Spring rates?
12-04-2003, 11:43 AM
#3
Generally someone that want's to know their cars stock spring rates, want's to have a baseline to draw on for considering their options to make a different choice. That is why I went to the effort to get the stock spring rates you see posted above. Be carefull, not all manufactuers are working from what I would call a "sensicle" page. Know what is true and to not wonder from it. Also keep in mind that some systems alter the front to rear spring rate balance, keep track of this as well and use you own views on how you are willing to allow this applied spring rate useage to effect the handling balance of the car, ask yourself if it is a move in the right direction or the wrong direction. Sometimes it's easy to make a different choice, Tein for example allows you to easily purchase a pair of front springs with different rates for $165 each.
I also recommend that you research progessive springs and the compromises they entail and see where you stand before you make a choice, if lowering springs are in the mix as opposed to coilovers, which usually use linear springs (KW coilovers being progressive).
I also recommend that you research progessive springs and the compromises they entail and see where you stand before you make a choice, if lowering springs are in the mix as opposed to coilovers, which usually use linear springs (KW coilovers being progressive).
12-05-2003, 06:17 AM
#4
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Thanks for the info, Gsedan35. That's what I'm doing. I refuse to by "Joe's Lowering Springs" that lower 1" without knowing their rate. I figured someone here knew what the stock rates are. Next, I get to climb under with a tape measure and find out that rate at the wheel. Then I can decide what rate is best for me. In the past, I've had to really push to get rates from the manufacturers. Some don't seem to know what they are, and given my measurements, they don't really care. I've seen 25lb/in difference between two springs in the same box.
You'll never see progressive springs on my car.
Having a wide selection of springs certainly makes coilovers attractive. $165 per pair is not bad.
Asterix
You'll never see progressive springs on my car.
Having a wide selection of springs certainly makes coilovers attractive. $165 per pair is not bad.
Asterix
12-05-2003, 07:05 AM
#5
protocav, how did you arrive at these #'s? Did you put them in a spring tester, compress to say 3 inches, divide this # by 3? Or was it arrived at purely mathematically? I've been looking for accurate #'s for a long time.
BTW....the above is the method recommended to me by a TRW engineer a few years ago when I was setting up my Lotus.
BTW....the above is the method recommended to me by a TRW engineer a few years ago when I was setting up my Lotus.
12-05-2003, 08:48 AM
#6
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The shop that measured my springs in the past uses one of the four scales of a Intercomp corner weight checker and a hydraulic press. The guy puts the scale on the press, then the spring. He compresses the spring one inch, zeros the scale, then compresses the spring another inch. This method works great. Compressing the spring another 2 inches isn't necessary. Of course, this works only for linear springs. The guy has checked many springs this way and it's quite accurate.
Asterix
Asterix
12-05-2003, 09:17 AM
#7
Thanks Asterix. Your method sounds right to me. I just guessed at the 3 inch #. Some shops only compress the spring 1 inch, which is a bogus #, as the first inch isn't a "true" representation of the real spring rate. Even linier springs aren't 100% linier. The rate should be checked close to ride height, and then again at it's compressed height at full corner load compression height. I'm curious as to how the many aftermarket spring manufactures check their rates. I think you're smart to not trust claimed rates and re-check them.
Now, how did Chad come up with his #'s?
Now, how did Chad come up with his #'s?
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12-05-2003, 10:53 AM
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these are rates that i have seen posted all over the g35driver forums...but i don't know where they actually come from. the person who posted them seemed pretty confident, however, and i think that they might have been associated with nissan somehow. they are the same for the 350z. i think the rsr springs are probably the best right now. they have the same spring rates as stock, they are linear, and they drop the z .6" front and rear. this probably would not affect the ride much. also, another manufacturer who seems to know what the hell they are doing (meaning: not raising the front rate and lowering the rear rate) is espelir. they give a 10% stiffer spring in the front and in the rear, to keep the same balance. this is only their active GT springs, and i believe that it is a 1" drop all around. these are linear by the way.
as far as measuring the springs, the TRW engineer way is certainly a good one, allthough more than necessary. being a mechanical engineer myself, i find that the simplist answer is usually the best. springs are rated in pounds per inch, right? well there is certainly no magic there. it means: how many pounds does it take to compress the springs one inch. some may argue that it is inaccurate to measure the springs while on the car, however, because of stiction and hysteresis caused by the suspension; also other factors like leverage or any mechanical advantages given by the suspension. if you compress the spring with 500lbf of force, and it goes down and inch, then it is a 500lb/in spring.
hopefully this will be helpful.
another veryimportant thing to consider is the damping of the shock. the spring is only 50% of the equation. if you add stiff springs and don't have the damping (actually rebound) to match the spring, it is going to bounce all over the place.
have fun!!
chad
as far as measuring the springs, the TRW engineer way is certainly a good one, allthough more than necessary. being a mechanical engineer myself, i find that the simplist answer is usually the best. springs are rated in pounds per inch, right? well there is certainly no magic there. it means: how many pounds does it take to compress the springs one inch. some may argue that it is inaccurate to measure the springs while on the car, however, because of stiction and hysteresis caused by the suspension; also other factors like leverage or any mechanical advantages given by the suspension. if you compress the spring with 500lbf of force, and it goes down and inch, then it is a 500lb/in spring.
hopefully this will be helpful.
another veryimportant thing to consider is the damping of the shock. the spring is only 50% of the equation. if you add stiff springs and don't have the damping (actually rebound) to match the spring, it is going to bounce all over the place.
have fun!!
chad
12-05-2003, 11:38 AM
#9
OK.....the RSR add appx. 10% rate with a .6" drop. Sounds like about what I'm looking for. As to your OEM spring rates #'s.....I'm still a bit skeptical. I guess I need to find someone locally that has swapped springs and borrow their stock springs to check myself. The car's been out 1 1/2 years, no one can provide accurate #'s yet?
Not saying your #'s are inacurate, but I need to know the testing method.
Not saying your #'s are inacurate, but I need to know the testing method.
12-05-2003, 12:41 PM
#10
Originally posted by Asterix
Next, I get to climb under with a tape measure and find out that rate at the wheel. Then I can decide what rate is best for me.
Next, I get to climb under with a tape measure and find out that rate at the wheel. Then I can decide what rate is best for me.
12-05-2003, 06:35 PM
#11
Originally posted by EnthuZ
OK.....the RSR add appx. 10% rate with a .6" drop. Sounds like about what I'm looking for. As to your OEM spring rates #'s.....I'm still a bit skeptical. I guess I need to find someone locally that has swapped springs and borrow their stock springs to check myself. The car's been out 1 1/2 years, no one can provide accurate #'s yet? Not saying your #'s are inacurate, but I need to know the testing method.
OK.....the RSR add appx. 10% rate with a .6" drop. Sounds like about what I'm looking for. As to your OEM spring rates #'s.....I'm still a bit skeptical. I guess I need to find someone locally that has swapped springs and borrow their stock springs to check myself. The car's been out 1 1/2 years, no one can provide accurate #'s yet?
Not saying your #'s are inacurate, but I need to know the testing method.
Here is a complete listing of all the spring rate info I have been able to gather on several aftermarket springs, unfortunately their all progressive of course, the exception being the as mentioned RSR springs and the stock springs. I only ask that this info not be exported to any other web site.
Eibach part numbers, drop amount, spring rates
and toll free number with ext for tech
350Z 1"front 1"rear 6364.14 296/384 front 316/421 rear
G35s 1.1"f 1.1"rear 6363.14 259/334 front 359/413 rear
G35c 1"front 1"rear 6365.14 229/337 front 274/463 rear
1-800-222-8811 Ext 114 (ummm,....that ext number didn't come
from me,...ooooooookaaaaaaaaaay
)Stock spring rates
F/R in lb/in
350Z and G35 coupe: 347/419
G35 sedan with sport: 357/407
Nismo S-Tune suspension 350Z and G35 coupe
448lbs linear front and 504lbs rear progressive
(Of course I did not say the above line and was never here
)Kg/mm springs for 350Z
http://www.kgm.co.jp/catalogue/dr21/...FIARLADY-Z.htm
DR21 super sport 15mm drop
260/419 front 266/431 rear
DRacing 30mm drop
266/478 front 266/507 rear
http://www.rs-r.com/suspension_springs.htm#spring_data
30-N200 15mm or .6" drop front and rear
345LBS front 417LBS rear
12-05-2003, 10:26 PM
#12
Gsedan35, thanks for coming forward explaining how you got the #'s. Also thanks for posting some of the alternate spring rates.
But, looking at your #'s. the RSR's are NOT 10% stiffer. Hope they are though. An old rule of thumb I've used is that a 10% ride height reduction requires at least a 10% rate increase. Though this is only for keeping the car off it's bump stops, not for handling improvements. And yes, I'm aware of the different moment arms, etc.
But, looking at your #'s. the RSR's are NOT 10% stiffer. Hope they are though. An old rule of thumb I've used is that a 10% ride height reduction requires at least a 10% rate increase. Though this is only for keeping the car off it's bump stops, not for handling improvements. And yes, I'm aware of the different moment arms, etc.
02-23-2004, 09:11 AM
#15
Originally posted by protocav
these are rates that i have seen posted all over the g35driver forums...but i don't know where they actually come from. the person who posted them seemed pretty confident, however, and i think that they might have been associated with nissan somehow. they are the same for the 350z. i think the rsr springs are probably the best right now. they have the same spring rates as stock, they are linear, and they drop the z .6" front and rear. this probably would not affect the ride much. also, another manufacturer who seems to know what the hell they are doing (meaning: not raising the front rate and lowering the rear rate) is espelir. they give a 10% stiffer spring in the front and in the rear, to keep the same balance. this is only their active GT springs, and i believe that it is a 1" drop all around. these are linear by the way.
as far as measuring the springs, the TRW engineer way is certainly a good one, allthough more than necessary. being a mechanical engineer myself, i find that the simplist answer is usually the best. springs are rated in pounds per inch, right? well there is certainly no magic there. it means: how many pounds does it take to compress the springs one inch. some may argue that it is inaccurate to measure the springs while on the car, however, because of stiction and hysteresis caused by the suspension; also other factors like leverage or any mechanical advantages given by the suspension. if you compress the spring with 500lbf of force, and it goes down and inch, then it is a 500lb/in spring.
hopefully this will be helpful.
another veryimportant thing to consider is the damping of the shock. the spring is only 50% of the equation. if you add stiff springs and don't have the damping (actually rebound) to match the spring, it is going to bounce all over the place.
have fun!!
chad
these are rates that i have seen posted all over the g35driver forums...but i don't know where they actually come from. the person who posted them seemed pretty confident, however, and i think that they might have been associated with nissan somehow. they are the same for the 350z. i think the rsr springs are probably the best right now. they have the same spring rates as stock, they are linear, and they drop the z .6" front and rear. this probably would not affect the ride much. also, another manufacturer who seems to know what the hell they are doing (meaning: not raising the front rate and lowering the rear rate) is espelir. they give a 10% stiffer spring in the front and in the rear, to keep the same balance. this is only their active GT springs, and i believe that it is a 1" drop all around. these are linear by the way.
as far as measuring the springs, the TRW engineer way is certainly a good one, allthough more than necessary. being a mechanical engineer myself, i find that the simplist answer is usually the best. springs are rated in pounds per inch, right? well there is certainly no magic there. it means: how many pounds does it take to compress the springs one inch. some may argue that it is inaccurate to measure the springs while on the car, however, because of stiction and hysteresis caused by the suspension; also other factors like leverage or any mechanical advantages given by the suspension. if you compress the spring with 500lbf of force, and it goes down and inch, then it is a 500lb/in spring.
hopefully this will be helpful.
another veryimportant thing to consider is the damping of the shock. the spring is only 50% of the equation. if you add stiff springs and don't have the damping (actually rebound) to match the spring, it is going to bounce all over the place.
have fun!!
chad
I think you hit the nail on the head as far as the stock springs/shock damper settings! That's why we need the Konis!
02-23-2004, 10:53 AM
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All this is realy confusing to me. I used to drive a VW Golf and went with an Eibach spring and bilstein shox. The drop was perfect and handling was excellent.
I am looking for a spring that will drop the Z evenly in front and back, at the same time improving handling without bouncing around. Again I am considering Eibach. Would I have to change stock shox and get aftermarket ones along with Eibach springs? Or can I just swap the springs and keep the stock shox? Anyone here have Eibach springs? Please post pics!
I am looking for a spring that will drop the Z evenly in front and back, at the same time improving handling without bouncing around. Again I am considering Eibach. Would I have to change stock shox and get aftermarket ones along with Eibach springs? Or can I just swap the springs and keep the stock shox? Anyone here have Eibach springs? Please post pics!
02-23-2004, 07:06 PM
#17
Originally posted by dwnshift
I have comeup with the rear spring rates to be in the 330-345 LB/in range. this was done on our spring tester. I can take some pictures ...but I have done it a number of ways and come up wiht the same rate.
I have comeup with the rear spring rates to be in the 330-345 LB/in range. this was done on our spring tester. I can take some pictures ...but I have done it a number of ways and come up wiht the same rate.
02-23-2004, 07:36 PM
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I have RS-R springs.. I like them very much.
They easily aligned within specs... it lowered the car .6. The ride quality was slightly improved actually and handeling was improved as well.
They easily aligned within specs... it lowered the car .6. The ride quality was slightly improved actually and handeling was improved as well.
02-23-2004, 08:18 PM
#19
Originally posted by GaryK
I haven't even looked at the front yet, but the motion ratio for the rear springs in stock location is 0.36. If you're looking at coilovers too, the motion ratio for those is 1 and I came up with an angle correction of 0.9945.
I haven't even looked at the front yet, but the motion ratio for the rear springs in stock location is 0.36. If you're looking at coilovers too, the motion ratio for those is 1 and I came up with an angle correction of 0.9945.
02-23-2004, 09:51 PM
#20
Originally posted by dwnshift
I have comeup with the rear spring rates to be in the 330-345 LB/in range. this was done on our spring tester. I can take some pictures ...but I have done it a number of ways and come up wiht the same rate.
I have comeup with the rear spring rates to be in the 330-345 LB/in range. this was done on our spring tester. I can take some pictures ...but I have done it a number of ways and come up wiht the same rate.
I'll bet you'll come up with 291 for the front.
