The relative benefits of a pull rod suspension

[Jersey Tom]

even a regular joe can analyse a suspension and aerodynamic setup in his bedroom

They can analyze it, sure. Doesn't mean they'll come up with a good answer.

Bottom line - pull rods aren't a new thing. Every design engineer going into last season was well aware of what they are. There are pro's and con's of everything.. can't just isolate one item without affecting others. At the end of the day you have to decide what arrangement you think is going to work best with your total car system.

This fascination everyone has with eyeballing photos and pictures and making sensational claims of why pull rods or any other mechanical contraption is so good is silly if you ask me. Almost as silly as FSAE kids who stare at other teams cars for inspiration. "Well, team X has such-and-such on their car and they won, we need to have that too!!" not realizing that it's possible it will work WORSE with your design philosophy, or may not be the best solution at all.

[marcush.]

JT ..assuming one has a philosophy for his car ..you are absolutely right.
I think the exercise is just how much integration you are able to do without ending with a overcomplicated mess.
I find it quite intriguing to see Newey playing down the talks about going pullrod
the same happened when talk was rised about flexy wings and floor...
interestingly genius Newey´s team chooses to be very secretive about their inventions ...do they want to make the competitors look just there, maybe?

it´s not pull rod ,it´s not wingflex ..it´s the system thinking that is making Neweys cars go quicker.

[ringo]

F1 is all about copying what the next guy has.
A good example is the exhaust blown diffusers. They were around years ago, then they disappeared for some reason. Now they're back.
We can't look at the time period where they weren't used to come to the conclusion that they must have been detrimental to the car's performance.
Old ideas can become advantageous once the implementation is in sync with the rest of the car.

If we had 2 cars exactly the same all the way down to the gearbox/engine interface.
The only difference being the rear suspension. And assuming both cars are made to work optimally with their respective suspensions.
Which one would have the aero, C.O.G. advantage? Pullrod or Push rod?
Let's be honest here.

As small as the advantage is, it's worth having becuase it doesn't hurt to have it.
Another example is ferrari's ducted wheels. Had wheels not be required to be homologated, you could bet your bottom dollar the other teams would copy it.

[Jersey Tom]

F1 is all about copying what the next guy has.

I'd correct that to say...

Losing is all about copying what the next guy has.

If we had 2 cars exactly the same all the way down to the gearbox/engine interface.
The only difference being the rear suspension. And assuming both cars are made to work optimally with their respective suspensions.
Which one would have the aero, C.O.G. advantage? Pullrod or Push rod?

IMO this is exactly the thought process and mentality which makes these discussions null and void... you'll never have something isolated like that and there's no answer. It depends on the rest of the car. For Red Bull, maybe pullrod is the better option. For Ferrari, maybe pushrod is the better option.

The fact that after all these years of development there is no clear trend of all teams picking one or the other should really drive this home.

[Tim.Wright]

I find it quite intriguing to see Newey playing down the talks about going pullrod...

I find the contrary interesting. The fact that so many people are playing up the advantages of the humble pull rod axle to the point where it is seen as some new must have accessory.

When I designed pull rod suspension for the front axle of our FSAE car in 2008, I also did not think much of it. I pondered the pros and cons and in the end it was the best package considering the rest of the front end design. I actually felt like a conformist because I was presenting yet another double wishbone pull rod axle to the FSAE world.

Other teams ran push rod on the front because their chassis was different. What works in a Red Bull, will not by default work in a McLaren.

The final thing I will say here is that the decision to use one axle concept is an OUTPUT of the design stage. I.e. its the end product. I can guarantee that no team sat down and started with the pull-rod idea as an INPUT and said "right how do we fit this in".

Tim

[myurr]

Ringo, if it is as clear cut as that then why did the MP4-25 not include a pull rod design when they went to all the trouble of redesigning their entire rear suspension package and aero concept?

Either it's not as clear cut as you think, or you're a lot cleverer than the entire of the McLaren design team and we should be bowing down to you.

[ringo]

I find it quite intriguing to see Newey playing down the talks about going pullrod...

I find the contrary interesting. The fact that so many people are playing up the advantages of the humble pull rod axle to the point where it is seen as some new must have accessory.

It's not being played up. But every drop of performance counts. Every single gram, every single mm in lowering C.O.G.

A push rod can be a winning package of course. But it still is a fundamental disadvantage to a pull rod aero and C.O.G. wise. Agree?
All the examples in the past also seem to be at the front and not at the back. So it's a bit disingenuous to compare back then to now.

and seeing as though all F1 cars nowadays are basically the same thing. I would go as far to say that the pull rod can be mindlessly slapped on any car and give an improvement in C.O.G. and aero. By nature of it's geometry it gives these benefits.

I said the same thing with the ebd, if we go back to that thread. I was being burned at the stake for making such claims, and before you know it, ebds were popping up all over grid.
People were saying "oh teams need to reanalyze this and that" " it's impossible" etc. Lo and behold a few weeks and a few bumps in the road, but they did it and they got a lot of performance from it.

Copying is the golden rule! This is why Mclaren are protecting their new car from prying eyes.

[ringo]

Ringo, if it is as clear cut as that then why did the MP4-25 not include a pull rod design when they went to all the trouble of redesigning their entire rear suspension package and aero concept?

Either it's not as clear cut as you think, or you're a lot cleverer than the entire of the McLaren design team and we should be bowing down to you.

Remember the 25 didn't use pull rod becuase they wanted to fully exploit the regulations on the DDD.
They had the biggest diffuser out of all the teams, but it was also the most sensitive.
That is the reason behind them not using pull rod suspension. Their diffuser started way way back behind the rear wheel center line. That is clear cut to me, and i think that's the reason for not going pull rod.

If they continue to use push rods in 2011, then maybe there is some considerations that we aren't aware of. For now with the limited knowledge that we have, we have an idea of what factors the engineers want in a competitive car, and the pull rods have an advantage in those factors.

[Tim.Wright]

I would go as far to say that the pull rod can be mindlessly slapped on any car and give an improvement in C.O.G. and aero. By nature of it's geometry it gives these benefits.

Thats it I give up...

Tim

[Jersey Tom]

I find it quite intriguing to see Newey playing down the talks about going pullrod...

I find the contrary interesting. The fact that so many people are playing up the advantages of the humble pull rod axle to the point where it is seen as some new must have accessory.

It's not being played up. But every drop of performance counts. Every single gram, every single mm in lowering C.O.G.

Except nothing exists in and of itself without impacting other items. I mean FFS man, do you really think the whole field of F1 engineers are idiots and somehow let this slip them by after however many years of having already used it?

[marcush.]

Hm ..JT ..but just why was the RB6 the best part of a second quicker than the rest at times if some idiots were not a bit smarter than others even after all those decades spent in the business..

Mclaren clearly had their numbers wrong and produced a car too often on the wrong side of the fence...
Ferrari needed a BIG overhaul of their car
Mercedes gave up on theirs at mid season AFTER not accepting that their concept was not a match for even the top three cars ,try as they might.

I don´t say its pushrod alone .it is not .
RB6 is the most consequent car on the grid and maybe that includes going to pushrod 2 years ago.

[747heavy]

All the examples in the past also seem to be at the front and not at the back. So it's a bit disingenuous to compare back then to now.

nothing new under the sun
if you go back to the mid/end 80´s early 90´s pull rod rear was quite common in F1, even in combination with push rod front.

example Tyrell 017 from 1987





Arrows A11 (1990)


as a side note, if you look closely at the photos, you will see that both cars had EBD´s as well.
There is a lot of fashion / flavour of the month thinking in motor racing.

March Indy Cars also used pull rod front and rear suspensions for a while

[ringo]

Nice examples, though they are coil over.
But we're seeing the slight benefits here aren't we?
Disadvantages and complications? Not apparent form these pictures.

To be honest for a side mounted coil over, there is virtually no difference with pull and push rod. Torsion bar with heave spring is a different story.

Any with torsion bar setup mounted within the gearbox?
That's the modern day innovation, i'm talking about.

[Jersey Tom]

No one is denying that there CAN be advantages to running a pull rod suspension.

But its not ALWAYS the BEST choice for ALL cars with how everything needs to be packaged, integrated, serviced, etc. There are many other things that have to be taken under consideration, even if they aren't "plain-as-day" visible to your average Joe looking at pictures.

[mep]

But we're seeing the slight benefits here aren't we?

Actually in case of the Tyrrel I see that the exhaust is very close to important suspension parts. Something I don't see as benefit. I also don't like the flat angle the pullrod has it increases the forces in the suspension members.
I like to have the wishbones mounted as low as possible.
Reasons to stick with pushrods. However I don't think it make a big difference if you have pull or pushrod. RedBull got its big advantage from its aero.