Can anyone help me in filling out this form?

http://www.racingaspirations.com/?p=292

Preferably for a v35 g35 sedan.

Or does anyone know any of these numbers?

Corner Weight
Unsprung Weight
Suspension Leverage

Spring rates i can find no problem, but this is meaningless. Does anyone know the wheel frequencies?

Thanks.

 

Bigger question I have. Who would you be giving the results to?

I tried to develope a suspension system using Bilstein parts with one of the nation's most respected Mazda tuners. He had a great resume and talked a really REALLY good talk. In the end I was out over $2000 because while he knew the Miata inside and out. He simply could not figure out the FM platform. He refused to do anymore work to fix what wasn't even liveable. All he did was **** and moan about his labor costs. He even tried to claim he did R&D work that I handed to him. In the end I could not resell the POS he created, sent it directly to Bilstein for them to fix.

So, deal only with someone that has actuall R&D time with a Z or G rolling chassis or has one at his disposal. DO NOT GET BURNT like I did.

 

Don't quite know yet. Mulling the idea of turning the car into a track car, was curious where the stock spring rates landed and what options are out there. Really curious as to why a lot of the aftermarket lowering springs are softer than stock, makes no sense to me.

Haha, I looked into fatcat motorsports years ago, I think I remember seeing your review back then. Never went for it and just kept chugging along on my blown bushings and probably blown shocks.

 

I believe that calculator that you are using is meant to be applied to each corner 1 at a time not to the whole vehicle or front or rear. So corner weight refers to the total weight of that corner if you were to put the car up on 4 scales it would be the individual scale reading.

Unsprung weight is easiest described as any weight that the vehicle springs push down. or any part that moves when your suspension travels. Sprung weight is everything the springs hold up.
so unsprung weight would be the wheels, tires, brakes, hubs, suspension arms, axles stuff like that.

So for this application unsprung weight would be be unsprung at each corner.

Suspension leverage is the amount of movement of the spring VS movement of the wheel. for example if your wheel moves up 2 inches and that 2 inch of travel results in 1 inch of suspension travel then you have a 1:2 or 2:1 not sure in what format they want it in. Although I don't know what it is for the G35.


Also I recommend that you don't use that to determine what spring ratio to go with... Talk to a someone who is experienced with suspension design and even better if it was specifically for the G35 or 350z. That is a very rudimentary calculator. And if you need that to calculate something as simple as spung weight than you definitely shouldn't be designing your own suspension setup.

Also that calculator doesn't take in effect the angle of the shock to vertical because that also has an effect on spring rate.

Read up and do your HW before tackling this. That calculator only calculates the most basic suspension formulas. I recommend you start with the book "fundamentals of vehicle dynamics" by gillespie.

There are lots of other things to take into account like ratio of the effective spring rate front and rear...

 

Right... I know the definition of those terms, I was asking if anyone has the numbers. And you are correct, unsprung weight would be the corner unsprung weight, which I don't really know how to calculate myself even if I did have scales short of taking the car apart.

Shocks have no effect on wheel frequencies.

Exactly right, and wheel frequency IS a measure of effective spring rates. Spring rates by themselves are fairly meaningless.

And I am trying to do my HW, which is why I need wheel frequencies. And I'm not going to just blindly pay someone to put something on my car. I don't trust alot of people anyway. It seems like every third thing I read on suspension contradicts the previous 2 (i.e. sway bars). So in part of doing the research, I need the fundamentals, which these are a part of.

 

What I meant by shock angle is in the front where the spring is a coil on shock setup. It has an effect because the spring is at an angle as well which is what I meant.

 

You are correct, that website approximates it probably to 90 degrees. It doesn't really have that big of an effect until it gets pretty big angle. (I beleive it's sin(spring angle) in the formula, which at 75% would give you like a 3.5% difference in value)

If you want to test it out, let me know.

Here is one that takes it into account.

http://www.hypercoils.com/spring-rate-calculator/

 

http://farnorthracing.com/autocross_secrets16.html

^i personally like this calculator a lot more. It seems more accurate to the numbers I see in the real world. If you're just looking for spring frequency then all you need to fill out are:

corner weights
front&rear unsprung weights
desired spring rates(listed as chassis spring rate)
front&rear motion ratio

then for tire spring rates just put 9999 unless you have the means of finding out that figure.

From what i've learned a stock z is roughly 1.3hz front and 1.4hz rear with a G35 being slightly lower than that because of the extra sprung weight. I'm currently running 1.9hz front and 2hz rear but not by choice, just what i ended up with before i learned about all this. I've heard that most street tires dont like to go above 1.8hz unless youre running really really sticky tires (rs3,r1r, etc)

 

and to answer OP's question,

spring leverage(motion ratio) for the front is .68 while the rear depends on whether youre running oem style coilovers or true type. OEM= .64 TRUE=.97

To figure out corner weights, you'd need to throw your car onto scales. You can make a educated GUESS however by figuring out the stock curb weight and weight distribution of your car and do the math from there. For example, a 3500lbs car with 54% weight distribution.(a g35 coupe essentially)

3500x.54= 1890lbs
then divide by 2 because theres two wheels in front

1890/2=945lbs

now for the rear

3500x.46=1610lbs
1610/2=805lbs

so now you can guesstimate that your corner weights will be

LF-945 RF-945

LR-805 RR-805

I really wouldnt use these calculations for actually picking out springs but it'll kinda get you going in the right direction. Plus, my math doesnt account for driver weight or cross weight.

As for unsprung weight.... youre on your own as I dont even know myself. I've heard stock unsprung weights are around 110-125lbs but I dont know how credible that is.