Yaris wheel rate ratio (06+) ?

[dsc_pat]

Hello,

Does anyone know the approximative convertion ratio for spring rate / wheel rate on a yaris 2006+ ? motion ratio...

I would like to compare spring rates with the honda equivalent, in wich i have experience with. I don't know how to calculate it myself, and I am wondering if any of you guys knew about that ratio.

For those wondering what the hell I am talking about...here is a quick explanation :

Let's say you install 500lbs*inch springs on a SUBARU, It might feel very very very stiff driving the car.

If you install the same 500 lbs springs on a Honda Accord, it might feel pretty ok.

The difference here is in the suspension geometry design, wich result in a different wheel rate.

For those numbers people :

(**HYPOTHETIC NUMBERS, NOT REAL NUMBERS)

subaru : 500lbs * 1.0 motion ratio = 500 lbs wheel rate

accord : 500lbs * 0.7 motion ration = 350 lbs wheel rate...

The feeling won't be the same.

So, i would like to know the motion ratio of the Yaris, to know what I am buying and looking for as springrates for my yaris...

thanks

P

[dsc_pat]

the front is about 1:1

[brickhardmeat]

extremely soft

[dsc_pat]

nope. Actually, it's pretty good. It means that a 500lbs spring rate will give a 500 lbs wheel rate, wich is great.

[brickhardmeat]

So if a spring rate is say 6kg this would be a much stiffer spring correct? but you are saying a 1.1 is not soft? Just trying to gain some understanding here.

[dsc_pat]

1:1 is the ratio spring rate:wheel rate. It means the the geometry of the suspension will not result in any kind of waste/gain of spring rate. The feeling of a spring rate is relative to the wheel rate, not the spring rate itself. Next time your friend tells you his 400lbs springs feels confortable on his car, make sure you know what kind of suspension geometry and motion ratio he has. A 400lbs spring rate on a 0.5 motion ratio car results in a 200 lbs wheel rate, wich will give a pretty smooth ride compared to a 1:1 design.

6kg*cm = 336lbs*po springs

1:1 means that the wheel rate is equal to the spring rate. It is fondamental to know what will be the resulting wheel rate, to be able to compare spring rates from a make or a chassis to another.

I would like to know the rear motion ration of the yaris to make a good choice of spring rate...I only have experience with 92-00 Honda chassis

A good way to determine it is measuring the shock travel needed to move the wheel 1 inch. (or X inches) burt I wanted to know if anyone knew it before I do it...

[brickhardmeat]

nice, thanks

shit you sound like you actually know what your talking about

that's new to me

[suttonschinook]

subscribed! This looks to be the beginnings of a very informative thread!

[churp]

The rear springs are vertical and appear from the side view to be in a straight line (not ahead or behind) with the wheel bearings/spindles ....so wouldn't this also 1:1??

edit: If I understand you right ....you are talking about is the ratio of wheel movement (vertically) to spring compression distance.

[dsc_pat]

churp, you understand it very well.

it allows you to calculate the «waste» (it isn't a waste at all btw...) of spring rate. It allows you to evaluate the wheel rate.

The shock can be vertical and have a different motion ratio than 1:1. The variation comes from the lenght of the suspension arm.

I'll try to calc. it myself in the next few weeks...

[Biggie™]

Originally Posted by dsc_pat

The variation comes from the lenght of the suspension arm.

Not the length of the arm per say, but the attachment location of the strut/shock in relation to the lower suspension arm. If the strut/shock attaches at the end of the arm, you get a 1:1 ratio of movement, while a strut/shock attached only half way up the lower arm will give you a 2:1 ratio, and so on. Also the actual angle of the strut/shock will effect that ratio as well.

The rear of the Yaris is a bit tricky, as the spring attaches directly to the suspension arm and doesn't need a strut/shock to function or stay in place. Also, I haven't measured it, but from brief observation it seems the rear spring on the Yaris might sit slightly behind the center point of the wheel. The means the rear ratio could actually increased slightly, so a 3 kg/mm spring might have an effective rate of 3.1 kg/mm.

I think it's great you guys are interested in the complexities of the Yaris suspension and encourage you to do more research. But knowing these ratios will help very little when comparing optimal spring rates between completely different cars. The differences in suspension design (strut, multi-link, double wishbone), vehicle weight, weight distribution, drive train layout, sway bar rates and tire size will make a direct comparison rather useless.

[dsc_pat]

Yeah didn't wanted to go into details but you resumed it very well, thanks for sharing this.

Saying that knowing these ratio will not help is false, it will greatly help me have a starting point on what kind of rate I should start with/buy. Of course, my preferences will be decided behind the steering wheel, but I'll know approximatly what to get at first and start from there. The yaris is my daily driver and it sees the track once in a while, when the civic is taking a break or getting fixed, but i'd still not want to go out and buy any spring rates to realize by myself that the spring rates I use are totally not what I wanted. I'm pretty sure you understand that well.

PS. torsion beam motion ratio are always pretty near of 1:1 (thanks to my VW racer friends)