Steering issue under load with track tires

[Nickel]

Guys, I've been searching to see if I can find something consistent but I haven't so far.

So I was driving on Little Switzerland today in Boone, NC and something odd is happening in high g load right hand corners. In corners that are similar to ones like gravity cavity on the tail of the dragon, essentially what is happening is in mid corner, the steering is locking me out and dangerously not letting me to continue steering and I have to back out. I'm not getting a warning light for the electric power steering.

Car has TRD springs, alignment is around -1-5F/-2R, Carbotech XP8s and 235/40R18 Hankook RS4's.

[alphasaur]

this sounds terrifying

[Ohio Enthusiast]

Most likely the EPS is overloaded, overheating and shutting off. This means you're left without assist for the steering which makes it significantly more difficult to turn the steering wheel (and keep it turned).
This might happen with a stock setup, and happens more often with wider tires, stickier tires and more caster. It also happens much more frequently on the track where steering loads are higher.
Hankook RS4 at 235 width will certainly cause this.

Plenty of threads around this issue and how to work around it.

[Nickel]

Originally Posted by Ohio Enthusiast

Most likely the EPS is overloaded, overheating and shutting off. This means you're left without assist for the steering which makes it significantly more difficult to turn the steering wheel (and keep it turned).
This might happen with a stock setup, and happens more often with wider tires, stickier tires and more caster. It also happens much more frequently on the track where steering loads are higher.
Hankook RS4 at 235 width will certainly cause this.

Plenty of threads around this issue and how to work around it.

I've seen quite a few but sometimes without the right key words, I'm running into unrelated threads. Do you happen to know of a thread you could link me where someone has worked around this?

[Ohio Enthusiast]

Here's one - https://www.ft86club.com/forums/showthread.php?t=90718

[Nickel]

Originally Posted by Ohio Enthusiast

Here's one - https://www.ft86club.com/forums/showthread.php?t=90718

Yeah that's one I've been eye balling for a little while. I'm on lowering springs so I couldn't raise it. Spoke to a local from the dragon, he actually ended up giving up on the chassis because of this. I'll have to take up to the dragon and see what happens there and then go from there.

[Ohio Enthusiast]

Originally Posted by Nickel

Spoke to a local from the dragon, he actually ended up giving up on the chassis because of this.

As far as I understand this has been improved in later years, perhaps 2015 or 2017. I think I saw some mention of people upgrading to a later year EPS unit but I'm not sure.

This recent thread mentions it happening on a 2014 but not on a 2017 (but another poster says it's still present in 2022...).

Looks like there're no fixes for this, though, other than reducing caster.

[NoHaveMSG]

Check to make sure it isn't rubbing anywhere. I have issues with rub and EPS cutout.

[Nickel]

I've checked clearance in all areas and nothing is rubbing anywhere. I've spent the last several days finding any information I can on this. It doesn't really seem like there is a real fix. I'm going to get my caster checked and see if I can lower it and maybe that will take some stress off of the EPS and lighten the issue a bit.

[TunaNoCrust]

I get it on my 2019 fairly frequently, it still will steer, just need to use some force. I had rubbing issues from my coil perches and end links rubbing the chassis, but no rub issues with my coilovers now. Still getting EPS shut off.

[NoHaveMSG]

Originally Posted by TunaNoCrust

I get it on my 2019 fairly frequently, it still will steer, just need to use some force. I had rubbing issues from my coil perches and tie rods rubbing the chassis, but no rub issues with my coilovers now. Still getting EPS shut off.

I am assuming you meant endlinks and not tie rods. Which one's are you running? I had a lot of issues until I went with the whitelines. I notice the thickness of the rod end was much narrower than others I had tried and they no longer hit. This is with -3.6 front camber though I have maxed camber at the knuckle before adjusting the top hats. I am probably going to -4 next year so that could change.

[TunaNoCrust]

Originally Posted by NoHaveMSG

I am assuming you meant endlinks and not tie rods. Which one's are you running? I had a lot of issues until I went with the whitelines. I notice the thickness of the rod end was much narrower than others I had tried and they no longer hit. This is with -3.6 front camber though I have maxed camber at the knuckle before adjusting the top hats. I am probably going to -4 next year so that could change.

Hahaha yes, thank you. Completely stock suspension SACH dampers, TRD Springs, TRD sway bars. I too was looking for slimmer end links, but ended up getting coilovers and that solved all my rubbing problems. I am at -4 up front with a single camber bolt and 95% maxed out camber plates.

[whataboutbob]

I've also experienced this on occasion with my 2013 running Hoosiers in autocross. Never found a fix.

[rice_classic]

Three of us have done several full race season on Hoosier A7s without the EPS ever being an issue. I find it odd that so many people on street tires or even autox cars have this issue, so odd in fact, that I think it's not EPS.



A lot of aftermarket stuff poorly accounts for other aftermarket stuff and stuff can bind. Remember the joke "Interchangeable parts don't."



End Links are a great example - some folks have put steering rack limiters so that they can't turn too sharply in the paddocks because it would break their end links. I'm thankful that my strut+end link choice didn't create that scenario for me.



I suspect the OPs issue is not EPS related and instead something is rubbing or something is binding.