Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Go Back   Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum > General > Tech Talk

Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars


Reply
 
Thread Tools Display Modes
Old 07-15-2004, 08:23 PM   #1
Quyen
 
Join Date: Jun 2004
Location: Abbotsford, BC
Posts: 8
Trader Rating: (0)
Quyen is an unknown quantity at this point
Feedback Score: 0 reviews
Could someone explain spring preload (coilovers)

I always hear about spring preload, but can't find an explanation. Could someone just give me a quick overview, thx
Quyen is offline   Reply With Quote
Sponsored Links
Old 07-15-2004, 11:56 PM   #2
heated heavy
Zilvia Member
 
heated heavy's Avatar
 
Join Date: Jun 2003
Location: Southern California
Posts: 286
Trader Rating: (0)
heated heavy is an unknown quantity at this point
Feedback Score: 0 reviews
how about you search like a man rather than wait for someone to tell you.
heated heavy is offline   Reply With Quote
Old 07-16-2004, 12:03 AM   #3
Quyen
 
Join Date: Jun 2004
Location: Abbotsford, BC
Posts: 8
Trader Rating: (0)
Quyen is an unknown quantity at this point
Feedback Score: 0 reviews
i knew someone was gonna say that. I did search, ppl talk about it but no one really explained what it was. Sorry i just don't know that much about suspension
Quyen is offline   Reply With Quote
Old 07-16-2004, 12:11 AM   #4
Maeda
Nissanaholic!
 
Maeda's Avatar
 
Join Date: Dec 2002
Location: Camp Snake Bite, CA *RIP*
Posts: 2,356
Trader Rating: (0)
Maeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura about
Feedback Score: 0 reviews
You can PRELOAD the springs by compressing them with the perch thing. This will in effect give you stiffer springs (they get stiffer as they get more compressed) initially at the cost of suspension travel.

Atleast thats how I understand it.

I wouldn't do anything that comprimises my suspension travel, unless I knew I wasn't going to need it.
__________________
Maeda is offline   Reply With Quote
Old 07-16-2004, 07:39 AM   #5
sykikchimp
WOW addicted
 
sykikchimp's Avatar
 
Join Date: Dec 2001
Location: the moon
Age: 40
Posts: 6,518
Trader Rating: (0)
sykikchimp has a spectacular aura aboutsykikchimp has a spectacular aura aboutsykikchimp has a spectacular aura aboutsykikchimp has a spectacular aura aboutsykikchimp has a spectacular aura aboutsykikchimp has a spectacular aura about
Feedback Score: 0 reviews
Send a message via AIM to sykikchimp
There are 2 kinds of springs. Progressive, and Linear.

With progressive springs, as they compress the lighter rate coils compress, and force higher rate colis into action. Effectively increasing spring rate as they are compressed. Stock 240sx springs are progressive. (most stock springs are.) This type of spring is good for street driving b/c they are comfortable over small bumps, but tighten up as you start turning, or braking harder.

Linear springs are the same spring rate no matter how much they are compressed. Almost all coilover systems come with linear rate springs. Linear springs are much better for sport driving, b/c they are much mroe predictable, and make tuning your suspension much easier.

You can only preload springs with threaded shock body coilovers.

To preload a spring, you compress it b/w the upper and lower spring perches by adjusting the lower collar with the spanner wrench.

With linear springs:
When you put the weight of a corner of a car (probably around 700lbs) over your spring it compresses to absorb that weight. With 400lb spring, it will compress about 1 3/4". So, if you start with the lower collar so that it is just tight enough to hold the top of the spring against the upper perch this would be 0 preload. Raise the collar 1 3/4", and you now have 700lb's of preload. (arbitrary #'s for the sake of illustration.) Since you have preloaded the spring, the same weight as the car's corner, when you put the car on that spring, it will not compress at all, and will simply sit on top of the spring. If you were to hit a bump, the force would still compress the spring the same amount it normally would if you had set the spring to 0 preload. Now if you set the spring to say 900lbs of preload, when you hit the bump (say its a bump that generates around 250lbs of upward force), the spring will compress much less b/c the spring is already beyond the load specified to absorb the bump. Since there is only 50lbs beyond the preload, the spring will only compress about 1/8th inch, and the car will likely be launched over the bump.

You will likely never ever preload a spring beyond the weight of the corner of the car it is on for that exact reason. Springs are there to absorb bumps, if there are any bumps at all, this is a bad idea.

What good is preloading the spring then?

It can provide you with more suspension travel in certain situations. In the ideal world, having the spring at 0 preload would place the piston inside the shock exactly halfway through it's stroke (middle of shock) once the car's weight is resting on the spring. This is almost never the case. by preloading the spring, you can adjust the amount of rebound, or compression travel you have in the shock. If you preload like 200lbs, this will give you more compression travel, and will help keep your car from bottoming out when cornering. You have to be careful though, b/c you don't want to sacrifice too much rebound travel, or you could cause all sorts of other problems.

Progressive springs:
With progressive springs, preloading the spring does all the same things as linear springs, but it also increases the initial rate of the spring. So say you have a spring with a 200lb/in initial rate, and a 400lb/in max rate. (all progressive springs are rated this way.) Preloading 200lb's will compress the spring just under 1". Since the rate goes up with a function, it will have increased to probably somewhere around 250lb/in by the time you reach a 200lb preload. So now your initial rate is 250lb/in, with a max 0f 400lb/in.

You will likely never deal with this though, b/c very few coilover systems come with progressive springs, and remember you can't preload without adjustable spring perches. (coilovers)


-Charles
__________________
sykikchimp is offline   Reply With Quote
Old 07-16-2004, 01:12 PM   #6
ISTOTOSAO
Zilvia Junkie
 
ISTOTOSAO's Avatar
 
Join Date: Jan 2003
Location: SB Mts, CA
Age: 39
Posts: 546
Trader Rating: (6)
ISTOTOSAO will become famous soon enoughISTOTOSAO will become famous soon enoughISTOTOSAO will become famous soon enoughISTOTOSAO will become famous soon enough
Feedback Score: 6 reviews
Charles: This is excelent. It is good to see someone sharing their knowledge with those of us less familiar with these fields. Thank you.

Steven
__________________
Steven- "You don't know me, but I am better than you."
ISTOTOSAO is offline   Reply With Quote
Old 07-16-2004, 01:46 PM   #7
Quyen
 
Join Date: Jun 2004
Location: Abbotsford, BC
Posts: 8
Trader Rating: (0)
Quyen is an unknown quantity at this point
Feedback Score: 0 reviews
Yea thanx alot, that more then answered my ?.
Quyen is offline   Reply With Quote
Old 07-16-2004, 09:28 PM   #8
Maeda
Nissanaholic!
 
Maeda's Avatar
 
Join Date: Dec 2002
Location: Camp Snake Bite, CA *RIP*
Posts: 2,356
Trader Rating: (0)
Maeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura aboutMaeda has a spectacular aura about
Feedback Score: 0 reviews
Quote:
Originally Posted by sykikchimp
What good is preloading the spring then?

It can provide you with more suspension travel in certain situations. In the ideal world, having the spring at 0 preload would place the piston inside the shock exactly halfway through it's stroke (middle of shock) once the car's weight is resting on the spring. This is almost never the case. by preloading the spring, you can adjust the amount of rebound, or compression travel you have in the shock. If you preload like 200lbs, this will give you more compression travel, and will help keep your car from bottoming out when cornering. You have to be careful though, b/c you don't want to sacrifice too much rebound travel, or you could cause all sorts of other problems.

-Charles
And I stand corrected. I'm still leaving my preload at zero due to LA driving.
But thank you for that illuminating article Charles.
__________________
Maeda is offline   Reply With Quote
Old 07-16-2004, 10:01 PM   #9
420sx
Post Whore!
 
420sx's Avatar
 
Join Date: Jun 2004
Location: Texas
Age: 38
Posts: 3,960
Trader Rating: (0)
420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future420sx has a brilliant future
Feedback Score: 0 reviews
put this in FAQ so nobody will ask again. important stuff
__________________
hydropgrahics!
ls1......
420sx is offline   Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 07:20 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
vB.Sponsors
Copyright © 1998 - 2019, Zilvia.net™