OEM primacy HP vs OEM PS4S stiffness

[gcmak]

Originally Posted by RToyo86

I have stock sized PS4S on a set of 8" wheels. The difference in stretch vs 7" wheels may effect the responsiveness of the tire.

I view the PS4S as a straight upgrade. Grip, response, road noise, wet performance.
The main downside to me is that the factory spring rates clearly weren't designed for that amount of grip. Last summer on stock springs I could easily put the car on the bump stops in corners.
The car still handled great, but it obviously felt different. Pros/cons.

I wasn't a fan of how it felt. Since adding RCE yellows and camber bolts the suspension feels way happier dealing with the extra grip.


Primacys are a ton of fun on the street. So grip limit is so approachable, you get chirps and squeals before you get near the limit. Really just depends on how you like to drive...

This is helpful to hear your feedback on the impact to the stock suspension after adding more grip. It'll be something I'll look out for when I swap to something like the RT660's with stock suspension and stock wheels.

Everything is connected after-all. Brakes will be the next area of focus.

[Capt Spaulding]

Originally Posted by CSG Mike

My question for you would be, why are you needing to countersteer? Did the rear step out on its own, or did you get a little exuberant with throttle application?

The latter.

[CSG Mike]

Originally Posted by Capt Spaulding

The latter.

If you start going faster, it'll still happen even with stickier tires!

That said, I do love the feeling of when the car just hooks and you go, rather than dealing with wheelspin.

[grumpysnapper]

Originally Posted by CSG Mike

If you start going faster, it'll still happen even with stickier tires!

Although the speed/accuracy of the drivers inputs then become even more critical....

[CSG Mike]

Originally Posted by grumpysnapper

Although the speed/accuracy of the drivers inputs then become even more critical....

Mmmmm depends on the tire. Some tires break away progressively, while others are abrupt.

MPS4S is fairly progressive, especially with the soft sidewall and the tread squirm.

[grumpysnapper]

Originally Posted by CSG Mike

Mmmmm depends on the tire. Some tires break away progressively, while others are abrupt.

MPS4S is fairly progressive, especially with the soft sidewall and the tread squirm.

For sure, but I guess my point is more that the forces released increase with speed/grip... the tail moving out at 100mph on stickier tyres requires a different skill set to those needed on a wet round-about at 25mph on lower grip.

[CSG Mike]

Originally Posted by grumpysnapper

For sure, but I guess my point is more that the forces released increase with speed/grip... the tail moving out at 100mph on stickier tyres requires a different skill set to those needed on a wet round-about at 25mph on lower grip.

I actually teach people to deal with this for a living. The forces are identical if the conditions are identical! If you can do it at 25mph, you can do it at 100mph!

However, the release at 100mph dry will probably be more progressive than 25mph wet, with a larger window for recovery, since the yaw impulse that started the unwanted rotation is likely smaller. I'll have much busier hands in a tight low speed slide than in a big high speed slide. However, if an 86 with sticky tires is loose at 100 mph, I'll be pretty darn impressed!

Slicks are a different story, but they don't belong on the street to begin with.

[grumpysnapper]

Originally Posted by CSG Mike

I actually teach people to deal with this for a living. The forces are identical if the conditions are identical! If you can do it at 25mph, you can do it at 100mph!

However, the release at 100mph dry will probably be more progressive than 25mph wet, with a larger window for recovery, since the yaw impulse that started the unwanted rotation is likely smaller. I'll have much busier hands in a tight low speed slide than in a big high speed slide. However, if an 86 with sticky tires is loose at 100 mph, I'll be pretty darn impressed!

Slicks are a different story, but they don't belong on the street to begin with.

Nah, the energy forces are not identical... the energy released in a 100 mph tank slapper is far far greater than at 25 mph.
The energy released when a sticky tyre loses (and gains) grip is higher than when a low grip tyre gives up in a comparable situation. Cornering forces are higher.
Hand speed and reaction times need to be much sharper at high speeds, particularly when gripping back up, when the car immediately wants to follow the nose.
I feel its a bit glib to say that anyone who can catch/recover a slide at 25mph can do it at 100mph... (particularly on sticky rubber.)
Excluding race tracks, how many drivers do you know who can actually cleanly recover an 86/BRZ when the tail unexpectedly comes out at 100mph in a long sweeper that they have misjudged, in the real world. Or 90 mph. Or 80 mph. Or even 70mph?

[churchx]

grumpysnapper: in certain conditions it's not that hard. After all, the quicker one corrects, the less correction needed. And when one pushes near limit, be it slow corner in wet or high speed one in dry, one on track imho should always anticipate possible slide due mismanaged mass transfer mid corner or too eager accelerating out of corner, this anticipation imho noticeably cuts reaction time to correct. Of course, concentration during daily driving is much lower .. but then again one shouldn't push dangerously on public roads either, leaving much higher safety margin. And if no skills (and especially due lesser concentration level & more uncontrollable variables), one shouldn't drive on public roads without nannies too.

[grumpysnapper]

Originally Posted by churchx

grumpysnapper: in certain conditions it's not that hard. After all, the quicker one corrects, the less correction needed.

Thats true, in certain conditions, and with certain skill sets. And talent or hard work.
For most drivers difficulty increases with speed, as the skill sets needed increase.
99.9% of drivers are not driving on the track, and the tyres we are talking about are also mostly used in the real world on real roads.
The reality is that real world road driving is what our cars were primarily designed for, and that's also where most still (hopefully for a little while longer) get our pleasure from.

[CSG Mike]

Originally Posted by grumpysnapper

Nah, the energy forces are not identical... the energy released in a 100 mph tank slapper is far far greater than at 25 mph.
The energy released when a sticky tyre loses (and gains) grip is higher than when a low grip tyre gives up in a comparable situation. Cornering forces are higher.
Hand speed and reaction times need to be much sharper at high speeds, particularly when gripping back up, when the car immediately wants to follow the nose.
I feel its a bit glib to say that anyone who can catch/recover a slide at 25mph can do it at 100mph... (particularly on sticky rubber.)
Excluding race tracks, how many drivers do you know who can actually cleanly recover an 86/BRZ when the tail unexpectedly comes out at 100mph in a long sweeper that they have misjudged, in the real world. Or 90 mph. Or 80 mph. Or even 70mph?

The kinetic energy held by the car is greater, yes, but the lateral force exerted by the tires is not significantly changed without aerodynamic intervention.

Outside of the racetrack, the average driver doesn't have the opportunity to safety attempt correcting rotation at those 70-100mph speeds!

[Capt Spaulding]

I have the OEM wheels and tires in storage. I would really like to refit those, find a skid pad and spend some time getting to know the car closer to its limits, but I'm hundreds of miles from a track and Texas is still in the grip of Sars-Cov2.

I doubt I can persuade a local mall or the university I just retired from to let me set up a 200ft circle in one of their parking lots.

[grumpysnapper]

Originally Posted by Capt Spaulding

I have the OEM wheels and tires in storage. I would really like to refit those, find a skid pad and spend some time getting to know the car closer to its limits, but I'm hundreds of miles from a track and Texas is still in the grip of Sars-Cov2.

I doubt I can persuade a local mall or the university I just retired from to let me set up a 200ft circle in one of their parking lots.

Sounds like a bummer...but well sighted back roads are your friends, and if you can find some dead end ones, all the better.
A very quiet run up and back to check any potential safety concerns to others and for yourself. Then a quick spirited run or two... then off to another piece of bitumen magic.
Smooth gravel is also an awesome way to enjoy the car moving under you... just keep "slow in, fast out" as a repeating mantra.
I travel with a mounted iPad mini showing google earth, in conjunction with a gps, and its amazing what roads are out there that can be spotted by satellite, away from heavy population density.
Also when it rains I'll head out to quiet industrial areas, just after sun down (not too late, as you dont want to be anywhere near the place if its a hooning hot spot), and there are great opportunities to slide on wet bitumen. I check safety/problems before hand, and again, dont hang around very long in one spot.
Just remember though that your old tyres might have gone "off" quite quickly.