ronald55555

anyone know the motin ratio for the 96-00 civics? or is it same as the itr

used the search function, but i could only find it for the integra.

GSpeedR

I believemost Hondas are very similar. The Integra is 1.5/1.35.

Chris F

What's a motion ratio?

solo-x

got a measuring tape? go find out for us and post it up so the next guy trying to find out will know. if you want to get fast, you're gonna have to get dirty at one point or another.

nate

GSpeedR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F &raquo;</TD></TR><TR><TD CLASS="quote">What's a motion ratio?
</TD></TR></TABLE>

It's a type of bird that was believed to be extinct in the late 40's, but was recently "discovered" off the coast of Madagascar, and has had a strong following from automotive engineers ever since.

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">It's a type of bird that was believed to be extinct in the late 40's, but was recently "discovered" off the coast of Madagascar, and has had a strong following from automotive engineers ever since.</TD></TR></TABLE>

Is it important?

CRX Lee

The Honda wishbone suspension cars that we have measured at Koni have all been right in the .7:1 (shock/spring:wheel) range plus or minus a few points. The Civics and Accord after 2001 have changed a bit but the rest have all been quite similar.

GSpeedR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F &raquo;</TD></TR><TR><TD CLASS="quote">Is it important?</TD></TR></TABLE>

yep...i'm setting up a foundation where people can donate money to support it and make sure we don't lose it again. IM me for Paypal info.

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CRX Lee &raquo;</TD></TR><TR><TD CLASS="quote">The Honda wishbone suspension cars that we have measured at Koni have all been right in the .7:1 (shock/spring:wheel) range plus or minus a few points. The Civics and Accord after 2001 have changed a bit but the rest have all been quite similar.</TD></TR></TABLE>

By this, I'm surmising that this measures the ratio of the distance that the spring travels, compared to the wheel... Is that the centerline of the wheel, or the face of the rotor? Should be similar anyway.

What's this measure matter, for picking sprinrates and such? I really hadn't thought about it before, but I suppose if you have a ideal 12kg/mm spring, and you add 12kg to one corner, it doesn't really move 1 mm.

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">yep...i'm setting up a foundation where people can donate money to support it and make sure we don't lose it again. IM me for Paypal info.</TD></TR></TABLE>


SAVE THE MOTION RATIOS!

allenp

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F &raquo;</TD></TR><TR><TD CLASS="quote">

By this, I'm surmising that this measures the ratio of the distance that the spring travels, compared to the wheel... Is that the centerline of the wheel, or the face of the rotor? Should be similar anyway.

What's this measure matter, for picking sprinrates and such? I really hadn't thought about it before, but I suppose if you have a ideal 12kg/mm spring, and you add 12kg to one corner, it doesn't really move 1 mm.</TD></TR></TABLE>

The "motion ratio" is used to calculate the "wheel rate" which is the spring rate seen by the wheel through the suspension linkage lever arm. For example, if you have a 500 lb/in spring on a suspension with a 0.7:1 ratio (spring travel to wheel travel) the wheel rate (excepting tire influence) will be 0.7*500 = 350 lb/in.

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allenp &raquo;</TD></TR><TR><TD CLASS="quote">The "motion ratio" is used to calculate the "wheel rate" which is the spring rate seen by the wheel through the suspension linkage lever arm. For example, if you have a 500 lb/in spring on a suspension with a 0.7:1 ratio (spring travel to wheel travel) the wheel rate (excepting tire influence) will be 0.7*500 = 350 lb/in.</TD></TR></TABLE>

Right. Makes sense.

Jack Black

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by allenp &raquo;</TD></TR><TR><TD CLASS="quote">The "motion ratio" is used to calculate the "wheel rate" which is the spring rate seen by the wheel through the suspension linkage lever arm. For example, if you have a 500 lb/in spring on a suspension with a 0.7:1 ratio (spring travel to wheel travel) the wheel rate (excepting tire influence) will be 0.7*500 = 350 lb/in.</TD></TR></TABLE>

Actually, that would be 500 * (0.7 ^ 2) = 245.

Jack Black

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">what kind of funky lever are you talking about?</TD></TR></TABLE>

http://e46m3performance.com/tech/wheel_rate/

Jack Black

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">no need for lengths</TD></TR></TABLE>

Levers? Lengths? I'm confused...

Wheel rate is spring rate times motion ratio squared. No lengths required.

MattD@Stoptech

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Agent Smith &raquo;</TD></TR><TR><TD CLASS="quote">
Wheel rate is spring rate times motion ratio squared. No lengths required.
</TD></TR></TABLE>


yesh


Modified by El Pollo Diablo at 6:10 PM 4/12/2005

Jack Black

Borrowing the terminology from that article, L1/L2 is equal to ds/dw.

The reason you square the motion ratio is because the spring force at the wheel is reduced by two factors:

1 - The distance that the spring is compressed is decreased, thus the KD force is reduced.

2 - The wheel has a lever arm with which to act against the spring.

Consider the previous example. MR = 0.7, K = 500 lb/in...

If the wheel moves 1 inch, the spring is compressed an amount that is proportional to the motion ratio. Thus the KD force at the spring perch (FP) is:

FP = (1 * 0.7) * 500 = 350

The force at the wheel is further reduced by the lever arm. The lever arm ratio is by definition the motion ratio thus the force at the wheel (FW) is:

FW = 0.7 * FP = 0.7 * 350 = 245

MattD@Stoptech

*light bulb*

completely discounted the additional lever

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Agent Smith &raquo;</TD></TR><TR><TD CLASS="quote">Levers? Lengths? I'm confused...</TD></TR></TABLE>

Great, now that we've cleared that up!!!

So, wheel rate is the spring rate ratio...

Motion ratio is the simple linear ratio in distance compressed by the spring versus distance travelled by the wheel.



So, if x is 3, y is 2, z is 1, then
Motion ratio is 2/3 (.67)
Wheel rate is 4/9 (.44)

Is that right?
[Edit, it makes sense that the wheel rate gets squared, because the lever gives us a 3:2 mechanical advantage in force, which increases the spring length compressed, and then we get more distance travelled along the end of the lever by by a 3:2 ratio... so if we apply a pound of force to the end of the lever, we get 3:2 * 3:2 = 9/4ths as much distance as the spring by itself would get. Since springs are measures in (force/distance) units, the wheel rate is 4/9.

-Chris

MattD@Stoptech

Do you really need z when you have y and x

motion ratio = y/x

wheel rate = spring rate * motion ratio ^2

assuming the wheel is connected to the Z end of the stick

unless i'm having another brain fart

Chris F

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Agent Smith &raquo;</TD></TR><TR><TD CLASS="quote">

http://e46m3performance.com/tech/wheel_rate/
</TD></TR></TABLE>

Goddamnit, I should learn to read. Thanks for the link!!!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by El Pollo Diablo &raquo;</TD></TR><TR><TD CLASS="quote">Do you really need z when you have y and x

motion ratio = y/x

wheel rate = spring rate * motion ratio ^2

assuming the wheel is connected to the Z end of the stick

unless i'm having another brain fart</TD></TR></TABLE>

Looks good to me.

hispanic panic

Revive.

Came across this thread in a search. Are wheel rates the same front to rear? I'm asking specifically for a crx