Differential fox

[David 09]

Hello,

FOX is inspired Formule Renault 2000.

Thus is it possible to have the same differential and we can not change.

[Lateralus]

This may be coming in a future patch when an option for limited setups is implemented.

[David 09]

ok thank you

And formula Renault 2000 has no anti-roll bar so it would be possible to replace

[tristancliffe]

Erm - http://upload.wikimedia.org/wikipedia/commons/d/da/Formula_Renault_engine.jpg
An anti-roll bar is clearly visible. At the front roll stiffness is provided by the monoshock assembly, which is approximated by LFS's anti-roll bar settings.

In short - you're wrong, they do have anti-roll bars.

[David 09]

http://www.gurneyflap.com/Resources/renaultsus.jpg

[tristancliffe]

There it is again in your picture. One lovely anti-roll bar ready and willing to resist twisting.

Edit: Is that even a FR2.0? That rear wing looks mighty fancy, and the wishbones look rather beefy. Oh, and the exhausts are a bit massive for a 2.0. Is it not a 3.5 World Series car?

[David 09]

there is a spring

[tristancliffe]

Yes, there is a spring. Well done. 10/10 for observation.

But there is also an anti-roll bar. It's not a "conventional" type like on that wiki picture, but it's a vertical twisting type that also doubles up as the lever for the spring I think.

[David 09]

I just want the same system on the FOX

[tristancliffe]

An anti-roll bar? The FOX already has one. The exact mechanism isn't modelled, so it doesn't make any difference. Plus your picture is not of a FR2.0, and the FOX is not meant to be an exact replica of a FR2.0.

[Rocket47]

You, my friend are talking to a wall =D

"I want an antiroll bar"

"The fox has it already, see?"

"It is a spring"

See :D

[Forbin]

Anti-roll bars are springs.

Personally, I love roll. 50+ degrees of roll feels awesome. :biggrinfl

[blakehoo88]

50+ degrees of roll feels awesome.

have fun doing barrel rolls in the corner :x

[AndroidXP]

Just for your information David, the anti-roll bar in a monoshock suspension is the part marked in orange:

http://www.lfsforum.net/attachment.php?attachmentid=96878&stc=1&d=1259615836

The anti-roll strength is determined by how much this bar resists twisting (blue arrows, twisting in a direction depending on which wheel tries to move upwards).

If both both left and right suspension move equally, there is no twisting and only spring and damper influence the wheel's vertical movement. In this case the whole T-shaped segment moves back and forth (green arrow), compressing the spring.

If for example only the right wheel drives over a kerb and is thus pushed up, the triangle part rotates counter-clockwise (it rotates around the green part which is where it's mounted), pushing the damper rod and pulling on the spring rod. Since only the right wheel tries to move up, the anti-roll bar now has to twist clockwise to allow (or not allow) this to happen.


Obviously this means if LFS tries to simulate a monoshock suspension (front susp. of FBM for example) the ARB should have a very limited adjustability and be rather strong in general, which isn't the case at the moment. Though this should be fixable very easily with simple setup restrictions in the future.

[Forbin]

Anti-roll bars are springs.

Personally, I love roll. 50+ degrees of roll feels awesome. :biggrinfl

have fun doing barrel rolls in the corner :x
Or this:

http://i528.photobucket.com/albums/dd329/Forbin85/Misc/summit-shenny.png

[AndroidXP]

Whoa there, look at that badly tuned suspension. You really should put some anti-roll bars (http://img.epinions.com/images/opti/50/1d/pr-Bike_Parts_Accessories-Bell_Training_Wheels-resized200.jpg) on it!

[duke_toaster]

There it is again in your picture. One lovely anti-roll bar ready and willing to resist twisting.

Edit: Is that even a FR2.0? That rear wing looks mighty fancy, and the wishbones look rather beefy. Oh, and the exhausts are a bit massive for a 2.0. Is it not a 3.5 World Series car? If it's any interest, it's running treaded tyres - therefore presumably not either of them.

[Forbin]

Is it just me or does it look like there is no pivot for the control arms, only what appears to be a leaf spring? At least on the right rear wheel, upper rear control arm.

[AndroidXP]

I wondered the same thing, actually. Maybe it's bendy metal - then that bar would act as a weak spring, too, but that seems like a strange design decision.

[pasibrzuch]

Just (...) (pic) future.
Cunning!

I guess specs of this suspension differs from what we use in lfs to get the same result?

[AndroidXP]

Not sure if I understand your question correctly, but to semi-accurately simulate a monoshock suspension in LFS all we need to do is:

1) Only allow symmetrical editing of the spring strength since there is only a single spring (this is already the case, as we cannot modify spring stiffness asymmetrically anyway)

2) Set the ARB to a high value and lock it or only allow minimal editing

The second point is the reason why the default FBM setup has 100 N/mm front ARB. Other than that nothing else needs to be done to get nearly the same behaviour. Of course a proper simulation (that allows you to use more realistic values) would be preferable, and I believe a few details are different - at least the spring plays a different role on resisting body roll in addition to the anti-roll bar.

[tristancliffe]

If it's any interest, it's running treaded tyres - therefore presumably not either of them.Well, grooved slicks, but yes I agree, it must be something else. Yet I can't think of an F1 car with that livery (not that you often see an F1 car at that angle), and it doesn't have the F1 quality to it...

Is it just me or does it look like there is no pivot for the control arms, only what appears to be a leaf spring? At least on the right rear wheel, upper rear control arm.I don't get which bit you mean. the twisting 'roll bar' is pivoted fore-aft at the bottom to transmit movement/forces into the shock. Although I think it would bend a lot itself too.

[AndroidXP]

As I understood he means the rear mounting point of the upper wishbone.

[Forbin]

Yep, right next to the rear mounting point of the shocks.

[tristancliffe]

Ah, a flexure. Widely used in single seaters these day (albeit in the upper echelons!), as it removes the stiction of a joint. Whilst there is obviously more resistance in a flexure, it's a consistent, measurable resistance that can be used in the suspension stiffness calculations. Stiction (i.e. friction in a joint - stiction is generally an aeronautical term... On a tangent, I remember when people on this forum got confused what a yump is in rallying; oh, those were the days) isn't predictable or consistent. It's there, is quite noticeable, and then suddenly drops away. Not good.

Flexures - first seen on the front wishbones of F1 cars about 10 years ago - are simply better. As long as you life them (i.e. replace them after a certain mileage or time, because they will work harden and suffer from fatigue).

[amp88]

Yet I can't think of an F1 car with that livery (not that you often see an F1 car at that angle), and it doesn't have the F1 quality to it...

From this page (http://www.gurneyflap.com/formula1renault.html) it looks as though it is a Renault F1 car (the R24). Take a look at the last image in the block of R24 images. I can't see the original imaged linked to anywhere on that page from a quick glance though.

[Forbin]

Stiction (i.e. friction in a joint - stiction is generally an aeronautical term... On a tangent, I remember when people on this forum got confused what a yump is in rallying; oh, those were the days) isn't predictable or consistent. It's there, is quite noticeable, and then suddenly drops away. Not good.

I am familiar with that term, actually. It's often found in press releases for new motorcycles, at least race reps. It's usually (probably always) in reference to the forks and a special coating they put on the major sliding pieces to reduce stiction.

[legoflamb]

Why did they make the arm pull on the rods to compress the mono-shock? There is a stretching force the on the tie-rod ends that compress the spring. I thought compression resistance was better than stretch resistance, because there is less tendency for a part to break. To much compression might just bend a part, but too much stretch and the part may break.

[Forbin]

Under a compression force, the rods might be more prone to buckling if the alignment is not perfect. At least under a tensile force, they're stretched into shape.

[legoflamb]

I see. I have always associated springs with compression and expansion forces. As long as it has been engineered for its purpose, which I assume it has been, that it would not break under its normal operational stresses. Now that way seems more logical for the application of "rods."

[Forbin]

And all that from someone with an electrical engineering degree. :D I often think I should have done mechanical, tbh.

[K--]

Right time to clear a few things up ...

The pic show in post 5 is indeed the rear end of the renault R24 (2004) f1 car, the rear suspension setup in that car has been used for several seasons since and almost every other team use the same configuration (exception being this years red bull technologies cars the use pull rods)

The setup is as follows,
carbon fibre double wishbones, and carbon fibre pushrods. (the wishbones have a designed spring flex in the vertical direction)
The pushrods act on titanium rockers which have inbuilt torsion springs (twist) around the pivot point.
The rockers then have push rods to dampers on either side and they have pull rods that connect the two sides together via the J (jounce) damper. The J damper consists of standard coil over damper unit and is used to control the pure vertical movement of the car.

This setup allows the car to have 'soft' independent suspension when only one wheel is excited (say over a kurb) and quite a 'hard' suspension when both wheels are simultaneously loaded (down force at high speed, pitch under acceleration)

In automotive terms you pretty much always compress a spring under jounce as the static weight of the vehicle provides a 'preload' onto the spring.
If you were to stretch the spring under load you would have to weld the springs to the spring cups and eventually the welds would fatigue and your suspension would collapse

[pasibrzuch]

Not sure if I understand your question correctly
I meant it would work slightly different in comparision to double whishbones we have in lfs.
Wasn't sure, but K-- put some light on it:
This setup allows the car to have 'soft' independent suspension when only one wheel is excited (say over a kurb) and quite a 'hard' suspension when both wheels are simultaneously loaded (down force at high speed, pitch under acceleration)

My thought was, they didn't put this fancy suspension to be fancy, or save 400g of weight, because there is one spring less... I didn't know such things about ss's :shy:

Would be great to have this on BF1 or FO8.

[tristancliffe]

I'm not so sure I agree, although I am prepared to learn if I'm wrong.

The picture, which is indeed an R24, is of a typical monoshock design that decouples roll and ride (or roll and jounce if you prefer). Over kerbs and rolling into corners there is very little resistance to motion other than that provided by the aforementioned flexures and the T-type anti-roll bar. In plain ride - i.e. two wheels moving together - then the wheel rate is much higher.

This, so far, has nothing whatsoever to do with J-damper, Inertia dampers or anything else 'clever', and would work as a satisfactory suspension system on its own.

If the damper unit under the main spring is a J-damper, then that isn't used as a normal damper to control the general expansion and contraction of the spring unit, but to counteract the fluctuations of contact patch loads that would make "The Limit" harder to find as it would constantly vary. It's an addition to the suspension system, but not one that is part of the 'soft roll, stiff ride' arrangement.

[David 09]

Thank you AndroidXP.

Here is a documentation of formule renault 2.0


http://www.julietonelli.com/telechargements/pdfauto2009/divers/Dossier_de_presse_Nouvelle_Formula_Renault_2.0_Web .pdf

http://ups.imagup.com/06/1259715300.jpg

If the right wheel goes up, it follows the red arrows.

This moves the anti roll bar (green), giving it compresses the spring.

When the spring can be compressed, it will follow the blue arrow but the suspension of the left wheel prevents.

The only movement possible is to follow the pink arrow.

Are the property's how it works?

[tristancliffe]

No, that is wrong.

When the right wheel moves, the beelcrank rotates and moves one damper and one pushrod. The pushrod then turns the second bellcrank, which moves the other wheel (via its bellcrank) in the other direction, just like an anti-roll bar. The pivot axis of the second bellcrank is the anti-roll bar - the vertical section.

In pure ride - i.e. both wheels moving together, there is no twisting of the second bellcrank, just rotation of the pivot at the base of the 'anti-roll bar', causing the heave/ride spring to move.

[Shotglass]

which moves the other wheel (via its bellcrank) in the other direction, just like an anti-roll bar.

quite the opposite
a normal fully functional anti roll bar would move both wheels in the same direction (most usually up) whereas monoshock designs are naturally pro roll (so to speak)
you can see this quite nicely in some older netkar version if you take all the anti roll out of the monoshock cars

[tristancliffe]

Apologies. I was so excited by the monoshock part of the topic that I got a bit confuzzled. You are indeed correct, and I shouldn't make such a silly mistake - especially when I clearly knew it. Sorry.

But the point still stands that there is an anti-roll bar, and it isn't a FR2.0, so the topic, essentially, is dead.

Off topic anyone?

[legoflamb]

Off topic

It is amusing that flexures started being developed after gokart technology really started booming.

[tristancliffe]

Why is it amusing? It's almost entirely unrelated (other than it being materials flexing).

[legoflamb]

Why is it amusing? It's almost entirely unrelated (other than it being materials flexing).

Its the flexing being related that I am forming my conspiracy theory on. There is no hard evidence that the development of the two are related, it just seems that way because of the time period. It is amusing (to me anyway) because gokarting had the reputation of being a kid's sport.

[Forbin]

It's still a kid's sport. Sometimes the kids are a bit bigger and may have facial hair. Or gray hair. :)

One of my motorcycle trackday buddies, an instructor, is 56 years old. He often tells me he wonders what he's going to do when he grows up. :D

IMO, no one who races ever really grew up.

[legoflamb]

The last time I went to my local track I was racing some old guys. I think they were in their late forties.

[tristancliffe]

Its the flexing being related that I am forming my conspiracy theory on. There is no hard evidence that the development of the two are related, it just seems that way because of the time period. It is amusing (to me anyway) because gokarting had the reputation of being a kid's sport.

Right... So since flexing of the chassis as the primary means of suspension has been used in karting for years, you think that is the basis for the recent (ish) use of flexures as a replacement for spherical bearings in some 'top end' single seaters suspension systems?

What next? That the flexing in gokarts is the basis for horse whips? Or the basis for clarinet reeds? Just because both use flexing and, indeed, both use flexing in a suspension context, doesn't mean that one is based on the other. Flexing, elasticity and rigidity etc. are basic engineering principles (actually, it's not all that basic really, depending on how far you go into the topic).

[Forbin]

The last time I went to my local track I was racing some old guys. I think they were in their late forties.
My motorcycle club racing series has a sub-class called Formula 40 in a few of the classes for such people. There are actually quite a few riders who qualify. :)

[tristancliffe]

A few of the drivers in Monoposto are well over 60. However, youth seems to favour the downforce classes, where anyone competitive is under 40, and the vast majority under 30. The wingless categories seem to have a greater ratio of competitive older drivers - I wonder if this is because older drivers tend to err towards wingless cars, or if the physical effort of driving without downforce is more suitable for older drivers? Or maybe it's purely a cost thing?

I'm hoping to rent a wingless car (probably a Formula Vauxhall Junior - the antithesis of my current car in almost every way) at some point in 2010 so I can see what they're like. Constantly sideways seems to be the norm - although not 'drifting'. Nobody in FFord fits their stickers on backwards on one side of the car.

[legoflamb]

... Just because both use flexing and, indeed, both use flexing in a suspension context, doesn't mean that one is based on the other. Flexing, elasticity and rigidity etc. are basic engineering principles (actually, it's not all that basic really, depending on how far you go into the topic).

I was making a stupid comment for humor by alluding to a false conclusion based on fact-less assumptions.

...I'm hoping to rent a wingless car (probably a Formula Vauxhall Junior - the antithesis of my current car in almost every way) at some point in 2010 so I can see what they're like. Constantly sideways seems to be the norm - although not 'drifting'. Nobody in FFord fits their stickers on backwards on one side of the car.

I hope to hear of your experiences in the Formula Vauxhall if you get the chance to rent one.

[tristancliffe]

I'd write about it on my website, and probably a more brief version in my "Cliffe Crashes Out of the Lead" thead (which, fortunately, is misnamed most of time). I've only crashed out of the lead once in 3 seasons ;) :p

[Shotglass]

flexure technology has been around a lot longer than this
tristan testing a new flexure for his dallara (http://farm1.static.flickr.com/59/196654793_39ffbfd046.jpg)

[Forbin]

Looks more like me a year ago. :D

I don't recall those being very flexible, actually. Not that I ever had them. :razz:

[Shotglass]

the ones pictured clearly have some bit of flex in them
whether by design or by being cheap im not entirely sure
or maybe the kid is just too ame... i mean fat for them :p

[legoflamb]

Ha funny. last time I checked I only weighed 200 lbs.