370Z Motion Ratios
 

Hey everyone - did a good bit of searching but couldn't find a clear answer. Has anyone calculated the motion ratios for the 370Z? From what I can see there are obviously some factors which may change it from car to car, but overall for a street car I can't see it being too far off if someone has measured it near-stock. Speaking to someone from Hyperco trying to figure out what spring rates would be right for my track/autox Z. Thanks for your help!

Andrew / PharmDZ

This article mentions OEM Z34 motion ratio

https://www.edmunds.com/car-reviews/...alkaround.html

I've been a car-nut for most of my life... and i have never heard of a Motion Ratio. WHAT, exactly, is that? :ugh2:

Don't know if this will help but here it is:
Measuring the Motion Ratio

My simple brain understanding in the form of a question...when the wheel moves up by one inch, how much does the spring and/or shock move up by?

I gave this thread a 5 star rating. :tup:

Thanks everyone for your help!

That article is wrong. Motion ratio is about where the control arm has leverage over the spring. Where the strut attaches has nothing to do with it in a divorced setup like what is on the 370. The front is .65 and the rear is .55. This is from my independent measurements and I found it elsewhere as well.

edit: .55 rear motion ration if you are still divorced spring. if you are true type then it is in fact 1:1 (like a .98 or something if you want to get really particular)

:iagree:

@OP, assuming you're running the "full" suspension math the other big thing you'll need to know are the weights (corner and unsprung corner). These will most likely vary from car to car depending on what type of weight reduction methods you've done.

I have my corner weights from corner balancing the car, but how can I more accurately get the unsprung corner weight? What does that include anyways?

iirc, the unsprung weight is everything from the chassis connection out. That would be control arms, upright, brakes, wheel, and tire.

Hmmm okay. I'll have to see how to get the weights for a couple of these parts. The rotors/wheels/tires are easy. The rest I'll have to dig a bit. Thanks again Gomer.

Take the wheel assembly off and weigh that. Take the damper and spring assembly out and weigh that. Then, use a bathroom scale to weight the unsupported suspension parts left on the car. you want to hit the scale at close to full droop to make sure most of the suspension is supported by the scale.

It won't be as accurate as weighing off the car, but we are talking a pretty minor margin of error difference.