Shaking

[Thomby]

Notably, you can still downshift a few gears, while using Smart Cruise Control..

Just using the paddles? Does the drive mode matter? I would've assumed it would deactivate cruise, like tapping the brake, I guess because I'm thinking of manuals where you can't shift during cruise because the clutch will deactivate it.

 

[LordKOTL]

Notably, you can still downshift a few gears, while using Smart Cruise Control..

VVV

Just using the paddles? Does the drive mode matter? I would've assumed it would deactivate cruise, like tapping the brake, I guess because I'm thinking of manuals where you can't shift during cruise because the clutch will deactivate it.

I haven't tested that, but I think the all modes but Sport would shift back after a minute or so. Might not be the perfect panacea unless your always in Sport, but maybe an option.

 

[D.J.]

Just using the paddles? Does the drive mode matter? I would've assumed it would deactivate cruise, like tapping the brake, I guess because I'm thinking of manuals where you can't shift during cruise because the clutch will deactivate it.

You can downshift a few gears, just using the paddles, regardless of drive mode, while using smart cruise control.

How long it remains in the selected gear before switching back to drive, is dependent on a few factors. I don't have any long downhills near me to test with.

 

[lil_lurking_stinger]

I have experienced - at least anecdotally, that when I brake more aggressively for a shorter time, rather than gently for a longer time, my rotors tend to remain pulsation free for longer.

Anecdotally

Came here to mention this as well. Medium-Hard & steady braking have insulated me from most of the rotor issues others have experienced even though I’m still on stock rotors. I do plan to upgrade in the future, when needed. But I’d say higher quality brake pads will scrub off most of the deposits on your rotors if you’re pushing this car a bit.

Only ever experienced the rotor issue on my first pair of brake pads with the car as I was trying to baby the car.

 

[LordKOTL]

Okay, so back with an actual test...

This past weekend went to / from Sakt Lake City along I84, which had plenty of long hill descents and speed limits of 70+mph.

I used Smart cruise control down one 6% gradient and I got a tiny bit of shudder on stock rotors and PowerStop Z26 pads. I just let the car do it's thing; she didn't automatically downshift and she just lightly rode the brakes to maintain speed.

The rest of the downhill gradients I had the gauges up in my driver info screen between the speedo and tach, and whenever the torque dial was at 0 lb-ft I disengaged the cruise control and let her coast (while in gear), downshifting manually if necessary and firm braking if necessary.

No shudder, even long gradients at 80MPH+.

I think my hypothesis is correct; pad deposits are apt, or more apt, to glaze the rotors in Smart Cruise Control downhill where the car effectively rides the brakes to control speed. Downshifting manually may help, but the best bet is to disengage smart cruise control, coast the car in gear and downshift/firm brake when needed.