At what 60' do you start pulling a tire?
Re: At what 60' do you start pulling a tire? [quote]Originally posted by Colonel:
<strong>In a perfect world where traction is always perfect, neither the back or the front suspension would ever move and ALL power would be utilized in propelling the car forward.</strong><hr></blockquote>
If that were the case though, then lowered cars with big tires would be a good combo, but its not.
The axle needs to be able to drive itself under the car somewhat.
Anyone have any thoughts about the physics aspect of this at all?
<strong>In a perfect world where traction is always perfect, neither the back or the front suspension would ever move and ALL power would be utilized in propelling the car forward.</strong><hr></blockquote>
If that were the case though, then lowered cars with big tires would be a good combo, but its not.
The axle needs to be able to drive itself under the car somewhat.
Anyone have any thoughts about the physics aspect of this at all?
D(irecto)r Pepper
Joined: Nov 2001
Posts: 1,952
Likes: 0
From: Houston Raceway Park...in TEXAS.
Re: At what 60' do you start pulling a tire? But ya see.. your trying to prove all this "theory". I'm just trying to explain what works.
I might not have the vocabulary to tell you WHY or HOW it works to your satisfaction. But after years of experimenting... i CAN tell you WHAT works on MY car.
I dont limit upward momentum as a goal. I do try to raise the rear of the car and i do try to PLANT BOTH rear tires. This seems to inherently work to keep the rear from squating and the front from lifting (GOOD).
If a car lifts up the front left wheel 2' in the air but only extends the shock on the passenger side front with out lifting the tire (been there done that)... he is WASTING energy.
You need the weight transfer to plant the tires. You dont need a whees stand to turn a great 60'.
P.S., Body roll off the line sucks rocks.
BTW, I think the obfuscating lowered car analogy was, well wrong. (no offense)
Colonels words of PERFECT traction were right on. You woldn't NEED the weight transfer, or tire planting or any other crutch if the tires would just grab and keep hold...all the while projecting the car in a forward line. (not upward line)
Campbell
I might not have the vocabulary to tell you WHY or HOW it works to your satisfaction. But after years of experimenting... i CAN tell you WHAT works on MY car.
I dont limit upward momentum as a goal. I do try to raise the rear of the car and i do try to PLANT BOTH rear tires. This seems to inherently work to keep the rear from squating and the front from lifting (GOOD).
If a car lifts up the front left wheel 2' in the air but only extends the shock on the passenger side front with out lifting the tire (been there done that)... he is WASTING energy.
You need the weight transfer to plant the tires. You dont need a whees stand to turn a great 60'.
P.S., Body roll off the line sucks rocks.
BTW, I think the obfuscating lowered car analogy was, well wrong. (no offense)
Colonels words of PERFECT traction were right on. You woldn't NEED the weight transfer, or tire planting or any other crutch if the tires would just grab and keep hold...all the while projecting the car in a forward line. (not upward line)
Campbell
Re: At what 60' do you start pulling a tire? Well, wheelstands are counterproductive. Too much hook and weight transfer and the car is on the back bumper.
Magnus, as you know back when I went 11.15 at US41 (you were there), the car squatted way too much and just went up and down too much.
I am shootin' for a 1.45 on 26" ET Streets. I am installing rear Hals and V8 springs back in the rear.
Magnus, as you know back when I went 11.15 at US41 (you were there), the car squatted way too much and just went up and down too much.
I am shootin' for a 1.45 on 26" ET Streets. I am installing rear Hals and V8 springs back in the rear.
Re: At what 60' do you start pulling a tire? I think the Colonel is right on. Raising the front any more than needed for traction is simply wasted energy. The ideal car would have perfect traction and launch paralell to the ground, thus harnassing most of the engines power to forward movement.
D(irecto)r Pepper
Joined: Nov 2001
Posts: 1,952
Likes: 0
From: Houston Raceway Park...in TEXAS.
Re: At what 60' do you start pulling a tire? For me?
1.) Wheels up look good for the camera.
2.) Wheels up are bad for E.T.
"I'll choose number "2", and yes, thats my Final Answer."
That is my two cents. It works for me.
You want the car to raise up, (the WHOLE car) not just the front.
This will push the rear DOWN into the track there by aiding traction.
Would HAL shocks help? I would like to try them.... but as of yet. My 60's are good and the car is hooking. But, if I am not spinning...why spend the money?....consistentcy?
In conclusion: I do not really see how the ennergy of the car coming down, will help the car accelerate in a horizontal line.
Can anyone else throw an opinion in on this one?
Raughammer
1.) Wheels up look good for the camera.
2.) Wheels up are bad for E.T.
"I'll choose number "2", and yes, thats my Final Answer."
That is my two cents. It works for me.
You want the car to raise up, (the WHOLE car) not just the front.
This will push the rear DOWN into the track there by aiding traction.
Would HAL shocks help? I would like to try them.... but as of yet. My 60's are good and the car is hooking. But, if I am not spinning...why spend the money?....consistentcy?
In conclusion: I do not really see how the ennergy of the car coming down, will help the car accelerate in a horizontal line.
Can anyone else throw an opinion in on this one?
Raughammer
Re: At what 60' do you start pulling a tire? But, if the car WANTS to pull the front end up and you weigh it down by keeping the front shocks stiff, the engine has to work harder to move the car forward.
I don't see energy being lost by preventing the front from coming off the ground. I see it as energy being lost by keeping the front from coming off the ground.
Say the front end comes off the ground 1 foot. Take the angle at which the car is now at.. a few degrees, now measure the distance on the tire between the horizontal axis and the newly created line... you have half an inch maybe? So thats how much you have lost. But, when the car comes back down, it "twists" the axle itself back to a horizontal line, while at the same time making up for your lost half inch..
follow?
Anyone have any thoughts?
I don't see energy being lost by preventing the front from coming off the ground. I see it as energy being lost by keeping the front from coming off the ground.
Say the front end comes off the ground 1 foot. Take the angle at which the car is now at.. a few degrees, now measure the distance on the tire between the horizontal axis and the newly created line... you have half an inch maybe? So thats how much you have lost. But, when the car comes back down, it "twists" the axle itself back to a horizontal line, while at the same time making up for your lost half inch..
follow?
Anyone have any thoughts?
Re: At what 60' do you start pulling a tire? [quote]Originally posted by Magnus:
<strong>
Say the front end comes off the ground 1 foot. Take the angle at which the car is now at.. a few degrees, now measure the distance on the tire between the horizontal axis and the newly created line... you have half an inch maybe? So thats how much you have lost. But, when the car comes back down, it "twists" the axle itself back to a horizontal line, while at the same time making up for your lost half inch..
</strong><hr></blockquote>
2 thoughts:
The energy required to raise the car 1 foot off the ground is far in excess of the energy required to push the car 1 foot down the track.
The engine torque used to twist the car and pull the front wheels is converted to potential energy at the point the car reaches its peak height of 1 foot off the ground. The potential does not get transfered to the drivetrain when the car lands on the ground. It is burned up as heat and friction in the suspension (e.g. shocks & springs). Thus it does not help move the car forward.
That's my theory.
<strong>
Say the front end comes off the ground 1 foot. Take the angle at which the car is now at.. a few degrees, now measure the distance on the tire between the horizontal axis and the newly created line... you have half an inch maybe? So thats how much you have lost. But, when the car comes back down, it "twists" the axle itself back to a horizontal line, while at the same time making up for your lost half inch..
</strong><hr></blockquote>
2 thoughts:
The energy required to raise the car 1 foot off the ground is far in excess of the energy required to push the car 1 foot down the track.
The engine torque used to twist the car and pull the front wheels is converted to potential energy at the point the car reaches its peak height of 1 foot off the ground. The potential does not get transfered to the drivetrain when the car lands on the ground. It is burned up as heat and friction in the suspension (e.g. shocks & springs). Thus it does not help move the car forward.
That's my theory.
Re: At what 60' do you start pulling a tire? Well, I broke out my physicis book yesterday and talked to a few physics friends of mine.. we are all not certain. I should have a professors view point by the weekend...
But here is how I see it..
When the front end lifts, the forward force vector is no longer in line with the center of mass. As the front lifts up, the center of mass moves upward and toward the rear of the car. When the force vector is perpindicular to the plane of the car, it should take less energy to move the car at that point. But then its fighting the G vector on the front of the car around the center of mass.
But, as the front lifts up, it pulls itself off of the front suspension... which is good. But then it starts to pick up the front suspension and that weight begins to hang... which is bad.
Yes, huge wheel stands are bad.. thats not what we want.
I'd like to understand the physics of it.
But here is how I see it..
When the front end lifts, the forward force vector is no longer in line with the center of mass. As the front lifts up, the center of mass moves upward and toward the rear of the car. When the force vector is perpindicular to the plane of the car, it should take less energy to move the car at that point. But then its fighting the G vector on the front of the car around the center of mass.
But, as the front lifts up, it pulls itself off of the front suspension... which is good. But then it starts to pick up the front suspension and that weight begins to hang... which is bad.
Yes, huge wheel stands are bad.. thats not what we want.
I'd like to understand the physics of it.
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Re: At what 60' do you start pulling a tire? As has been said, the only purpose of raising the front of the car at launch is to transfer as much weight to the back tires as possible in order to avoid spinning and the associated reduction in ET.
From the point that the front tires leave the ground it is apparent that the entire weight of the car is on the back tires so raising the front further can add no additional weight to the rear.
Although this means that there is no purpose to further raising the wheels, wheelstanding is not substantially detrimental to ET because most of the potential energy stored during lifting of the front end is relased to the tires as work as the it comes down.
This is provided the front does not come up so high that wheelie bars come in contact with the ground (which lifts weight from the rear tires) or is up so high and long that it becomes an air resistance issue. It is also provided that the front comes down relatively slowly because if it comes down fast much of the energy is absorbed as heat in the shocks when it lands rather than back into the drivetrain as torque and rotation.
Steve
From the point that the front tires leave the ground it is apparent that the entire weight of the car is on the back tires so raising the front further can add no additional weight to the rear.
Although this means that there is no purpose to further raising the wheels, wheelstanding is not substantially detrimental to ET because most of the potential energy stored during lifting of the front end is relased to the tires as work as the it comes down.
This is provided the front does not come up so high that wheelie bars come in contact with the ground (which lifts weight from the rear tires) or is up so high and long that it becomes an air resistance issue. It is also provided that the front comes down relatively slowly because if it comes down fast much of the energy is absorbed as heat in the shocks when it lands rather than back into the drivetrain as torque and rotation.
Steve
Teching In
Joined: Feb 2002
Posts: 18
Likes: 0
From: New Hartford CT
Re: At what 60' do you start pulling a tire? I'm sorry, but what is a 60'???????
Recently purchased a 2001 T/A... Looking to do some mods so I've been frequenting the forums.. Lotsa information here! Very comforting to find such a great environment. Hoping to contribute at some point as well!
Ps. Apologies for any 'foolish' inquieries.
Take Care.... <img src="graemlins/gr_angel.gif" border="0" alt="[angel]" />
Recently purchased a 2001 T/A... Looking to do some mods so I've been frequenting the forums.. Lotsa information here! Very comforting to find such a great environment. Hoping to contribute at some point as well!
Ps. Apologies for any 'foolish' inquieries.
Take Care.... <img src="graemlins/gr_angel.gif" border="0" alt="[angel]" />
Teching In
Joined: Feb 2002
Posts: 18
Likes: 0
From: New Hartford CT
Re: At what 60' do you start pulling a tire? I'm sorry, but what is a 60'???????
Recently purchased a 2001 T/A... Looking to do some mods so I've been frequenting the forums.. Lotsa information here! Very comforting to find such a great environment. Hoping to contribute at some point as well!
Ps. Apologies for any 'foolish' inquieries.
Take Care.... <img src="graemlins/gr_angel.gif" border="0" alt="[angel]" />
Recently purchased a 2001 T/A... Looking to do some mods so I've been frequenting the forums.. Lotsa information here! Very comforting to find such a great environment. Hoping to contribute at some point as well!
Ps. Apologies for any 'foolish' inquieries.
Take Care.... <img src="graemlins/gr_angel.gif" border="0" alt="[angel]" />
D(irecto)r Pepper
Joined: Nov 2001
Posts: 1,952
Likes: 0
From: Houston Raceway Park...in TEXAS.
Re: At what 60' do you start pulling a tire? A "60" is a measurement of time.
The "60" in question is the first 60 feet of a drag strip.
We as racers time ourselves in that section of the track and later talk about the measurement in question.
For example a normal 60' for a bone stock F-body. Would be about 2.1 or so for an auto and 2.3ish for a M6.
As we learn to drive these cars, add stickey tires and add suspension bolt ons. The 60' time will begin to decrease.
As a rule of thumb. As you removed a tenth of a second from the "60" it is usually worth 2 tenths on the other end of the track. (this is not an absolute fact)
The better the 60, the better your E.T.
Clear? or clear as mud?
The "60" in question is the first 60 feet of a drag strip.
We as racers time ourselves in that section of the track and later talk about the measurement in question.
For example a normal 60' for a bone stock F-body. Would be about 2.1 or so for an auto and 2.3ish for a M6.
As we learn to drive these cars, add stickey tires and add suspension bolt ons. The 60' time will begin to decrease.
As a rule of thumb. As you removed a tenth of a second from the "60" it is usually worth 2 tenths on the other end of the track. (this is not an absolute fact)
The better the 60, the better your E.T.
Clear? or clear as mud?