Ridetech and QA1 recommending completely different spring rates for 69 Camaro

[Ryanater]

I am looking to get a set of front coilovers for my 69 Camaro. I have an LS1 with a T56 transmission. The car will hopefully see some track time in the future so performance is my main concern. So before I make the purchase I wanted to do my research.

I called QA1 first and they recommended 400lb springs up front for my setup. I then called Ridetech who recommended a 650lb spring rate for the front. Well obviously that is a massive difference!!

I'm trying to figure out why they have such a huge difference between spring rates. I'm no expert when it comes to shocks/springs but I would sure think there would be an ideal range that a performance spring rate should be with my configuration. Is this possibly due to completely different damping rates offered by QA1 shocks compared to Ridetech shocks?

My next question is pretty typical.... Does anyone have any advice on which ones to go with? Or possibly any other suggestions.

[Bryce]

I would agree with Ridetech. The have cars in the top at most of our events. What car does QA1 have?

There is no way to give spring rates without more info....
What does the car weigh?
Motion ratio?
shock travel?

[Rod]

different spring makers, ridetech uses HyperCo, Qa1 uses? Qa1, thats all, between Ridetech and Qa1< I pick ridetech, I used QA1 for2 years pretty good shock, I switched to ridetechs last year and its a much superior shock and the Hyperco spring is better than the QA1 spring

[Ryanater]

I would agree with Ridetech. The have cars in the top at most of our events. What car does QA1 have?

There is no way to give spring rates without more info....
What does the car weigh?
Motion ratio?
shock travel?

Well I think both companies have data on the 69 camaros with LS1s. And why would the motion ratio change between manufactures?

[marolf101x]

There are a number of things which can influence the spring rate selection; vehicle weight, motion ratio, desired wheel rate, desired frequency, spring preload amount, etc.

System Design:
One big thing we are overlooking in this post is that these two products are of different design. The Ridetech unit is a true coil over, meaning that the coil spring is contained on either end by the shock assembly. The QA1 unit is a hybrid coil over, meaning the upper spring mount is similar to the OE setup, mounting in the upper spring pocket, while the lower is connected to the shock.

The true coil over design requires a little more space on the top as you have to have the spring secured, while the hybrid design does not require these parts. As such, the Ridetech coil overs require a lower control arm change. By dropping the lower shock mounting location we maintain proper suspension travel while also placing the shock in a double shear mount configuration. Remember, this one bolt is now holding up the weight of the car, so it better be strong!

Wheel Rates, Spring Rates, Spring availability, Spring Preload, and Coil Bind:
By partnering with Hyperco (a widely respected racing spring manufacturer) we have afforded the customer a wide range of spring rates to choose from. This is important as there are many springs that will hold up the same car, but only a few that will work properly.
Take this example: Your Camaro weighs 3600#. . .let's say 55% front (1980#), and 45% rear (1620#), and 50/50 Right/Left. So the RF corner weighs 990#. Let's say 1000# for easy math. And let's say it has a motion ratio of 2:1, again for easy math. So the RF spring must hold up 2000# at ride height. Well, you could put a 2000lb/in spring in there. . .it'll hold up the car, but will ride like hell. Or you could put a 500lb/in spring in there and crank in 4 inches of preload. . .again the car will be held up, but it'll be a pretty soft ride, which will likely result in the coil spring bottoming out (what is called coil bind).
So how do we know which spring to use? Wheel Rates. Take the example above. The 2000lb/in spring would'nt let the wheel/tire move much at all, while the 500lb/in spring would have the wheel/tire bouncing down the road. What you want is a rate that is somewhere in the middle.
When you enter the information into our spring rate calculator this is being considered in the background. We don't just give you a spring that will hold up the car. . .we give you a choice of spring rates, all of which are tailored to what will make the car perform the best in the selected discipline.

[Ryanater]

There are a number of things which can influence the spring rate selection; vehicle weight, motion ratio, desired wheel rate, desired frequency, spring preload amount, etc.

System Design:
One big thing we are overlooking in this post is that these two products are of different design. The Ridetech unit is a true coil over, meaning that the coil spring is contained on either end by the shock assembly. The QA1 unit is a hybrid coil over, meaning the upper spring mount is similar to the OE setup, mounting in the upper spring pocket, while the lower is connected to the shock.

The true coil over design requires a little more space on the top as you have to have the spring secured, while the hybrid design does not require these parts. As such, the Ridetech coil overs require a lower control arm change. By dropping the lower shock mounting location we maintain proper suspension travel while also placing the shock in a double shear mount configuration. Remember, this one bolt is now holding up the weight of the car, so it better be strong!

Wheel Rates, Spring Rates, Spring availability, Spring Preload, and Coil Bind:
By partnering with Hyperco (a widely respected racing spring manufacturer) we have afforded the customer a wide range of spring rates to choose from. This is important as there are many springs that will hold up the same car, but only a few that will work properly.
Take this example: Your Camaro weighs 3600#. . .let's say 55% front (1980#), and 45% rear (1620#), and 50/50 Right/Left. So the RF corner weighs 990#. Let's say 1000# for easy math. And let's say it has a motion ratio of 2:1, again for easy math. So the RF spring must hold up 2000# at ride height. Well, you could put a 2000lb/in spring in there. . .it'll hold up the car, but will ride like hell. Or you could put a 500lb/in spring in there and crank in 4 inches of preload. . .again the car will be held up, but it'll be a pretty soft ride, which will likely result in the coil spring bottoming out (what is called coil bind).
So how do we know which spring to use? Wheel Rates. Take the example above. The 2000lb/in spring would'nt let the wheel/tire move much at all, while the 500lb/in spring would have the wheel/tire bouncing down the road. What you want is a rate that is somewhere in the middle.
When you enter the information into our spring rate calculator this is being considered in the background. We don't just give you a spring that will hold up the car. . .we give you a choice of spring rates, all of which are tailored to what will make the car perform the best in the selected discipline.

I think I understand the differences in systems designs. What I don't understand is how or why that would affect the desired spring rate for my application so drastically. Or do they...?

The weight, motion ratio, wheels/tires, and application would all be the same with my car no matter which set of coilivers I go with right?

So maybe the desired spring rate for my application wouldn't depend so much on the coiliver brand? Or is there something I'm missing here that would make 400lb springs perform better with QA1's system and 650lb springs perform better with ridetech's system?

[Bryce]

I still think that QA1 has less experience than Ridetech. QA1 suggested springs that fit but not neccessarily work in the autocross/performance world. I would trust ridetech.

[Bryce]

Well I think both companies have data on the 69 camaros with LS1s. And why would the motion ratio change between manufactures?

There are so many camaros built that the weights range from 2900lbs to 3900lbs. The springs would be significantly different rates.

[marolf101x]

Both the 400# and 650# can fit on your Camaro and hold the car up. The difference starts when the suspension moves.

Let's do another example. . .if both springs are 8" free standing and the spring must hold up 2000#. . .each spring will add its rate each inch it is compressed. (this is assuming a linear spring rate. If the spring is progressive all this goes out the window as the spring would add more than the stated rate each inch it is compressed. This is exactly what our air springs do, and in some instances we use air springs to get the progressive rate.)

So the 400# spring "pushes" 400# when compressed 1", 800# when compressed 2", 1200# when compressed 3", 1600# when compressed 4", and 2000# when compressed 5". Leaving you with 3" of travel (actually less, but since I don't know at what height the QA1 springs reach coil bind I'll just use the overall numbers.)

The 650# spring "pushes" 650# when compressed 1", 1300# when compressed 2", 1950# when compressed 3". Leaving 5" of travel. (now I do know the numbers for the Hyperco spring. . .they reach coil bind at 80% of travel, so an 8" spring will coil bind at 1.6" height. So technically you have 3.4" of spring travel left over for compression movement, which equates to 6.8" of actual suspension travel when you have a 2:1 motion ratio.)

So you have two springs with different rates holding the car up. But what happens when you hit a bump or turn a corner and the spring compresses another inch? The 400# spring goes from 2000# (at ride height) to 2400#; while the 650# spring goes from 1950# (at ride height) to 2600#. So even though they both hold up the car, the heavier spring will "push" more when compressed. This could mean a lot of things. . .in this situation most likely the lighter spring would bottom out long before the heavier spring.

From what I can tell QA1 only offers 400# and 550# springs, and most of their customers won't be running autocrosses and don't care what the wheel rate is, so they error on the lighter spring rate side.
We, on the other hand, have a TON of springs to choose from, so our spring rate calculator gives you a choice of 3 springs, all falling well within the range of desired wheel rates. Can you change from there? Sure you can. . .but you have to know what you are getting. If the car is strictly a road course car you may want 1000lb/in. . .but I wouldn't drive it on the street!

[Ryanater]

Thanks for that explanation! I assumed that was the case. It didn't make sense that you would get the same performance with 2 extremely different spring rates. I was told that a 450lb spring would rattle my teeth out. Which didn't make a whole lot of sense since I am running Hotchkis big block springs right now that are 600lbs.

I appreciate the help everyone.

[Bryce]

Britt,

As usual, good tech!

[Ryanater]

I have one more question that came up while looking at the spring rate calculator.

What exactly is the ride height from extended height used for? Shouldn't that directly depend on your spring rate and not the other way around? Plus they are coilovers so the ride height can be adjusted.

Hopefully that made sense.

[cactuss4]

Britt what happened to the 68 Camaro AWD project?

Tory

[marolf101x]

it's in my garage and gets worked on once in a while. I now have two daughters, an 18 month old and a 13 day old so I haven't had much garage time. I'm also "throwing together" a 1992 Camaro, so I work on the AWD car when I find the time.

[MonzaRacer]

IE I would say Britt gets to "dust" the car once a month at best if not simply lay a hand on it walking out the door,,,,,,

[Classic Nova & Performance]

Great information/explanation Britt. I'm sure that will help a lot of people with spring rate questions. I go through that explanation several times a week, although not as well as you did. I'm stealing some of your explanation for my future calls. :-)

[MCB Matt]

We sold QA1 for years, often had problems with coil bind....Ridetech is a much better choice, thats why i no longer sell QA1, too many issues and with Ridetech offering a CORRECT lower arm to mount them in you will have a much better suspension.

PM me if you need more info on the diff. We have experienced with the two.

Matt