The relative benefits of a pull rod suspension

[ringo]

I still think you're overstating the advantages. Both Ferrari and McLaren would have looked at a pull rod setup for last years cars, both dismissed it as not being the optimal solution so the benefits cannot be that significant.

Red Bull's speed didn't come from having a pull rod setup, although with their design philosophy it would have had a minor benefit. Their speed was, IMHO, primarily due to the EBD, front wing, flexing body parts, and a design that was not as pitch sensitive as the McLaren.

Where have you heard this?
You can't go wrong with pull rod suspension. Aside from servicing, it has no drawbacks.

[autogyro]

Going from the not ideal geometry of pull rod suspension and the obvious reduced optimization of aero with push rod, I think I would be looking back at direct wishbone actuated torsion bar suspension with the addition of linked heave springing. Certainly something similar.

[myurr]

Where have you heard this?
You can't go wrong with pull rod suspension. Aside from servicing, it has no drawbacks.

Neither team ran with it last year so they obviously rejected it as a solution - and given the amount spent on designing and developing these cars I would find it ludicrous if someone were to suggest that they didn't see these amazing benefits of push rods and didn't look into it in more detail.

Whilst the Ferrari was much more of an evolution, the McLaren was very different to the previous years car and featured a heavily revised rear suspension setup. So they definitely could have switched design were there this massive benefit along with zero drawbacks.

[Jersey Tom]

Yes yes, pull rod suspensions are so new and advantageous and a no-brainer... clearly if a team like Ferrari would just try them they'd move forward leaps and bounds, with no reason to go back...

[Tim.Wright]

Where have you heard this?
You can't go wrong with pull rod suspension. Aside from servicing, it has no drawbacks.

Ringo, you have to kill this idea of pull rod suspension being the be all and end all or rear axle designs. Its complete BS. Forcing a pull rod axle into the back of any car will not automatically give you an advantage.

I hate to break it to you but in terms of a suspension system, they will function identically. The differences you get are second order effects like packaging and a small weigh benefit.

For some teams, with their own gearbox/diffuser design, these second order effects might actually be negative therefore the pull rod is not the optimal solution there. I can guarentee this is why McLaren/Ferrari are not using it.

However, if you post was sarcastic. I take back everything and applaud you because you got me.

Tim

[raymondu999]

how would you get a weight benefit? Or do you mean CoG?

[marcush.]

In a world of tenths and hundredth of seconds ,Everything counts.
On one hand we discuss in more than one thread about the significance of 20HP in a F1 car boasting 750+Hp and on the other hand you shrug off a reduction of crosssection in a most critical area combined with a reduction of CoG,a potential
reduction of unsprung mass coming on top of this (with the pullrod loaded in tension when the car goes into bump ,so overload conditions will not try to buckle the rod but stretch it)
Nobody would say Pullrod will turn lame duck into a winning package but it is more than obvious that Neweys rearend is a lot more sophisticated and refined than anything else we currently see in terms of concept.
Mclaren detail design and effort is worlds above what we see at RedBull .

[Florio]

Although i'm a tech novice, wouldn't a pull rod be alot more suitable? Yes it has the disadvatages concerning the effects on the chassis etc, but, the DDD is dead and again, the emphasis is based on the rear wing now. This is obviously helped by the packaging benefits and aero too.


Just my two cents.

[Tim.Wright]

how would you get a weight benefit? Or do you mean CoG?

I mean the CG location.

In a world of tenths and hundredth of seconds ,Everything counts.
On one hand we discuss in more than one thread about the significance of 20HP in a F1 car boasting 750+Hp and on the other hand you shrug off a reduction of crosssection in a most critical area combined with a reduction of CoG,a potential
reduction of unsprung mass coming on top of this (with the pullrod loaded in tension when the car goes into bump ,so overload conditions will not try to buckle the rod but stretch it)

There is no inherent reduction in cross section you get from running a pull rod. Damper and springs go low, that means something else has to come up.

The reduction in unsprung mass would be negligible. Really. Also remember a pull rod puts the upper wishbone under a lot more stress than a push rod, so it has to be made stronger and therefore heavier which negates some of your low CG benefits

Nobody would say Pullrod will turn lame duck into a winning package

Well some people are, hence my post.

Tim

[marcush.]

Obviously newey has found a possibility to reduce cross section,Tim ...
His rear is so low compared to all other cars and not wider so I´m afraid he is
proving you wrong.
all other cars carry a nasty bulge exactly between the rear wheels housing the Bellcrank bearing putting almost half of the bridgewing into their shadow and possibly even influencing the mainwing.

As for the bending loads on the upper wishbone .yes ..and you do away with it at the bottom or you put the rod directly to the upright and got no direct bending load ,only compression.

the CoG benefit of putting the dampers a few mm deeper into the gearbox housing and possibly the torsionsprings a swell is really not much tbh,especially at the rear.
so in the end it comes down to a potential aero benefit.

[myurr]

Obviously newey has found a possibility to reduce cross section,Tim ...
His rear is so low compared to all other cars and not wider so I´m afraid he is
proving you wrong.
all other cars carry a nasty bulge exactly between the rear wheels housing the Bellcrank bearing putting almost half of the bridgewing into their shadow and possibly even influencing the mainwing.

As for the bending loads on the upper wishbone .yes ..and you do away with it at the bottom or you put the rod directly to the upright and got no direct bending load ,only compression.

the CoG benefit of putting the dampers a few mm deeper into the gearbox housing and possibly the torsionsprings a swell is really not much tbh,especially at the rear.
so in the end it comes down to a potential aero benefit.

And McLaren in particular prove you wrong - they had the opportunity, they redesigned their entire rear end suspension, yet they stuck with the push rod. If the pull rod is such an aero win and their aero is so inefficient because of the compromise the push rod causes, why didn't they move to a pull rod setup?

[forty-two]

Obviously newey has found a possibility to reduce cross section,Tim ...
His rear is so low compared to all other cars and not wider so I´m afraid he is
proving you wrong.
all other cars carry a nasty bulge exactly between the rear wheels housing the Bellcrank bearing putting almost half of the bridgewing into their shadow and possibly even influencing the mainwing.

As for the bending loads on the upper wishbone .yes ..and you do away with it at the bottom or you put the rod directly to the upright and got no direct bending load ,only compression.

the CoG benefit of putting the dampers a few mm deeper into the gearbox housing and possibly the torsionsprings a swell is really not much tbh,especially at the rear.
so in the end it comes down to a potential aero benefit.

And McLaren in particular prove you wrong - they had the opportunity, they redesigned their entire rear end suspension, yet they stuck with the push rod. If the pull rod is such an aero win and their aero is so inefficient because of the compromise the push rod causes, why didn't they move to a pull rod setup?

If you're talking about the MP4-25, then I suggest that the implementation of the F-Duct may very likely have had an impact here. Remember that the "default" outlet for the F-Duct was low, just above the gearbox. Perhaps this compromised or at least had an impact upon their design decisions?

[myurr]

And McLaren in particular prove you wrong - they had the opportunity, they redesigned their entire rear end suspension, yet they stuck with the push rod. If the pull rod is such an aero win and their aero is so inefficient because of the compromise the push rod causes, why didn't they move to a pull rod setup?

If you're talking about the MP4-25, then I suggest that the implementation of the F-Duct may very likely have had an impact here. Remember that the "default" outlet for the F-Duct was low, just above the gearbox. Perhaps this compromised or at least had an impact upon their design decisions?

That duct was very narrow and central to the car and entirely in the upper half of the car. I don't think this would have had any bearing on their choice of suspension layout, especially if it has the unequivocal benefits that ringo believes.

[ringo]

Where have you heard this?
You can't go wrong with pull rod suspension. Aside from servicing, it has no drawbacks.

Ringo, you have to kill this idea of pull rod suspension being the be all and end all or rear axle designs. Its complete BS. Forcing a pull rod axle into the back of any car will not automatically give you an advantage.

I hate to break it to you but in terms of a suspension system, they will function identically. The differences you get are second order effects like packaging and a small weigh benefit.

For some teams, with their own gearbox/diffuser design, these second order effects might actually be negative therefore the pull rod is not the optimal solution there. I can guarentee this is why McLaren/Ferrari are not using it.

However, if you post was sarcastic. I take back everything and applaud you because you got me.

Tim

They work the same, but the secondary benefits are more important.
Key words Aero Dynamics and C.O.G.

Not becuase Ferrari and Mclaren never use it can to you come to the conclusion it's useless. Redbull never run KERS in 2009, neither did Brawn. Is KERS useless now?
There could be so many reasons for not using the pull rod suspension in 2010, maybe the car was already too far into developement. We know Ferrari began early.
Maybe they wanted to stick to what they know works.

I am not saying it's the holy grail, but it's definitely a step in the right direction. It has no drawback and comes with some nice benefits aero wise and C.o.G wise, especially for single diffuser cars.
I said a similar thing about the F duct not having net drawbacks and some thought it was too good to be true.

[ringo]

And McLaren in particular prove you wrong - they had the opportunity, they redesigned their entire rear end suspension, yet they stuck with the push rod. If the pull rod is such an aero win and their aero is so inefficient because of the compromise the push rod causes, why didn't they move to a pull rod setup?

If you're talking about the MP4-25, then I suggest that the implementation of the F-Duct may very likely have had an impact here. Remember that the "default" outlet for the F-Duct was low, just above the gearbox. Perhaps this compromised or at least had an impact upon their design decisions?

That duct was very narrow and central to the car and entirely in the upper half of the car. I don't think this would have had any bearing on their choice of suspension layout, especially if it has the unequivocal benefits that ringo believes.

They wanted as much room for the DDD. Next year DDD are banned.
pull rods it is for 2011.
The stress in the upper control arm is also exaggerated. The size and weight of the part wont change much.

some news on the car:

GaryPaffett

A busy day at the MTC yesterday. Sim running on the MP4-26 then some filming in the simulator. Back in the sim today for more setup work.