The relative benefits of a pull rod suspension

[segedunum]

I'm not really sure why people are apparently feeling the need to defend push-rod suspensions on here for. There's no need to, and no, if Ferrari beats Williams it will not vindicate the push-rod as being the sensible way to go given current regulations.

The simple fact of the matter is that a pull-rod suspension gives you all the openings you need in all the right places for a single diffuser as we have now. You can do what you like with a push-rod but it will clearly be a set of compromises, because using Ferrari as an example they have done things to their suspension that they wouldn't otherwise have done. That's it. Not sure what people are making of this to be honest.

[myurr]

Nope, but you still can't tell me a weakness that it has to push rod.

You clearly refuse to read/listen to posts as I've listed several reasons several times, including in the post you're replying to, and others have done so to. You're either too boneheaded to allow new thoughts into your skull or lying about your opinion just to wind each other up.

You accept that the pull rod isn't perfect - what do you see as it's weaknesses?

It would fit, but it would have to be covered with bodywork, which would interfere with the airflow, check the 2010 mercedes benz with the bumps on the gearbox.
The gearbox would automatically have to be wider as well to fit the heave springs and dampers. So basically you would have a huge lump on the car, and they would have to find openings to send cooling air.

Why would it have to be packaged like that? Red Bull's push rod seems so well packages because they lengthened the gear box, as you rightly point out due to their fuel tank installation allowing it, allowing them to fit the components internally to the gear box casing. Why couldn't they do the same with the push rod, just at the top of the gear box instead of the bottom?

Pull rods don't magically require less components than push rods, they just place them differently.

Just because the rear of that car looks good to your CFD capable eyeball, it doesn't mean it's the optimal solution. It may cause upstream compromises due to the packaging of the internals, such as the fuel tank, that mean a different layout and less tight rear result in a better car.

Now, you are fishing for compromises. The redbull's tank is not short becuase of the pull rod. Mclaren and mercedes have long narrow tanks. The tank is short becuase they want it to be that way.

Just like Red Bulls rear isn't as tight as it is solely because of the pull rod - it's because the fuel tank is short and the gear box is long. If they didn't have that layout then their rear would be less tight, possibly even than Ferrari's. Ferrari have been able to move the dampers etc. forward like Red Bull have - Red Bull may not have that option with a shorter gearbox.

This isn't fishing, it's looking at the car as a whole - something you refuse to do when considering the suspension layout.

What if it's more optimal for the exhausts to be closer to the centre of the car where a pull rod interferes but a push rod does not? What if the rear of the Red Bull is curved too tightly for some conditions and suffers from separation of the air flow, such that a slightly less compact rear actually performs better across the whole range of conditions?

You see your bias? You are assuming other teams overlook pretty straight forward wind tunnel stuff, but ferrari is the only who who got it just right.
I am sure the teams have analyzed the air flow around the side pods ahead of the gearbox.

Not at all, and you're still looking at this all wrong. I'm saying there's more than one way to do it, you're saying pull rod is the only optimal solution. Your biased assumption is that Ferrari are wrong and have external reasons, such as fear, for not choosing the optimal solution for their car. My assumption is that Ferrari aren't stupid or afraid and that they have come up with what is their optimal layout - just because it's different to Red Bull doesn't invalidate either's choices or mean that one or the other is stupid or scared of change, it just means they've selected different compromises and come up with different designs that are optimal in their eyes.

In trying to argue with me you always seem to assume that I am saying push rod is superior to pull rod - I'm not at all, and this is the bit you can't get your head around. I'm saying that each has it's place and the one that is optimal for a given car will be determined by the rest of the design. Sometimes pull rod will be best for a team, sometimes push rod.

Clearly with McLaren's side pods, for example, the pull rod was probably the only way to go as otherwise the suspension would have interfered with their design. Equally if you want to mount your exhausts closer to the centre of the car then a pull rod may interfere possibly making the push rod the optimal choice.

For whatever reason Ferrari believe that their design is the best for them. Just because they didn't choose the pull rod, it doesn't make them wrong.

RB6 had the most down force last year for a reason.

The biggest flaws in this statement are the assumption that the RB6 had the most amount of down force physically possible, and therefore is the only valid design, and that the suspension layout was a primary factor in this.

[marcush.]

what is the ultimate pullrod concept -williams everything as low as possible,maximising flow to the top of the beam wing or RedBullstyle pullrod with a long narrow box trying to maximise flow under the beam....but then Mercedes pulrod does not compromise as much with pullrod angle to the fore...
What can be seen on the 2011 grid is only Ferrari has decided to stay with the
concept and dragged sauber to use it as they supply their box as well.
So this leaves Virgin ,Sauber and Ferrari as the last to use this concept at the rear...
proving that the bad boys here were right:if in doubt copy .Intriguingly the new pullrod users have chosen to not copy the whole concept of the RedBull...hm .This leads me to the conclusion that pullrod offers some distinct opportunities to implement original concepts in packaging the rear,whereas the pushrod rear was a bit of a done deal and not much coming in the last years.

[Richard]

For what it's worth, Scarbs did a good review that highlights the key issues

He concluded "There’s no one answer to which is best, you look at your design requirements and pick which solution works, best. "

http://scarbsf1.wordpress.com/2010/10/1 ... odynamics/

Also, I see the topic was discussed here 7 years ago in the context of front suspension, no one worried about the back in those days viewtopic.php?f=6&t=740

[PlatinumZealot]

It's obvious that pull rod has more advantages than push rod in 2011. Why are people still fighting this?

Sure Ferrari may go on to win WDC, but the writing is on the wall guys; only 3 teams use the pushrod in 2011. At this rate I don't expect to see any push-rod on the field in 2012.

[ringo]

Nope, but you still can't tell me a weakness that it has to push rod.

You clearly refuse to read/listen to posts as I've listed several reasons several times, including in the post you're replying to, and others have done so to. You're either too boneheaded to allow new thoughts into your skull or lying about your opinion just to wind each other up.

What are they? It's hard to read through 3000 word esssays on nothing
In bullet points please, nothing more:

You accept that the pull rod isn't perfect - what do you see as it's weaknesses?

I am asking you above .

Why would it have to be packaged like that? Red Bull's push rod seems so well packages because they lengthened the gear box, as you rightly point out due to their fuel tank installation allowing it, allowing them to fit the components internally to the gear box casing. Why couldn't they do the same with the push rod, just at the top of the gear box instead of the bottom?

No no, the pull rod allows them to lengthen while keeping the top narrow.
Look on the virgin picture and notice how the rods need to be spaced to fit the parts.

This isn't fishing, it's looking at the car as a whole - something you refuse to do when considering the suspension layout.

No you are trying really hard. I'll go with RedBull, Mclaren, Renault, Mercedes etc. have to say.
I guess Ferrari the team of "aerodynamics are for people who can't build engines"
and Virgin must have the same packaging needs.

Not at all, and you're still looking at this all wrong. I'm saying there's more than one way to do it, you're saying pull rod is the only optimal solution. Your biased assumption is that Ferrari are wrong and have external reasons, such as fear, for not choosing the optimal solution for their car.

pull rod doesn't have to be the absolute optimal solution. It just has to be better relative to push rod, at what it's trying to achieve aerodynamically.

Ferrari aren't wrong at all. The made the right move from the cluttered push rod, but they didn't go all the way for some reason.

My assumption is that Ferrari aren't stupid or afraid and that they have come up with what is their optimal layout - just because it's different to Red Bull doesn't invalidate either's choices or mean that one or the other is stupid or scared of change, it just means they've selected different compromises and come up with different designs that are optimal in their eyes.

It's not an optimal layout for them. They never said that. Read the interview again. Suppose they change in 2012 what are you going to say?

RB6 had the most down force last year for a reason.

The biggest flaws in this statement are the assumption that the RB6 had the most amount of down force physically possible, and therefore is the only valid design, and that the suspension layout was a primary factor in this.

It doesn't matter, they did have the most , and it was in part the their suspension choice. Why can't you look on the car as a whole?

But you know what, i'm going to demonstrate this with a little example soon enough.
It's about time we got technical up in this thread.
Stay cool.

[RacingManiac]

It's obvious that pull rod has more advantages than push rod in 2011. Why are people still fighting this?

Sure Ferrari may go on to win WDC, but the writing is on the wall guys; only 3 teams use the pushrod in 2011. At this rate I don't expect to see any push-rod on the field in 2012.

Not fighting for pushrod, the argument here is the merit for engineering process. As stated many times before, pushrod or pullrod is just a path leading to optimum packaging for EACH TEAMS, weighing in their own individual trade-offs and design consideration. That is not the same for everyone, and it is simply too simplistic to assume what works for one will automatically works for another.

pull rod doesn't have to be the absolute optimal solution. It just has to be better relative to push rod, at what it's trying to achieve aerodynamically.

Its not as if the rest of the teams are aiming to be "better" than pushrod, they are trying to design a car with the best design they can. I'd certainly hope that their design is optimized to their own need. As a design engineer I certain hope what I drew up is the optimal design given what I have to work with...


Here is the Ferrari interview

http://www.autosport.com/news/report.php/id/89132

"We evaluated different suspension configurations, and also pull-rod suspension like the one Red Bull introduced," he explained at the launch of the new Ferrari F150 on Friday.

"There are different possibilities - one is for aero volumes and we have found a way, which is not so visible on the car right now, to reduce the volume of the push rod suspension in an extreme way.

"That means we could reduce the rear volume, so our version is far more compact compared to the previous ones. We believe we have reached a similar level of packaging to the other ones."

That to me sounds like its optimized for them....

Definition for Optimization:
http://dictionary.reference.com/browse/optimization

"5. ( tr ) to find the best compromise among several often conflicting requirements, as in engineering design"

"Mathematics . a mathematical technique for finding a maximum or minimum value of a function of several variables subject to a set of constraints, as linear programming or systems analysis."

There is no ONE right answer, which is the whole point why some of us are still arguing the point....

Really though I just want to pounce the Zebra that Ciro posted...

[myurr]

It's obvious that pull rod has more advantages than push rod in 2011. Why are people still fighting this?

Sure Ferrari may go on to win WDC, but the writing is on the wall guys; only 3 teams use the pushrod in 2011. At this rate I don't expect to see any push-rod on the field in 2012.

OMG in 2010 only two teams used a pull rod layout... the writing's on the wall, no way they're going to do anything... jeezy creezy talk about making the wrong decision... lolz

[Richard]

[...]

Lets deal with the technical facts:

- There are two cars with push rod suspension.
- There have been comments about how the Ferrari suspension reaches so far forwards.
- So it seems common sense to compare the geometry of the two suspension set ups.

[myurr]

Nope, but you still can't tell me a weakness that it has to push rod.

You clearly refuse to read/listen to posts as I've listed several reasons several times, including in the post you're replying to, and others have done so to. You're either too boneheaded to allow new thoughts into your skull or lying about your opinion just to wind each other up.

What are they? It's hard to read through 3000 word esssays on nothing
In bullet points please, nothing more:

I gave you bullet points, you ignored them. Go back and read the previous posts, cause I'm tired of having to type the same stuff out for you only for you to ignore it again and pretend that it was never written.

You accept that the pull rod isn't perfect - what do you see as it's weaknesses?

I am asking you above .

And I answered. Now it's your turn so stop dodging the question. You admit that the pull rod isn't perfect but refuse to list any weaknesses. Man up and be honest about whether or not you can see any disadvantages at all to the pull rod.

Why would it have to be packaged like that? Red Bull's push rod seems so well packages because they lengthened the gear box, as you rightly point out due to their fuel tank installation allowing it, allowing them to fit the components internally to the gear box casing. Why couldn't they do the same with the push rod, just at the top of the gear box instead of the bottom?

No no, the pull rod allows them to lengthen while keeping the top narrow.
Look on the virgin picture and notice how the rods need to be spaced to fit the parts.

The pull rod does no such thing - either layout can be adapted as Ferrari prove. Virgin's solution is a traditional layout - Red Bull's is not, and part of the ingenuity of their system is the way they've been able to lengthen the gear box and fit the parts within it. You really need to understand that both layouts essentially use the same parts and that the pull rod is nothing magical, it just a push rod upside down. Either can be fitted within a gear box, if space allows.

This isn't fishing, it's looking at the car as a whole - something you refuse to do when considering the suspension layout.

No you are trying really hard. I'll go with RedBull, Mclaren, Renault, Mercedes etc. have to say.
I guess Ferrari the team of "aerodynamics are for people who can't build engines"
and Virgin must have the same packaging needs.

Talk about deflecting - since when has following the majority meant anything in F1 or anywhere else. Think for yourself rather than just slavishly copying what the majority of the grid does. Ferrari show there's more than one way to do it, and yet you refuse to even contemplate that possibility. Hell, Red Bull even showed you how to do it when they switched to the pull rod and yet you hide behind "well most of the grid do this...".

You really and honestly believe that Ferrari are still the team that would claim "aerodynamics are for people who can't build engines" or are you just being a twat again? Seriously...

Not at all, and you're still looking at this all wrong. I'm saying there's more than one way to do it, you're saying pull rod is the only optimal solution. Your biased assumption is that Ferrari are wrong and have external reasons, such as fear, for not choosing the optimal solution for their car.

pull rod doesn't have to be the absolute optimal solution. It just has to be better relative to push rod, at what it's trying to achieve aerodynamically.

Ferrari aren't wrong at all. The made the right move from the cluttered push rod, but they didn't go all the way for some reason.

Again you admit the pull rod isn't absolutely optimal, but cannot list any reasons why. You also fall into the same trap of thinking aerodynamics are the only consideration - they may be important but they are not the 100% only consideration at all.

So in what way did Ferrari not go the whole way? As far as I can see the only difference between the two solutions is which way the rod slopes, there don't seem to be any other aero compromises forced by the suspension layout. The only discrepancy in performance terms appears to be C of G, and Ferrari obviously believe their layout has more advantages than disadvantages so this C of G difference cannot be a significant factor for them.

My assumption is that Ferrari aren't stupid or afraid and that they have come up with what is their optimal layout - just because it's different to Red Bull doesn't invalidate either's choices or mean that one or the other is stupid or scared of change, it just means they've selected different compromises and come up with different designs that are optimal in their eyes.

It's not an optimal layout for them. They never said that. Read the interview again. Suppose they change in 2012 what are you going to say?

They believe it is the better layout for them - they wouldn't have selected it otherwise. What exactly are you expecting me to read and discuss? Did Ferrari say "we chose the wrong layout because we're scared?"

If they change in 2012 then I'll say that they have re-evaluated their options and come up with a different compromise. When one of the teams switches back to a push rod, as the inevitably will at some point in the future, then what will you say?

RB6 had the most down force last year for a reason.

The biggest flaws in this statement are the assumption that the RB6 had the most amount of down force physically possible, and therefore is the only valid design, and that the suspension layout was a primary factor in this.

It doesn't matter, they did have the most , and it was in part the their suspension choice. Why can't you look on the car as a whole?

But you know what, i'm going to demonstrate this with a little example soon enough.
It's about time we got technical up in this thread.
Stay cool. [/quote]

Now you're just being obtuse - I am looking at the car as a whole, it's you that is obsessed with one suspension choice always being the right one rather than saying that one or other can be the best choice depending on the car as a whole. Feel free to get technical any time you like, so far you've eschewed scientific principal and said that one suspension type is always better than the other regardless of the rest of the car and come up with excuses when a top team disagrees with you.

Of course it matters if Red Bull had the absolute optimal design or not. If they did not, and you seem to covertly agree that this is the case, then you cannot hold them up as being the optimal design and claim that their solution is the only valid one. Yes they had the best car last year, but I seriously doubt that given enough time and resources a top team like Ferrari or McLaren (or even Red Bull) couldn't come up with a better solution, and there is no guarantee that this solution would include a push rod layout. You seem to be so wedded to the idea that it is perfect that you cannot possibly even contemplate there being an alternative or a situation where, because of compromises elsewhere on the car, the pull rod is not the best choice.

[Steven]

Please mind you all that this is supposed to be a technical thread. I would appreciate that posts stick to facts, compare geometry and the likes, and leave out the opinion.

I also have the impression that in these last few pages some have forgotten to think before posting. A post with a single smily is ALWAYS going to be deleted without notice when I see one across a technical thread.

Additionally, some posts have moved to the Virgin MVR-02 thread. So pretty please stick to pull rods.

Oh and also... teams make their choices based on simulations and calculations. It's not like "wow we need this, let's see how it fits". They will also pick the best option for their package. There's no point in dubbing them faulty cars because they have a different rear suspension layout. There's MUCH more to it than that.

Thank you.

[Lorenzo_Bandini]

i have found a great post in another forum

Alot has been said about radical and conservative approaches to car design and Ferrari have a good blend of both radical and conservative elements in the F150th Italia.Aldo Costa says that the design of the rear Push Rod suspension is radical.A very different approach from what all the other teams are doing by copying Red Bulls Pull Rod suspension.The Ferrar is a combination of Pull Rod front suspension and Push Rod rear suspension and thought out extremely well.

The advantage of pull rod suspension like Red Bull is that the components are lower to the ground than push rod thereby giving an all important lower centre of gravity with also space saving at the rear for more streamlined bodywork and aero benefits especially with a more compact engine like the Renault which frees up more space.But the drawback in pull rod is that it doesn't work as good as push rod suspension on the rebound after compression.In other words,push rod suspension at the rear maintains traction better than pull rod even with a higher centre of gravity which is the drawback of pushrod

With alot less downfoce available due to the banning of the double diffussor,an efficient push rod suspension at the rear will be more effective in maintaining traction on rebound.It's more flexible than pull rod which is stiffer.Pull rod works better with more downforce but up to 30% or more downforce is lost this year with only a single diffussor allowed.

A smaller gearbox allows for a more efficient push rod design and Ferrari have acheived that.You can tell just by looking at the rear end of the F150th Italia that Ferrari have acheived a masterpiece in push rod design with many of the benefits of space saving and LCG of pull rod but yet having an advantage of better traction than what pull rod offers.

Fantastic work Ferrari!! Well done for not copying Red Bull like all the others!

[Onch]

i have found a great post in another forum

The Ferrar is a combination of Pull Rod front suspension and Push Rod rear suspension and thought out extremely well.

[tadzio89]

i have found a great post in another forum

The Ferrar is a combination of Pull Rod front suspension and Push Rod rear suspension and thought out extremely well.

Pull rod works better with more downforce but up to 30% or more downforce is lost this year with only a single diffussor allowed.

[Onch]

Pull rod works better with more downforce but up to 30% or more downforce is lost this year with only a single diffussor allowed.

Found it a bit strange too but as I am not suspension expert I thought this could possibly be true. Hope someone knowledgeable will come along to clear that up...

The post actually seems to have been written by a Ferrari fan that does not really understand what he is talking about, but manages very well to do 'as if'...