Different ride height same springs and wheel size

scope22 · 12-10-2015, 12:47 PM

Car 1: Sport wheels stock tire size, swift springs, stock shocks
Car 2: F14 (255/35/19) (305/30/19) wheels, swift springs, koni yellow shocks

why does car 2 ride 1 inch lower then car 1?

before you tell me that tire size is different, i measured from the top of the rim to the bottom of the fender. Dealer mechanic told that custom wheels (regardless that they're also 19s) will make ride height different but that doesn't make sense to me.

EzDz · 12-10-2015, 01:09 PM

My only thought would be koni yellows

Silly Rabbit · 12-10-2015, 02:05 PM

Wheel width can also affect ride height. 1" seems like a lot though. If you know the details, go HERE and it will give you a good idea of what to expect when changing wheels and tires.

90 ST · 12-10-2015, 02:19 PM

Quote:

Originally Posted by Silly Rabbit

Wheel width can also affect ride height. 1" seems like a lot though. If you know the details, go HERE and it will give you a good idea of what to expect when changing wheels and tires.

The over all diameter from stock tires to the 255/305 combo mentioned is very close. It would have to be the shocks, and/or maybe a different part number on the spring?

scope22 · 12-10-2015, 08:06 PM

It's my understanding that shocks do not affect ride height, and swift makes sport and spec r but both have same ride height

POS VETT · 12-10-2015, 08:27 PM

What are the differences in offsets?

BGTV8 · 12-10-2015, 08:48 PM

Spring rate or overall length must be different if tyre OD is the same

scope22 · 12-10-2015, 10:03 PM

What i have are the standard deep concave f14s
19x9.5 +20 - 255 35
19x11 +15 - 305 30

according to willtheyfit.com my ride heigh should be about an inch lower (5/8s) so it matches up to what i measure, but that is due to the tire being lower profile, but when i measure from the bottom of the fender to the top of the rim, i'd expect it to be the same as my 09 unless what BGTV8 is saying is true...either way i guess i need to get some coilovers

Rusty · 12-10-2015, 10:27 PM

Remembering reading that someone else who had installed the Koni shocks had a lower ride height. Something about the shock length/how the spring perch on the front was mounted. If you search, you may fine it. Can't remember all the details.

nis350 · 12-10-2015, 11:12 PM

Swift springs only lower the car about 1 inch. There is no way there is one inch difference due to the same diameter wheels.

Have you compared car one with another stock Z? Perhaps car one has the stock springs?

Quote:

Originally Posted by scope22

Car 1: Sport wheels stock tire size, swift springs, stock shocks
Car 2: F14 (255/35/19) (305/30/19) wheels, swift springs, koni yellow shocks

why does car 2 ride 1 inch lower then car 1?

before you tell me that tire size is different, i measured from the top of the rim to the bottom of the fender. Dealer mechanic told that custom wheels (regardless that they're also 19s) will make ride height different but that doesn't make sense to me.

POS VETT · 12-11-2015, 05:52 AM

The differences in offsets (the Forgestar set has lower numbers) create a longer leverage arm on the springs. The result is like loading the springs with more weight, thus compressing them further. In order to drop the ride height by 5/8", the springs only need to compress a fraction of that due to the suspension design.

I say it's to be expected.

scope22 · 12-11-2015, 06:26 AM

you sir know your stuff, thanks, i think the dealer was trying to say this but didn't know how. rep point for you

Quote:

Originally Posted by POS VETT

The differences in offsets (the Forgestar set has lower numbers) create a longer leverage arm on the springs. The result is like loading the springs with more weight, thus compressing them further. In order to drop the ride height by 5/8", the springs only need to compress a fraction of that due to the suspension design.

I say it's to be expected.

scope22 · 12-11-2015, 06:27 AM

they're both in my garage....i think pos vet is right, its the only explanation

Quote:

Originally Posted by nis350

Swift springs only lower the car about 1 inch. There is no way there is one inch difference due to the same diameter wheels.

Have you compared car one with another stock Z? Perhaps car one has the stock springs?

12-10-2015, 12:47 PM	#1 (permalink)
scope22 A True Z Fanatic Join Date: Apr 2012 Location: Roswell, GA Posts: 1,179 Drives: wife crazy Rep Power: 56	Different ride height same springs and wheel size Car 1: Sport wheels stock tire size, swift springs, stock shocks Car 2: F14 (255/35/19) (305/30/19) wheels, swift springs, koni yellow shocks why does car 2 ride 1 inch lower then car 1? before you tell me that tire size is different, i measured from the top of the rim to the bottom of the fender. Dealer mechanic told that custom wheels (regardless that they're also 19s) will make ride height different but that doesn't make sense to me. Last edited by scope22; 12-10-2015 at 12:48 PM. Reason: changed title

12-10-2015, 01:09 PM	#2 (permalink)
EzDz Enthusiast Member Join Date: Aug 2015 Location: Pittsburgh Posts: 309 Drives: 2016 370z Nismo Tech Rep Power: 11	My only thought would be koni yellows __________________ Nismo \| Moore Performance \| AAM \| Tein \| PPE \| Tomei \| Eibach \| Z1 Sponsored: Mishimoto

12-10-2015, 02:05 PM	#3 (permalink)
Silly Rabbit Track Member Join Date: Sep 2013 Location: Brookston, IN Age: 55 Posts: 683 Drives: '12 PW Touring Sport Rep Power: 619	Wheel width can also affect ride height. 1" seems like a lot though. If you know the details, go HERE and it will give you a good idea of what to expect when changing wheels and tires. __________________ NISMO R Tune Intakes \ Fast Intentions RHFC \ Borla CBE \ EcuTek Tuned\ SPL Camber Arms \ Powertrix Coilovers \ Swift Springs \ Avant Garde \ Wicked CAS \ Morimoto XB Halos \ Custom Fenders \ Hotchkis Sways \ NLP Splitter

12-10-2015, 10:27 PM	#9 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 69 Posts: 35,524 Drives: 2011 Nismo GM 6M Rep Power: 2684439	Remembering reading that someone else who had installed the Koni shocks had a lower ride height. Something about the shock length/how the spring perch on the front was mounted. If you search, you may fine it. Can't remember all the details. __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

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12-10-2015, 08:06 PM	#5 (permalink)
scope22 A True Z Fanatic Join Date: Apr 2012 Location: Roswell, GA Posts: 1,179 Drives: wife crazy Rep Power: 56	It's my understanding that shocks do not affect ride height, and swift makes sport and spec r but both have same ride height

12-10-2015, 08:27 PM	#6 (permalink)
POS VETT Track Member Join Date: Apr 2015 Location: Columbus OH Posts: 612 Drives: Z34\|C4LT4\|C6Z06\|V25 Rep Power: 3367	What are the differences in offsets?

12-10-2015, 08:48 PM	#7 (permalink)
BGTV8 A True Z Fanatic Join Date: Dec 2009 Location: 03350 Australia Posts: 1,516 Drives: 09 Nissan 370Z M6 Rep Power: 39974	Spring rate or overall length must be different if tyre OD is the same

12-10-2015, 10:03 PM	#8 (permalink)
scope22 A True Z Fanatic Join Date: Apr 2012 Location: Roswell, GA Posts: 1,179 Drives: wife crazy Rep Power: 56	What i have are the standard deep concave f14s 19x9.5 +20 - 255 35 19x11 +15 - 305 30 according to willtheyfit.com my ride heigh should be about an inch lower (5/8s) so it matches up to what i measure, but that is due to the tire being lower profile, but when i measure from the bottom of the fender to the top of the rim, i'd expect it to be the same as my 09 unless what BGTV8 is saying is true...either way i guess i need to get some coilovers

12-11-2015, 05:52 AM	#11 (permalink)
POS VETT Track Member Join Date: Apr 2015 Location: Columbus OH Posts: 612 Drives: Z34\|C4LT4\|C6Z06\|V25 Rep Power: 3367	The differences in offsets (the Forgestar set has lower numbers) create a longer leverage arm on the springs. The result is like loading the springs with more weight, thus compressing them further. In order to drop the ride height by 5/8", the springs only need to compress a fraction of that due to the suspension design. I say it's to be expected.