Technical Analysis: WRC Cars 2017

Well Nick, if Metal Matrix "Composite" is not a composite material, then what is? :) For once, the public copy of the regulation shows the same information as the working copy in this case:

https://www.fia.com/file/61689/downl...token=hVJqMBK-

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The use of composite is allowed for the following parts:
 Timing cover
 Air filter box
 Air ducts for cooling (cockpit and boot (FR) / radiators / intercooler / engine auxiliaries / brakes)
 Homologated exterior bodywork parts (see article 902)
 Windscreen lower trim
 Door trims (FR)
 Dashboard (FR)
 Seats
 Supports and fixings fitted inside the cockpit (except seat brackets) and inside the rear boot
 Protection covers fitted inside cockpit and inside rear boot (FR)
 Foot rest for driver and codriver (FR)
 Console / support for switches…
 Steering wheel
 Heat shields
 Protections of the bodywork parts (side, floor, inner wheel arch)
 Leakproof box for fuel tank (see article 401) (FR)
 Underbody protections (see article 902)
 Mountings for front and rear bumpers
 Headlight units and tail light units
 Additional headlights housings (see article 503)
 Paddles for power assisted gearshift control
 Supports and fixings fitted inside the engine compartment (except engine / transmission supports)
 Discs for differentials
 Baffles fiited inside engine oil sump and transmission housing
 Fuel tank internals
 Engine parts: see HOMOLOGATION REGULATIONS FOR 1.6 TURBO ENGINES
 Electric connecting box
All composite material parts fitted directly on the engine (parts mentioned in Article 3) and the parts fitted in the cockpit or in the boot mentioned above (FR) must be made from fire‐
retardant material (seats and driver / codriver equipment / energy‐absorbing material: see FIA standarts). The external face of the part must have a V0 level of acceptance respecting
the "UL94" US standard (fire‐retardance capability).

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Basically, this list precludes any meaningful use of MMC on these cars.

Somewhere in this discussion indeed lies the truth about the finish on the part. What can I say, it's painful to see all three cars go out with the same broken part (whatever the circumstances), and it's not the first time they failed this year...

Unfortunately a bad design can not be saved by a coating or process at the end of the day. If they had hub failures breaking the connection for the lower wishbone at the ballpoint for many rallies than its time to design a new hub. Or at lease revised the connection of the ball joint to hub. I bet they will do this moving forward.

On thing I noticed when looking at the pics was the diameter of the l tapered ball joint stud. It was unnecessarily huge in my opinion. Never see Any WRC cars use such a large stud. This could result to huge loads on the hub and also reduce the amount of thickness in that area due to space limitations. On most arms we’ve worked on we would use a 5/8 heim (rose) joint or 14 mm in metric. The Hyundai ball joint stud looks huge. Like 20 mm, but this could be the image being zoomed in. The shear loads on a 14/16 mm heim or rose joint is more than enough for lower control arms used in McPherson suspension. I bet they will also change mountings for the shock body and the shock top mounts as well because the loads are going straight up from the ball joint to the top mounts. I’ve been lucky enough to see Toyota, Ford and Citroen suspension components and in terms of design and tech (not strength) Toyota is above Citroen which is above Ford. Have no clue what Hyundai stuff looks like. They’re actually pretty good at keeping things behind the scenes :). Oh and the weight of the Toyota assemblies is incredibly light.

In a wheel arch,some air ducts are closed. And what sensor behind the rear window?
Attachment 1447
Attachment 1448

I would guess that those are reflectors for the timing beam. Someone correct me if I'm wrong.

So, does anybody have any insight as to why the Toyotas struggled so much in low traction?

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Originally Posted by steve.mandzij

So, does anybody have any insight as to why the Toyotas struggled so much in low traction?

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They were claiming that they had a weight disadvantage due to the design of the rear wheel arches. The car was keeping mud there (allegedly 100+ kilos).

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Originally Posted by steve.mandzij

So, does anybody have any insight as to why the Toyotas struggled so much in low traction?

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Biggest problem was that they did all testing in dry weather, it was +20 temperature when Lappi tested.
Rear of car is/was too heavy (because of up to 120kg of mud) and front of car was way too light, so no grip in front and car was not turning.

More weight on the rear is bad for nearly everything but not for the traction, quite the opposite.

What Pantealex wrote seems to be plausible explanation to me.

Diff and suspension settings are also key. Also I'm not sure of the speeds at Wales, but aero would not play a huge role if it's mainly tight and slow.

Toyota will be changing their aero for 2018. I hear it is even more futuristic looking than the current car.

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Originally Posted by racerx1979

Diff and suspension settings are also key. Also I'm not sure of the speeds at Wales, but aero would not play a huge role if it's mainly tight and slow.

Toyota will be changing their aero for 2018. I hear it is even more futuristic looking than the current car.

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According to Mäkinen interview the aerodynamic changes aren`t dramatic but mostly for easier service (for instance current front bumper is a 1 piece damper and when the splitter brakes they have to change the whole bumper) so the new version will have a separately changable splitter.

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Originally Posted by racerx1979

Diff and suspension settings are also key. Also I'm not sure of the speeds at Wales, but aero would not play a huge role if it's mainly tight and slow.

Toyota will be changing their aero for 2018. I hear it is even more futuristic looking than the current car.

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Wales is definitely not tight and slow, watch some of the many youtube videos and you will see they are often going quite quickly ;)

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Originally Posted by Munkvy

Wales is definitely not tight and slow, watch some of the many youtube videos and you will see they are often going quite quickly ;)

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Evans' average speed in Wales was 103 km/h which is pretty average for a gravel rally. Finland was 126 km/h, Poland 116 km/h, Argentina 98 km/h, Portugal 94 km/h and Sardegna 91 km/h. Wales has fast sections, but also lots of tight hairpins.

You don't need any aero in hairpins but You need it in fast sections. If a stage has a lot of slow points like hairpins and junctions and still has average speed over 100 km/h it's in fact pretty quick. The sections between those slow points have to be of much higher average speed than the stage as a whole.

Evans had covering plates on the wheelarches while Ogier and Tanak had them at least semi-open... why?

https://www.ewrc.cz/images/2017/phot..._3899-edit.jpg
https://www.ewrc.cz/images/2017/phot...-ogier-ndz.jpg

Now I noticed this too. In videos all the M-Sport cars have them open and then taped shut.
Maybe it has something to to with them collecting mud

I tried to look find the answer in this thread but didn’t see one.
Why are Toyota using 2 radiators? It looks like a radiator on either side of the intercooler.
https://uploads.tapatalk-cdn.com/201...c5f6590044.jpg

Is it possible that the Toyota suspension components are machined hollow and then filled with some sort of structural foam? I don't think that would technically be called a composite material, so it seems like it would be a way of getting some of those properties (lightness, rigidity) while avoiding the regulation.

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Originally Posted by sonnybobiche

Is it possible that the Toyota suspension components are machined hollow and then filled with some sort of structural foam? I don't think that would technically be called a composite material, so it seems like it would be a way of getting some of those properties (lightness, rigidity) while avoiding the regulation.

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From pure technical point of view (i.e. disregarding the tech regs), in theory yes, but in practice very unlikely, as the current state of the readily available structural foams is such that their stiffness is significantly lower than the steel that the wishbones are made from. Maybe if you were to use a 3D metal (i.e. steel) printed lattice attached to the inside of the wishbone skins, then you might be onto something.

I often wish I'd stayed in engineering school. I hate technical 'anoraks' but I do love technical things, like this thread.

Love this thread.....Looking forward to observations regarding the changes between the 2017 and 2018 cars. What are you guys seeing that a newbie heading into his second season of love for this sport should know? Who has made the most changes?

Revman, teams were allowed a certain number of "jokers" to spend on updating homologated parts (it's not free-for-all like F1 for example), split between engine and chassis. How they count each update is a bit open to debate, so one joker could be a single new hole on the OEM chassis or 1 bodywork and all other panels that connect to it... So for you it would be a bit of work (but fun) trying to figure out who used the jokers on what without looking at the homologation dossier. It's a "use it or lose it" situation so one can assume every team used their full allowance (or maybe not??). For 2018 there are less jokers available, so they must be more selective about what is worth upgrading this way. Then there are parts which are homologated but multiple options are allows and can be added through the year (every 3 months) without restriction. The distinction between the two types of homologation would not be obvious without reading the technical regulation, unfortunately.

So what it all means is, some cars may look obviously different externally, while some may not, but you bet all of them would have had upgrades throughout 2017 and between the seasons for parts where jokers were not needed. I think most cars had one or two clear deficiencies, which would have been the focus of upgrades. We will now wait for Monte Carlo 2018 to see how well they improved them.

Are wiring harnesses/ECU box/electric gubbins homologated?

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Originally Posted by sonnybobiche

Are wiring harnesses/ECU box/electric gubbins homologated?

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Mostly, yes.

Thank you for this reply. Tremendous. Do you see any trends regarding the aero (given that this is what we can see)? I read on one site that Toyota may have narrowed the front bodywork, revised the "grill" area, and added an upper dive plane to offset the massive wing. All speculation, or do you think this is a legit analysis?

I have one question...

Does anyone remember whether they kept using cross-tyre setups with 2017 cars? I am asking because unlike the old generation cars the new ones have active center differential.

Does anyone know why in the WRC they use only one shift pedal where you pull to change gears up and push to change gear down instead of the two pedals they use in other series?

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Originally Posted by Watson

Does anyone know why in the WRC they use only one shift pedal where you pull to change gears up and push to change gear down instead of the two pedals they use in other series?

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I guess the purpose is to keep left hand handle the steering wheel while the right hands are all about shifting & handbraking.

Mitsubishi experiment double paddles in 2005 though

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Originally Posted by mArvAlcao17

I guess the purpose is to keep left hand handle the steering wheel while the right hands are all about shifting & handbraking.

Mitsubishi experiment double paddles in 2005 though

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Oh I see. Rallycars probably have more turning lock and therefore more turns from lock to lock so the shiftpedal on the left might be clumsy to reach in certain situations.

Usual lock-to-lock rotation in WRC cars is 1,5 if I am not mistaken.

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Originally Posted by Mirek

I have one question...

Does anyone remember whether they kept using cross-tyre setups with 2017 cars? I am asking because unlike the old generation cars the new ones have active center differential.

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I can`t remember which rally it was but at least Latvala used cross setting as he complained about the behavior when they hadn`t used it i testing and the car felt nervous on the rally, also based on the Michelin reports of what tires each crew had they would almost have been forced to use cross settings.

I'm also interested in the cross tyre setup. What are the pros and cons? I understand the drivers have a limited amount of tyres per rally so sometimes that's what they have to do. But how much does the diff balance it out?

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Originally Posted by AnttiL

I'm also interested in the cross tyre setup. What are the pros and cons? I understand the drivers have a limited amount of tyres per rally so sometimes that's what they have to do. But how much does the diff balance it out?

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Yes, and what is the thinking? For example, a softer tire goes to which wheel on a four wheel drive race car under what circumstances (surfaces)?

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Originally Posted by AnttiL

I'm also interested in the cross tyre setup. What are the pros and cons? I understand the drivers have a limited amount of tyres per rally so sometimes that's what they have to do. But how much does the diff balance it out?

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If I remember right it was Juho Hänninen in 2011 Monte Carlo who used it first (or at least it was first widely discussed case) when Škoda team (and Petter Solberg) fucked-up tyre choice and lost the fight for victory there. He used it out of necessity and it worked much better than let's say two winter tyres in front and two slicks in the rear.

I believe the main rationale lies in the fact that limitted-slip differential helps to bring overall grip level of the axle closer to the level of the better wheel. In that case an axle with only two wrong tyres benefits in no way from having LSD in between. Therefore if You have two better tyres it's better to place one in front and one in the rear (cross) and by that enhance a bit the grip on both axles instead of having one good and one useless.

its just that 2 good wheels on the front give to much oversteer, and 2 good wheels on the back too much understeer. so they use on wrong wheel and 1 good wheel on each axle, which gives a more stable feeling.
the only reason they do that is because they can't carry for spares in the boot.

some close photos from yaris and new canards and front wing from https://twitter.com/Traxx_WiF/media

https://pbs.twimg.com/media/DSs9QKfX0AAJBTW.jpg
https://pbs.twimg.com/media/DSs9QKoXUAA8QPR.jpg
https://pbs.twimg.com/media/DSs9QKqXUAAkRQ3.jpg

Those are still prototype parts, just saying ;)

When do the current WRCar regulations run until?

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Originally Posted by Revman

Thank you for this reply. Tremendous. Do you see any trends regarding the aero (given that this is what we can see)? I read on one site that Toyota may have narrowed the front bodywork, revised the "grill" area, and added an upper dive plane to offset the massive wing. All speculation, or do you think this is a legit analysis?

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Agree on all points. Now that more detailed pictures are showing up online, it's even clearer what they did. I particularly like the outlets towards the side of the car on their new front bumper. Pre-2017 cars all had this type of openings on the side, which help manage the air around front wheels. For 2017, the tech reg didn't appear to allow this treatment at first... But clearly with some clever thinking, it's still possible. Good for them! There are other details which are probably very difficult to photograph. Maybe they got some help from the aero department in Cologne? :D

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Originally Posted by Mirek

If I remember right it was Juho Hänninen in 2011 Monte Carlo who used it first (or at least it was first widely discussed case) when Škoda team (and Petter Solberg) fucked-up tyre choice and lost the fight for victory there. He used it out of necessity and it worked much better than let's say two winter tyres in front and two slicks in the rear.

I believe the main rationale lies in the fact that limitted-slip differential helps to bring overall grip level of the axle closer to the level of the better wheel. In that case an axle with only two wrong tyres benefits in no way from having LSD in between. Therefore if You have two better tyres it's better to place one in front and one in the rear (cross) and by that enhance a bit the grip on both axles instead of having one good and one useless.

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Interesting. The cross tyre setup was a new concept for me when I joined WRC. I do recall the WRC TV commentators were discussing the merits of left-to-right mix, instead of cross. Apparently this could give them more confidence because the car will behave more predictably, albeit at different grip levels left and right.

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Originally Posted by RS

When do the current WRCar regulations run until?

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"The principles of the technical and homologation regulations for the 2017-2019 WRC car were approved by the World Motor Sport Council."