Technical Analysis: WRC Cars 2016

[Lundefaret]

The modern WRC regulations stipulates that the cars are very similar. But still there are differences, that make for different characteristics, pros and cons.

I thought we could have a thread where we collect the information we have on the 2016 factory WRC cars, including differences and similarities.

The more information we get on the set up of the different drivers, the better.
Lets see how much specific knowledge in this area there is on this forum :)

[Lundefaret]

Suspension:

Citroën:
The main things that is characteristic for the Citroën DS3 WRC is:
- That the dampers go in an almost straight angle (90 degrees) from the top mount to the top of the hub.
This means that there is as little friction as possible, but it will be a disadvantage regarding travel - especially on droop - if I understand this correctly.
- That there is adjustability in the suspension mounting points on the chassis. This is important to get low ride hight (or any change in ride hight), and still be able to change the geometry, allowing for eks adjustability in sideways roll. (Correct me if Im wrong).
- The DS3 set up is seen as a set up that prioritises tarmac, and is typically French.
- There is a belief that the dampers on the current DS3 WRC is to old fashion to be really competitive, but trust me: Ogier would be World Champion in this too.

Hyundai i20 WRC 2016
Hyundai has choses this typically French route, and has mounted the dampers in the same way as Citroën. To get the full benefit of this, You really should be a Nose End First driver, or You will fight with understeer.
Hyundai choosing this route when it comes to the suspension is maybe the most controversial part of the new design.

Ford Fiesta WRC
M-Sport has been in the fore front when it comes to suspension travel. The angular mounting of the dampers are a typical M-Sport signature, and is visible when the Fiesta (or earlier the Focus) was pictured with max droop, and the car looks like it has several metres of travel - tough the real number is some what more sober than that.
M-Sport has also been the ambassador of Reiger, by many seen as the pinnacle of privateer rally suspension (especially gravel/snow).

Volkswagen
Volkswagen is a "copy" of Ford, with angular mounting. The suspension movements on the Volkswagen has set a new standard in WRC. The long travel and excellent dampers is unbelievably good on gravel and snow, but it has also shown a great ability on tarmac.

[TWRC]

Suspension:

Citroën:
The main things that is characteristic for the Citroën DS3 WRC is:
- That the dampers go in an almost straight angle (90 degrees) from the top mount to the top of the hub.
This means that there is as little friction as possible, but it will be a disadvantage regarding travel - especially on droop - if I understand this correctly.
- That there is adjustability in the suspension mounting points on the chassis. This is important to get low ride hight (or any change in ride hight), and still be able to change the geometry, allowing for eks adjustability in sideways roll. (Correct me if Im wrong).
- The DS3 set up is seen as a set up that prioritises tarmac, and is typically French.
- There is a belief that the dampers on the current DS3 WRC is to old fashion to be really competitive, but trust me: Ogier would be World Champion in this too.

Hyundai i20 WRC 2016
Hyundai has choses this typically French route, and has mounted the dampers in the same way as Citroën. To get the full benefit of this, You really should be a Nose End First driver, or You will fight with understeer.
Hyundai choosing this route when it comes to the suspension is maybe the most controversial part of the new design.

Ford Fiesta WRC
M-Sport has been in the fore front when it comes to suspension travel. The angular mounting of the dampers are a typical M-Sport signature, and is visible when the Fiesta (or earlier the Focus) was pictured with max droop, and the car looks like it has several metres of travel - tough the real number is some what more sober than that.
M-Sport has also been the ambassador of Reiger, by many seen as the pinnacle of privateer rally suspension (especially gravel/snow).

Volkswagen
Volkswagen is a "copy" of Ford, with angular mounting. The suspension movements on the Volkswagen has set a new standard in WRC. The long travel and excellent dampers is unbelievably good on gravel and snow, but it has also shown a great ability on tarmac.
Regarding the DS3's dampers and suspension, the layout is basically the evolution of what the Xsara and C4 had, even the reservoir mountings in the wheelarches are pretty much the same. As far as the dampers go, they're basically the same as they started with in 2011, only minor, internal improvements were made AFAIK.

As to which is the best, in my mind there's no doubt it's VW's. On tarmac it's just unbelieveable, no matter what, the car is just glued to the road, enables super smooth driving, and the car seems very easy to drive.

[Mirek]

VW is not a copy of M-Sport. Volkswagen is further developed copy of Fabia S2000 which took a lot from the Reiger/M-Sport philosophy but presents some important changes. For example rear dampers are mounted opposite than on M-Sport cars. The reason is IMO to bring the damper mass towards the center of gravity.

M-Sport designs were always let's say less "centric" than for example French ones (for example spare wheel position on Focus WRC and early Fiesta S2000 makes center of gravity lower but in the same time it's bad solution for body inertia). Part of this goes also to the dampers. M-Sport uses rear dampers inclining backwards which means all their mass is behind the rear axle. I can not evaluate the suspension itself (how much better/worse it is to have the inclination backwards or frontwards) but for the body inertia it's for sure better to have the Škoda/VW option.

Polo WRC is a direct development of Fabia S2000, the suspension scheme is same. The biggest difference is the use of Sachs dampers which are fundamentally different (I think, or at least they appear so). A much more substantial change which Škoda uses on Fabia R5 may one day appear on Polo too if there is a positive experience.

What also stroke me (despite being observed only on R5 cars) is that Sachs setup (Fabia) uses a lot softer helper springs than Reiger one (Fiesta R5).

[Mirek]

The heavily inclined dampers are good for travel but they are not good for some other things. One is high inner friction as was mentioned, the other is that the high caster angle causes really big forces in steering which may lead to issues with reliability (and it has been indeed an issue of both M-Sport cars and early Fabia S2000).

[janvanvurpa]

Suspension:

Citroën:
The main things that is characteristic for the Citroën DS3 WRC is:
- That the dampers go in an almost straight angle (90 degrees) from the top mount to the top of the hub.
This means that there is as little friction as possible, but it will be a disadvantage regarding travel - especially on droop - if I understand this correctly.
- That there is adjustability in the suspension mounting points on the chassis. This is important to get low ride hight (or any change in ride hight), and still be able to change the geometry, allowing for eks adjustability in sideways roll. (Correct me if Im wrong).
- The DS3 set up is seen as a set up that prioritises tarmac, and is typically French.
- There is a belief that the dampers on the current DS3 WRC is to old fashion to be really competitive, but trust me: Ogier would be World Champion in this too.

Hyundai i20 WRC 2016
Hyundai has choses this typically French route, and has mounted the dampers in the same way as Citroën. To get the full benefit of this, You really should be a Nose End First driver, or You will fight with understeer.
Hyundai choosing this route when it comes to the suspension is maybe the most controversial part of the new design.

Ford Fiesta WRC
M-Sport has been in the fore front when it comes to suspension travel. The angular mounting of the dampers are a typical M-Sport signature, and is visible when the Fiesta (or earlier the Focus) was pictured with max droop, and the car looks like it has several metres of travel - tough the real number is some what more sober than that.
M-Sport has also been the ambassador of Reiger, by many seen as the pinnacle of privateer rally suspension (especially gravel/snow).

Volkswagen
Volkswagen is a "copy" of Ford, with angular mounting. The suspension movements on the Volkswagen has set a new standard in WRC. The long travel and excellent dampers is unbelievably good on gravel and snow, but it has also shown a great ability on tarmac.


Nååååå, pojken, ut me det. If you have numbers a little more accurate than “looks like meters" and "less than the others" by all means post it up.

And one thing certainly lacking since the rise of Social Media : PHOTOGRAPHS of the sort of thing you are referencing....
Post photographs...Compare and contrast visually is only way to begin to makes sense of any of this..

Tack ska du ha!

[AndyRAC]

The modern WRC regulations stipulates that the cars are very similar. But still there are differences, that make for different characteristics, pros and cons.

I thought we could have a thread where we collect the information we have on the 2016 factory WRC cars, including differences and similarities.

The more information we get on the set up of the different drivers, the better.
Lets see how much specific knowledge in this area there is on this forum :)

I have to be honest - because of the regs, I find the current WRCars probably the least interesting of current world motorsport machines.

[Mirek]

I wonder why? Because of the look, the used technologies or because of the appearance?

[Gregor-y]

Maybe the technology. If I recall some of the suspension points on my second generation Impreza are based on experience with the WRC.

[Mirek]

True that there's nothing groundbraking on today's WRC but it's hard to ballance with spectacle because the true development sacrifices spectacle for effectivity. The 2017 cars will be more advance but most likely quite boring cars to watch compared to the current ones. I personally prefer those we have now from what's going to come in 2017.

[itix]

There is nothing wrong with the machinery. Maybe they could do with a bit more power and nothing changed in the rest of the car but I doubt that you could make the cars more spectacular with any other comprehensive rules change.

The inwards caster angle (which is not called inwards caster angle but I have forgotten what it is actually called) seem to be virtually nil (or 90 degrees or however you put it) on all the current WRC machinery, am I right?

So in my mind the main reason for VW dominance must be "a bit of everything". From onboards they seem to have a much better engine as from any given moment where cars exit the corner or take off from the start line they always seem to arrive at the next corner faster to what you compare them with.

At the same time, you lot say that it looks more easy to drive. I don't actually understand a shit of this so can't really judge. I understand this with low centre of gravity and the importance of the contact with the road surface and all of that but I just don't have the know how to translate it to technical details. I've come to understand that the dampers these days are basically oil filled with ball bearing type support for taking up horizontal forces to minimise friction but i am sure that all the big companies do this today. The reservoir, is it some form of small gas accumulator in there which you can alter? I very much doubt that all of it is oil with the suspension travel they have. It is impossible to compress oil that much.

One thing I can tell is that the manufacturers manage boost control very differently. Hyundai still has a relatively pronounced chirp on shut throttle body... I think it is VW that also has a pretty distinct chirp as well (but different in sound). They all have exactly the same bore and stroke according to themselves (83 and 73.8 mm) so the difference, which is audible, must come from things like boost management, difference in the ALS systems and other electronic engine controls as well as minimising mechanical and thermal losses. I am pretty sure that the airflow to the engines is as optimised behind the restrictor as it can get so most effort is probably in maintaining boost pressure as close to the FIA 2.5 bar mandated number as possible at all times.

If I remember the rules correctly you are locked to one set of gear and differential ratios for the entire season so I am fairly sure this is close to optimised as well.

This leaves us with things like the body stiffness, difference in dampers and spring rates, geometry and length of wishbones, weight of components and how low you can ballast the car, neutrality in turn in and weight transfer and predictability for the driver I guess. A car that's easy to drive would also give you confidence to push everywhere.

[janvanvurpa]

I have to be honest - because of the regs, I find the current WRCars probably the least interesting of current world motorsport machines.

I dunno..I find the complete and utter lack of good detailed information diminishes my interest.
I wish I could get nice line drawings, clear unobstructed photos of the suspension showing the suspension geometry and angles just to ponder...
I know this is motorsport and the first part of the word is MOTOR and most "fans" and even most lower level participants seem to fixate on motor....and there's been some really good and meaty discussion right here over the years on the motors, but the real decisive difference between our collectively beloved rally cars and other types of cars is mainly been in suspension (and to some degree in diff design--and function), especially if you look at rally cars over a period of time...
This idea has some merit if we recall not so many years ago when Juha Kankunen made a guest starring role in WRC Finland YEARS and YEARS after he was last in serious competition and he was asked what he thought of the car..He seemed his normal casual self when asked about motor and power "Oh we had plenty power back then" but when he got to suspension and brakes, his eyes lit up...there was what evidently was for him the big revelation.

But instead of good clear photos of parts and pieces and parts installed.....and being able to see and wonder about this huge advances instead....


people want to discuss in detail paint schemes.:snore:

mon dieu ma pauvre sport

[janvanvurpa]

Maybe the technology. If I recall some of the suspension points on my second generation Impreza are based on experience with the WRC.

No not really..Look at the entire rear of the car....The upright or knuckle, subframe, mounting, is totally different design with the strut being entirely forward of the hub on your car while all the Group a and Whirled Rally cars had normal conventional upright with the strut fixed directly above the hub..
The old Group A rules under which first Le-gassy and GC8 were homologated mandated that suspension mounting points had to be within +or - I think 15mm, maybe 20mm.
This locked in design to some degree, but nothing was the same in any way.. Have you seen the site selling all kinds of Surau WRC spares?..Fascinating seeing the hege variety of parts there

WRC rear upright and hub:
http://www.subaruwrcspares.com/resources/_wsb_440x472_Upright+Hub++RR.jpg

OEM
http://www.licmotorsports.com/sites/default/files/imagecache/product_full/_mg_0316.jpg

One of these is not like the udder.

[TWRC]

There is nothing wrong with the machinery. Maybe they could do with a bit more power and nothing changed in the rest of the car but I doubt that you could make the cars more spectacular with any other comprehensive rules change.

The inwards caster angle (which is not called inwards caster angle but I have forgotten what it is actually called) seem to be virtually nil (or 90 degrees or however you put it) on all the current WRC machinery, am I right?

So in my mind the main reason for VW dominance must be "a bit of everything". From onboards they seem to have a much better engine as from any given moment where cars exit the corner or take off from the start line they always seem to arrive at the next corner faster to what you compare them with.

At the same time, you lot say that it looks more easy to drive. I don't actually understand a shit of this so can't really judge. I understand this with low centre of gravity and the importance of the contact with the road surface and all of that but I just don't have the know how to translate it to technical details. I've come to understand that the dampers these days are basically oil filled with ball bearing type support for taking up horizontal forces to minimise friction but i am sure that all the big companies do this today. The reservoir, is it some form of small gas accumulator in there which you can alter? I very much doubt that all of it is oil with the suspension travel they have. It is impossible to compress oil that much.

One thing I can tell is that the manufacturers manage boost control very differently. Hyundai still has a relatively pronounced chirp on shut throttle body... I think it is VW that also has a pretty distinct chirp as well (but different in sound). They all have exactly the same bore and stroke according to themselves (83 and 73.8 mm) so the difference, which is audible, must come from things like boost management, difference in the ALS systems and other electronic engine controls as well as minimising mechanical and thermal losses. I am pretty sure that the airflow to the engines is as optimised behind the restrictor as it can get so most effort is probably in maintaining boost pressure as close to the FIA 2.5 bar mandated number as possible at all times.

If I remember the rules correctly you are locked to one set of gear and differential ratios for the entire season so I am fairly sure this is close to optimised as well.

This leaves us with things like the body stiffness, difference in dampers and spring rates, geometry and length of wishbones, weight of components and how low you can ballast the car, neutrality in turn in and weight transfer and predictability for the driver I guess. A car that's easy to drive would also give you confidence to push everywhere.
Found this on another forum, it explains the external reservoir dampers better than I could:

"The interior of a shock is a closed system, but as the shaft goes in and out of the damper body, the available volume in the system changes because the shaft takes up some space.

Since the oil is incompressible, you have to have some gas in there to account for this change in volume. Separating the gas from the oil with a sliding piston keeps the oil from frothing up. But it also makes the shock body very long unless you 'remote' the part that has the piston in it. That's the whole purpose of the reservoir. The amount of oil that flows into the reservoir as the shock compresses is the exact volume of the shock shaft that has entered the damper body."

Here (http://www.ds3wrc.fr/article-la-technique-les-amortisseurs-ii-le-reglage-61668757.html)'s a good site on the DS3's suspension geometry; the reservoir is the big tube hanging off the top of the damper, or in a Reiger rally damper's case, it's the purple tube attached to the bottom of the damper body. Hope this helps. :)

[Gregor-y]

WRC rear upright and hub:
http://www.subaruwrcspares.com/resources/_wsb_440x472_Upright+Hub++RR.jpg

OEM
http://www.licmotorsports.com/sites/default/files/imagecache/product_full/_mg_0316.jpg

One of these is not like the udder.
Did the homologation rule for mounting still hold sway in 2001? It's definitely a different location unless the struts are massively misshapen. Now that the rust's fixed I'm waiting to see if the next failure will be the wheel bearings which is why I'm a little familiar with these parts. All the yahoos want to use ceramic this and polyurethane that which can't be comfortable or long-lived.

[Tomvwb]

Mirek, Don't think about the helper spring to much, its never used while normal driving only used when there are jumps. But the difference between the sachs en the reiger is that the reiger has developed a pure mechanical hydraulic system RCV. this system feels when the wheel is not touching the road and releases the rebound so that the wheel is making faster ground contact. thats why there is a lager helper spring, to push the unsprung weight as fast as possible out, even until the last mm.

About this topic, there are a lot of suspension designs, made for a lot of reasons, travel, brake cooling, forces, but most important how the geometry changes while body roll or travel changes. because this is the actual wheel grip together with the load on that wheel.

About the new I20 WRC, there are some complains about understeer, but remember who tested the car , Abbring is always driving very much understeer and also searching a set-up for this. witch results in fast corner speed and early on throttle with great traction on rear. but he has already proven that's a fast way of driving (check again Kevin's palmares, the only vw test driver that could match the speed of Ogier in 2012, not consistent but on some stages.:D). other drivers will adapt this driving style or change the setup slightly.

[Toyoda]

This thread is brilliant,
It actually reminds me of another annoying thing that WRC doesn't do but F1 does.
F1 frequently have articles about various aspects of the F1 cars and the differences between them, often semi detailed schematics and the pros and cons of the different designs, engine, aero components, suspension etc
Would be sweet if the WRC official journalists got off the ass and did some real analytical stuff! Instead of the fan boy and regurgitated crap articles they do at the moment.

Interesting that Hyundai continued down the French route, even though Neuville did his best season with MSport and Paddon's style I imagine also would not suit it? Surely
copying and improving on the most successful car (VW) would be a logical method for the development of Hyundai's new car? Or is it an experience (engineer/design personal) /safe (previous data from old i20) option thing?

[AndyRAC]

It's not just F1, the WEC has loads of details about the different technical aspects of the cars. As you say, WRC journalism isnt great, in fact it's so poor it's not funny. We mostly get PR pieces rather than serious journalism.

[Mirek]

Mirek, Don't think about the helper spring to much, its never used while normal driving only used when there are jumps. But the difference between the sachs en the reiger is that the reiger has developed a pure mechanical hydraulic system RCV. this system feels when the wheel is not touching the road and releases the rebound so that the wheel is making faster ground contact. thats why there is a lager helper spring, to push the unsprung weight as fast as possible out, even until the last mm.

Thanks, I know about the Reiger rebound control but I didn't realize that the helper spring is actually a part of it. Now it makes sense to have stronger ones. It brings a small disadvantage of added unsprung weight. Can't say how much is the difference but the helpers on Fiesta are a lot more massive than on Fabia. I guess it's not so significant but it's another difference to full picture.


Interesting that Hyundai continued down the French route, even though Neuville did his best season with MSport and Paddon's style I imagine also would not suit it? Surely
copying and improving on the most successful car (VW) would be a logical method for the development of Hyundai's new car? Or is it an experience (engineer/design personal) /safe (previous data from old i20) option thing?

I would say that it's about personal experience. I believe the i20 was designed mainly by former Peugeot/Citroën guys.

[Karukera]

So partly is the Polo.
Besides Skoda's technical legacy, FX Demaison is a PSA shaped engineer, Sainz last WRC drives and development at Citroën took an early grip on the Polo and Ogier came from the successful DS3.

[itix]

This thread is brilliant...! We should have a lot more technical discussions in the forum!

[TyPat107]

There is nothing wrong with the machinery. Maybe they could do with a bit more power and nothing changed in the rest of the car but I doubt that you could make the cars more spectacular with any other comprehensive rules change.

The inwards caster angle (which is not called inwards caster angle but I have forgotten what it is actually called) seem to be virtually nil (or 90 degrees or however you put it) on all the current WRC machinery, am I right?


You are thinking of "camber" I think.

I was searching for pictures of wrc/r5/s2000 engine bays the other day and stumbled upon a Ford Fiesta street car forum. A technician from m-sport was commenting that thinking has changed for current generation cars as far as the intake system goes. He said they are using smaller diameter charge piping, intercoolers, and smaller diameter throttle bodies to improve engine response. He also said doing so didn't have much affect on top end power because they removed the turbo restrictor and the car made nearly 600hp.

[Mirek]

The camber on asphalt is usually between 2 and 3° I think. Less on loose surface. I think that camber reliance in a setup of car with McPherson struts shall be somewhat eliminated to minimum because the camber changes hugely with the damper travel.

[itix]

You are thinking of "camber" I think.

I was searching for pictures of wrc/r5/s2000 engine bays the other day and stumbled upon a Ford Fiesta street car forum. A technician from m-sport was commenting that thinking has changed for current generation cars as far as the intake system goes. He said they are using smaller diameter charge piping, intercoolers, and smaller diameter throttle bodies to improve engine response. He also said doing so didn't have much affect on top end power because they removed the turbo restrictor and the car made nearly 600hp.

Camber is the angle of the wheel to the ground. I was actually thinking about the angle of the damper to chassis (relative to flat ground). You can have backwards or forwards angle (caster) and "outwards" angle which is called something else... maybe damper camber but that sounds weird to me.

Super interesting about the inlet dim. and the restrictor. I guess they optimized the intake to create as ideal flow as possible and make sure the restrictor was still the bottle neck. It still doesn't make 100% sense to me as they would have potential for pressure losses and you'd want to have as little under pressure as possible on the turbine side to optimize air flow through the turbine.

[skarderud]

Just Wonder of some specnumbers.
I find that the polo, officially, has 329hk and 430nm in the engine. How far of is it really? I going for a radiointervju and they going to ask of stuff like that:)

[Mirek]

Good question. Maybe somebody has real figures for these 1.6T WRC cars.

Afaik Fiesta R5 Evo or Fabia R5 have around 450 Nm of torque and I'm quite sure WRC cars have more. Also the peak power is around 305-310 Hp for these R5 cars and more for PSA ones (I believe). Therefore I think that WRC have more than 330 Hp.

[Toyoda]

Ok, Question to those of more knowledge,
The Hyundai boy's were continuously complaining about poor lateral grip, I also noticed that in videos such as this https://www.youtube.com/watch?v=Q42jT7AsNFE the Hyundai's are bouncing at the rear end after large jumps.
In order to increase lateral grip would they have tried to soften the back suspension (perhaps also lower the car? lower COG less body roll?) and hence the result is it bottoming out over the big jumps?
or if not how would you go about fixing this kind of thing, what have the VW and Citreon guys cooked up that improves their lateral grip?

Many thanks :)

[Zeakiwi]

Quite complex.
I would suspect the VW/ Citroen have a better 'blade setup?' design between the rear suspension and the antiroll bar.
http://tinyurl.com/hvafxqg (VW sus rear pic)
Probably have different shock absorber valving etc
https://youtu.be/GhUE7LIxAso
Guess that Hyundai went a bit heavy with the antiroll bar or coil springs etc causing weight to reduce on inside wheel - reducing cornering speeds.
http://reigersuspension.com/wordpress/English/auto/rally/wrc/

https://youtu.be/cVzpoF3S48w (Reiger Rally Shock absorber explained)

[br21]

Hyundai is not using Reigers anymore in their 2016 cars. Same goes for 2017 car and R5.

[Mirek]

By the way has anybody already seen a photo of VW 2017 suspension? I'm curious to see if they keep following the Fabia S2000 scheme or if they decided to switch to what Škoda has been trying with the R5 or something completely different.

[dimviii]

Hyundai is not using Reigers anymore in their 2016 cars. Same goes for 2017 car and R5.

what are they using?

[AMSS]

what are they using?

Extreme shox Italy

[Zeakiwi]

Extreme from Italy. 2 fastest times out of 24 from Finland
http://extremeshox.com/en/index

[dimviii]

Extreme from Italy. 2 fastest times out of 24 from Finland
http://extremeshox.com/en/index

must be the new name of the old ''EXTREME TECH''?

[AMSS]

Imagine how many fastest times Hyundai could have had with proper dampers.... :)

[Sulland]

Imagine how many fastest times Hyundai could have had with proper dampers.... :)

Why do you mean that the current dampers are not proper?

[Mirek]

must be the new name of the old ''EXTREME TECH''?

I thought the same.

[itix]

Imagine how many fastest times Hyundai could have had with proper dampers.... :)
I like Sulland wonder why you'd think that.

We are talking about probably the best funded team of them all here... With three years of experience in the sport and individuals with I very much doubt that haven't tested enough to make an informed choice. I guess suspension like everything else is homologated, so it's not like you can just swap it as you like.

Also this is by far my favorite thread :)
We are a forum full of knowledge, why isn't there more activity here?

Edit: Mirek, I guess you mean the negative caster angle both front and rear that the Skoda and the Fiesta WRC share (don't know about the R5 car, haven't checked).

[AMSS]

I was at Tommis jump on Ouninpohja everybody who was there must agree, they jumped up and down again after landing badly, like old gr.B. And this was just one jump. They had big problems with rear traction clearly visible not only on the event but already on PET they had this issue. During the event they tried to get more traction in the rear by softening it way too much.
OK it`s not the dampers fault as janvanvurpa wrote it`s the people making adjustments (either damper suppliers or Hyundais engineers) that lack knowledge in what their doing. For instance Reiger and Öhlins for sure has this know how but for some reason Hyundai has opted to not use them...

[Mirek]

Edit: Mirek, I guess you mean the negative caster angle both front and rear that the Skoda and the Fiesta WRC share (don't know about the R5 car, haven't checked).

I am hardly a suspension specialist but I believe that it's positive castor what they use, i.e. the lead point is ahead of the wheel contact point (the geometry has a stabilizing effect).

Anyway that was not my point. I meant if they use the dampers positioned in / \ shape like Fabia S2000/Polo WRC, in // shape like Fiesta S2000/WRC, in II like French cars and Hyundai or in something like _I_I from Fabia R5. The castor angle is another question as it is also positive with Fabia R5 even with vertical damper behind the wheel hub (thanks to the position of lower ball joint).

[dimviii]

For instance Reiger and Öhlins for sure has this know how but for some reason Hyundai has opted to not use them...

+1

as we have seen from fiesta and works minis they are landing very smooth and progressive.

[Lundefaret]

Regarding caster angle: Even if the damper is mounted diagonally doesnt mean its got a lot of caster angle.
Its the theoretical line between mounting of the wheel and the top mount that decides this. So you can have the same caster angle on a diagonal damper like Ford and VW, as on a straight up-and-down one like Citroën and Hyundai.
The positive with the diagonal damper is that it allows for longer damper travel, but since its movement is not in line with the theoretical caster angle it will have more friction.

[itix]

I am hardly a suspension specialist but I believe that it's positive castor what they use, i.e. the lead point is ahead of the wheel contact point (the geometry has a stabilizing effect).

Anyway that was not my point. I meant if they use the dampers positioned in / \ shape like Fabia S2000/Polo WRC, in // shape like Fiesta S2000/WRC, in II like French cars and Hyundai or in something like _I_I from Fabia R5. The castor angle is another question as it is also positive with Fabia R5 even with vertical damper behind the wheel hub (thanks to the position of lower ball joint).

As I have understood it, caster angle is the angle the suspension has relative to the normal of the road and negative is supposed to be when it lean "backward" from the upright (I.e. The upper contact point is behind the lower contact point). I am not an expert either so I might be wrong though.

I see what you mean with the Fabia being a bit special though because the contact point of the suspension is very far towards the back on the upright.

Unless I remember wrong VW will be getting a new body shell as well so the set up on their test mule might not be the final one.

Edit: it looks like I remembered the Fabia R5 wrong. From my memory it had the contact points in front of the upright and the damper going forwards but it seems it was the opposite. Apologies for that.

[itix]

Regarding caster angle: Even if the damper is mounted diagonally doesnt mean its got a lot of caster angle.
Its the theoretical line between mounting of the wheel and the top mount that decides this. So you can have the same caster angle on a diagonal damper like Ford and VW, as on a straight up-and-down one like Citroën and Hyundai.
The positive with the diagonal damper is that it allows for longer damper travel, but since its movement is not in line with the theoretical caster angle it will have more friction.
Aha... Thanks a bunch! I guess that's why skoda has gone down the route of mounting the damper so far back on the upright.

If it is still allowed to have "ball bearing structure" inside the damper like in the old days I can't imagine friction is a big issue on these dampers though.

[Mirek]

As I have understood it, caster angle is the angle the suspension has relative to the normal of the road and negative is supposed to be when it lean "backward" from the upright (I.e. The upper contact point is behind the lower contact point). I am not an expert either so I might be wrong though.

I see what you mean with the Fabia being a bit special though because the contact point of the suspension is very forward on the upright.

Unless I remember wrong VW will be getting a new body shell as well so the set up on their test mule might not be the final one.

Basically this what Lunde said ;)


Regarding caster angle: Even if the damper is mounted diagonally doesnt mean its got a lot of caster angle.
Its the theoretical line between mounting of the wheel and the top mount that decides this. So you can have the same caster angle on a diagonal damper like Ford and VW, as on a straight up-and-down one like Citroën and Hyundai.
The positive with the diagonal damper is that it allows for longer damper travel, but since its movement is not in line with the theoretical caster angle it will have more friction.

I think that You confuse it a bit. When the lead point (i.e. the point where You cross the road surface by a line connecting upper and lower joints - steering axis) is ahead of the contact point between the wheel and the surface You have a positive castor - when You steer from straight direction You lift the car body and therefore its own weight brings steering back to straight direction. It gives a stabilizing effect to the steering but brings very high forces and it's one of the reasons why rally cars have often problems with power steering.

I don't think any rally car ever had negative castor but maybe I am wrong. I think some circuit cars have zero or close to zero castor but I am not sure.

As Lunde said You can have positive castor with nearly whatever position of damper as You can place the lower joint elsewhere than at the damper axis. That's the case of Fabia R5 with very extraordinary damper position.

@ Lunde: From what I learned about the Fabia R5 damper position the other disadvantages of diagonal settings are very high forces in steering and worse brake cooling (the damper is placed in the air flow) but as You said the main point is the friction (and the steering reliability). I'm curious about 2017 VW car to see if this idea how to get rid of those negative effects gets also in VW or if it is maybe found not that good like it theoretically shall be.

[itix]

I think that You confuse it a bit. When the lead point (i.e. the point where You cross the road surface by a line connecting upper and lower joints - steering axis) is ahead of the contact point between the wheel and the surface You have a positive castor - when You steer from straight direction You lift the car body and therefore its own weight brings steering back to straight direction. It gives a stabilizing effect to the steering but brings very high forces and it's one of the reasons why rally cars have often problems with power steering.

I don't think any rally car ever had negative castor but maybe I am wrong. I think some circuit cars have zero or close to zero castor but I am not sure.

As Lunde said You can have positive castor with nearly whatever position of damper as You can place the lower joint elsewhere than at the damper axis. That's the case of Fabia R5 with very extraordinary damper position..

Ah yeah! You are right, my grey cells have started to work again.

Now that you mention it, it makes sense in my head again. Caster angle polarity is relative to the contact patch on the ground of the wheel and nothing else. The angle of the damper itself towards the normal of the road is irrelevant.

[danon]

so many explanations, words and waste of time... for a 2 min vid

https://www.youtube.com/watch?v=Gh7gWJAvOvs

[itix]

so many explanations, words and waste of time... for a 2 min vid

https://www.youtube.com/watch?v=Gh7gWJAvOvs
I've seen it ages ago danon. It's a great video, and so are most of his videos for a theoretical understanding of many aspects of a car.

Problem is me and my memory mixing things and terms up ;)

[OldF]

I didn’t find any pictures of caster layout with the damper in front or rear of the upright so I had to make my own. I hope I got it right.

One thing I begun thinking about when I made the pics is the position of the steering axis relative to the wheel centre. As you can see on the second pic the steering axis doesn’t go true the wheel centre. What kind of affect does this have to the handling (steering axis true wheel centre or not)?

http://i267.photobucket.com/albums/ii284/OkdF/Caster%201_zpsirw41j9b.jpg

http://i267.photobucket.com/albums/ii284/OkdF/Caster%202_zpsu8awhjar.jpg

[Mirek]

In my opinion the steering axis must pass the wheel center at least because of fixed driveshaft length.

By the way asphalt Fabia S2000 had by the default approximately 8,5°castor with the angle of damper being roughly guessing 20°.

For Focus WRC02 I found castor 6,5° on gravel and 7,8° on tarmac.

[OldF]

As I understand the drive shaft length is not completely fixed. The inboard joint give little flexibility to the length but is it enough to cope with suspension movements plus if the steering axis doesn’t go true the wheel center.

http://www.freeasestudyguides.com/constant-velocity-joint.html

http://www.freeasestudyguides.com/graphics/cv-joint.png

[TyPat107]

I know there weren't many out there now but the Mini WRC fit in with this same generation of car. I couldn't find much technical detail out there, does anyone on here have any info on them. I can find hundreds of pictures of the engine at the same angle but I'd love to see any more information about the car. I also haven't been able to find pictures of the rear suspension.

[Mirek]

From ewrc.cz. Probably the best Mini ever even though used mostly only as an RRC car.

http://www.ewrc.cz/images/2015/photos/rallye_umava_klatovy_2015/ben_img_3229.jpghttp://www.ewrc.cz/images/2015/photos/rally_bohemia_2015/shl_img_0235.jpg
http://www.ewrc.cz/images/2014/photos/int_jnner_rallye_2014/jfr_dsc_0083.jpg
http://www.ewrc.cz/images/2014/photos/rallye_esk_krumlov_2014/jou_14ck38.jpg
http://www.ewrc.cz/images/2014/photos/rallye_esk_krumlov_2014/jfr_dsc_0010.jpg
http://www.ewrc.cz/images/2014/photos/agrotec_petronas_syntium_rally_hustopee_2014/pel__e1_3017.jpg
http://www.ewrc.cz/images/2014/photos/barum_czech_rally_zln_2014/gry_44.jpg
http://www.ewrc.cz/images/2014/photos/int_jnner_rallye_2014/jan_116.jpg

You can find probably more if You go through photos of Václav Pech in the database. These are only from 2014-2015.
http://www.ewrc-results.com/profile.php?p=3534&t=Vaclav-Pech-jun