FK8 Master Spring Thread!

boosted180sx

Senior Member
Joined
Mar 27, 2017
Threads
25
Messages
5,038
Reaction score
5,087
Location
torrance, ca
Vehicle(s)
2017 CTR, 2016 ILX
Country flag
where i believe ALL springs available should have done was provide both front and rear linear - not one end only - at a no more than 25% increase in stiffness equally front and rear.
This I agree with. I'm personally not a fan of progressive springs.

I did however ditched my eibachs for swifts with no regrets.
Eibachs to me had too soft of a rear spring rate for my liking. Now I just need to get adjustable sway bars to fine tune it. Maybe some Karcepts.
Sponsored

 

02SilverSiHB

Senior Member
First Name
Mike
Joined
Jan 3, 2018
Threads
53
Messages
2,676
Reaction score
1,678
Location
Annapolis, MD
Vehicle(s)
2019 FK8
Vehicle Showcase
1
Country flag
it's hard to educate people who don't want to learn or have the experience and knowledge to even discuss intelligently.

you're the same guy who spews "hondata blows up motors" when you have no idea what tuning is about.

please explain to me 3 critical elements of handling tuning in the areas of: 1) mechanical balance, 2) aero balance, and 3) center of gravity....AND for each during low speed cornering and high speed cornering.

go explore the limits of the factory setup before you hurt yourself doing things you shouldn't be.

if you can't technically explain the results and impact of suspension tuning and jump right to you uneducated comments above, then i know it's out of your league.

ps - for the record eibach does not sponsor me although many other product companies do - that's not simply a discount that you think is a "sponsorship" but it's actually joint development and pre-production feedback done for such companies.
funny. You have me confused with someone else...brought to you by Carls jr
 

ctrmofo

Banned
Banned
Joined
Mar 21, 2018
Threads
43
Messages
1,778
Reaction score
2,433
Location
planet earth
Vehicle(s)
'13 lambo lp550-2, '18 honda ctr cw (r-12321), 14' porsche cayman s, '16 porsche macan s, '13 mini jcw nme stage 1, '15 audi s3 apr stage 2, '15 audi q3, '12 monster 1100 evo, '16 triumph thruxton r, deposited for '19 lambo huracan performante
Vehicle Showcase
2
Country flag
He's an active member and runs the kit himself so I don't really have a problem with him advocating for them. The general consensus on the forums is that the Eibachs are pretty good and ride fairly close to stock, you are one of the few (maybe only) that has been actively posting about them being bad. That's not to discredit how you feel, or the mechanics behind what is covered in that Youtube video either. I haven't ridden in a CTR other than a stock one so I can't say anything about any spring with any certainty, but based on what I know:
  • Springs that keep rates close to OEM will ride better because an OEM damper is designed to work for a certain spring rate, so going way stiffer is going to be a mismatch
  • Springs that have a larger drop will usually perform worse since you're reducing the travel more on a damper that was designed to have more travel
Therefore, a spring that keeps rates close to OEM and keeps the drop modest should, in theory not have a really adverse effect on how car handles. Full coilovers introduce their own set of issues and negatives too. I have my own worries about going with any suspension change as I enjoy the car stock and just wish it was a little lower, I am leaning towards Spoon as available information puts them at the closest to the stock ride as anything so it's potentially worth the cost to me. I'm also tempted to just not drop it and go with a wheel/tire combo that would fill out the wheel arches more (something like a 255/40/18 tire) and just leave it at that.
you are correct....keep the changes as close to stock as possible and be incremental not dramatic. once you do dramatic changes it leads to other issues. everything is a system not a part on its own...change one thing it impacts the other. same thing with wheels. for those who go way out there and run on wheels with width over 9.5" and offset less than +45, they're all lying if they don't introduce torque steer and rubbing all over. ppl will do or say anything to justify bad decisions really.

you've said it correctly on both points above - first person to say so - and what i've been saying all along. i've written about this before in detail. don't go more than 25% increase in rates if you do just springs either end. the lower you go the stiff it becomes due to simple physics. less suspension travel requires higher rates else car bottoms out. stiffer rates means harsher ride...that simple. if you go above 25% increase, you will shorten the life of the stock dampers since they're not matched to the springs. that leads to more cost to replace and another install to be had.

therefore, whether you go eibach pro kit, h&r, or spoon - all of them should be fairly incremental and fact that they all chose progressive for either end or both ends means the ride is actually BETTER than stock which are linear rate front and rear. those who don't seem to understand this claim it's a harsher ride means they lack knowledge. the maker of the springs chose progressive springs to "soften" the increase in rates if you will...that's why they chose progressive. otherwise if they made them linear all around while increasing the rates - you will complain of harhness and won't buy their springs.

NO ONE should go full coilvers for the streets, honestly. i've done so many coilovers on prior cars built for track days and not what you want to live with everyday...from too stiff to clankings that come naturally with aluminum hats and top mount metal balls. again, physics...metal on metal will make noises and drive you nuts. not to mention ppl think it's cool and badass to do coilovers because they can adjust height, but in reality they never change height once set and looks bling bling badass. in fact MOST don't even do it right and get the proper corner balancing done after installing coilovers.

don't use tire size as a way of "filling out the gap". it's not the proper approach and will introduce other things. regardless, good approach to your thinking above...most don't think of such.
 

02SilverSiHB

Senior Member
First Name
Mike
Joined
Jan 3, 2018
Threads
53
Messages
2,676
Reaction score
1,678
Location
Annapolis, MD
Vehicle(s)
2019 FK8
Vehicle Showcase
1
Country flag
He's an active member and runs the kit himself so I don't really have a problem with him advocating for them. The general consensus on the forums is that the Eibachs are pretty good and ride fairly close to stock, you are one of the few (maybe only) that has been actively posting about them being bad. That's not to discredit how you feel, or the mechanics behind what is covered in that Youtube video either. I haven't ridden in a CTR other than a stock one so I can't say anything about any spring with any certainty, but based on what I know:
  • Springs that keep rates close to OEM will ride better because an OEM damper is designed to work for a certain spring rate, so going way stiffer is going to be a mismatch
  • Springs that have a larger drop will usually perform worse since you're reducing the travel more on a damper that was designed to have more travel
Therefore, a spring that keeps rates close to OEM and keeps the drop modest should, in theory not have a really adverse effect on how car handles. Full coilovers introduce their own set of issues and negatives too. I have my own worries about going with any suspension change as I enjoy the car stock and just wish it was a little lower, I am leaning towards Spoon as available information puts them at the closest to the stock ride as anything so it's potentially worth the cost to me. I'm also tempted to just not drop it and go with a wheel/tire combo that would fill out the wheel arches more (something like a 255/40/18 tire) and just leave it at that.
Funny also. I dont actively discredit eibach. I've owned them in the past. I'm just saying I dont care for aftermarket springs on this car. That includes all springs. I'll end up with coilovers or just go back to factory springs.
 

ctrmofo

Banned
Banned
Joined
Mar 21, 2018
Threads
43
Messages
1,778
Reaction score
2,433
Location
planet earth
Vehicle(s)
'13 lambo lp550-2, '18 honda ctr cw (r-12321), 14' porsche cayman s, '16 porsche macan s, '13 mini jcw nme stage 1, '15 audi s3 apr stage 2, '15 audi q3, '12 monster 1100 evo, '16 triumph thruxton r, deposited for '19 lambo huracan performante
Vehicle Showcase
2
Country flag
This I agree with. I'm personally not a fan of progressive springs.

I did however ditched my eibachs for swifts with no regrets.
Eibachs to me had too soft of a rear spring rate for my liking. Now I just need to get adjustable sway bars to fine tune it. Maybe some Karcepts.
yep, for me personally...i LOVE a stiff suspension setup as that's all i've pretty much known and built for track cars. i like instant response in all directions.

it's more that the rear is progressive than it is soft actually. if the rear are linear, i believe the 16% increase in rate would even things out. however, i understand your need for the swift. my only thought on the swift is they went way too stiff on the rear rate which is 60% or so increase vs front rate increase which i think is about 25% (don't remember off top of my head). therefore, the car has induced oversteer and more lift throttle oversteer as i've experienced. i've driven a local guy's car with the swift and yes rear is definitely much stiffer and you know it.

i'd be curious how you'd like it with the karcepts bar. i love the karcepts because it makes it so tunable for track (10 mins to adjust) and for street on asphalt vs concrete. daily i have it on 1 of 9. at autox i go 3-4 on concrete and 1-2 on asphalt. you'll love the quality of the bar since it's gorgeous and exceptional quality. make sure to check the clearance of the bar right above the exhaust (stock or aftermarket) and adjust the exhaust hangers to give at least 1/2" clearance. some ppl have reported clanking with their exhaust. grp got nearly 1" clearance vs the karcepts bar when they did the install.
 


Ouhei

Senior Member
First Name
Alex
Joined
Nov 1, 2018
Threads
8
Messages
459
Reaction score
464
Location
Raleigh, NC
Vehicle(s)
2019 CW CTR
Country flag
you are correct....keep the changes as close to stock as possible and be incremental not dramatic. once you do dramatic changes it leads to other issues. everything is a system not a part on its own...change one thing it impacts the other. same thing with wheels. for those who go way out there and run on wheels with width over 9.5" and offset less than +45, they're all lying if they don't introduce torque steer and rubbing all over. ppl will do or say anything to justify bad decisions really.

you've said it correctly on both points above - first person to say so - and what i've been saying all along. i've written about this before in detail. don't go more than 25% increase in rates if you do just springs either end. the lower you go the stiff it becomes due to simple physics. less suspension travel requires higher rates else car bottoms out. stiffer rates means harsher ride...that simple. if you go above 25% increase, you will shorten the life of the stock dampers since they're not matched to the springs. that leads to more cost to replace and another install to be had.

therefore, whether you go eibach pro kit, h&r, or spoon - all of them should be fairly incremental and fact that they all chose progressive for either end or both ends means the ride is actually BETTER than stock which are linear rate front and rear. those who don't seem to understand this claim it's a harsher ride means they lack knowledge. the maker of the springs chose progressive springs to "soften" the increase in rates if you will...that's why they chose progressive. otherwise if they made them linear all around while increasing the rates - you will complain of harhness and won't buy their springs.

NO ONE should go full coilvers for the streets, honestly. i've done so many coilovers on prior cars built for track days and not what you want to live with everyday...from too stiff to clankings that come naturally with aluminum hats and top mount metal balls. again, physics...metal on metal will make noises and drive you nuts. not to mention ppl think it's cool and badass to do coilovers because they can adjust height, but in reality they never change height once set and looks bling bling badass. in fact MOST don't even do it right and get the proper corner balancing done after installing coilovers.

don't use tire size as a way of "filling out the gap". it's not the proper approach and will introduce other things. regardless, good approach to your thinking above...most don't think of such.
I'm done with full coilovers on my cars, I've run them for years and since I spend 99% of my time on the street the trade offs aren't worth it to me anymore. They used to be needed, but OEM dampers have come a long way.

When I say use the tire to fill the gap I just mean running the 40 series tire on an 18" wheel (which is technically the correct downsizing). People usually go for a 35 series on the 18", but at stock height it looks a little funky. There's a guy on IG running 18x10 +41 with a 255/40/18 on stock height and the gap doesn't look bad at all:

 

02SilverSiHB

Senior Member
First Name
Mike
Joined
Jan 3, 2018
Threads
53
Messages
2,676
Reaction score
1,678
Location
Annapolis, MD
Vehicle(s)
2019 FK8
Vehicle Showcase
1
Country flag
This I agree with. I'm personally not a fan of progressive springs.

I did however ditched my eibachs for swifts with no regrets.
Eibachs to me had too soft of a rear spring rate for my liking. Now I just need to get adjustable sway bars to fine tune it. Maybe some Karcepts.
Man...I wish I could post an opinion without bei
I'm done with full coilovers on my cars, I've run them for years and since I spend 99% of my time on the street the trade offs aren't worth it to me anymore. They used to be needed, but OEM dampers have come a long way.

When I say use the tire to fill the gap I just mean running the 40 series tire on an 18" wheel (which is technically the correct downsizing). People usually go for a 35 series on the 18", but at stock height it looks a little funky. There's a guy on IG running 18x10 +41 with a 255/40/18 on stock height and the gap doesn't look bad at all:

Yeah a 40 series is what I should have gone with. That's one issue I'm going to hate when I go back to factory springs with these winter tires I'm on...the gap will look weird
 

ctrmofo

Banned
Banned
Joined
Mar 21, 2018
Threads
43
Messages
1,778
Reaction score
2,433
Location
planet earth
Vehicle(s)
'13 lambo lp550-2, '18 honda ctr cw (r-12321), 14' porsche cayman s, '16 porsche macan s, '13 mini jcw nme stage 1, '15 audi s3 apr stage 2, '15 audi q3, '12 monster 1100 evo, '16 triumph thruxton r, deposited for '19 lambo huracan performante
Vehicle Showcase
2
Country flag
I'm done with full coilovers on my cars, I've run them for years and since I spend 99% of my time on the street the trade offs aren't worth it to me anymore. They used to be needed, but OEM dampers have come a long way.

When I say use the tire to fill the gap I just mean running the 40 series tire on an 18" wheel (which is technically the correct downsizing). People usually go for a 35 series on the 18", but at stock height it looks a little funky. There's a guy on IG running 18x10 +41 with a 255/40/18 on stock height and the gap doesn't look bad at all:

yep, i agree...i don't plan on using or doing anymore coilover installs. reason they're great - simplicity in installation. take out whole stock setup and stick in whole new setup, no need for compressors etc.

ah ok...well i was referring to keep speedo exactly dead on and no moving rotational mass out any further than stock. the perfect zero change to speedo and circumference is 245/40/18 which is what i just did with my titan 7 18" wheels and michelin snow tires...so vs that 255/40/18 pics you showed will be slight less sidewall of course. now that setup with 18x10+41 is way too much wheel really. he can't lower the car without any rubbing for sure.

in the end, modest lowering springs with proper wheel and tires will give you huge smiles for the buck if done right and little investment...while maintaining close to stock dynamics as much as possible. eibach, h&r, and spoon are all good and fine so no need to worry and over analyze. go for it and enjoy!
 

Ouhei

Senior Member
First Name
Alex
Joined
Nov 1, 2018
Threads
8
Messages
459
Reaction score
464
Location
Raleigh, NC
Vehicle(s)
2019 CW CTR
Country flag
yep, i agree...i don't plan on using or doing anymore coilover installs. reason they're great - simplicity in installation. take out whole stock setup and stick in whole new setup, no need for compressors etc.

ah ok...well i was referring to keep speedo exactly dead on and no moving rotational mass out any further than stock. the perfect zero change to speedo and circumference is 245/40/18 which is what i just did with my titan 7 18" wheels and michelin snow tires...so vs that 255/40/18 pics you showed will be slight less sidewall of course. now that setup with 18x10+41 is way too much wheel really. he can't lower the car without any rubbing for sure.

in the end, modest lowering springs with proper wheel and tires will give you huge smiles for the buck if done right and little investment...while maintaining close to stock dynamics as much as possible. eibach, h&r, and spoon are all good and fine so no need to worry and over analyze. go for it and enjoy!
Yeah. I want to keep the speedo error to a minimum out of preference. I know that setup would have rubbing issues if he lowered, I was just using it as an example of something that I think looks great at stock height. Mainly because I do love how the car rides stock and I'm worried about messing that up.

That said, my plan as of now is Spoon springs with some 18x9.5 +38 (gram light 57DR) and a 265/35 tire (Firestone Indy 500, runs a little narrow). Should keep speedo error to under 2% and not require rubbing or camber work. Ideally I'd prefer running a 9" wide wheel so running a 245/40 tire would be better, but no one makes one that looks good (IMO).
 

ctrmofo

Banned
Banned
Joined
Mar 21, 2018
Threads
43
Messages
1,778
Reaction score
2,433
Location
planet earth
Vehicle(s)
'13 lambo lp550-2, '18 honda ctr cw (r-12321), 14' porsche cayman s, '16 porsche macan s, '13 mini jcw nme stage 1, '15 audi s3 apr stage 2, '15 audi q3, '12 monster 1100 evo, '16 triumph thruxton r, deposited for '19 lambo huracan performante
Vehicle Showcase
2
Country flag
Yeah. I want to keep the speedo error to a minimum out of preference. I know that setup would have rubbing issues if he lowered, I was just using it as an example of something that I think looks great at stock height. Mainly because I do love how the car rides stock and I'm worried about messing that up.

That said, my plan as of now is Spoon springs with some 18x9.5 +38 (gram light 57DR) and a 265/35 tire (Firestone Indy 500, runs a little narrow). Should keep speedo error to under 2% and not require rubbing or camber work. Ideally I'd prefer running a 9" wide wheel so running a 245/40 tire would be better, but no one makes one that looks good (IMO).
check around on that 9.5 and +38 with 265. depending on the tire model you use, it's cutting it very close.

yes it's odd but not many 9" width. usually 8.5 or 9.5 and some 10" width which is way too wide. someone did 9.5 and +22m offset with 265 and lowered on eibach claiming zero rubbing LOL...i call BS big time!
 


boosted180sx

Senior Member
Joined
Mar 27, 2017
Threads
25
Messages
5,038
Reaction score
5,087
Location
torrance, ca
Vehicle(s)
2017 CTR, 2016 ILX
Country flag
yep, for me personally...i LOVE a stiff suspension setup as that's all i've pretty much known and built for track cars. i like instant response in all directions.

it's more that the rear is progressive than it is soft actually. if the rear are linear, i believe the 16% increase in rate would even things out. however, i understand your need for the swift. my only thought on the swift is they went way too stiff on the rear rate which is 60% or so increase vs front rate increase which i think is about 25% (don't remember off top of my head). therefore, the car has induced oversteer and more lift throttle oversteer as i've experienced. i've driven a local guy's car with the swift and yes rear is definitely much stiffer and you know it.

i'd be curious how you'd like it with the karcepts bar. i love the karcepts because it makes it so tunable for track (10 mins to adjust) and for street on asphalt vs concrete. daily i have it on 1 of 9. at autox i go 3-4 on concrete and 1-2 on asphalt. you'll love the quality of the bar since it's gorgeous and exceptional quality. make sure to check the clearance of the bar right above the exhaust (stock or aftermarket) and adjust the exhaust hangers to give at least 1/2" clearance. some ppl have reported clanking with their exhaust. grp got nearly 1" clearance vs the karcepts bar when they did the install.
Yeah. I understand the need for progressive springs because so many people care for ride comfort but linear imo is better in the fact that the car will behave the same at all times and not just under load.

Oh, you can definitely feel that the rear is stiffer than stock with the swifts. But with the motion ratio of the rear suspension, it's not as stiff as the rates show though.
i wanted to go cheap and get some eibach rsb but i wasn't sure if that will give me enough adjust ability to tune it to how I want it. We shall see which one.
 

HONDA X

Senior Member
Joined
Aug 29, 2017
Threads
4
Messages
208
Reaction score
76
Location
SoCal
Vehicle(s)
S2000
Country flag
not sure about "the best". it's very similar to eibach pro kit. don't what what "the best" springs really are since they are pretty much same with linear front and progressive rears when it comes to aftermarket, with the exception of swift which are opposite (progressive front, linear rear).

only difference is spring rate and height. eibach pro kit, h&r, and spoon are all same lowering height. swift are 0.25" lower and stiffer. really nothing magical about spoon springs other than the brand name which you pay for.
Spoon Sports is a top quality brand if you look at their drop it’s a true .08 inch drop where as the eibach prokit claims to be a .08 inch drop but the rear sits noticeably lower than the front. Some claim the eibach prokit to have a 1 inch drop in the rear and a .08 inch up front. Also, the design of the Spoon Sports lowering springs are slightly different compared to the conventional lowering springs. The design might look minimal but it plays a huge factor in the way the feels and handles. Then again it’s Spoon Sports it’s know to be one of the top brands in JDM world and can’t ever go wrong with that brand since everything is made with accuracy and precision that has been well put together.
 
Last edited:

ctrmofo

Banned
Banned
Joined
Mar 21, 2018
Threads
43
Messages
1,778
Reaction score
2,433
Location
planet earth
Vehicle(s)
'13 lambo lp550-2, '18 honda ctr cw (r-12321), 14' porsche cayman s, '16 porsche macan s, '13 mini jcw nme stage 1, '15 audi s3 apr stage 2, '15 audi q3, '12 monster 1100 evo, '16 triumph thruxton r, deposited for '19 lambo huracan performante
Vehicle Showcase
2
Country flag
Spoon Sports is a top quality brand if you look at their drop it’s a true .08 inch drop where as the eibach prokit claims to be a .08 inch drop but the rear sits noticeably lower than the front. Some claim the eibach prokit to have a 1 inch drop in the rear and a .08 inch up front. Also, the design of the Spoon Sports lowering springs are slightly different compared to the conventional lowering springs. The design might look minimal but it plays a huge factor in the way the feels and handles. Then again it’s Spoon Sports it’s know to be one of the top brands in JDM world and can’t ever go wrong with that brand since everything is made with accuracy and precision that has been well put together.
sure i don't disagree with the name brand. keep in mind JDM is meaningless when it comes to fk8 ctr. you guys seem to forget - the US market is the first market to be introduced the fk8 platform and every other country was second including japan. so JDM is useless these days. also it's spoon USA not spoon japan that is working on the r&d. i know one of the partners/owners of spoon USA and have had discussions in recent times. japan gets very few fk8 ctr so if you believe they do work for "JDM" then it's inaccurate. most if not all are done here so it's USDM to be technically correct ;-)

note: stock fk8 ctr does NOT have even "gap" or wheel spacing front and rear to start with. if you go look at your stock ctr now or take a measurement, you'll see stock is actually uneven for a reason front rear. just note that. keep that in mind when lowering and not focus on net one end vs other but total net change. if you care only about even wheel gap reduction, that's ok.

i've used so much spoon parts in the past as far back as 1997 or 1998 to even tell you how much spent....plus mugen an toda cams etc. that was then, this is now. game and market has changed dramatically.
 

ctrmofo

Banned
Banned
Joined
Mar 21, 2018
Threads
43
Messages
1,778
Reaction score
2,433
Location
planet earth
Vehicle(s)
'13 lambo lp550-2, '18 honda ctr cw (r-12321), 14' porsche cayman s, '16 porsche macan s, '13 mini jcw nme stage 1, '15 audi s3 apr stage 2, '15 audi q3, '12 monster 1100 evo, '16 triumph thruxton r, deposited for '19 lambo huracan performante
Vehicle Showcase
2
Country flag
Yeah. I understand the need for progressive springs because so many people care for ride comfort but linear imo is better in the fact that the car will behave the same at all times and not just under load.

Oh, you can definitely feel that the rear is stiffer than stock with the swifts. But with the motion ratio of the rear suspension, it's not as stiff as the rates show though.
i wanted to go cheap and get some eibach rsb but i wasn't sure if that will give me enough adjust ability to tune it to how I want it. We shall see which one.
guarantee eibach 2 position sway bar will leave you disappointed. pop the extra $200 and go for gold and get the karcepts ;-) knowing how much you play with your car, you'll want to swap out the eibach for more adjustability.
 

boosted180sx

Senior Member
Joined
Mar 27, 2017
Threads
25
Messages
5,038
Reaction score
5,087
Location
torrance, ca
Vehicle(s)
2017 CTR, 2016 ILX
Country flag
guarantee eibach 2 position sway bar will leave you disappointed. pop the extra $200 and go for gold and get the karcepts ;-) knowing how much you play with your car, you'll want to swap out the eibach for more adjustability.
do it once do it right.
If only I lived by that quote when modding cars lol.
Sponsored

 


 


Top