What Spring Rate Do I Need? - QA1 Quick Tip

What spring rate do I need on my car? is a common question. Here's how to determine the ideal range of spring rates for your car.

-----------------------------------
About QA1: Founded in 1993, QA1 specializes in providing performance shock absorbers, suspension components, carbon fiber driveshafts, rod ends, spherical bearings, springs, ball joints and more for a variety of markets, including circle track racing; drag racing; street performance; and street rodding, as well as several industrial markets. Whether you’re looking for improved ride quality, show-stopping appearance, or faster times, QA1 delivers.

You can follow us at:

800.721.7761

[davidelliott]

It a bit of work but you can weigh your axle by -
jack up the car
Put weigh scale under each wheel.
Disconnect the shocks so wheels are sitting on the scales.
Read off the weights. Suspension arms at mid travel give the closest figure.

[smartdummy]

I think this how you calculate unsprung spring rate or what spring you need.

So if your rear end was 1500 pounds and you subtract tires, axle, brakes, etc and you end up with 1200 pounds,
your spring should be able support that weight without bottoming out.
So if you take 1200 and devide by 4 you'll get 300
So you need a spring with a rate of 300 or a longer spring. This would be 25% compression for a 16 inch spring.

450 pounds in the example seems like a small amount, unless he was referring to a small car?

[joelhauser]

well done, very clear and informative. Thank you

[jamesmerkel]

general car> setup 25-35% of the wt on each corner would b idle. Cars r front wheel drive & front engine so yeah all up front not race car mid engine idle, & diff then a 4 by 4 set up. Is front axle solid or IFS is back solid or IRS how much travel is factor in how much wt u want to put on it + if truck the rear is going to see most of added wt or ppl wt 2 door front will gain etc.

[Zukuri]

Hookes law!! F=kx, could use simulink and play with different zetas.

[trismfx]

I have a 1929 model a. My front springs are nearly completely compressed when sitting. It has a stock 302 engine. Any idea what weight front suspension springs you'd recommend?

[jamesmerkel]

comment 51:must see/hear video: not just how much wt per corner but more important spring weighing method how much wt on this spring on this corner current setup as far as what is on in the car & how it is sitting. Kind of the same thing but truer in a way number, & it's not a fixed number, bc like a trailer raise or lower hitch & wt is diff.

[peppers]

So my stance car weights fuck all so I should run 600 rate 5 inch springs so I don't ground out or rub arch?

[cameronearnshaw]

I want to put coilovers on my '73 AMC Javelin. The original front spring has a free height of 14.31 inches and a spring rate of 307 lbs. If I purchase a coil-over that is 10" long, should choose the same spring rate as the original (assuming I want the car to ride as before) or do I need to select a different rate since the coil-over is shorter?

[tonyhuerta]

What would I need for a 68 C10? Ls3 engine, I need front and rear. Oh and what do you recommend, single or double adjustability?

[wiskyme]

Jeep wrangler JK 2013 whats the 2.5” coil spring rate front and rear please ?

[simrandevgan]

Hello
I have 2012 Hyundai Sonarta GLS 2.4. What spring rating should i go for?
Pleae let me know i am very confused.
Thanks

[williamlewis]

Hi I got a question before I purchase which is the most popular coil over front and back the 350, 450, 550, 650?

[gsbasra]

Hey can you give me any idea about how much( in percent) spring should compress under a car's weight if its an ATV

[NeutronX]

What do you mean softer spring rate? Higher or lower number weight to compress 1 inch?

[joracer]

2018 shaw dirt late model 3 tenths low bank stop and go slick dirt track what rf spring do i need? Corner weight is 500lbs

[dons]

I'm confused about something. He says that you always want 25 - 30% of the spring compressed. So if that's an 11 inch spring, that's 2.75 - 3.30 inches. However he also says that you can tell how much weight is on a spring from the car, by how much the spring compresses. What I don't understand is what that knowledge actually gives you? Seeing as you must have a certain amount of the spring compressed, seems you are limited by what actual weight of spring you need, because any stiffer than what the car already weighs on it and it won't compress at least 25%, and any softer and it will compress more than 30%. How would you use this knowledge when selecting race car springs when you are actively TRYING to make a car more stiffer? Because the weight of the car is a constant. Seems to me you would get to a point where the stiffer a spring you install, the less it will obviously compress? Which is bad? But isn't that the point of a stiffer spring?

[RyL]

300 lbs for a solid rear axle set up. How much would you estimate for a typical double wishbone front suspension?

[static_Tricolor_camry]

BC Racing Coliovers are 6k Front, and 5k Rear, I think that's too soft for my car since I plan on lowering my car to a 2.8 inch Drop in the Front, and a 2.6 inch in the Rear, they do customized the Spring rates for you, but the question is I don't know how much each corner weights. I might just take the Spring rates they offer 6k and 5k and call it a day, I don't want to go too high on the Spring rate only to make my car ride like crap, or I might do 8k for the Front, and 6k for the Rear. This is confusing.

[zhinoos]

Hi thanks for the information
want to ask a question
I have a machine of 150kg weight and i'm wondering which spring do I need for it
how can I make the calculation ?