initial throttle up from antisquat, if it has sat down some. Droop load rotates the car on entry when the car is slowing.

[racer-15]

So does the bar angle create more traction or the downforce of the body? thanks

[MasterSbilt_Racer]

So does the bar angle create more traction or the downforce of the body? thanks

Other than raising the car from ride height to race height, bar thrust does very little and decreases quickly once the car leaves the corner.

[95shaw]

How is weight derived from aero downforcce applied to LR tire if not through the bars?

[MasterSbilt_Racer]

How is weight derived from aero downforcce applied to LR tire if not through the bars?

You have 2 lr shocks, a spring, a 5th coil, rr suspension. Lots of force paths. The top bar is actually put in tension from the force of the spring behind. It spends a lot of time with little to no compression on it.

[95shaw]

You have 2 lr shocks, a spring, a 5th coil, rr suspension. Lots of force paths. The top bar is actually put in tension from the force of the spring behind. It spends a lot of time with little to no compression on it.

I guess I am not really feeling it.

The lr spring compresses as load is applied. We have used the bars to get to race height, with a zero index birdcage, so the droop load is less than at static ride height.

The shocks still compress, regardless of valving, or we would not get back to static ride height.

5th coil picks up its load in the middle of the car, near static cg. and distributes it to both rear tires. biased by position of lift arm on rearend.

The RR tire cannot be loaded excessively more than LR tire, or car will be verry loose.

Ultimately, need to load the LR somehow.

[Kromulous]

Interesting conversation, i do know the Spoiler on a SLM is wicked on down force. I rode one of my Motorcycles behind a SLM on an open trailer one day, and wow ! The air flow off that spoiler was insane.

Anyway, how many lbs force do you think is being applied MBR? rough cut i know, ball park guess? 400 lbs or better?

How much force does the lower rod feel? I know we tried a set of the "special rods" once, and he said he could feel the difference, so it must be applying a bit of load, because on the smasher they we're set to move at 1000 lbs

[MasterSbilt_Racer]

I guess I am not really feeling it.

The lr spring compresses as load is applied. We have used the bars to get to race height, with a zero index birdcage, so the droop load is less than at static ride height.

The shocks still compress, regardless of valving, or we would not get back to static ride height.

5th coil picks up its load in the middle of the car, near static cg. and distributes it to both rear tires. biased by position of lift arm on rearend.

The RR tire cannot be loaded excessively more than LR tire, or car will be verry loose.

Ultimately, need to load the LR somehow.

The 5th coil picks up both sides of the car. Where do you think that 1200# comes from? The j bar becomes a load carrying device too. I think you'd be shocked what is left on the lr tire at maximum lateral weight transfer, at least through the load paths you are thinking about.

[MasterSbilt_Racer]

Interesting conversation, i do know the Spoiler on a SLM is wicked on down force. I rode one of my Motorcycles behind a SLM on an open trailer one day, and wow ! The air flow off that spoiler was insane.

Anyway, how many lbs force do you think is being applied MBR? rough cut i know, ball park guess? 400 lbs or better?

How much force does the lower rod feel? I know we tried a set of the "special rods" once, and he said he could feel the difference, so it must be applying a bit of load, because on the smasher they we're set to move at 1000 lbs

Thrust load comes from relative acceleration. When you are gaining speed off the corner, the bars see a high load. It drops off quickly. How high does compression go on the lr top? I'm not entirely sure.

[Kromulous]

I guess you could find out how much the aero load could be, if you decreased your droop load a bit at a time and see if the car begins to lower on the straights.

Compression in the shocks will slow this, but high gas pressure could provide some lift thou via rod pressure.

How fun would it be to test all this stuff with the proper equipment !

[95shaw]

Thrust load continues all the way down the straight, even though acceleration drops off.

That aero load comes at a cost. No free lunch.
If not applying enough thrust to at least overcome drag, you are decellerating.

The steep bar angles make it easier to stay up against the chain so less thrust force is needed to maintain than was required to get on the bars initially. This allows the car to hold the added aero weight on the LR at race height.

[MasterSbilt_Racer]

Thrust load continues all the way down the straight, even though acceleration drops off.

That aero load comes at a cost. No free lunch.
If not applying enough thrust to at least overcome drag, you are decellerating.

The steep bar angles make it easier to stay up against the chain so less thrust force is needed to maintain than was required to get on the bars initially. This allows the car to hold the added aero weight on the LR at race height.

Thrust is directly proportional to acceleration. The car is held up by the need to overcome the loads on the birdcage to rotate it back clockwise.

[Jking24]

I was not their so i can't give all the details but a freind raced two weeks ago and after the heat they noticed the lr tire had gotten into the door. Their not the most observant racers. They pulled the door out and proceeded to eat another hotdog out whatever it is they usually do between races i got a phone call after the heat starting that the car was decent but about half way through the heat the car suddenly got realy tight in. Not knowing anything about the door and tire at the time i just advised him what i would do moving forward given the track conditions he had described. He ran the whole feature. They got back to the trailer after fading from the pole to fifth or sixth and they noticed the tire sitting funny in the wheel well. Finally they looked under the car and the lf top rod had ripped the threads out of a half nut and come off the bird cage. I can't say for sure when it actually came off but the car was raced for at least some amount of laps with no top bar. I would not even thought it could be possible. I can't imagine that ten years ago that would have been possible on say a straight 200#lr spring

[95shaw]

So you are saying that the droop load on the LR spring provides some of the force needed to turn the birdcage clockwise.

Doesn't that mean that the loads are being carried by the bars until that happens?