FIA Rally Working Group: the future of WRC and the rally sport

[Mirek]

Mirek, try not to get so offended that someone other than you does not know what you know and is merely putting out suggestions. This is after all meant to be a friendly exchange of ideas between like-minded motorsport fans, nothing serious. We are not the FIA working group so anything discussed here has no bearing on it at all.

I do however appreciate the knowledge you have shared here, it is all interesting information to find out.



I genuinely find this bizarre to get my head round, but also fascinating info to find out. My understanding of a locked diff (sorry, it’s still a diff if it’s splitting torque) is that when turning corners the front/rear speed difference, as well as the left/right speed difference of the wheels would create unwanted slippage to the point of wheels ‘skipping’. It’s been a long time since my university days learning about powertrains and I wasn’t paying much attention back then clearly!



Best to just leave it be as I thought then, I don’t even have an issue with outright speed of Rally2s anyway.



You assume that it is common knowledge that most deadly rally accidents are by 4WD Group N cars? I would like to see evidence of this being the case and the reason for it.



Funnily enough I’ve never worked at Peugeot Sport so no, I didn’t know this. Again it’s fascinating to find out that info, not widely available or reported to my knowledge.



Never said I did. Never claimed to be an expert. And yes I know what a sequential gearbox means, colloquially a stick operated sequential gearbox is referred to as a sequential gearbox and a paddle operated sequential gearbox referred to as a paddle shift - even though a paddle shift may also refer to an epicyclic gearbox or some form of automated manual gearbox with paddle shifters. But don’t let that stop you from getting up on your high-horse.



With exception of the 2011 ones? So surely the Rally2s also don’t have a big enough power band for 5-speed? The 307 was the ONLY one to make use of a 4-speed box and its fair to say that didn’t turn out well.

Sorry for not answering earlier, I was on holidays and didn't read the forum. Also sorry for sounding too arrogant. My bad.

I genuinely find this bizarre to get my head round, but also fascinating info to find out. My understanding of a locked diff (sorry, it’s still a diff if it’s splitting torque) is that when turning corners the front/rear speed difference, as well as the left/right speed difference of the wheels would create unwanted slippage to the point of wheels ‘skipping’. It’s been a long time since my university days learning about powertrains and I wasn’t paying much attention back then clearly!

The cars do suffer a lot from understeering but they somehow managed to cope with it with suspension geometry and diff ramp angles. If you remember the 2011 WRC cars were being driven ridiculously sideways on the loose surface at their beginnings. The reason for that was the abscence of the center differential.

You assume that it is common knowledge that most deadly rally accidents are by 4WD Group N cars? I would like to see evidence of this being the case and the reason for it.

I don't have exact statiastics but when the gr.N 4WD cars were still a thing (unlike today) the far majority of tragic accidents happened with them. I can name a lot of them from my head but I don't think it is necessary. Only here in Czechia we had more than 10 dead from gr.N accidents (most of them spectators). In most cases the reason was the same - uncontrolled rebound of the powered rear axle which was caused mainly by too short suspension travel. Simply said bouncing cars are always spectacular but also always dangerous.

Several examples of the uncontrolled rear axle rebound after a short youtube search.
https://www.youtube.com/watch?v=kF9WuVrd8so (this one ended tragically for one spectactor)
https://www.youtube.com/watch?v=J3Ocf5KwVr0
https://www.youtube.com/watch?v=8SOeOa13ypo
https://www.youtube.com/watch?v=2gb0dmFdUAQ
https://youtu.be/9Wj-WX-h5B4?t=199 (not an accident but an extreme case of a gr.N car with very short rear axle travel, in this case the rear axle was not driven so it could not cause a spin)

With exception of the 2011 ones? So surely the Rally2s also don’t have a big enough power band for 5-speed?

No, I am sorry but it isn't that easy. 2011 WRC cars and R5/Rally2 cars have the same turbo boost but also different restrictor size and often also different bore/stroke ratio. The WRC cars had the peak power in higher RPM than the R5/Rally2 have because there was enough air for feeding the engine in high rews. The R5/Rally2 have relatively flatter power band because they run out of air quickly. Simply said from the peak power to the RPM limiter the power is relatively constant because it is limited by the restrictor and the R5/Rally2 achieve the peak power about 1000-2000 RPM earlier.

The 307 was the ONLY one to make use of a 4-speed box and its fair to say that didn’t turn out well.

It didn't go well in terms of reliability and I wrote about that. The problems had nothing to do with the performance.