Technical Analysis: WRC Cars 2017

[Lundefaret]

Hi Jan, no need to shout, I am very happy to clarify what I meant - you quoted the last 50 years - would you list all the rally cars that have been designed from the ground up as rally cars, i.e. not based on production cars, that have employed the Macpherson strut? I do not pretend to know the complete rally history and with my limited knowledge of the world, I am happy to admit that the only one that comes to my mind is Lancia Stratos rear suspension, but that's why we have this forum where everyone can contribute, enriching the knowledge of the others. So, yes please, I will be happy to learn more regarding the above question.

This is a question of definition?

How many cars has there been that has been designed from the ground up to be a rally car?

Lancia Stratos

Ford RS 200 (double A Arm)

Renault 5 Turbo (double A Arm) (since this is a version of the Renault 5, this is open for discussion)

We also have the other group B cars (except Audi Sport quattro in all its versions, and the Citroën BX), but they were all at least made to look like production relatives (Pug 205, Lancia S4, MG 6R4) which put constraints on their design).

Worth mentioning is the Audi Group S, but it never raced (all other Group S prototypes were also designer with an eye on a production car, inc the Lancia Delta, the Opel Kadett, the Toyota MR2, the Lada etc.

I may be forgetting some cars - please feel free to contribute

[janvanvurpa]

Hi Jan, no need to shout, I am very happy to clarify what I meant - you quoted the last 50 years - would you list all the rally cars that have been designed from the ground up as rally cars, i.e. not based on production cars, that have employed the Macpherson strut? I do not pretend to know the complete rally history and with my limited knowledge of the world, I am happy to admit that the only one that comes to my mind is Lancia Stratos rear suspension, but that's why we have this forum where everyone can contribute, enriching the knowledge of the others. So, yes please, I will be happy to learn more regarding the above question.

I was not shouting, merely trying to use color and italics to give tone to the specific part of what you were saying that I was baffled about..In speech we can use tone--rising inflection or a raised eyebrow...
Rally has thru time for most people always been based on road going cars*, hence the minimums needed to qualify for homologation in the 5000 or 2500 range (excpet the baddest of the Group 4 cars at 400 units and group B at 200 units....And post 1968 most cars were struts on front in term of models and numbers made..
Group 4 Escort, widely acknowledged as the coolest car in all human history, and Fiat 131 were high performance competition cars.. Sierra Coswoth, all the Lancia Delta Intergrales were high performance competition cars.
as were all the Group A Gaylants, Legacys, Lancer Evos, Imprezas and ALL the World Rally cars ...
The sticking point was the phrase "designed from the ground up"

[NickRally]

Thanks Jan, I am aware of these facts and vehicles. To clarify what I meant by “from the ground up”, for me it is when the designers are given “clean sheet of paper” (or a “blank screen” these days) to design the best possible car within the constraints of the rules, without having to base their designs on existing vehicles. I have been designing racing cars for a living for 20 years now and certainly appreciate when I have the freedom to do so (which for me is actually most of the time ).
The cars that fit the above description, that I know about, are not that many – Stratos, 037 (for the most part), RS200, Audi Group S, ECV 2, Moskvich Gr.B/S – from these, as far as I am aware (but happy to be corrected), only the Stratos designers opted for Mcpherson strut suspension (at the rear).
Most of the other extreme Gr.B cars had to observe the silhouette of the original car they were supposed to promote and as such it sometimes meant not enough packaging space for the designers to have a completely unrestricted choice of suspension type (as was the case with Metro 6R4), while others had enough space to fit double wishbone suspensions.
Talking about the Stratos, I suspect the reason for the strut suspension was still the lack of packaging space, but it was the choice of the designers to implement a transverse engine and a short wheelbase concept restricting the available volume.
As far as I remember (without going through all the posts), the original discussion about the Macpherson strut suspension started with itix asking if Macpherson strut is there because of the tech regs and also pondering the pros and cons of the Macpherson strut vs double wishbone suspension and which one would allow for better performance. We settled on the fact that the Macpherson strut is prescribed by the regs (and it would appear that way when reading them), but even if it wasn’t, it still offered the best choice due to the constraints coming from the overall packaging of the current WRC cars, which are still based on production layouts. At this point, I started wondering if there were any examples where the designers were allowed to choose what they want (either by the marketing departments/accountants or by the regs), but had still opted for the Macpherson strut suspension, and the only vehicle I could think of was the Stratos, which once again was most likely the result of choosing transverse engine and short wheel base concept in the first place.

[AnttiL]

Chris Williams, the Chief Rally Engineer at M-Sport talks about the 2017 regulations and how things have gone so far.

https://rallysportmag.com/feature-li...r-regulations/

[mknight]

Interesting points from my view:

“Some teams have gone full on in every area of design and pushed into areas thought were out of bounds. Others have been more conservative and have not exploited some of the new freedoms to the maximum."

With my limited knowledge I see 2 main areas where some cars are pushing the limits:

- Citroen with different damper mountings for Gravel/Tarmac
- Toyota with the extensive rear aero going "into" the bodywork instead of just wheelarches

Anyone else has other candidates?


"But going forward now it is harder to find extra performance. You could spend a lot of money analysing what everybody else already has, compare it to what you have and implementing the best of both worlds. That’s actually quite an expensive project."

I'd guess this is one of the 2 main ways of going faster now. The other one is optimizing setup for different events.

"In areas where teams have concentrated their test work in the past they may excel."

Clearly this holds more than ever with new cars that some teams have not really tested on specific roads while others test all the time there. (ref. Toyota in Finland/Sweden roads, Citroen on smooth tarmac, probably M-Sport in GB).
In this comparison it will be interesting to see how Australia works out.


have there been any unexpected problems?

CW: We have seen a lot of damage to wheels this year.

First time I hear about this, something to do with extra speed + downforce in corners?

[AnttiL]

CW: We have seen a lot of damage to wheels this year.[/I][/b]

First time I hear about this, something to do with extra speed + downforce in corners?

And wider cars?

[mknight]

And wider cars?

In general that should contribute as well, but he says the issue first came up on pre-event test for Corsica.

Example vid from the test here: https://www.youtube.com/watch?v=Vx4lyg9V56Y

During a test on a road like that damage from touching rocks on the side of the road due to wider car shouldn't be the main factor. (as opposed to a narrow-road gravel rally, where wider car just doesn't fit no matter which line the driver takes)

For tarmac, that's valid provided you keep same distance from the walls and in cuts as before. If you don't it's more of a problem of the driver not used to the wider car than the car itself.

[racerx1979]

Toyota is using exotic materials for suspension components. Titanium, Magnesium and some crazy hardened steel (same stuff used by Porsche for GT3 crankshafts). The damper, hub and control arms on the Toyota's are insanely lightweight.

[br21]

I think what Mr. Williams was telling it was the wear of the tires, not the physical damage to the rims/tires. Big wear is because big downforce, so high corner speeds, good grip under braking plus extra power, plus few other things.

Titanium and magnesium are again allowed for 2017 WRC cars?!

[AMSS]

Toyota is using exotic materials for suspension components. Titanium, Magnesium and some crazy hardened steel (same stuff used by Porsche for GT3 crankshafts). The damper, hub and control arms on the Toyota's are insanely lightweight.

Are you sure? I don`t know the rules for the current WRC 17 spec cars exactly but at least for the previous generations both titanium and magnesium was prohibited, would be strange to allow it now when the cars got enough more expensive anyway..
But if they allow it again than sure why not