Suggestions for Spring Rates - Track Car
#17
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well w/ 600# fronts and stock rears w/ just a big swaybar i would say bump it up to some 700 or so rear coilovers/ some Racer's Edge mounts of course and maybe drop that rear bar down slightly or it'll be oversteer city.
#18
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Thanks to everyone... The advice and insight is greatly welcomed... Well the season is over and I will can not test out the advice... Next step is to remove the rear t-bars, up to 750# rears on a set of konis with the rear bar soften.
#19
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From what I've read on here in other threads... rear coilover spring rates on a 944/951 are only about 56% effective, due to the location and angle of the spring relative to the wheel center. So, 750# rear springs with t-bar delete will result in an effective rate of 420#.
Supposedly, front spring rates are 90% effective, so your 600# front springs have an effective rate of 540#.
Following the same logic, you would need 964# (= 540# / .56) rear springs to match the effective rate of the fronts. Or, go with something like 466# (= 750# * .56 / .90) front springs to match the 750# rears.
I'm no expert, but I would say with 600# front, 750# rears, and no t-bars, you will have an understeer setup.
Supposedly, front spring rates are 90% effective, so your 600# front springs have an effective rate of 540#.
Following the same logic, you would need 964# (= 540# / .56) rear springs to match the effective rate of the fronts. Or, go with something like 466# (= 750# * .56 / .90) front springs to match the 750# rears.
I'm no expert, but I would say with 600# front, 750# rears, and no t-bars, you will have an understeer setup.
#21
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keep the 30 mm t-bars and add a coil over with 650# springs and you'll be pretty close front to rear.
Otherwise you are looking at a BIG rear spring!
Otherwise you are looking at a BIG rear spring!
#22
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As I recall, effective spring rate = (motion ratio) ^2 x spring rate
So for example:
Front Effective Rate = (.91)(.91)x 600 lb/in. = 0.828 x 600 = 497 lb/in.
No Torsion Bars
Rear Effective Rate = (.65)(.65) x 750 lb/in. = 0.423 x 750 = 317 lb/in.
Yes, there seems to be some debate about the rear motion ratio.
https://rennlist.com/forums/showpost...0&postcount=45
So for example:
Front Effective Rate = (.91)(.91)x 600 lb/in. = 0.828 x 600 = 497 lb/in.
No Torsion Bars
Rear Effective Rate = (.65)(.65) x 750 lb/in. = 0.423 x 750 = 317 lb/in.
Yes, there seems to be some debate about the rear motion ratio.
https://rennlist.com/forums/showpost...0&postcount=45
#23
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Yes. lets say {550# spring -23.5mm t-bar(126#)}/.56=757.14
or (550-126)/.56=757.14
The actual spring is carrying less load. The larger t-bar is carrying MORE load. So the spring rate, for a set number goes down as the t-bar goes up.
(550-177)/.56=666.xx
same coil spring doing less work.
177# I belive is a 25.5mm t-bar.
or (550-126)/.56=757.14
The actual spring is carrying less load. The larger t-bar is carrying MORE load. So the spring rate, for a set number goes down as the t-bar goes up.
(550-177)/.56=666.xx
same coil spring doing less work.
177# I belive is a 25.5mm t-bar.
#25
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As I recall, effective spring rate = (motion ratio) ^2 x spring rate
So for example:
Front Effective Rate = (.91)(.91)x 600 lb/in. = 0.828 x 600 = 497 lb/in.
No Torsion Bars
Rear Effective Rate = (.65)(.65) x 750 lb/in. = 0.423 x 750 = 317 lb/in.
Yes, there seems to be some debate about the rear motion ratio.
https://rennlist.com/forums/showpost...0&postcount=45
So for example:
Front Effective Rate = (.91)(.91)x 600 lb/in. = 0.828 x 600 = 497 lb/in.
No Torsion Bars
Rear Effective Rate = (.65)(.65) x 750 lb/in. = 0.423 x 750 = 317 lb/in.
Yes, there seems to be some debate about the rear motion ratio.
https://rennlist.com/forums/showpost...0&postcount=45
#26
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Yes. lets say {550# spring -23.5mm t-bar(126#)}/.56=757.14
or (550-126)/.56=757.14
The actual spring is carrying less load. The larger t-bar is carrying MORE load. So the spring rate, for a set number goes down as the t-bar goes up.
(550-177)/.56=666.xx
same coil spring doing less work.
177# I belive is a 25.5mm t-bar.
or (550-126)/.56=757.14
The actual spring is carrying less load. The larger t-bar is carrying MORE load. So the spring rate, for a set number goes down as the t-bar goes up.
(550-177)/.56=666.xx
same coil spring doing less work.
177# I belive is a 25.5mm t-bar.
#27
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Here's a very good explanation of the motion ratio and effective (wheel) spring rates. I think trucho has got it exactly right. LINK
So, to factor in t-bars, figure out what the effective (wheel) rate is for helper/coilover springs, and figure out what the effective rate is for the t-bar (many threads have this chart), and add them together.
So, to factor in t-bars, figure out what the effective (wheel) rate is for helper/coilover springs, and figure out what the effective rate is for the t-bar (many threads have this chart), and add them together.
#28
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I didn't make up the equation, I just plugged in the numbers. The numbers show an inverse relation between the coil spring and the t-bar( which ofcourse is also a spring, but not in a linear sense.)
That more complicated equation is above my pay grade.
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#29
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Here's a very good explanation of the motion ratio and effective (wheel) spring rates. I think trucho has got it exactly right. LINK
So, to factor in t-bars, figure out what the effective (wheel) rate is for helper/coilover springs, and figure out what the effective rate is for the t-bar (many threads have this chart), and add them together.
So, to factor in t-bars, figure out what the effective (wheel) rate is for helper/coilover springs, and figure out what the effective rate is for the t-bar (many threads have this chart), and add them together.
#30
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Here's a very good explanation of the motion ratio and effective (wheel) spring rates. I think trucho has got it exactly right. LINK
So, to factor in t-bars, figure out what the effective (wheel) rate is for helper/coilover springs, and figure out what the effective rate is for the t-bar (many threads have this chart), and add them together.
So, to factor in t-bars, figure out what the effective (wheel) rate is for helper/coilover springs, and figure out what the effective rate is for the t-bar (many threads have this chart), and add them together.