Technical Analysis: WRC Cars 2017

[AMSS]

For me.
FORD - Has developed into the best overall package at the minute, engine seems very strong.

HYUNDAI - Still pretty strong overall, but but a few cracks appearing (no pun intended). Understeer in high traction, weakness of castings to impacts.

TOYOTA - Best chassis, but the team is still learning event to event and the car isn't always on point at the beginning. Reliability still an issue.

CITROEN - Inconsistent, the best on smooth, high traction. Watching the live TV it is clear as day, it just turns a tighter line than the others and can be driven within itself. On low traction, bumpy surfaces its all over the place. Suspension seems the worst of all. I guess we will see in Wales/Australia if the recent testing has made some gains.

Agreed

Ford seems to be overall the easiest package with good reliability and no direct weaknesses in handling though it doesn`t shine either in any certain area it seems (or maybe slow technical gravel they have the best grip..), basically a championship winning car

Hyundai was the fastest car beginning of the season but seems Toyota and Ford have slightly pulled away, seems to have a strong engine.

Toyota seems to have a fast car with the best aerodynamics, maybe struggle a bit with the suspension on slow technical gravel and technical reliability needs improvement.

Citroen fastest on tarmac, gravel still a big question mark (bearing in mind Meeke had a very good starting position on Friday)

[EstWRC]

Regarding the gearbox issue that Tänak had. How big difference it is running with gravel gearbox instead of tarmac one on tarmac rally ? Is it a big disadvantage or not?

[AnttiL]

Regarding the gearbox issue that Tänak had. How big difference it is running with gravel gearbox instead of tarmac one on tarmac rally ? Is it a big disadvantage or not?

Probably just different gear ratios? It didn't seem to slow him down that much...

[AnttiL]

Looking back now, Hyundai seems to have a big history this season with suspension/steering failures from relatively minor collisions

Monte Carlo Neuville
Sweden Neuville
Argentina Sordo (fixed on the road)
Sardegna Paddon
Finland Paddon (hit the same stone as Tänak, who got away with just a puncture)
Finland Paddon (2nd day)
Germany Neuville
Spain Sordo
Spain Mikkelsen
Spain Neuville

The only other similar issues that come to mind are Østberg's suspension failures in Argentina and Sardegna, but I haven't watched the onboards to know how if he goes off or not, but I got the impression that his team has a weaker part or a part not changed as often as M-Sport. Lappi knocked the suspension in Poland but the most damage was to the engine (the same as Latvala in Spain?). Hänninen also did something similar in Finland but they were able to keep it together to service and didn't even slow down that much.

[Mirek]

Regarding the gearbox issue that Tänak had. How big difference it is running with gravel gearbox instead of tarmac one on tarmac rally ? Is it a big disadvantage or not?

IMO nobody of us can say how big handicap it is. Probably the main issue is that the center and front differentials are one unit with the gearbox (I think they are). At least front one is mechanical and since You can't open it You have to drive with wrong ramps in it. That means You have to change maps of the center one to somehow cope with it, i.e. it for sure isn't optimal.

[EstWRC]

Thanks like always mirek!

[dimviii]

IMO nobody of us can say how big handicap it is. Probably the main issue is that the center and front differentials are one unit with the gearbox (I think they are). At least front one is mechanical and since You can't open it You have to drive with wrong ramps in it. That means You have to change maps of the center one to somehow cope with it, i.e. it for sure isn't optimal.

that's exactly the problem,the diffs ramps and preloads,than the shorter gravel gear ratios.Gravel diffs are more ''tight''
considering that,Tanaks pace was excellent vs Ogier.

[racerx1979]

The time lost on high speed sections with lower gravel rations could be a big factor too.

Tanak did an amazing job.

[racerx1979]

A few images of the Yaris suspension set-up.

The control arms and subframes are works of art. Formed and welded components which are lightweight yet extremely strong.

toy 1.jpg
toy 2.jpg
toy 3.jpg

[NickRally]

Going back to the Hyundai upright failures and looking at them from structural point of view rather than drivers' errors, I was wondering where do the rules stand on MMC (metal matrix composites)? I haven't got the time to check, but won't be surprised if they are banned. Maybe Mrpengski can let us know.
I am only saying this to exclude the possibility that the usage of this low strain to failure high notch sensitive, but light and stiff material is the culprit, given that the failures occurred around the lower joint threaded area with the thread acting as a "notch".
Excluding this, I assume the uprights are machined from forged billets, then shot peened for better fatigue resistance, giving the surface its matt appearence.
The other option is that the uprights are made from extruded aluminium billet (or even worse, cast billet - very hard to believe), which will give lower structural properties.
Next questio is what kind of ali alloy as some of the high performance structural aluminium alloys can be low strain to failure high notch sensitive.
Final point - is Hyundai's structural "rock touch" load case, that the suspension components are designed to, severe enough to cope with the events encountered on the side of the road? It is a very fine balancing act between ending with not too heavy components and not too weak components.