on F1 cars and cars like the carrera gt, the strut is not linear with the movement of the suspension arms. maybe thats not the bset way to describe it but what i mean is, on a civic for example the damper moves in the same direction as the suspension travels.

but on a carrera gt the suspension arms move up and down (obviously) but the damper isnt "inline" with the motion of the suspension arms. it looks more like it resists movement or dampens movement based on forward to back movement not up and down.

i am having a little trouble understanding this.

i see some linke between the pushrod of the damper and the part that connects to the control arms. do those peices redirect the movement?

here is a pic:
http://www.rsportscars.com/fot...0.JPG

please, talk some knowledge into my dumb self...

 

also here is the rear suspension. is that what they call a pullrod suspension? i have heard of such bet never seen it. i may be wrong...

http://images.google.com/imgre...a%3DN

 

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

i see some linke between the pushrod of the damper and the part that connects to the control arms. do those peices redirect the movement?
.</TD></TR></TABLE>

Yes. That cam is bolted to the subframe and pivots. So as the suspension moves up and down, that rod moves with it.

 

It's usally refered to as "pushrod" suspension. They do this on F1 cars because it's much more arodynamic to have the shocks mounted inside the chassis than hanging out directly in the wind. On closed wheel sports cars they usally use this setup for easy access to adjust the shock absorbers & ride height from above.

It works the same way as any other suspension with slightly added complexity. Where the coilover would normally be located there is a pushrod instead (seen as a titanium colored rod coming up out of the suspension). The pushrod is attached to a rocker arm which in turn is attached to the coilover. If the suspension is compressed, that push rod will be pushed up. The pushrod will turn the rocker arm. The rocker arm will compress the coilover spring.

Your picture looks slightly more confusing because the Cararra GT has those long silver sway bar end links attached directly to the rocker arm also (extending rearward). If you look closely you can see the sway bar mounted to the very back of the chassis with it's torque arms pointed straight up (black U shaped bar).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94eg! &raquo;</TD></TR><TR><TD CLASS="quote">It's usally refered to as "pushrod" suspension. They do this on F1 cars because it's much more arodynamic to have the shocks mounted inside the chassis than hanging out directly in the wind. On closed wheel sports cars they usally use this setup for easy access to adjust the shock absorbers & ride height from above.
</TD></TR></TABLE>

I'd imagine the main reason would be the removal of the unsprung weight.

 

It adds unsprung weight (shock shaft, push-rod & rocker arm are still sprung). Thats probably why the pushrod is made of titanium...

 

Isn't the pushrod lighter than the coilver, and aren't F1 cars using pushrod activated torsion bar assembly?

If you add up the spring or torsion bar, damper, anti-roll bar linkage weights, versus one pushrod I'd wager money you come out well ahead.

Now I'm curious if the main reason was aerodynamics or weight savings, I'm sure it's a combo of both, but which reason came first?

 

Yeah the pushrod is lighter than the coilover, but the coilover is still part of the "sprung" system. You have to compare all the parts together even though they are mounted in unconventional locations.

Which has more sprung weight?
* inverted shock all by itself
* inverted shock + pushrod + rocker arm

 

How is the coilover part of the "sprung" system? It's weight/mass due to gravity is not accelerated everytime the wheel moves up or down, neither is the rocker arm.

 

I can always count on learning something new and interesting when entering the suspension forum.

It is the same way on the Ariel Atom 2 correct? I cannot find a good picture of it but when I saw it on Top Gear I wondered why the springs/shocks seemed to be laying down.

 

The term "unsprung weight" can be misleading since most people relate weight to the direction of gravity. Unsprung Mass actually makes more sense when describing suspension. Reducing mass of the articulated components allows them to be controlled easier...

 

<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">How is the coilover part of the "sprung" system? It's weight/mass due to gravity is not accelerated everytime the wheel moves up or down, neither is the rocker arm.</TD></TR></TABLE>

Yes it is. The mass of the shock piston, top hat, rocker arm, push rod, and I'm guessing about half the mass of the spring itself is all being accelerated and decelerated with every movment of the suspension system.

 

you guys who are talking about just weight issues, are forgeting another important fact about the benefit of pushrod system. if you look at the triangular linkage, you can see that it turns the linear motion into a circular motion as it pivots. the effect is that the suspension is now tuned to be progressive. and you can change that linkage to tune the progressiveness of the suspension response.

btw, f1 doesnt use coil springs.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94eg! &raquo;</TD></TR><TR><TD CLASS="quote">The term "unsprung weight" can be misleading since most people relate weight to the direction of gravity. Unsprung Mass actually makes more sense when describing suspension. Reducing mass of the articulated components allows them to be controlled easier...</TD></TR></TABLE>

I agree with you there, but my point still stands. With the pushrod-rocker-arm arrangement under bump only the pushrod's weight is adding to the spring-rate (and the inertia of the damper/spring part being moved, which is fairly small since the rocker-arm reduces the throw of the damper.) In a conventional arrangement the weight of the damper, spring, and sway bar linkage would be adding to the spring-rate.

Correct me if I'm seeing this wrong.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">you guys who are talking about just weight issues, are forgeting another important fact about the benefit of pushrod system. if you look at the triangular linkage, you can see that it turns the linear motion into a circular motion as it pivots. the effect is that the suspension is now tuned to be progressive. and you can change that linkage to tune the progressiveness of the suspension response.

btw, f1 doesnt use coil springs.</TD></TR></TABLE>

thats the answer i was looking for. now it all makes a lot more sense.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">you guys who are talking about just weight issues, are forgeting another important fact about the benefit of pushrod system. if you look at the triangular linkage, you can see that it turns the linear motion into a circular motion as it pivots. the effect is that the suspension is now tuned to be progressive. and you can change that linkage to tune the progressiveness of the suspension response.

btw, f1 doesnt use coil springs.</TD></TR></TABLE>

You talking about the rocker arm? What do you mean by "progressive?" It's a simple lever.

 

<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">

You talking about the rocker arm? What do you mean by "progressive?" It's a simple lever.</TD></TR></TABLE>

yes, its a lever. draw a diagram... you can do it.

i tihnk i mean digressive actually... hmmm... either way. relative motion is no longer linear.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94eg! &raquo;</TD></TR><TR><TD CLASS="quote">It's usally refered to as "pushrod" suspension.
</TD></TR></TABLE>


my bad, when i looked at the picture i thought that the rod attached to the sway bar was the only link between the damper. i dint even notice how it was attached at that triangle thing to the damper as well as the sway bar link.

in other words i know that is a pushrod type suspension but i looked at the pic wrong and thought that the only connection between the control arm and the shock was at the bottom of the shock assembly. therefore when the suspension arms moved the shock was pulled from the bottom. my bad.


also, i dont know about f1 cars but i promise you that they did this for aeodynamic reasons on the carrera. the underbody of that car is the most aerodynamically "correct" vehicle that i have ever seen.

 

<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">

I agree with you there, but my point still stands. With the pushrod-rocker-arm arrangement under bump only the pushrod's weight is adding to the spring-rate (and the inertia of the damper/spring part being moved, which is fairly small since the rocker-arm reduces the throw of the damper.) In a conventional arrangement the weight of the damper, spring, and sway bar linkage would be adding to the spring-rate.

Correct me if I'm seeing this wrong.

</TD></TR></TABLE>

Honestly I don't know if thats really the case (this may be outside my understanding of suspension). I would think that added unsprung mass actually reduces your effective spring rate. With added mass you need additional spring rate to controll it. I do see that gravity pulling downward on the piston may effect your spring rate, but I can't imagine something that minor being part of the spring rate selection equation.

I totaly understand progressive tuning idea, but I'm trying to compare apples to apples. Somehow I doubt that street driven super sports cars like the Cararra GT have swapable rocker arms for that tuning purpose.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tyson &raquo;</TD></TR><TR><TD CLASS="quote">you guys who are talking about just weight issues, are forgeting another important fact about the benefit of pushrod system. if you look at the triangular linkage, you can see that it turns the linear motion into a circular motion as it pivots. the effect is that the suspension is now tuned to be progressive. and you can change that linkage to tune the progressiveness of the suspension response.

btw, f1 doesnt use coil springs.</TD></TR></TABLE>

If your talking race cars, then your conventional style setup could just use multiple upper & lower shock mounting points to accomplish the exact same effect. Mounting the damper & spring at different angles would be the exact same thing as swaping in different rocker arms...

 

in the farthest shock it is clear to see that the bar runs down to the sway bar but in the close shock it looks like it is mounted too close to be connected at the top and the swaybar kin of blends in with the car

 

mr. eg. you are very much correct. the other benefit of pushrod system is the ability to relocate the suspension components, and repackage them elsewhere. like for aero reasons.

 

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

yes, its a lever. draw a diagram... you can do it.</TD></TR></TABLE>

lol, I have a diagram for you.

But you lost me with the "progressive" talk, and circular motion. Apart from translating a large displacement of the pushrod bar into a small displacement of the damper/spring what else is benefited?

 

think of a piston and crankshaft...

 

The motoion of suspension never was linear to begin with.

If the geometry is correct, all the rocker arm does is create a new motion ratio...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94eg! &raquo;</TD></TR><TR><TD CLASS="quote">The motoion of suspension never was linear to begin with.

If the geometry is correct, all the rocker arm does is create a new motion ratio...</TD></TR></TABLE>

That's what I'm seeing, Tyson is aparently disagreeing though.