Struggler, this forum should be for discussion so that we can all learn from each other. Its not about winning and losing. Id rather be "put right" than remain ignorant on a matter for ever, and am happy to reply and discuss matters politely with others who hopefully do the same.
Drag Setup
Started by
LhMusL
, Jan 31 2006 04:44 PM
83 replies to this topic
#52
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Posted 11 February 2006 - 02:31 AM
Devils Advocate is a good movie, im watching it at the moment. 
lol, sorry this forum needs more humor.
Please continue, this is all very interesting stuff, i like hearing peoples different point of views.
lol, sorry this forum needs more humor.
Please continue, this is all very interesting stuff, i like hearing peoples different point of views.
#53
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Posted 22 February 2006 - 10:33 AM
I was just reading this thread as I've got the same dillema with my car, which has bugger all weight in the arse end. It used to have massive strong springs in the back for towing purposes back when the car was heavier, when I used to go over those small speed humps, I would get a shock "BANG!!" from the rear end. Last night I change the spring with 6cylinder rear springs from annother Torry, they were like half the thinkness and half the weight. I also used the white pedders shock absorbers (8006P, Type P3073) from the same vehicle I got the replacement springs off (the Pedders 8006P shockers that were on my car were labelled P4092). I haven't driven the car yet to test it, but I may need to change the shockers as I'm not sure what they are. Maybe CHOPPER can shed some light on this (if I'm not on his ignore list that is 
)
My car previously had is ass up in the air, and unfortunately it still has. Hopefully with the new setup and this height it may have more safe travel (tyres not grinding in to the body) when it squats. Previously on the quarter mile, with no stall converter and 3:1 Limo gears she would not squat at all, when you watch the video and couldn't stall up and get traction. I'm hoping this will change next time. If I get a better time, I'll know that it works.
Anyway I was reading the debate and there were some interesting concepts and ideas that everyone put in and I thought I would put my 2cents in and hopefully add to this and create a bit of a clearer picture. Take note, I'm note going to take sides.
The example with the plank on an angle with two strings was an interesting one and when stationary, both points DO exert the same vertical force on the strings. But this is a STATIC model. If you replace the strings with elastic bands and now accelarate the plank forward with the highest point forward then you will find that the weight (downwards vertical force) distribution will be biased towards the back and thus will exert more downwards force onto the rear elastic band. This theory can be proven with Vector analysis and with Static and Dynamic theorem, a lot of which involves Newtons Laws and the maths is fairly basic, the rest is trigonometry, algebra and a couple of differential equations.
It also suggests that, where the elastic bands, being equivalent to springs (not quite, but in one direction yes) that the profile of the car can make a difference with the front being higher. On the static model, if you get a plank of wood and place one corner on a spring loaded scale and hold it there at say 15 degress to the floor and slowly lift it to a vertical position, you will see the scale reading increase and thus more weight, more force, F-MxA where A=9.81m/s squared.
The arguement that softer springs don't increase rear force?. Well if they assist in the weight transfer to the rear of the car as described above, on take off and if they assist in rear vertical downward travel distance and thus on take off the rear of the car can accelerate downwards easier and for a lengthened period then with the extra weight and extra downwards acceleration we have extra force, with the vehicle accelaraing forwards, we also have and extra vertical vector component of downwards force assuming the vehicle has squatted down and the front has raised. Annother point is that with the extra travel and time of squat there is far less impulsive force or shock upon the wheels allowing them to grab traction.
Therefore softer springs at the back can allow for more rear downwards force, travel, weight distribution and thus ultimately traction.
Anyway, in more extreme examples, where cars launch with both front wheels off the ground and the rear end squats real hard and far, you cannot say that the rear of the car is not getting more force than when stationary because it obviously is and in the same example, with taller and toughened suspension on the rear, raising its ass up in the air, it would be doubtfull that the car would ever launch again.
The reason that a car will lean to the right does have to do with the clockwise direction that the motor turns, it also has to do with the gear setup in the diff, (which will also match the direction of the motor turn of course), wich is usually biased to the right axle in a lot of differentials.
Anyway, I may have to get me some piss weak springs (shorter than standard) and some shockers like 60/40's or something for the rear of my car. Can anyone suggest where I can start looking?, or where I can get these?, how much etc?
)My car previously had is ass up in the air, and unfortunately it still has. Hopefully with the new setup and this height it may have more safe travel (tyres not grinding in to the body) when it squats. Previously on the quarter mile, with no stall converter and 3:1 Limo gears she would not squat at all, when you watch the video and couldn't stall up and get traction. I'm hoping this will change next time. If I get a better time, I'll know that it works.
Anyway I was reading the debate and there were some interesting concepts and ideas that everyone put in and I thought I would put my 2cents in and hopefully add to this and create a bit of a clearer picture. Take note, I'm note going to take sides.
The example with the plank on an angle with two strings was an interesting one and when stationary, both points DO exert the same vertical force on the strings. But this is a STATIC model. If you replace the strings with elastic bands and now accelarate the plank forward with the highest point forward then you will find that the weight (downwards vertical force) distribution will be biased towards the back and thus will exert more downwards force onto the rear elastic band. This theory can be proven with Vector analysis and with Static and Dynamic theorem, a lot of which involves Newtons Laws and the maths is fairly basic, the rest is trigonometry, algebra and a couple of differential equations.
It also suggests that, where the elastic bands, being equivalent to springs (not quite, but in one direction yes) that the profile of the car can make a difference with the front being higher. On the static model, if you get a plank of wood and place one corner on a spring loaded scale and hold it there at say 15 degress to the floor and slowly lift it to a vertical position, you will see the scale reading increase and thus more weight, more force, F-MxA where A=9.81m/s squared.
The arguement that softer springs don't increase rear force?. Well if they assist in the weight transfer to the rear of the car as described above, on take off and if they assist in rear vertical downward travel distance and thus on take off the rear of the car can accelerate downwards easier and for a lengthened period then with the extra weight and extra downwards acceleration we have extra force, with the vehicle accelaraing forwards, we also have and extra vertical vector component of downwards force assuming the vehicle has squatted down and the front has raised. Annother point is that with the extra travel and time of squat there is far less impulsive force or shock upon the wheels allowing them to grab traction.
Therefore softer springs at the back can allow for more rear downwards force, travel, weight distribution and thus ultimately traction.
Anyway, in more extreme examples, where cars launch with both front wheels off the ground and the rear end squats real hard and far, you cannot say that the rear of the car is not getting more force than when stationary because it obviously is and in the same example, with taller and toughened suspension on the rear, raising its ass up in the air, it would be doubtfull that the car would ever launch again.
The reason that a car will lean to the right does have to do with the clockwise direction that the motor turns, it also has to do with the gear setup in the diff, (which will also match the direction of the motor turn of course), wich is usually biased to the right axle in a lot of differentials.
Anyway, I may have to get me some piss weak springs (shorter than standard) and some shockers like 60/40's or something for the rear of my car. Can anyone suggest where I can start looking?, or where I can get these?, how much etc?
Edited by TORANR AMORE, 22 February 2006 - 10:35 AM.
#54
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Posted 22 February 2006 - 01:32 PM
Toranamore:The example with the plank on an angle with two strings was an interesting one and when stationary, both points DO exert the same vertical force on the strings. But this is a STATIC model. If you replace the strings with elastic bands and now accelarate the plank forward with the highest point forward then you will find that the weight (downwards vertical force) distribution will be biased towards the back and thus will exert more downwards force onto the rear elastic band. This theory can be proven with Vector analysis and with Static and Dynamic theorem, a lot of which involves Newtons Laws and the maths is fairly basic, the rest is trigonometry, algebra and a couple of differential equations.
It also suggests that, where the elastic bands, being equivalent to springs (not quite, but in one direction yes) that the profile of the car can make a difference with the front being higher. On the static model, if you get a plank of wood and place one corner on a spring loaded scale and hold it there at say 15 degress to the floor and slowly lift it to a vertical position, you will see the scale reading increase and thus more weight, more force, F-MxA where A=9.81m/s squared.
Have you actually tried what you suggested?
Both identical rubber bands will extend by the same amount if accelerating the plank forward.
Place the plank on some bathroom scales and lift the other end vertically, use a string tied onto it to make sure you are only applying a vertical force, observe the scales.
Sure if you manage to balance the plank on its end you can let go of the string, but to that point, the scales will read exactly half of the weight of the plank
#55
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Posted 22 February 2006 - 02:01 PM
??? 
Are you agreeing with everything else I said but not the plank example?
I have performed similar experiments to prove the theory many years ago. I also did the math and this was quite some time ago and it is correct, the equations balance. It would take a good while for me to jog the memory cells and go over it all again, but at this point in time I can draw a picture illustrating the vectors involved as I'm not sure we are talking about the same thing. Did you understand what I was on about before?
But for now, I'll just say that yes the rubber bands will extend by roughly the same amount in that example but the back (lower) point of the plank will experience a GREATER downward force vector than the top one. Don't focus too much on this analogy, remember elastic bands are not springs and car springs don't stretch at 45degrees from the car when it launches. If the wheels of the vehicle where on imaginary scales at the drags, don't you think that the rear ones would show a greater weight when the car launches, than when its stationary?
As for the the plank on the scales, I have done it many times(not with a plank), I did it last night with something similar. If you hold the plank by one end at 45 degrees from the ground (vertical force only) then the spring loaded scales will require less force to hold up the entire mass because the vertical upward component on the other end (your hand) is taking the rest, thus the scales will show less, then tilt the plank up vertically and the scales will show its true weight.
It takes weight to compress a spring in a car with the use of gravity and/or assisting force, so naturally in order for the rear springs a the back of a car to compress when it lauches or takes off, there would be more force being exerted there, thus more 'weight distribution' as its called, don't confuse weight with mass. Weight is mass (Kg) x gravity (9.81m/s squared)
Are you agreeing with everything else I said but not the plank example?I have performed similar experiments to prove the theory many years ago. I also did the math and this was quite some time ago and it is correct, the equations balance. It would take a good while for me to jog the memory cells and go over it all again, but at this point in time I can draw a picture illustrating the vectors involved as I'm not sure we are talking about the same thing. Did you understand what I was on about before?
But for now, I'll just say that yes the rubber bands will extend by roughly the same amount in that example but the back (lower) point of the plank will experience a GREATER downward force vector than the top one. Don't focus too much on this analogy, remember elastic bands are not springs and car springs don't stretch at 45degrees from the car when it launches. If the wheels of the vehicle where on imaginary scales at the drags, don't you think that the rear ones would show a greater weight when the car launches, than when its stationary?
As for the the plank on the scales, I have done it many times(not with a plank), I did it last night with something similar. If you hold the plank by one end at 45 degrees from the ground (vertical force only) then the spring loaded scales will require less force to hold up the entire mass because the vertical upward component on the other end (your hand) is taking the rest, thus the scales will show less, then tilt the plank up vertically and the scales will show its true weight.
It takes weight to compress a spring in a car with the use of gravity and/or assisting force, so naturally in order for the rear springs a the back of a car to compress when it lauches or takes off, there would be more force being exerted there, thus more 'weight distribution' as its called, don't confuse weight with mass. Weight is mass (Kg) x gravity (9.81m/s squared)
Edited by TORANR AMORE, 22 February 2006 - 02:03 PM.
#56
_Yella SLuR_
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Posted 22 February 2006 - 02:17 PM
I thought that the "Punch & Judy Show" was banned ages ago! Obviously not.
#57
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Posted 22 February 2006 - 02:49 PM
<_< Errr... yeh, no worries Yella SLuR, I'll be Punch and you can be Judy.
What's the problem? Is there one? I'm trying to help some people here and clarify some things in the Tech Department and I've been very friendly. But since I don't have your permission I'll just throw up a link.
devilsadvocate and anyone else interested, weight transfer works, and weight is a force, don't confuse weight with mass. Altering your suspension (springs) can increase weight transfer and make it more efficient (shockers). I'm not trying to contradict anyone and like I said before, I'm not taking sides.
Weight transfer towards the back of the vehicle on take off is termed squatting or squat and is the opposite to this example showing a vehicle stopping - de-accellerating, they talk about squatting here also:
http://www.monroe.co...derdynamics.asp
Definition of weight transfer:
Weight Transfer: Weight transfer is critical to traction. Vehicles are set up to provide a desired weight transfer to rear wheels. When the vehicle accelerates, the front wheels lift and the weight shifts to the rear wheels, which makes them less likely to spin.
To LhMusL, Pedders make 90/10 Drag Shock's, their product code/type is 1333
I spoke to one of their dealers in Victoria and he said the white comfort gas ones I have are about 20% firmer than the original ones used in Toranas and the two different types I have are both the same and have the same valve rate, only difference is the year they were made.
He said they can rebuild them for about $190 a pair and make them into 30/70's or whatever I like. He said I wont get much of a difference with 50/50's based on his experience with customers doing this and the results/feedback they get.
Over and Out!
What's the problem? Is there one? I'm trying to help some people here and clarify some things in the Tech Department and I've been very friendly. But since I don't have your permission I'll just throw up a link.
devilsadvocate and anyone else interested, weight transfer works, and weight is a force, don't confuse weight with mass. Altering your suspension (springs) can increase weight transfer and make it more efficient (shockers). I'm not trying to contradict anyone and like I said before, I'm not taking sides.
Weight transfer towards the back of the vehicle on take off is termed squatting or squat and is the opposite to this example showing a vehicle stopping - de-accellerating, they talk about squatting here also:
http://www.monroe.co...derdynamics.asp
Definition of weight transfer:
Weight Transfer: Weight transfer is critical to traction. Vehicles are set up to provide a desired weight transfer to rear wheels. When the vehicle accelerates, the front wheels lift and the weight shifts to the rear wheels, which makes them less likely to spin.
To LhMusL, Pedders make 90/10 Drag Shock's, their product code/type is 1333
I spoke to one of their dealers in Victoria and he said the white comfort gas ones I have are about 20% firmer than the original ones used in Toranas and the two different types I have are both the same and have the same valve rate, only difference is the year they were made.
He said they can rebuild them for about $190 a pair and make them into 30/70's or whatever I like. He said I wont get much of a difference with 50/50's based on his experience with customers doing this and the results/feedback they get.
Over and Out!
#58
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Posted 22 February 2006 - 04:15 PM
Torana more, no im not agreeing with everthing else you have said, have not gone through it , as it appeared to carry on from the logic you used in your 1st paras.
Where does you definition of weight transfer come from? The Monroe link doesnt mention that softer springs will enhance weight transfer, Im not saying it doesnt happen its just doesnt depend on the initial angle of the car or the softness of the springs. Its mainly a function of how high the centre of mass of the vehicle is from the axle line, if its the same level, not much at all, like in a formual one car.
I challenge you to do the plank thing carefully, as I suggested supporting the higher end by a string-at least 15cm long, that way it cant be influenced by the experimenter, or are you now saying that Im correct in saying the weight distribution will be 50/50 until you have the beam standing on its end.
Weight transfer is really a bad expression, but it seems like we'll have to use it for the time being, the forces over the axles change but the weight(force due to gravity) on the car at all points remains the same. Weight transfer is really like in the Italian job, when the gold shifts about in the bus.....
Yes, sensible polite discussion is fine.... dont worry about Yella, just increasing his post count.
Where does you definition of weight transfer come from? The Monroe link doesnt mention that softer springs will enhance weight transfer, Im not saying it doesnt happen its just doesnt depend on the initial angle of the car or the softness of the springs. Its mainly a function of how high the centre of mass of the vehicle is from the axle line, if its the same level, not much at all, like in a formual one car.
I challenge you to do the plank thing carefully, as I suggested supporting the higher end by a string-at least 15cm long, that way it cant be influenced by the experimenter, or are you now saying that Im correct in saying the weight distribution will be 50/50 until you have the beam standing on its end.
Weight transfer is really a bad expression, but it seems like we'll have to use it for the time being, the forces over the axles change but the weight(force due to gravity) on the car at all points remains the same. Weight transfer is really like in the Italian job, when the gold shifts about in the bus.....
Yes, sensible polite discussion is fine.... dont worry about Yella, just increasing his post count.
#59
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Posted 22 February 2006 - 04:51 PM
Umm not an expert here but dont you meen the "center of gravity", is there such a thing as center of mass?Its mainly a function of how high the centre of mass of the vehicle is from the axle line
John
#60
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Posted 22 February 2006 - 08:06 PM
ToranaSS: You can use one or the other when in the presence of a gravitational field. However, centre of mass applies wherever one is and therefore is the term that is always correct.
#61
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Posted 22 February 2006 - 10:54 PM
ok ok ok, there is a difference between the CoG and CoM, but I won't get into that, (For a static body in equilibrium, CoG and CoM are the same) I'll assume we are talking about Centre of Gravity, which effectively can shift as an object is displaced in various ways, including in this example of a vehicle taking off or launching. The CoG is shifted moreso in the example where there are softer springs and more travel etc. According to the math the positioning of the vehicle can also aid in this. Don't take my word for it, I'm only an engineer, if your not sure, you may want to speak to a specialist in suspension or do a lot of google searching and research the topic.
The term 'weight transfer' is common in this field and in this case I simply googled it and copied and pasted it from this site:
http://www.musclecar...omotive-2.shtml
As for the plank on the scales, I haven't changed my story, In my first statement I said:
And my second statement on this:
Now in both cases, the weight increases, but it doesn't just jump discretely from 50/50 to full weight. In theory it's 50/50 when the plank is horizontal with one end on the scale. When you lift it the weight display on the scale will increase liniarly as the plank is raised vertically until its vertical and the scales show 100%. But this also suggests that when your at 45degrees there will be more weight exerted on the scale than your original 50/50. This also direclty reflect on the example with a vehicle that is not level from front ot back and is inclined upwards at the front.
Two guys are carrying a couch up a flight of stairs, who do you want to be? the guy below? or the guy at the top? Think about it.
LoL, this debate on CoG seems to be all over the internet and now its found its way here,
The term 'weight transfer' is common in this field and in this case I simply googled it and copied and pasted it from this site:
http://www.musclecar...omotive-2.shtml
As for the plank on the scales, I haven't changed my story, In my first statement I said:
On the static model, if you get a plank of wood and place one corner on a spring loaded scale and hold it there at say 15 degress to the floor and slowly lift it to a vertical position, you will see the scale reading increase and thus more weight, more force, F-MxA where A=9.81m/s squared.
And my second statement on this:
If you hold the plank by one end at 45 degrees from the ground (vertical force only) then the spring loaded scales will require less force to hold up the entire mass because the vertical upward component on the other end (your hand) is taking the rest, thus the scales will show less, then tilt the plank up vertically and the scales will show its true weight.
Now in both cases, the weight increases, but it doesn't just jump discretely from 50/50 to full weight. In theory it's 50/50 when the plank is horizontal with one end on the scale. When you lift it the weight display on the scale will increase liniarly as the plank is raised vertically until its vertical and the scales show 100%. But this also suggests that when your at 45degrees there will be more weight exerted on the scale than your original 50/50. This also direclty reflect on the example with a vehicle that is not level from front ot back and is inclined upwards at the front.
Two guys are carrying a couch up a flight of stairs, who do you want to be? the guy below? or the guy at the top? Think about it.
LoL, this debate on CoG seems to be all over the internet and now its found its way here,
Edited by TORANR AMORE, 22 February 2006 - 10:57 PM.
#62
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Posted 23 February 2006 - 05:30 AM
Toranamore: there is nothing intriniscally different to supporting one end of the plank vertically from underneath, and the other end vertically from above, you agreed with this situation before 50/50 distribution(as the CofM or C of gravity, Im not into a debate about this, cannot move along the plank)- and now you are saying it is different to support you further argumentsThe example with the plank on an angle with two strings was an interesting one and when stationary, both points DO exert the same vertical force on the strings.
You then go onto pointing out about carrying the couch up the stairs and about which end youd rather be on, did you miss the point about the plank hanging from the strings, I think you did, you have gone with the layman misconception.
Im over this for the moment Torananore, you quote "force vectors" and F=MA where A=9.81m/s^2
Im always very wary the moment people on this forum start throwing the term vector around, its not needed , vertical force is fine, and also when the use misrepresent basic high school formulas, its "a" not A and "m" not "M" and throw in the value of the earths gravitational field constant for what purpose?
Edited by devilsadvocate, 23 February 2006 - 05:33 AM.
#63
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Posted 23 February 2006 - 07:31 AM
Is this a Mass Debate? 
RACV MAN
RACV MAN
#64
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Posted 23 February 2006 - 09:47 AM
^ with the dick measuring around here you'ld think it!
#65
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Posted 23 February 2006 - 09:51 AM
Punch & Judy I was thinking Devils and Amor for the roles. Either way, one of them will have to be gay for it to work, not that there is anything wrong with that of course.
#66
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Posted 23 February 2006 - 10:21 AM
its a debate and a debate can head in many directions and miss the original question wich started the debate..
From my understanding this post was about 90/10 shockers and are they realy needed in a drag setup?
Well the debate and maths all comes down to wether or not the squating of a car actualy puts more load on the rear wheels or not...
Ricks eg: with the couch applies to the car setup i beleive. The eg: about the plank and the string, well who the bguck knows realy..
devilsadvocate: Just out of quriosity mate what level of education have go taken your self to.. Not been a smart ass here so dont SHOOT, honestly qurious as in what you do and how you became to know all the maths...
Yella Slur & TORUNYA : what are you 2 on about, why even post in here when you dont even have any intention to contribute to this debate? Go play in Off topic section theres plenty more kids in the sand pit over there to bully..
John
From my understanding this post was about 90/10 shockers and are they realy needed in a drag setup?
Well the debate and maths all comes down to wether or not the squating of a car actualy puts more load on the rear wheels or not...
Ricks eg: with the couch applies to the car setup i beleive. The eg: about the plank and the string, well who the bguck knows realy..
devilsadvocate: Just out of quriosity mate what level of education have go taken your self to.. Not been a smart ass here so dont SHOOT, honestly qurious as in what you do and how you became to know all the maths...
Yella Slur & TORUNYA : what are you 2 on about, why even post in here when you dont even have any intention to contribute to this debate? Go play in Off topic section theres plenty more kids in the sand pit over there to bully..
John
#67
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Posted 23 February 2006 - 10:26 AM
good onya ss
my post is in regards to some poor unt asking a simple question, and it turning into a frikin science show, why carry on about frikin E=mc2 when a set up is already proven quite well in the DR fraternity.
personally struggler has had a few years of experience with drag set-ups, as for other 2 invoved :finger:
my post is in regards to some poor unt asking a simple question, and it turning into a frikin science show, why carry on about frikin E=mc2 when a set up is already proven quite well in the DR fraternity.
personally struggler has had a few years of experience with drag set-ups, as for other 2 invoved :finger:
#68
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Posted 23 February 2006 - 10:33 AM
how do you know what the other 2 have been involved in?
If you dont like the science show change channel.. A question was asked and a debate has emerged and if im correct thats what forums are for.. Mow comeing in here and saying all thats going on is dick mesuring is wrong, think about it befor you attack me..
Look carefully at the section its posted in, yes thats right its in TECH section so science show it is like it or not..
Im being nice so dont get upset...
John
If you dont like the science show change channel.. A question was asked and a debate has emerged and if im correct thats what forums are for.. Mow comeing in here and saying all thats going on is dick mesuring is wrong, think about it befor you attack me..
Look carefully at the section its posted in, yes thats right its in TECH section so science show it is like it or not..
Im being nice so dont get upset...
John
#69
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Posted 23 February 2006 - 11:39 AM
Nowadays, when you do a google search for something you're really curious about, you tend to get a lot of results from different forums around the world. You always know which forums are crap when you see the topics your trying to research turn to clownery. It really shits me when I do a search for information and it can only be found in various forums and then I've got to waddle through all the shit that clowns post up in-between it all.
In forums throught the world, people debate things and the reader develops the conclusion. The world does not develop without difference.
devilsadvocate is no dummy, have you seen this?
http://www.gmh-toran...try_view&iden=9
Although I personally wouldn't go through all that effort, but if I did install hazard lights I would want them to work in all conditions, including reverse, in case I have to reverse up a road in traffic, if I'm forced to.
TORANASS made a point, and if I knew what background devilsadvocate came from I could pick the right language and either use or not use the physics talk.
Anyway,
Devilsadvocate, Sorry mate, I'm trying my best here
It can be fairly difficult to convey something like this in a forum and prove it purely with words. The terms used are accepted as a universal basic language of physics that everyone here would know or have encountered. This sort of problem is solved and proven diagramatically with vectors indicating force and direction. You can't really nit pick out certian sentences or phrases from a post not knowing what the author has really pictured in his mind.
Like someone said, the setup has been proven in the Drag Racing scene as zillion times, but I can't ever remember anyone ever explaining it with the laws of physics so that it can be a measurable thing. When you do internet searches you cannot find it, yet people always ask.
I'll try once again to make this simpler in point form and you tell me which line you don't agree with:
1. weight is a force involving mass x acceleration of gravity
2. On acceleration, take off, or launch, centre of gravity is displaced, shifted to the rear of the car
3. When this happens the car will squat
4. When the car squats under these conditions, the rear accelerates downward.
5. the time and level of this downward acceleration can be increased with increased displacement
6. One way of increasing vertical displacement is by using softer springs
7. With point 2 and point 4&5 we have increased downward force
8. By getting the car to squat MORE, you further increase weight transfer as in point 2, displacement and downwards acceleration of the rear of the car as point 4 and further increased downward force
9. By using softer springs you can get a car to squat more.
and the cycle goes around again.
Whether there is extra force created is indisputable as weight is force and there is acceleration, diplacement and shifting of centre of gravity and of course there will be extra vertical force on the rear wheels. Softer springs aids the whole process of rear displacement or squat invoving downward acceleration of mass and lets not forget there is a shifting of the centre of gravity when the car squats, when it takes off and launches.
I've changed the springs in my 14.3 Sec Stock 308 Torana from heavy towing springs that gave the car no 'give' in the rear end at all to 6 cylinder Torana standard springs which are 1/2 the thickness and you can compress them a bit by hand, unlike the otherones. If I'm wrong about all this then I should not see a difference/improvement in take off, stalling up, the first 60ft time or ET the next time I race.
In forums throught the world, people debate things and the reader develops the conclusion. The world does not develop without difference.
devilsadvocate is no dummy, have you seen this?
http://www.gmh-toran...try_view&iden=9
Although I personally wouldn't go through all that effort, but if I did install hazard lights I would want them to work in all conditions, including reverse, in case I have to reverse up a road in traffic, if I'm forced to.
TORANASS made a point, and if I knew what background devilsadvocate came from I could pick the right language and either use or not use the physics talk.
Anyway,
Devilsadvocate, Sorry mate, I'm trying my best here
It can be fairly difficult to convey something like this in a forum and prove it purely with words. The terms used are accepted as a universal basic language of physics that everyone here would know or have encountered. This sort of problem is solved and proven diagramatically with vectors indicating force and direction. You can't really nit pick out certian sentences or phrases from a post not knowing what the author has really pictured in his mind.
Like someone said, the setup has been proven in the Drag Racing scene as zillion times, but I can't ever remember anyone ever explaining it with the laws of physics so that it can be a measurable thing. When you do internet searches you cannot find it, yet people always ask.
I'll try once again to make this simpler in point form and you tell me which line you don't agree with:
1. weight is a force involving mass x acceleration of gravity
2. On acceleration, take off, or launch, centre of gravity is displaced, shifted to the rear of the car
3. When this happens the car will squat
4. When the car squats under these conditions, the rear accelerates downward.
5. the time and level of this downward acceleration can be increased with increased displacement
6. One way of increasing vertical displacement is by using softer springs
7. With point 2 and point 4&5 we have increased downward force
8. By getting the car to squat MORE, you further increase weight transfer as in point 2, displacement and downwards acceleration of the rear of the car as point 4 and further increased downward force
9. By using softer springs you can get a car to squat more.
and the cycle goes around again.
Whether there is extra force created is indisputable as weight is force and there is acceleration, diplacement and shifting of centre of gravity and of course there will be extra vertical force on the rear wheels. Softer springs aids the whole process of rear displacement or squat invoving downward acceleration of mass and lets not forget there is a shifting of the centre of gravity when the car squats, when it takes off and launches.
I've changed the springs in my 14.3 Sec Stock 308 Torana from heavy towing springs that gave the car no 'give' in the rear end at all to 6 cylinder Torana standard springs which are 1/2 the thickness and you can compress them a bit by hand, unlike the otherones. If I'm wrong about all this then I should not see a difference/improvement in take off, stalling up, the first 60ft time or ET the next time I race.
#70
_TORANR AMORE_
_TORANR AMORE_
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Posted 23 February 2006 - 11:46 AM
.......... it turning into a frikin science show, why carry on about frikin E=mc2 ............, as for other 2 invoved :finger:
Punch & Judy I was thinking Devils and Amor for the roles. Either way, one of them will have to be gay
What's going on? Have I offended anyone?
I'm trying to build an efficient/effective race car (like most people here), precalculating/estimating what the effects of what each change should do and what improvements it can make and then testing it. It IS a science, yet some people would say "ah shut the F*** up you F****** nerd, just chuck a turbo on it or give it some NOS, It'll be right". There's no harm in placing a theory against things and testing them and debating them and I'm sick and tired of being flamed for it.
#71
_devilsadvocate_
_devilsadvocate_
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Posted 23 February 2006 - 12:19 PM
"Yella Slur & TORUNYA : what are you 2 on about, why even post in here when you dont even have any intention to contribute to this debate? Go play in Off topic section theres plenty more kids in the sand pit over there to bully.."1. weight is a force involving mass x acceleration of gravity
2. On acceleration, take off, or launch, centre of gravity is displaced, shifted to the rear of the car
3. When this happens the car will squat
4. When the car squats under these conditions, the rear accelerates downward.
5. the time and level of this downward acceleration can be increased with increased displacement
Well put John.
Re qualifications, I dont wish to reveal any of my personal details on a public forum.
Toranamore, my apologies I was l little curt in my last post.
Anyway, of the points listed I have trouble with:
No.2: No mass shifts position along the length of the car significantly when accelerating(some lateral stretch from the springs), hence there is no major change in the position of the centre of gravity, until the front wheels actually lift of the ground. Certainly not enough to create a boot full of bricks effect that a car with mild springs has on launch.
It sort of follows that the rest doesnt add up for me also.
Its basically a rotational force around the centre of mass on the body of the car caused by the acceleration of the driveline moving forwards faster than the body sitting on top of it. Accelerate the car along by hauling it with the front bumper and there wont be any squat.
Edited by devilsadvocate, 23 February 2006 - 12:21 PM.
#72
_TORANR AMORE_
_TORANR AMORE_
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Posted 23 February 2006 - 06:07 PM
, Hahahahahahahaha, yank it by the K-Frame and there will. I remember being towed numerous times by tow rope, tied to various places and you don't get much squat from the bumper or any part from the upper body above the suspension, but you do get some squat when the car towing you yanks you forward accelerating off.Accelerate the car along by hauling it with the front bumper and there wont be any squat.
Ahhhhhh 'rotational force', that's a phrase I should've used, spot-on, your right, but that's additional to what I was describing and it also adds to the proof that softer springs helps the whole process.Its basically a rotational force around the centre of mass on the body of the car caused by the acceleration of the driveline moving forwards faster than the body sitting on top of it.
I drew up some basic pictures of examples of what I'm on about, I tried to make them look like Toranas, but they ended up looking like Ford Falcons instead, LOL
(this will probably open up in your internet explorer and shrink in size. you will have to press the resize button down the bottom to beable to read the text properly)
http://home.bigblue....ger/example.JPG
It's an example that also shows an extreme which looks a little silly because in it you have to assume the all four wheels are in contact with the road because obviously if the front wheels launch off the ground the back wheels cop all the weight (force).
Anyway, like rodomo said, What a massive debate, lol.
Edited by TORANR AMORE, 23 February 2006 - 06:08 PM.
#73
_devilsadvocate_
_devilsadvocate_
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Posted 23 February 2006 - 08:26 PM
Toranamore; I looked at your sketches.
Here�s the problem I see: you appear to be suggesting that because the car is at an angle with soft springs, that the c of M will then move closer to the rear axle and put more force on it. Im not sure about that, but anyway looking at the basic geometry, if the car was to tilt at 15deg to the horizontal during the start of a drag,(that is massive even though it doesn�t sound much) the C of M would only move closer by 3%.
You still appear fixed in the view that if you don�t see a squat then there isn�t a force there. If firm springs are used you wont see a much of a squat because the springs don�t allow you to visibly see the force. Its just as there are no springs youll see nothing either. (Sorry to use this again, but its like if you stick half a tonne of bricks in the boot with fixed springs, the rear end will look the same height as when it is empty, but there will be heaps more force over the rear axle)
Youll see the same compression on the tyres though as there is the same acceleration causing the same force of front to aft rotation due to the CofM being above the drive line.
Ive of no doubt that some drag racers have found a combo of soft springs and particular shocks may give great results on their car, but not for the reasons of more weight transfer.
Here�s the problem I see: you appear to be suggesting that because the car is at an angle with soft springs, that the c of M will then move closer to the rear axle and put more force on it. Im not sure about that, but anyway looking at the basic geometry, if the car was to tilt at 15deg to the horizontal during the start of a drag,(that is massive even though it doesn�t sound much) the C of M would only move closer by 3%.
You still appear fixed in the view that if you don�t see a squat then there isn�t a force there. If firm springs are used you wont see a much of a squat because the springs don�t allow you to visibly see the force. Its just as there are no springs youll see nothing either. (Sorry to use this again, but its like if you stick half a tonne of bricks in the boot with fixed springs, the rear end will look the same height as when it is empty, but there will be heaps more force over the rear axle)
Youll see the same compression on the tyres though as there is the same acceleration causing the same force of front to aft rotation due to the CofM being above the drive line.
Ive of no doubt that some drag racers have found a combo of soft springs and particular shocks may give great results on their car, but not for the reasons of more weight transfer.
Edited by devilsadvocate, 23 February 2006 - 08:32 PM.
#74
_Torana482HP_
_Torana482HP_
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Posted 23 February 2006 - 08:54 PM
lets take this to the extreme,
wheres the weight at if your car is standing on its end.. 1300kg on the back bumper!
what about at 45 degrees, a shitload of weight on the back tyres (and wheelie bars)
just what i think, squating the back springs will cause the car to take off on an angle, and there will be a weight transfer shift to the back wheels.
wheres the weight at if your car is standing on its end.. 1300kg on the back bumper!
what about at 45 degrees, a shitload of weight on the back tyres (and wheelie bars)
just what i think, squating the back springs will cause the car to take off on an angle, and there will be a weight transfer shift to the back wheels.
#75
_devilsadvocate_
_devilsadvocate_
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Posted 23 February 2006 - 09:05 PM
Torana 482hp, the angle at which the front wheels lift off the ground and all the weight is supported by the rear wheels is solely due to the softness of the rear springs. If no springs youll get all the weight over the rear wheels with only marginal tilt of the body (for front wheels to lift clear of road) for the same accel rate in both cases.
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