shock / spring upgrade... on the cheap

Jmatchley86 · 05-18-2020, 10:31 AM

I'v been pondering a cheap upgrade to my mostly stock suspension and wanted others input. From all of my reading our cars want a stiffer spring rate up front, but most aftermarket springs (I have swifts) have a lower front spring rate?

Currently i'm on koni yellows and swift springs but am wondering if an OEM spring out back would be better? It has a lower spring rate 8.1 vs 10.5 and would (theoretically) be a better ratio than having all 4 swifts on.

I would need to use a height adjuster out back but BC sells those for $50 each, and I have my oem springs...

OR am I being an idiot and should trust Swift since its a legit company and not someone bored at work on a Monday.

I know the ultimate answer is to go spend some cash on nice coilovers but i would prefer more seat time with what i'v got already.

JARblue · 05-18-2020, 11:25 AM

Just keep your swifts

Jmatchley86 · 05-18-2020, 12:25 PM

Quote:

Originally Posted by JARblue

Just keep your swifts

so your saying i'm just bored at work lol

DarkJak · 05-18-2020, 12:30 PM

I'd use the Swifts, and adjust with a bigger front sway if needed.

cv129 · 05-18-2020, 12:35 PM

What sway bar do you have in the back?

Jmatchley86 · 05-18-2020, 02:11 PM

Quote:

Originally Posted by cv129

What sway bar do you have in the back?

stock sways for front and rear. 100% oem except for the konis and swift springs

AlWakRa · 05-18-2020, 08:13 PM

Looks like you are bored

but what is the issue that you want to fix by the change? Anything while driving?

Quote:

Originally Posted by Jmatchley86

stock sways for front and rear. 100% oem except for the konis and swift springs

Front fat swaybar would be the way to go.

Jmatchley86 · 05-18-2020, 08:32 PM

Quote:

Originally Posted by AlWakRa

Looks like you are bored

but what is the issue that you want to fix by the change? Anything while driving?

Front fat swaybar would be the way to go.

just wondering why swift springs would come with a higher spring rate in back... and bored.

SS_Firehawk · 05-19-2020, 07:00 AM

Higher spring rate is because of the divorced spring design. The spring lives closer inboard and requires a higher rating to resist the additonal leverage compared to a true coil where it's at the shock tower. You'll kill your suspension geometry.

Jmatchley86 · 05-19-2020, 10:24 AM

Quote:

Originally Posted by SS_Firehawk

Higher spring rate is because of the divorced spring design. The spring lives closer inboard and requires a higher rating to resist the additonal leverage compared to a true coil where it's at the shock tower. You'll kill your suspension geometry.

This is the answer i'v been looking for. Thank you.

So this would mean that if you don't get a true coil you don't want a much lower spring rate in the rear. So a difference like 12k/10k wouldn't be idea. It would be more like 12/11?

Just trying to get a better understanding on it. Thanks in advance!

cv129 · 05-19-2020, 10:31 AM

Aero and Suspension Tuning With True Type Coilovers

True type requires lower spring rate due to spring location

AlWakRa · 05-19-2020, 03:03 PM

Quote:

Originally Posted by Jmatchley86

This is the answer i'v been looking for. Thank you.

So this would mean that if you don't get a true coil you don't want a much lower spring rate in the rear. So a difference like 12k/10k wouldn't be idea. It would be more like 12/11?

Just trying to get a better understanding on it. Thanks in advance!

You can go whatever you want, even 12/6 oem style, but the handling will be different, the car will understeer excessively. As I remember stock is like 8/8 or stiffer rear, which still understeer a little but becomes perfectly balanced with front negative camber. So, for companies, they use the motion ratio to get the perfect front and rear spring combo which will improve or preserve the handling characteristics.

05-18-2020, 10:31 AM	#1 (permalink)
Jmatchley86 Base Member Join Date: Jan 2017 Location: Fort Worth Posts: 159 Drives: 2011 370z 6MT Rep Power: 8	shock / spring upgrade... on the cheap I'v been pondering a cheap upgrade to my mostly stock suspension and wanted others input. From all of my reading our cars want a stiffer spring rate up front, but most aftermarket springs (I have swifts) have a lower front spring rate? Currently i'm on koni yellows and swift springs but am wondering if an OEM spring out back would be better? It has a lower spring rate 8.1 vs 10.5 and would (theoretically) be a better ratio than having all 4 swifts on. I would need to use a height adjuster out back but BC sells those for $50 each, and I have my oem springs... OR am I being an idiot and should trust Swift since its a legit company and not someone bored at work on a Monday. I know the ultimate answer is to go spend some cash on nice coilovers but i would prefer more seat time with what i'v got already. Sharad909 likes this.

05-18-2020, 11:25 AM	#2 (permalink)
JARblue A True Z Fanatic Join Date: Mar 2011 Location: Austin, TX Age: 43 Posts: 36,450 Drives: 11 Z34, 98 E36 M3 Rep Power: 2684440	Just keep your swifts __________________ 2011 370Z 6MT Sport Gun Metallic \| ARC \| CJM \| Ecutek \| FI \| Fujimura \| R2C \| SPL \| Stillen \| TWM \| Z1 \| ZSpeed \|

05-18-2020, 12:30 PM	#4 (permalink)
DarkJak A True Z Fanatic Join Date: Jun 2011 Location: Madison, WI Posts: 1,397 Drives: 2009 370Z Rep Power: 16804	I'd use the Swifts, and adjust with a bigger front sway if needed. JARblue, cv129, Memphis370Z and 1 others like this. __________________ @stupidtoycars \| My track vids 09 7AT\|MCS 2WNR\|Topgunz Rotrex\|Ecutek (Eugene)\|Maxxis RC1\|Titan-7 TS-5\|OSG LSD\|Rear Mount Derale Oil Cooler (WIP)+25 Trans Cooler\|Fismo\|G-LOC R12/R10\|Zeta III L\|NLR Wing and Splitter\|CJM Pan and Fuel Hat\|Radium Surge Tank\|AP Racing CP9668

05-18-2020, 12:35 PM	#5 (permalink)
cv129 A True Z Fanatic Join Date: Jul 2011 Location: Dallas, TX Posts: 3,236 Drives: 09 Nismo, 16 Nismo Rep Power: 163995	What sway bar do you have in the back? JARblue likes this. __________________ Setrab \| RE-71 \| SPL \| JRZ \| Nismo \| ARK \| Whiteline \| RacingBrake \| CJM Oil Pan \| Ti shield

05-19-2020, 07:00 AM	#9 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	Higher spring rate is because of the divorced spring design. The spring lives closer inboard and requires a higher rating to resist the additonal leverage compared to a true coil where it's at the shock tower. You'll kill your suspension geometry. AlWakRa, JARblue, Rusty and 3 others like this. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

05-19-2020, 10:31 AM	#11 (permalink)
cv129 A True Z Fanatic Join Date: Jul 2011 Location: Dallas, TX Posts: 3,236 Drives: 09 Nismo, 16 Nismo Rep Power: 163995	Aero and Suspension Tuning With True Type Coilovers True type requires lower spring rate due to spring location Jmatchley86 likes this. __________________ Setrab \| RE-71 \| SPL \| JRZ \| Nismo \| ARK \| Whiteline \| RacingBrake \| CJM Oil Pan \| Ti shield Last edited by cv129; 05-19-2020 at 11:22 AM.

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