Steering issue under braking !

[eron]

Originally Posted by killboy

I can make it happen on stock suspension, first turn, but only in compressive "dip" turns. It's not an overheating thing, it's not aftermarket suspension parts thing. It does require a good bit of grip, so stock tires won't do it for me. I'm pretty convinced it's the EPS being overwhelmed and doing a quick safety shut down/bypass. I don't see any realistic way to resolve it with upgrades either.

I have experienced this many times too. It only happens when I throw the car into a corner, throttle off, to scrub off speed. In these cases I am entering faster and with more over-steer than normal, using a banked turn or a dip to turn the car as the traction increases. I suspect that it is the stability control trying to correct what it thinks is an impending loss of control (the light flashes and it appears that the stability control never turns off completely...). It does not matter if I do the pedal dance... The only thing I have found which helps is to be smoother at corner entry. If I am over-steering less on corner entry it does not occur, or I can just muscle through it.


Now I just go in a little less aggressively and I think I am probably faster as a result.

[Sleepless]

Did some experiments with this steering issue.

Can make it happen easily with no braking so it is purely a steering issue.

It was at is worst with 225/45-17 Trofeo R tires (TW60 sticky) which were under inflated while experimenting with pressures. Pirelli recommend 28-30PSI hot but at 28 they rolled over on the sidewalls at moderate speeds and it was very difficult to steer. Steadily increasing pressure to 36PSI hot mostly eliminated the odd steering resistance.

My conclusion is that tire load and grip simply can overtax the power steering.

PS - Two other cars with Trofeo Rs were at the track (Cayman and E46 M3) and we all ran the same lap times. They ran at the recommended 30PSI so at first it was puzzling why I had to run at 36 when their cars are heavier. My theory is that it is the tall sidewalls of my 225/45-17 tires. They had much wider and lower profile 18's

So, two lessons learned yesterday

[Pat]

I'm really surprised no one has figured out a solution to this yet. Does anyone know of someone really addressing this issue? Thanks to everyone that has shared their personal experiences with this.
Disclaimer: I don't really understand how this stuff works
If it is just steering related it seems like adjusting something with Ecutek may resolve the issue. Do you guys think resolving this will require a different rack or electric motor? It's really unnerving to me.

[killboy]

Originally Posted by Pat

I'm really surprised no one has figured out a solution to this yet. Does anyone know of someone really addressing this issue? Thanks to everyone that has shared their personal experiences with this.
Disclaimer: I don't really understand how this stuff works
If it is just steering related it seems like adjusting something with Ecutek may resolve the issue. Do you guys think resolving this will require a different rack or electric motor? It's really unnerving to me.

It seems to be a situation where we are exceeding the mechanical capabilities of the stock steering booster. No amount of tweaking the tune or software will overcome this. It would require manufacturing a more powerful motor unit that still communicates with the factory controller without causing any issues. Highly unlikely any company is going to go through the trouble of designing and manufacturing such a niche piece for a handful of us.

[Pat]

Thanks, killboy. I'd be surprised if we were the first group of enthusiasts to experience such a problem. Does anyone know of other cars equipped with an electric rack that has this problem? If so, how have they addressed it?

[Rich196]

to bump and old thread, has anyone found a solution to this.
Happens to be when on hard trail braking. If I lift of the brakes sooner it doesn't happen.
Also happens under hard compressions.

For example here, at the bottom of T1 when I run out onto the curb, steering feels like it locks off, goes super heavy, bit like not having power steering.

Running Ohlins 6kg all round, stock sway bars and links. 235/40/17 on et38, on a r888 tyre around -3 degrees camber.

any suggestions

[86league]

Originally Posted by Rich196

to bump and old thread, has anyone found a solution to this.

I know this isn't exactly a 1 to 1 test, but I had this problem on my 2013 at 2 tracks in 1 corner at each. Happened just about every lap unless I was going very easy. I now have a 2020 and put the same suspension, wheels, tires and same compound brake pads on the 2020. Data traces show I'm driving the same speeds throughout the corners where I had issues (within my normal lap to lap variation at least).

The 2020 doesn't have the issue. I thought I'd read somewhere that the newer cars have a new power steering motor. Is that right?

If so - would the new EPS motor work on the older cars, or is it more involved with wiring/software, etc ?

[ROADRACER]

The 2020 doesn't have the issue. I thought I'd read somewhere that the newer cars have a new power steering motor. Is that right?

If so - would the new EPS motor work on the older cars, or is it more involved with wiring/software, etc ?[/QUOTE]



That is a very good question. I wonder if a 2020 power steering unit put into a older car could be the fix we have been looking for?
I have the same problem with my 2013 track car. My best guess is that it is not a overheating issue, but a over load (electrical) issue that basically trips a breaker momentarily.

[thin2win]

It's the alternator. I have a MoTec and log voltage at the dash and ecu. I would get dips in voltage during hard/trail braking. I borrowed an alternator and tested at NOLA back in Oct. No dips, no PS failures.

[Rich196]

Originally Posted by thin2win

It's the alternator. I have a MoTec and log voltage at the dash and ecu. I would get dips in voltage during hard/trail braking. I borrowed an alternator and tested at NOLA back in Oct. No dips, no PS failures.

So how did you fix it?

New stock altonatnor? Or a high capacity one of a different model?

Sent from my SM-G950F using Tapatalk

[jflogerzi]

Originally Posted by Rich196

So how did you fix it?

New stock altonatnor? Or a high capacity one of a different model?

Sent from my SM-G950F using Tapatalk

Sounds like a aftermarket one

Sent from my GM1915 using Tapatalk

[norcalpb]

Originally Posted by ROADRACER

The 2020 doesn't have the issue. I thought I'd read somewhere that the newer cars have a new power steering motor. Is that right?

If so - would the new EPS motor work on the older cars, or is it more involved with wiring/software, etc ?

That is a very good question. I wonder if a 2020 power steering unit put into a older car could be the fix we have been looking for?
I have the same problem with my 2013 track car. My best guess is that it is not a overheating issue, but a over load (electrical) issue that basically trips a breaker momentarily.

Yes, when I looked into it does look like the 2017 got a new motor and the 2020 got an even newer motor. The 2020 part # for the EPS ECU is also different than the 2017 part #. Not sure if it’s plug and play with these 2 items, but together they are like $1200...

[thin2win]

Originally Posted by Rich196

So how did you fix it?

New stock altonatnor? Or a high capacity one of a different model?

Sent from my SM-G950F using Tapatalk

Replaced with a stock

[eb66]

Originally Posted by thin2win

Replaced with a stock

You replaced it with a newer unit of the same version that came on the car or a different one?