steering knuckles

[gpshumway]

Originally Posted by Spuds

So you are comparing aftermarket control arms to OEM steering knuckles?

I'm comparing OEM control arms to OEM steering knuckles. The 2006 WRX came with aluminum control arms. Is it possible that Karen had installed say Mevotech arms in place of the Subaru ones and it escaped my memory? Sure, it's possible. I'm saying that people who've used their Subarus hard in the past have had durability issues with OEM parts. (5x100 hubs anyone?) They don't have the huge safety margins we imagine, especially when used for track/autocross duty.

Originally Posted by Spuds

And no, static and dynamic forces and their effects on materials are quite well understood. The difference is whether the maker of the part decided to spend time actually doing the math rather than slapping some parts together and saying it's good.

OEMs are not exempt from slapping parts together. The twins are quite obviously a frankenstein of parts-bin components. And the standard modeling they engage in may not include things like R-comp tires. As an example, take a look at 949 racings' discussion of wheel strength and racetrack use. (LINK) For a historical example, consider the suspension mounts on an E46 M3.


Like I said in my original post, given the history of OEM parts used for track duty, and the prevalence of such duty for 86 twins, some slight concern is warranted. The aluminum knuckles should at least be given special attention during pre-track tech inspections.

[DarkSunrise]

The 86/BRZ are widely tracked in Japan (and around the world). Japan’s hit show Best Motoring has featured plenty of heavily modified 86’s and BRZ’s, all of which are on cheater 200tw tires or stickier. I’m 100 percent confident Subaru/Toyota are aware that these cars get modified, tracked frequently and quite publicly. I imagine it would be quite embarrassing for them if something as simple as a revised aluminum steering knuckle became a common failure point, especially when their marketing dept had gone out of its way to highlight the upgrade (see Subaru’s demo days for the gen 2’s with the new part sitting side by side with the old iron knuckle). I guess you never know but that would be a massive black eye for Subaru IMO.

[NoHaveMSG]

Originally Posted by gpshumway

I'm comparing OEM control arms to OEM steering knuckles. The 2006 WRX came with aluminum control arms. Is it possible that Karen had installed say Mevotech arms in place of the Subaru ones and it escaped my memory? Sure, it's possible. I'm saying that people who've used their Subarus hard in the past have had durability issues with OEM parts. (5x100 hubs anyone?) They don't have the huge safety margins we imagine, especially when used for track/autocross duty.






OEMs are not exempt from slapping parts together. The twins are quite obviously a frankenstein of parts-bin components. And the standard modeling they engage in may not include things like R-comp tires. As an example, take a look at 949 racings' discussion of wheel strength and racetrack use. (LINK) For a historical example, consider the suspension mounts on an E46 M3.


Like I said in my original post, given the history of OEM parts used for track duty, and the prevalence of such duty for 86 twins, some slight concern is warranted. The aluminum knuckles should at least be given special attention during pre-track tech inspections.

Even though the twin is a parts bin car, an FEA is pretty easy to preform and as well as material science is understood I wouldn't be afraid of it. OEM parts are built to a service factor well above normal use. Looking at one, or even multiple outliers shouldn't be cause for much concern. A rash of 06' WRX's breaking them, then I would be worried.

[RayRay88]

Originally Posted by DarkSunrise

The 86/BRZ are widely tracked in Japan (and around the world). Japan’s hit show Best Motoring has featured plenty of heavily modified 86’s and BRZ’s, all of which are on cheater 200tw tires or stickier. I’m 100 percent confident Subaru/Toyota are aware that these cars get modified, tracked frequently and quite publicly. I imagine it would be quite embarrassing for them if something as simple as a revised aluminum steering knuckle became a common failure point, especially when their marketing dept had gone out of its way to highlight the upgrade (see Subaru’s demo days for the gen 2’s with the new part sitting side by side with the old iron knuckle). I guess you never know but that would be a massive black eye for Subaru IMO.

That's so true. Imagine their embarrassment if Gen 1 cars had overheated oil and fuel starvation on on track...

...oh wait a minute.

Lets not even mention the axles overheating, puking and dying. Or spun rods due to oil pressure loss with the shitty boxer oiling system.

[DarkSunrise]

Originally Posted by RayRay88

That's so true. Imagine their embarrassment if Gen 1 cars had overheated oil and fuel starvation on on track...

...oh wait a minute.

Lets not even mention the axles overheating, puking and dying. Or spun rods due to oil pressure loss with the shitty boxer oiling system.

Fuel starvation is pretty common with various cars on sticky tires and can usually be solved by filling between sessions. Axle issues aren’t really that prevalent within 1” or so of stock height. Oil pressure is probably the most glaring issue, but keep oil temps in check and use the right grade oil for your operating temps and you should be fine for typical track usage.

All that is different than not being able to design a simple steering knuckle with an adequate engineering safety margin. If you don’t trust Subaru to do that, I’m not sure why you’d own a BRZ to begin with.

[dave99rt]

Porsche has used aluminum knuckles on its cars (911, Boxster, Cayman) for 20+ years. Those are tracked regularly, commonly with only pads and fluids upgrades.
They weigh slightly more, have much more power, and have bigger tires than a BRZ/GR86. Nobody is reporting failed knuckles. It's a non-issue.
*Caliper threads stripping is the common issue on Porsches, people do caliper stud kits to avoid this.

The other European brands also offer vehicles with aluminum knuckles.
Some Lexus and all currently made Teslas use them also, IS-F for example.
Corvettes going back to the 80s have them. This is NOTHING new.

For all the people in the back: There is no reason to start questioning or worrying about something that's been done decades by multiple brands like it's some sketchy new concept.
Concerns about aluminum fatigue or failures should be basically zero unless you're rally racing or something similar...

[RayRay88]

Originally Posted by DarkSunrise

Fuel starvation is pretty common with various cars on sticky tires and can usually be solved by filling between sessions. Axle issues aren’t really that prevalent within 1” or so of stock height. Oil pressure is probably the most glaring issue, but keep oil temps in check and use the right grade oil for your operating temps and you should be fine for typical track usage.

All that is different than not being able to design a simple steering knuckle with an adequate engineering safety margin. If you don’t trust Subaru to do that, I’m not sure why you’d own a BRZ to begin with.

Personally I think the knuckles are a non issue. But if you think this car is perfect for track driving out of the box because Subaru/Toyota care about how the 1% of owners that will track this car then I’m not sure you understand how a car company works. The OEMs build these cars to a price point and most of the time the safety margin they built in gets far exceeded on the track. I won’t argue the finer points of what I mentioned but these and other things are just part of the ownership experience when tracking these vehicles. They’re great cars but it’s ok to question the decisions made when Toyota and Subaru design and build things. If you ever look at endurance/race versions of even some higher end Porsches, Corvettes and Ferraris you would be hard pressed to find a lot of things they share with their road going counter parts.

We are lucky to have such a large community of aftermarket companies that question/redesign and improve these vehicles from what is offered stock and they wouldn’t exist if we just shrugged our shoulders and blindly excepted what is Subaru/Toyota puts out.

[DarkSunrise]

Originally Posted by RayRay88

Personally I think the knuckles are a non issue. But if you think this car is perfect for track driving out of the box because Subaru/Toyota care about how the 1% of owners that will track this car then I’m not sure you understand how a car company works. The OEMs build these cars to a price point and most of the time the safety margin they built in gets far exceeded on the track. I won’t argue the finer points of what I mentioned but these and other things are just part of the ownership experience when tracking these vehicles. They’re great cars but it’s ok to question the decisions made when Toyota and Subaru design and build things. If you ever look at endurance/race versions of even some higher end Porsches, Corvettes and Ferraris you would be hard pressed to find a lot of things they share with their road going counter parts.

We are lucky to have such a large community of aftermarket companies that question/redesign and improve these vehicles from what is offered stock and they wouldn’t exist if we just shrugged our shoulders and blindly excepted what is Subaru/Toyota puts out.

Where are you getting that I think this car is “perfect for track driving out of the box”? That’s literally not what I said at all. I’ve been tracking my FR-S for nearly 10 years. I’m pretty well aware of the common failure points under track use. Most of those weaknesses are not uncommon. If you understand those weaknesses, it’s not that hard to build a fairly reliable track car for your typical hpde or TT use.

Subaru/Toyota are not going to screw up something as simple as an aluminum steering knuckle, especially for what is a chassis that’s entering its 10th year of production and development. If you don’t think it would be extremely embarrassing and costly to them if a car that they’re handing out NASA memberships with couldn’t survive a track day without losing a steering knuckle or some other vital part of the steering/suspension, I think you’re misunderstanding how badly the media and courts would take them to task for it.

[OwlDance]

So I'm not gonna pretend I know **** all about how knuckles affect driving feel but a cursory look into research cites that steel/iron knuckles have better longevity and tolerance to repeated flexing over time compared to aluminium and other materials. More or less down to plasticity. Make of that what you will. For the majority of us it should probably make 0 difference to I would argue more than 99.9% of drivers aside from parts fitment.

[racingfool]

Originally Posted by OwlDance

steel/iron knuckles have better longevity

Aluminum won't succumb to rust.

[Derka]

So are these backwards compatible? I have a 2022 brz and want to use my performance pack brembos with all the parts. So I was contemplating swapping to the gr86 steel knuckles. But can’t find info on them bolting up. Anyone want to trade? Lol

[69]

Originally Posted by racingfool

Aluminum won't succumb to rust.

aluminum has its own corrosion through oxidation. this happens in contact with the air and when it is in contact with different metals, especially ferrous ones where that corrosion will take a lot more than some heat to break. ever had a wheel seize to the hub? raw aluminum wheel plus the iron top hat of the rotor....yea not fun, even my 10lb sledge wasn't making progress.







but to everyone else, overall, i imagine both will last just fine...corrosion is a factor to some degree in both materials. we've all been there, we all get through it.



i think, just my speculation, that the aluminum may reduce road feel but make turn in sharper and the car respond better....being lighter yet just as stiff, or stiffer + "insert essay about unsprung weight here"



my '18 mustang gt has a lot of aluminum in the suspension, and i am not worried about it at all....much heavier, and much faster car with 460 whatever hp. i can only speculate that part of its numbess in road feel is the aluminum but then again my e39 had the same amount or more of aluminum suspension components and it had incredibly good road feel so its probably the epas making the mustang feel numb. (and the e39 was the v8 540 fwiw)


overall, aluminum, even just a couple pounds saved, should make the front end a little more responsive and sharp would be my conclusion....ymmv. i suspect it will be a very small difference that 99% won't notice but they will claim its night and day.

[Turdinator]

Originally Posted by timurrrr

https://minkara.carview.co.jp/smart/...4954/note.aspx

Gotta love google translate:
"There was a lower arm that I had replaced at home before, and it was the part that I decided to be cool when I attached it to the knuckle, so it was water in my ears."

[Caeser]

it's funny because I think Tsuchiya said the BRZ had better feedback in this vid

but anyway prob would need wheel bearings too.