Rf shock angle

[hunterracing]

Does moving the rf shock out farther on lower aframe soften or stiffen it thanks

[RaceEngineer]

Does moving the rf shock out farther on lower aframe soften or stiffen it thanks

Stiffens the wheel rate. Spring compresses more for same wheel movement. Would require softer spring for car to act the same.

[JLyons]

Is that theory or you seen on a pull down rig? Also is that just moving the shock out on the bottom or having a wide RF option and moving it all out?

[RaceEngineer]

Is that theory or you seen on a pull down rig? Also is that just moving the shock out on the bottom or having a wide RF option and moving it all out?

Don't need pull down rig, it's geometry. We are talking moving shock on the bottom.

[keeks]

I've been wrong before, but I think it's the other way around no? Add angle lowers wheel rate/spring rate?

[RaceEngineer]

I've been wrong before, but I think it's the other way around no? Add angle lowers wheel rate/spring rate?

The angle change isn't squat compared to the motion ratio change

[hunterracing]

We moved the spring out to outer hole same spring rate and could tell it wanna roll on rf as much

[RaceEngineer]

We moved the spring out to outer hole same spring rate and could tell it wanna roll on rf as much

Less likely to bend your lower as well.

[billetbirdcage]

RaceEngineer is correct the change in motion ratio of the lower mount over comes the angle change by a ton, so you still get a softening by going inboard or stiffer going outboard (assuming you get an angle change from NOT moving the upper mount)

If you want the math the see how much, here it is:

19" lower - 3" and 4" coilover mounts from the ball joint - 18 degree starting angle on the coilover in the outer hole (is 15* in inner hole) - 18" pin to pin measurement on coilover at ride hieght - travel is 4" at ball joint

4" movement at Ball joint the coilover compresses to:

outer hole: start 18.0" and ends at 14.702" = 3.298" for 4" at BJ
inner hole: starts at 17.716" and ends at 14.586 = 3.13" for 4" at BJ

If you want to do total motion ratio with coilover angle figured in: (note I'm not calculating the motion ratio at the wheel only the BJ

outboard hole = .801
inner hole (but keep angle the same by moving top mount also) = .751
inner hole (don't move upper - is a 3 degree change) = .763

keeks is correct that the angle change does stiffen the total motion ratio .012 but the leverage change on the lower makes a bigger difference for an over all change .049 - .012 = .038 change

[keeks]

This place is great. Thanks BBC.

[JLyons]

Awesome, I only have one location on my lower, but can the same be said on the RF if you moved the Rf upper and lower out 1” but kept the same mounting location at the top of the Shock?

[billetbirdcage]

You are still going to soften the rate at the wheel do to the increased angle of the coil over. I'm too lazy to do the math but any motion ratio calc will show you the difference by plugging in the right dims and just change the coil over angle. It's probably around 1 to 3% change

[JLyons]

So just got confused, so let’s say you are narrow rf and you move to wide rf, do you soften the spring rate to get the car to react the same? Like if you stayed the same rate you would be too stiff being out wide?

[billetbirdcage]

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

Plug the numbers in to get the motion ratio (A - B - spring angle is all you need to enter)

If you move the lower out 1" that changes the coilover angle, .0175" per inch is one degree so if you move 1" then 1 / .0175 = 57.14 then say you coilover pin to pin is 18" then divide the 57.14 by the 18.0 = 3.177 degree change. So change the degree to 3 degrees more and recalc to get new motion ratio

It's going to be roughly 1.5% softer so on a 300# RF spring it's 4.5# softer, which isn't enough to worry about since I don't think they make a 295.5# spring, lol.

*Note this is only rate, it does not account for any rollcenter or anything else that might change the way the car rolls.

[hunterracing]

Does the affect the same as bottom if you move it out or in at top on rf

[RaceEngineer]

Does the affect the same as bottom if you move it out or in at top on rf

Moving the top doesn't have an impact on the leverage. Distance wheel is from control arm pivot vs distance spring is from control arm pivot. You only have an angle change when moving the top.