Steering wheel resistance while threshold braking

[Pat]

Originally Posted by zdr93523

Pat,

I was just looking at a couple of your posts and the issues you're having. One thing is your hot psi is way too low for an R1 / R1S on our cars. The recommended hot psi from BFG is 36-42psi for a 2700-3000lb car and the R1S really likes to be on the high side of that.

This is fascinating to me. I've experimented with a wide range of hot temps, but nothing over 36 hot. I've read everything BFG has to say about it and know they recommend much higher pressures than what I ran last weekend. If you take a look at my posts from last October (?) you'll see I was running around 35 hot and experienced significant wear in the middle of the tread without much wear on the shoulders. That is very tough to argue with.
I'm really glad you posted. I follow your videos on YouTube and always like reading your posts, too. I value your input as much as just about anyone's on this site given your real-world track experience with the BRZ in addition to other higher horsepower cars. That's what makes this so interesting to me. I trust and value the opinions of people that are saying such different things about these tires. Some say 28 hot; some say 40 hot. That is a MASSIVE discrepancy.
In the end I trust how my tires show wear more than what trusted forum members have to say. But man....I just can't get over how different all of these trusted recommendations are. You don't see exceptionally high wear in the center of the tires at 40 hot? That just seems wild to me given my experience.

[Icecreamtruk]

Update: just had another time attack event yesterday. I was feeling balsy and pushed the car way beyond anything I've done before. I experience the steering resistance you guys are talking about. I was able to replicate it at will mid turn, it certainly has to do with how much force is being applied on the wheels. This was on stock suspension and R-compounds (maxxis RC1).

On the positive side, I shaved 2 whole seconds of my best time on that track. Good for 3rd time on my class, 18th overall (out of 51 cars).

[justatroll]

Originally Posted by Pat

Thanks, cjd. Unfortunately the corner that causes it the most is a decreasing radius turn, which makes my situation the opposite of yours in that it happens well before most of the turning is completed.

Ahh... Danny's Lesson.
I'm pretty sure youre not doing 70 or 80 when you turn in to that one, but anything's possible.

I spun last race weekend at 4 just before there from trail braking a little late.
I'm right at 100 at the brake zone into 3 (different car).

Some people pull the ABS fuse entirely to completely disable nannies, but that disables EBD as well.

Mark your sidewalls with chalk and see how far you are rolling the tire to help a little with evaluating tire pressures.

[Pat]

Originally Posted by justatroll

Ahh... Danny's Lesson.
I'm pretty sure youre not doing 70 or 80 when you turn in to that one, but anything's possible.

I spun last race weekend at 4 just before there from trail braking a little late.
I'm right at 100 at the brake zone into 3 (different car).

Some people pull the ABS fuse entirely to completely disable nannies, but that disables EBD as well.

Mark your sidewalls with chalk and see how far you are rolling the tire to help a little with evaluating tire pressures.

Thanks. You're right, I'm not at 70 or 80 entering T6. I should have been more precise with my words. That's where I start braking. Turning the steering wheel is at a slower speed.

[justatroll]

Originally Posted by justatroll

Ahh... Danny's Lesson.
I'm pretty sure youre not doing 70 or 80 when you turn in to that one, but anything's possible.

I spun last race weekend at 5 just before there from trail braking a little late.
I'm right at 100 at the brake zone into 4 (different car).

Some people pull the ABS fuse entirely to completely disable nannies, but that disables EBD as well.

Mark your sidewalls with chalk and see how far you are rolling the tire to help a little with evaluating tire pressures.

Originally Posted by Pat

Thanks. You're right, I'm not at 70 or 80 entering T6. I should have been more precise with my words. That's where I start braking. Turning the steering wheel is at a slower speed.

Sorry, I messed that up. Fixed above.
Danny's lesson is 6.

Ive had my BRZ out there with the stock tires so I never got serious.
My race car is a vintage 4 cyl boxer w/ hoosiers

[cjd]

Originally Posted by justatroll

Some people pull the ABS fuse entirely to completely disable nannies, but that disables EBD as well..

I was locking up one wheel almost every turn without ABS. I'm sure technique plays a role, but still - it isn't necessarily a magic bullet. EBD does help.

[DocWalt]

FWIW I'm having it happen with street tires (RE-71R) and it happens with or without pedal dance. It's simply the EPAS shutting down due to overloading. I doubt there's any way to fix it (within the CAN bus constraints and any reasonable sort of cost, lol)

[Sleepless]

I've had the same time experience as Doc; street tires or NT01s, pedal dance or not. I can make happen in the first corner so not an overheating issue either.

My theory is that it may be another safety nanny where the system thinks you shouldn't be adding steering input. It happens under trail braking to me the most; I don't think the the system likes aggressive trail braking.

[DocWalt]

FWIW I don't think it's specifically a braking issue, it's just that's normally when the front suspension is most loaded. It would happen on banked corners for me when the front end was compressed and I was on the gas.

I wonder if maybe it's deciding to shut down because it sees the added steering input, the high G forces, and the motor not able to spin to add assist and just shuts off instead of burning up the motor.

I decided to check the temp of the EPAS motor (with my hand...) after a drive home from work and it was toasty, I can only imagine how hot it gets on track and I've still not seen an overheat light.

[Pat]

Originally Posted by DocWalt

FWIW I don't think it's specifically a braking issue, it's just that's normally when the front suspension is most loaded. It would happen on banked corners for me when the front end was compressed and I was on the gas.

Great info. Thanks, DocWalt!

[zdr93523]

Originally Posted by Pat

This is fascinating to me. I've experimented with a wide range of hot temps, but nothing over 36 hot. I've read everything BFG has to say about it and know they recommend much higher pressures than what I ran last weekend. If you take a look at my posts from last October (?) you'll see I was running around 35 hot and experienced significant wear in the middle of the tread without much wear on the shoulders. That is very tough to argue with.
I'm really glad you posted. I follow your videos on YouTube and always like reading your posts, too. I value your input as much as just about anyone's on this site given your real-world track experience with the BRZ in addition to other higher horsepower cars. That's what makes this so interesting to me. I trust and value the opinions of people that are saying such different things about these tires. Some say 28 hot; some say 40 hot. That is a MASSIVE discrepancy.
In the end I trust how my tires show wear more than what trusted forum members have to say. But man....I just can't get over how different all of these trusted recommendations are. You don't see exceptionally high wear in the center of the tires at 40 hot? That just seems wild to me given my experience.

Thanks for checking out my YouTube! I don't post on here as much as I probably should. I definitely recommend running the higher pressure from experience.

What are your alignment settings, wheel, and tire size? That usually dictates tire wear on the track more so than the pressure.

P.S... I just finished my transition from Time Trial to Race group, so this weekend is going to be fun. I'm sure I'll upload a video!

[Pat]

Oooh, W2W racing! You're with the big boys now! Good luck.
If I remember right, I have a wheel you're familiar with. The K4R in 17 x 8, et 36(?). -3.2* camber front, stock rear, no toe all around. 225/45 BFG R1S.

[Pat]

I was just reading a new article on Jalopnik. Apparently this issue has been resolved in 2017 models. They said, "The power steering also doesn’t go ‘dead’ when you have to fight the car to a particularly reluctant apex, which was a big problem when fitting grippier tires to the old generation 86s and BRZs. On our hot 245-section Pirelli slicks the steering wheel would often just die in our hands completely." What are the chances this is just a programming issue? If so, could we get an update to earlier models?
The full article can be found here

[dradernh]

Originally Posted by Pat

...this issue has been resolved in 2017 models.

Excellent news!