Technical Analysis: WRC Cars 2017

[ESTR]

The question is: HOW DO THAT HYUNDAI of Neuville survive Argentina?? Germany and spain total disaster

[racerx1979]

The matte appearance from hard anodizing, not shot peening.

Not sure about Hyundai, but the Toyota hubs are forged monoblock body hubs (similar to AP uses for calipers). The other teams could possibly using billet hubs if not forged. Nobody would use cast alloy. MMC could be a possibility since a lot of the Manu's are using Pankl comoponents for suspension hubs, uprights etc and they use MMC for other racing forms. I'm not sure if MMC is allowed for WRC.

https://www.pankl.com/en/racing/driv...nology-design/
https://www.pankl.com/en/racing/drivetrain/products/

[NickRally]

ESTR - very simple - the suspension did not see loads exceeding its envelope

racerx1979 - I would be very surprised if the colour comes from hard anodizing rather than shot peening. Structural ali alloys do not hard anodize well and any hard anodizing significantly reduces the fatigue properties, while hardly really contributing to making the alloy that hard, while shot peening increases significantly the fatigue properties, which is critical for a suspension upright.
MMC wise, I will have to dig into the rules and find out if it is allowed (bear in mind it is not allowed for uprights in F1 after 2009), unless someone with inside knowledge is able to comment what the rules say. Anyway, I would be very worried if I had to use MMC for suspension uprights on a rally car.

[racerx1979]

I know for a fact the TGR hubs are hard anodized after being cryo treated. Shot peening sometimes contaminates the surface.

Some of the other manu's hubs may be shot peened before being hard anodized, but they are not shot peened and then left uncoated. The images of the Toyota hubs I pictured above are hard anodized. Also, shot peening is fairly old-tech in the motorsport world. Laser peening is used companies such as Pankl and Arrow.


Shot peening of Al alloys is commonly performed on aircraft parts to be hard anodized. The shot peening induces residual compressive stresses to compensate for the decrease in fatigue life due to the relatively brittle anodic coating. Common applications are hydraulic cylinders and pistons. All shot peening residues are chemically removed prior to anodizing. – MIL-S-13165C, paragraph 3.3.10.2; MIL-P-81985, paragraph 3.5.2.1. Nitric acid-based solutions are used.

Some great reads if you're into Metallurgy.

Effect of Shot Peening Variables on Fatigue of Aluminum Forgings,” Metal Progress, v. 120, No.2, p. 33-35 (1981) and
Hard Anodic Coatings on Aluminum Alloys: Evaluation and Control of Porosity,” Metal Finishing, p. 19-24 (December 1992).

[racerx1979]

And another study from long ago which shows the benefits of shot peening and anodized coatings.

If you don't feel like reading the whole thing go to page 19.

http://dtic.mil/dtic/tr/fulltext/u2/a108869.pdf

[NickRally]

All good reads, thanks racerx1979.
For clarity I should point out that race car suspension component design is part of my daily job.
In general anodizing (either of the hard or decorative kind) is not a great practice for highly stressed suspension components and can do more harm than good for reasons already stated.
Also talking about billets, all machined uprights start from some sort of billet, which in itself can be forged (best for strength), extruded (most common) and cast (worst for strength). For obvious reasons the first two options are preferred for suspension components.

[racerx1979]

I also work on chassis components focusing on motorsport for over 12 years . We use SolidWorks, CREO and Ansys for FEA.

I agree that most "highly" stressed components such as lower control arms are made of T45 or 4130 are not anodized because they are not made of aluminum .

But we are talking about hubs here which are machined from 7075 and then anodized. Some lower control arms are also anodized depending on the application and loads. Scroll down to see the Evo X R4 arms which came in red anodized for the left side and blue anodized for the right side. Typical old school wrc style components.

Ever seen Ohlins, Proflex or EXT shock bodies and reservoirs?

They are always anodized if aluminum and almost always nickel plated if steel. That's the titanium color you usually see.

Just like this AP caliper
https://www.essexparts.com/cp8350-tr...-left-anodized

And some more info from Brembo talking about hard anodized calipers and showing the same gold color. Anytime you see this color its hard anodized.
https://www.youtube.com/watch?time_c...&v=VQdAnQ8GZlA

Sometimes its a clear anodize and the aluminum will have a shiny polished look. Take a look at the components on Miko's old car. Tons of anodized parts (goldish and titanium components) and note the shiny hub. If this was shot peened it would have a dull finish. It's actually clear anodized after being polished.

Mikos car x-tech enginering solutions.jpg

Another hard anodized Subaru WRC machined hub.

99 impreza hub.jpg
S11 TARMAC.jpg
http://www.racetuners.com/shop/index...roducts_id=449

When using steel the components are nickel plated as shown here.
http://rallycarsforsale.net/ads/bran...s-impreza-wrc/

Evo X R4 lower wishbone in red anodize.
http://www.mml-sports.com/index.php/...rm-assembly-lh

Evo X uprights hard anodized.
https://www.brypar.com/shop/prime-r/...front-upright/

[NickRally]

Thanks racerx1979, I am happy to leave it at this.

[NickRally]

Went through the rules (or what is publicly available) and can't see a ban on MMC. Actually, as is usual, the rules are very badly written talking about where "composite material" is allowed, evidently only considering resin (or similarly) based composites here, but without clearly defining what constitutes "composite material" and as such leaves the door open for protests if a team decides to explore the use of MMC, although these can sometimes be more pain than gain.

[Mirek]

IMO it's more precisely described in homologation regulations.