Outer Limits 4x4 Board

Hello, I have done a search here on RTC dampeners, in a post it was mentioned that an RTC dampener with the spring removed when compressed and expanded had around a 70/30 split in the physical force needed.

My Q is - does a spring alone (any typical spring) also exhibit this same behaviour? ie more force is needed to either extend it .5 of its length or a .5 compression?

thanks fnq

fnqcairns wrote:My Q is - does a spring alone (any typical spring) also exhibit this same behaviour? ie more force is needed to either extend it .5 of its length or a .5 compression?

As a linear first approximation (which is actually quite good under two assumptions [1]) a spring will compress or extend the same distance when subjected to a compressional or extension force of the same magnitude. In Physics, this is referred to as Hooke's law. Hooke's law can be described by the equation F=-kx where F is the force applied, k is the spring constant (in N/m) and x is the change in length of the spring. Notice there is no restriction on the sign of F or x, only that F opposes x (ie. the force is a "restoring" force).

[1] the two assumptions are this: the spring does not exceed its elastic limit (exceeding the limit usually results in a spring which does not naturally return to its original length); and the spring constant remains fairly constant. The latter assumption is generally true in the presence of the former, however fails dramatically if the coils of the spring come into contact. In fact, some "extension" springs have the coils in contact at rest, and thus certainly fail the assumption. Further, "progressive rate" springs are designed to have some of the coils come into contact under compression, deliberately changing the spring rate. Both coils exhibit asymmetric compression/extension behaviour.

Thanks Heath - that sums it up! Now to chase up whether the afore mentioned 70/30 is correct for all the RTC dampners or should I say RTC shockabsorbers which may be the more correct term.

cheers fnq

The 70/30 wont be noticeable when driving with power steer and is ok.

Unless you dont have good steering geometry a good OME or similar S Damper will do the job to settle movement.

Bazzle

fnqcairns wrote:Thanks Heath - that sums it up!

I second that! Well said, Heath.

fnqcairns wrote:Now to chase up whether the afore mentioned 70/30 is correct for all the RTC dampners or should I say RTC shockabsorbers which may be the more correct term.

cheers fnq

From a fundamentals viewpoint, they're dampers - so you were right to begin with. Suspension is a classic example of a fundamental system in mechanics referred to as "mass-spring-damper." But "shock absorber" is the more commonly used term. I guess it hinges on the definition of "shock" - the spring (sort of) absorbs the force, the damper absorbs the energy.

Cheers,

Scott

Basically your springs hold up the car, and react to bumps. The shocks re-act to the movement of the springs, dampening the motion, and the oscillation of the springs. The sdampener basically dampens the feedback of the steering, taking the"shock" out of the reaction to force applied to the wheels or steering wheel.
Layto....

Yeah to me it smacks paying for a steering dampner that behaves more like a shock absorber in dampening design.
I really do not want to consider the RTC but I would like to see if I can cancel out some of the Nissan LHS pull and increase the self centering ability of the steering geomety on this car for driving on the blacktop.
Have half a mind to adapt the spring and carrier to a REAL steering dampner.
Hard to find good products sometimes.

cheers fnq

fnqcairns wrote:Have half a mind to adapt the spring and carrier to a REAL steering dampner.

This would be interesting. I would like to see the RTC spring style of the 4way across the the other brands such as procomp etc. I also have bad pull to the left.

Not wanting to get into the technicals too much - my personal experience with the Tough Dog RTC Steering Damper is if you need to replace your existing one - buy the RTC & set it up correctly. I found the vehicle is much more pleasent to drive both on & offroad. If you have massive steering & suspension mods it probably won't make a huge difference though.

It has saved my families lives. Had an idler arm fail on rough country road at about 70kph. The RTC helped to hold the steering centre rather than turning a wheel & rolling the car.

I have no affiliation with this product.

Mick