Spring Rates Question
#1
New Member
Thread Starter
Spring Rates Question
Hi Everyone,
I am running a fully stripped and caged 350z (~2800lb). I also have a true coilover setup with Buddy Club Spec Coilover Kit. I am running 10k front and 8k rear.
The rear feels light, and I am prone to oversteer. I am currently running a square setup on 17x9.5 wheels wrapped in 255/40/17 Federal RSRR.
Anyone else have a similar setup with different spring rates?
I am running a fully stripped and caged 350z (~2800lb). I also have a true coilover setup with Buddy Club Spec Coilover Kit. I am running 10k front and 8k rear.
The rear feels light, and I am prone to oversteer. I am currently running a square setup on 17x9.5 wheels wrapped in 255/40/17 Federal RSRR.
Anyone else have a similar setup with different spring rates?
#4
350Z-holic
iTrader: (13)
I run a 12 upfront and a 8s in the rears, about 150lbs heavier (mostly upfront) and I dont feel that my back end is loose (albeit Im not tracking). Do you have adjustable sways and/or the ability to adjust up your rebound rate?
Interested to see what others chime in with?
Interested to see what others chime in with?
#5
New Member
iTrader: (15)
^If you tracked your setup, it would be loose. In terms of OEM spring position you are both running rear rates that are *significantly* higher than the fronts (like almost twice the rate eg. 560f/1000r, or 672/1000r). Typically aside from the kits that have "drift" in the name, you really dont see these kind of rates being used at the track. Im not saying that they cant be made to work either. That is why it is so important to
Corner weights need to be taken into account otherwise this conversation will just be a SWAG.
Corner weights need to be taken into account otherwise this conversation will just be a SWAG.
The following users liked this post:
bealljk (08-18-2018)
#6
350Z-holic
iTrader: (13)
^one thing that factored into my decision to go 4k difference is that my rear end is lighter than an OEM setup ... I dont know 'exactly' where I'm at but most my weight reduction has come off the middle and rear of the car, furthermore, most my additional weight (turbos/headers/IC) were added to the front of the car. The decision to go 12 f / 8 r is that I pick up a 10k spring and I can go 10f / 8r or 12f / 10r and see what I like.
Lastly - All I know is that I know almost nothing - if I knew a little more, I'd know nothing.
Lastly - All I know is that I know almost nothing - if I knew a little more, I'd know nothing.
#7
New Member
Thread Starter
^If you tracked your setup, it would be loose. In terms of OEM spring position you are both running rear rates that are *significantly* higher than the fronts (like almost twice the rate eg. 560f/1000r, or 672/1000r). Typically aside from the kits that have "drift" in the name, you really dont see these kind of rates being used at the track. Im not saying that they cant be made to work either. That is why it is so important to
Corner weights need to be taken into account otherwise this conversation will just be a SWAG.
Corner weights need to be taken into account otherwise this conversation will just be a SWAG.
Last edited by bcoffin23; 08-19-2018 at 09:02 AM.
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#8
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#9
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#10
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Either way you are going to need to drop that rear rate by quite a bit...5k (280lbs) is a good number for that level of tire (roughly 625lbs OEM spring equivalent - some go softer yet depending on tire aero tracks and driver preference). Though it still wont match the 10k front rates and youll continue to have a "loose" car at the limit. I would be looking at 14k front minimum in addition to dropping the rear. Really, you should just get a new setup bc with those dampers, who knows.
#11
New Member
Thread Starter
I assume those weights are without you in it. They need to be with you in the car and actual weights, not just a swag, in order to make the calculations meaningful.
Either way you are going to need to drop that rear rate by quite a bit...5k (280lbs) is a good number for that level of tire (roughly 625lbs OEM spring equivalent - some go softer yet depending on tire aero tracks and driver preference). Though it still wont match the 10k front rates and youll continue to have a "loose" car at the limit. I would be looking at 14k front minimum in addition to dropping the rear. Really, you should just get a new setup bc with those dampers, who knows.
Either way you are going to need to drop that rear rate by quite a bit...5k (280lbs) is a good number for that level of tire (roughly 625lbs OEM spring equivalent - some go softer yet depending on tire aero tracks and driver preference). Though it still wont match the 10k front rates and youll continue to have a "loose" car at the limit. I would be looking at 14k front minimum in addition to dropping the rear. Really, you should just get a new setup bc with those dampers, who knows.
Not rumning any aero.
#12
New Member
iTrader: (15)
A 12/5 split with those corner weights will put you at almost even front and rear frequencies, which is generally to be avoided by conventional wisdom...thats why I suggested the 14kg/5kg split. But I do understand wanting to work within your current damper, so if you do go with 12kg front it may be prudent to go with a 6kg rear even though it is on the looser side, to stagger the ride frequencies slightly. By the rough numbers though, esp without exact corner weights and other variables. And this is one of those areas where the devil is definitely in the details. But unless there is money on the line were just having fun anyway right.
#14
New Member
iTrader: (15)
^one thing that factored into my decision to go 4k difference is that my rear end is lighter than an OEM setup ... I dont know 'exactly' where I'm at but most my weight reduction has come off the middle and rear of the car, furthermore, most my additional weight (turbos/headers/IC) were added to the front of the car. The decision to go 12 f / 8 r is that I pick up a 10k spring and I can go 10f / 8r or 12f / 10r and see what I like.
Lastly - All I know is that I know almost nothing - if I knew a little more, I'd know nothing.
Lastly - All I know is that I know almost nothing - if I knew a little more, I'd know nothing.
The following users liked this post:
bealljk (08-21-2018)
#15
350Z-holic
iTrader: (13)
I appreciate the time you put into this thread ... it's helped thus far!
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guitman32 (08-22-2018)
#16
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Thread Starter
Update:
I have confirmed that my rears are actually 6k, but my fronts are 10k.
We corner balanced the car today, and got the cross weights at 50/50. The front/rear is 54/46, however, so I need to get some more weight back there. The car weighs 2880 with 1/2 tank of gas without me in it.
I am planning to reroute the battery to behind the passenger seat. Would 12K front springs help move weight to the back?
I have confirmed that my rears are actually 6k, but my fronts are 10k.
We corner balanced the car today, and got the cross weights at 50/50. The front/rear is 54/46, however, so I need to get some more weight back there. The car weighs 2880 with 1/2 tank of gas without me in it.
I am planning to reroute the battery to behind the passenger seat. Would 12K front springs help move weight to the back?
#17
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MY350Z.COM
MY350Z.COM
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12/5 is very close to the Nismo T2 rates. I ran that for a while, now running 16/6k but my car also has aero and a couple hundred more pounds.
#18
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Thread Starter
I dont plan on using Aero anytime soon since going chassis mount is my only option and not in the budget right now.
My my question is: would upping the front rates to 12k transfer static weight to the rear?
#19
Super Moderator
MY350Z.COM
MY350Z.COM
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Nothing but moving things or height adjustments will do anything for static weight.
If your at 10/6 now, I would probably just up to 14/6 , but ideallly I had more traction with the 5k rear.
If your at 10/6 now, I would probably just up to 14/6 , but ideallly I had more traction with the 5k rear.