OEM Spring length.

GSS138 · 11-18-2013, 11:16 PM

OK I asked this before, but does anyone know the OEM front spring length?

NORAIN · 11-19-2013, 05:25 AM

12.25 inches...I had mine sitting in the garage from a recent Swift install.

Jordo! · 11-19-2013, 06:15 AM

You aren't planning on cutting a set are you?

If so, not a good idea...

You want a set with spring rates appropriate for the vehicle -- overall uncompressed height is kind of a separate issue.

Sh0velMan · 11-19-2013, 08:41 AM

Hopefully just having some custom springs made and needs overall height.

Chuck33079 · 11-19-2013, 08:43 AM

I would assume someone with a lot of track time like the OP isn't looking to cut his springs.

GSS138 · 11-19-2013, 11:59 AM

Lol thanks for the concern, but yes, I need to drop my car about 3" so I have a cutting torch right here in my pants :P

No I was trying to figure out if there is preload on our OEM suspension. I sort of already "know" there is, but I need an actual number so I can tweak and tune my little spreadsheet perfectly. I was figuring it was 12", so ty for the 12.25" measurement.

The front spring measures 11" at full droop and has a motion ratio of ~.61. But it is 9" at ride height. The front OEM springs are ~400 Lb springs and the front corner weights are around 850 lbs OEM as well. So it does not make sense that the spring is 9" at ride height, so I was guessing the spring was 12" with 1 inch of preload. But I needed some one to confirm because I don't know how to take that damn thing off nor would I try.

12.25 makes a lot more sense. This is all part of the monstrous suspension upgrade I will be doing sometime 2014. Planning now.

Sh0velMan · 11-19-2013, 12:09 PM

Did you measure/calculate that MR yourself or is that documented somewhere? Just curious.

GSS138 · 11-19-2013, 12:26 PM

It's easy to measure yeah did it myself.

Just take the length where the shock attaches to the lower arm, then divide that by the total length of the arm. There is also a correction factor that you have to make based on the shock angle from 90 degrees straight up from the lower arm. However our shock is somewhere around 80 degrees(10 degrees off of perpendicular) so the correction factor is really negligible.

I can't remember the exact lengths but the result is ~.61-.65. In our case this is the motion ratio of the spring and the shock. Since they are connected at the same places and are perfectly parallel.

Compare the front to the rear, and the rear spring perch is much further up the control arm(9"/18"- I remember this one). On the rear, our spring has a .50 motion ratio-that is why the rears have stiffer springs, car is lighter, yet the rear wheels have lower wheel rates(makes them softer). Basically the rear wheel has a very large mechanical advantage over its spring.

Jordo! · 11-19-2013, 09:31 PM

My apologies for assuming the worst

You clearly know your stuff and have a cool project in mind

GSS138 · 11-20-2013, 11:01 AM

Just a follow up on some things I found yesterday FYI.

Front Spring/Shock motion ratio does seem to be closer to .62 or .63 than .61.

Best I can tell there is very minimal preload on the spring. Maybe .25 of an inch. They probably did this to give it a "stiffer" feel vs preloading it more which would make it feel softer. Kinda corny on Nissan's part, but the effective wheel rate is still the same. They probably preload the G's a little bit more with the same spring to give it a softer ride.

And no sweat Jordo, I'm actually still kinda a noob at suspensions, but I have been reading and asking questions for months now. I finally seem to have a decent understanding of the math involved and have taken a lot of the VooDoo out of it for myself. There is a lot to know, and most people don't even want to attempt to explain it.

Luckily for me there is a guy at Koni that realized I was capable of basic geometry and algebra lol. He has written me some very extensive emails explaining things. Once I get this spreadsheet worked out(few more weeks). I will try to post a copy of it up. It is proving to be very useful to at least myself and I think some other people would like it too.

paperboy42190 · 11-22-2013, 05:33 AM

nice research!

ValidusVentus · 01-28-2014, 11:43 PM

Quote:

Originally Posted by GSS138

Just a follow up on some things I found yesterday FYI.

Front Spring/Shock motion ratio does seem to be closer to .62 or .63 than .61.

Best I can tell there is very minimal preload on the spring. Maybe .25 of an inch. They probably did this to give it a "stiffer" feel vs preloading it more which would make it feel softer. Kinda corny on Nissan's part, but the effective wheel rate is still the same. They probably preload the G's a little bit more with the same spring to give it a softer ride.

And no sweat Jordo, I'm actually still kinda a noob at suspensions, but I have been reading and asking questions for months now. I finally seem to have a decent understanding of the math involved and have taken a lot of the VooDoo out of it for myself. There is a lot to know, and most people don't even want to attempt to explain it.

Luckily for me there is a guy at Koni that realized I was capable of basic geometry and algebra lol. He has written me some very extensive emails explaining things. Once I get this spreadsheet worked out(few more weeks). I will try to post a copy of it up. It is proving to be very useful to at least myself and I think some other people would like it too.

I would be very interested in those emails as well as any info/data you have gathered. I have been in the midst of this type of research for several months myself. I wasn't very successful in measuring the motion ratios accurately lol, I went about it the harder way by mistake. As of this moment I was leaning towards getting some adjustable koni yellows, having Performance Shock @ Sonoma dyno match and revalve them to get the curves I want, (maybe adding an external reservoir and making them double adjustable) and pairing them with some linear Hypercoil race springs - found this thread while trying to figure out the proper spring lengths. I may also drive down to Fat Cat Motorsports and have a talk with them about bumpstops. I am going strictly for performance here while trying to keep the cost reasonable. Hope to hear back from you on this, I think we could both benefit from putting our heads together.

By the way, you planning to run Laguna Seca anytime this year?

GSS138 · 01-29-2014, 10:02 AM

I put it up somewhere else, but this is the worksheet I am currently working with.SuspensionWksht.zip

ValidusVentus · 01-30-2014, 02:07 AM

Cool, thx. So our OEM springs:

Front: ID=_2.5" ?
Uncompressed Height= 12.25"

Rear: ID=_60mm ?
Uncompressed Height=____?

GSS138 · 02-03-2014, 06:27 PM

I haven't measured the ID, but it's bigger than 2.5. More like 3.5 just eyeballing it. The rears I believe are the same length-12.25. If not they are 12, but makes sense that they are the same.

11-18-2013, 11:16 PM	#1 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	OEM Spring length. OK I asked this before, but does anyone know the OEM front spring length? __________________ Current Mods: Vorpal Weapon +5.

11-19-2013, 06:15 AM	#3 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	You aren't planning on cutting a set are you? If so, not a good idea... You want a set with spring rates appropriate for the vehicle -- overall uncompressed height is kind of a separate issue. __________________ Enjoy it. Destroy it.

11-19-2013, 08:41 AM	#4 (permalink)
Sh0velMan A True Z Fanatic Join Date: Jan 2012 Location: Dallas/Ft.Worth Posts: 3,349 Drives: Noisily. Rep Power: 20	Hopefully just having some custom springs made and needs overall height. __________________ Buy My Car! \| Build Thread

11-19-2013, 08:43 AM	#5 (permalink)
Chuck33079 A True Z Fanatic Join Date: Nov 2011 Location: Houston Posts: 12,265 Drives: 2011 370ztt Rep Power: 29538	I would assume someone with a lot of track time like the OP isn't looking to cut his springs. __________________ 2011 MB Touring-Sport-6sp-Nav/GTM TT/FI TT TDX/JTran/Kosmic/Eibach/Hotchkis/SPC/CSF/RPS/SoThatsWhereAllMyMoneyWent

11-19-2013, 11:59 AM	#6 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Lol thanks for the concern, but yes, I need to drop my car about 3" so I have a cutting torch right here in my pants :P No I was trying to figure out if there is preload on our OEM suspension. I sort of already "know" there is, but I need an actual number so I can tweak and tune my little spreadsheet perfectly. I was figuring it was 12", so ty for the 12.25" measurement. The front spring measures 11" at full droop and has a motion ratio of ~.61. But it is 9" at ride height. The front OEM springs are ~400 Lb springs and the front corner weights are around 850 lbs OEM as well. So it does not make sense that the spring is 9" at ride height, so I was guessing the spring was 12" with 1 inch of preload. But I needed some one to confirm because I don't know how to take that damn thing off nor would I try. 12.25 makes a lot more sense. This is all part of the monstrous suspension upgrade I will be doing sometime 2014. Planning now. __________________ Current Mods: Vorpal Weapon +5.

11-19-2013, 05:25 AM	#2 (permalink)
NORAIN Enthusiast Member Join Date: Jun 2013 Location: Wilmington, NC Age: 57 Posts: 323 Drives: 2011 370Z 6M SP Rep Power: 12	12.25 inches...I had mine sitting in the garage from a recent Swift install.

11-19-2013, 12:09 PM	#7 (permalink)
Sh0velMan A True Z Fanatic Join Date: Jan 2012 Location: Dallas/Ft.Worth Posts: 3,349 Drives: Noisily. Rep Power: 20	Did you measure/calculate that MR yourself or is that documented somewhere? Just curious. __________________ Buy My Car! \| Build Thread

11-19-2013, 12:26 PM	#8 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	It's easy to measure yeah did it myself. Just take the length where the shock attaches to the lower arm, then divide that by the total length of the arm. There is also a correction factor that you have to make based on the shock angle from 90 degrees straight up from the lower arm. However our shock is somewhere around 80 degrees(10 degrees off of perpendicular) so the correction factor is really negligible. I can't remember the exact lengths but the result is ~.61-.65. In our case this is the motion ratio of the spring and the shock. Since they are connected at the same places and are perfectly parallel. Compare the front to the rear, and the rear spring perch is much further up the control arm(9"/18"- I remember this one). On the rear, our spring has a .50 motion ratio-that is why the rears have stiffer springs, car is lighter, yet the rear wheels have lower wheel rates(makes them softer). Basically the rear wheel has a very large mechanical advantage over its spring. __________________ Current Mods: Vorpal Weapon +5.

11-19-2013, 09:31 PM	#9 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 418	My apologies for assuming the worst You clearly know your stuff and have a cool project in mind __________________ Enjoy it. Destroy it.

11-20-2013, 11:01 AM	#10 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	Just a follow up on some things I found yesterday FYI. Front Spring/Shock motion ratio does seem to be closer to .62 or .63 than .61. Best I can tell there is very minimal preload on the spring. Maybe .25 of an inch. They probably did this to give it a "stiffer" feel vs preloading it more which would make it feel softer. Kinda corny on Nissan's part, but the effective wheel rate is still the same. They probably preload the G's a little bit more with the same spring to give it a softer ride. And no sweat Jordo, I'm actually still kinda a noob at suspensions, but I have been reading and asking questions for months now. I finally seem to have a decent understanding of the math involved and have taken a lot of the VooDoo out of it for myself. There is a lot to know, and most people don't even want to attempt to explain it. Luckily for me there is a guy at Koni that realized I was capable of basic geometry and algebra lol. He has written me some very extensive emails explaining things. Once I get this spreadsheet worked out(few more weeks). I will try to post a copy of it up. It is proving to be very useful to at least myself and I think some other people would like it too. Jordo!, ValidusVentus, gomer_110 and 2 others like this. __________________ Current Mods: Vorpal Weapon +5.

11-22-2013, 05:33 AM	#11 (permalink)
paperboy42190 Base Member Join Date: Sep 2011 Location: Alhambra, CA Posts: 193 Drives: 2007 Acura TL Type-S Rep Power: 14	nice research!

01-29-2014, 10:02 AM	#13 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	I put it up somewhere else, but this is the worksheet I am currently working with.SuspensionWksht.zip Mitco39 likes this. __________________ Current Mods: Vorpal Weapon +5.

01-30-2014, 02:07 AM	#14 (permalink)
ValidusVentus Enthusiast Member Join Date: Jun 2011 Location: Washington State Posts: 400 Drives: #18 Z34 Rep Power: 23	Cool, thx. So our OEM springs: Front: ID=_2.5" ? Uncompressed Height= 12.25" Rear: ID=_60mm ? Uncompressed Height=____? __________________ Mods: Dedicated caged track car, lots of things. \|\|\| Valkyrie Autosport \|\|\|

02-03-2014, 06:27 PM	#15 (permalink)
GSS138 Track Member Join Date: Mar 2013 Location: Mission Viejo, CA Posts: 769 Drives: '12 370Z 6M Sport Rep Power: 13	I haven't measured the ID, but it's bigger than 2.5. More like 3.5 just eyeballing it. The rears I believe are the same length-12.25. If not they are 12, but makes sense that they are the same. __________________ Current Mods: Vorpal Weapon +5.

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