Spring rates
#61
Originally Posted by Outlaw
Does anyone have pictures or a list of parts use in setting up the upper mount for a 2.5 inch rear spring setup? This sounds like a great idea and if the upper mount can be adjusted up and down you could really fine tune the spring rate preload and ride height. If anyone has any info and or pictures on this I would be great full
Here's a pic of someone I know's car:
__________________
1966 Chevy II twin turbo LS3 project
2016 Z07 Carbon
1966 Chevy II twin turbo LS3 project
2016 Z07 Carbon
#64
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From: At the track
Slowhoe you arent making me mad. I like these discussions. I'm always trying to learn more. I'm not an engineer everything I know is from trial and error.
Dammn that looks like Jays Black car!!!!!!!!!!!!!!!!!!!
Dammn that looks like Jays Black car!!!!!!!!!!!!!!!!!!!
#67
Originally Posted by MADMAN
You have some good points Jay.
You would have to compress a 275lb spring more to hold the car at the ride height of a 315lb spring. The theory behind going to a lighter spring is that the 275lb. spring will lose stored energy quicker. The 275 will be compressed more initially and hold more stored energy at ride height but once the car starts to extend the front end the spring starts loosing energy.
You would have to compress a 275lb spring more to hold the car at the ride height of a 315lb spring. The theory behind going to a lighter spring is that the 275lb. spring will lose stored energy quicker. The 275 will be compressed more initially and hold more stored energy at ride height but once the car starts to extend the front end the spring starts loosing energy.
This statement is inaccurate however, as I find your original thieory to be. Let's look at the numbers...
At the same stationary ride height we have;
315# spring compressed to 5” holds 3150 lbs (for ease we’ll call it 3150 lbs of energy)
275# spring compressed to 5.73” holds 3151 lbs.
Now lets start to extend the front suspension. I don’t have exact numbers so I’m going to say that the spring changes compression height at a rate equal to 60% of the wheel travel. Meaning that if the wheel moves 1” in suspension travel that the spring changes in compressed height by .6”.
So, by moving lifting the front of the car up 1” we get spring forces of;
315# spring compressed to 4.4” = 2772 # of force pushing up on the front end
275# spring compressed to 5.13” = 2821 # of force pushing up on the front end
Moving the front up another 1” for a total of 2” of front end lift we get 1.2” of spring compression change and;
315# spring compressed to 3.8” = 2394 # of force pushing up on the front end
275 # spring compressed to 4.53” = 2491 # of force pushing up on the front end
If we theoretically say that the total amount of travel available is 3.01” and look at the force supplied by the springs at 3.00” then we have;
315# spring compressed to 3.2” = 2016 # of force pushing up on the front end
275 # spring compressed to 3.93” = 2161 # of force pushing up on the front end
So, what we actually have is more force applied to lifting the front of the car as the front end lifts during launch with the softer springs and an equal starting ride height for the two springs. Lowering the ride height of the car with one or both springs will change other factors that can influence how the car launches so I’m assuming that for this discussion initial ride height remain the same for each spring. The higher rate spring actually loses it’s ability to push the front end up once the suspension is extended over the resting ride height than the lighter spring does. The extra force that is being applied by the softer spring throughout the suspensions travel during the launch is what causes the car to wheelie or carry the front end easier with softer springs.
Fact is that the softer springs loose stored energy slower than the harder springs do.
#68
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From: Cecil County Raceway!!!
Originally Posted by TMC
Fact is that the softer springs loose stored energy slower than the harder springs do.
The inverse of that means is the harder springs impose kinetic energy faster to the chassis then...right??? if stored energy is lost slower...then kinetic energy is applied slower.
Wouldn't dumping all the available KE quickly would result in a prompt wheelstand
#69
Originally Posted by Fireball
Wouldn't dumping all the available KE quickly would result in a prompt wheelstand
KE is greater with the suspension exteded (not fully) and a lighter rate spring than a higher rate spring because the spring is still holding more force while the suspension moves through it's travel. Therefore the lighter rate spring will force the suspension to move more quickly while extended. The initial force applied is that of the springs while the car is at rest which is equal with both springs and holds no KE value as KE relates only to energy of masses in motion.
#73
So.. any of you guys think you can keep my front end down? I pull crazy wheelies and it never leaves straight when it dead hooks, I called Briggs and Stratton but they havent researched the suspension setup much????
#74
Ideally for the rear shocks Brian, would something with a stiff extend rate to pull the body down on the rear on the initial hit, and then a loose extension rate, so it doesnt pop back up and unload the rear be ideal? loosen the extend rate if the track goes away.
Unless on initial hit the shock is doing the opposite of what im thinkink by comressing first then extending
Unless on initial hit the shock is doing the opposite of what im thinkink by comressing first then extending
#76
I got a question to throw in the mix since rear spring rates and ride height was mentioned...
What's the best stance/ride height for best weight transfer? The car level, rake with rear sitting higher, or the front slightly higher than the rear? and Is there a certain front/rear ratio?
Thanks
What's the best stance/ride height for best weight transfer? The car level, rake with rear sitting higher, or the front slightly higher than the rear? and Is there a certain front/rear ratio?
Thanks
#77
Originally Posted by TMC
Nope. Because more lifting energy of the springs is lost before the wheels get off the ground wiht the stiffer springs. So, with less energy from the springs with the suspension near max extension the engine and rear end/tires need to have more power and grip to lift the front end. The softer springs will continue to apply more force to lift the car at larger suspension extensions.
KE is greater with the suspension exteded (not fully) and a lighter rate spring than a higher rate spring because the spring is still holding more force while the suspension moves through it's travel. Therefore the lighter rate spring will force the suspension to move more quickly while extended. The initial force applied is that of the springs while the car is at rest which is equal with both springs and holds no KE value as KE relates only to energy of masses in motion.
KE is greater with the suspension exteded (not fully) and a lighter rate spring than a higher rate spring because the spring is still holding more force while the suspension moves through it's travel. Therefore the lighter rate spring will force the suspension to move more quickly while extended. The initial force applied is that of the springs while the car is at rest which is equal with both springs and holds no KE value as KE relates only to energy of masses in motion.
This is not to discount any of MADMAN's track testing. You can talk theory all you want, but in the end it's how it works in practice that matters.
My .02
#79
Under what circumstances would a variable rate spring be helpful? Which would want a linear and which a variable?
Since wheelstands arent much a problem in stick cars, may linear be good for them under all circumstances and variable rate springs for auto? Just shooting thoughts out
Since wheelstands arent much a problem in stick cars, may linear be good for them under all circumstances and variable rate springs for auto? Just shooting thoughts out
#80
I am with Granny. I would like to know if the stiffer spring up front would be better for a stickshift car as the motor does not stay in the operating range after initial launch like an automatic with a small/high stall converter.
Jay, What rate are the Strange Front springs that go with their shocks. I am running Hal's up front with an oem stle lowering spring and would like to put a different spring up front. My car will pull the tires about a foot off the ground. It only carrys them for about 4to 5 feet because its an M6. I launch at 6000 RPM and as long as track prep is there I cut High 1.5s consistantly on the current setup.
Brad
Jay, What rate are the Strange Front springs that go with their shocks. I am running Hal's up front with an oem stle lowering spring and would like to put a different spring up front. My car will pull the tires about a foot off the ground. It only carrys them for about 4to 5 feet because its an M6. I launch at 6000 RPM and as long as track prep is there I cut High 1.5s consistantly on the current setup.
Brad