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Spooky handling on wet roads; PS All Season 4ZP - SOLVED
Did a search with no reports that I could find so posing the question here.
2017 ZO6/A8- Swapped out the original Pilot Super Sport ZPs to the PS all seasons earlier this year and had the local Chevy service shop (JBA in Glen Burnie MD) do a full alignment. No issues or complaints, but also hadn't driven in the rain until recently. I have driven the car countless times in the rain with no issues until now.
On concrete interstate road, light rain (no notable ponding) and at moderate speed (~60) the car feels like it is completely out of control, trying to spin. It does NOT feel like hydroplaning but more that the car is rotating with the back end coming loose. Able to regain control with a combo of counter-steering into the spin(s) and downshifting to add a bit of engine braking. Slow down to 40 or less and it maintains control but still squirrely feeling.
Not discounting the road itself and even considered wind contributors (including drafts from other vehicles) but this is NOT normal. Could this be an issue with the tires, the alignment, or even tire pressure (I typically run all 4 corners at 30-32)??? Just trying to figure out where to look...
Appreciate input in advance, as this scared the crap out of me!
/r
Allen
Last edited by Allen_B; 01-03-2024 at 05:40 PM.
Reason: Update title
They are mounted so they're rotating in the correct direction, correct? I could see where if they mounted both rear tires, then mixed them up installing them on the incorrect sides, that would cause an issue. I'd think you'd notice it in the dry, but maybe not?
If your rear wheels are losing traction the last thing you want to do is use engine braking or applying the parking brake. That just adds more g force to be handled by low tire grip levels and could cause them to break loose. When the rear tires break loose you have more difficulty steering because they provide lateral stability similar to the way a sailboat's lateral stability is provided by its keel/daggerboard. Usually what happens when the rear tires lose grip is the car rotates with the occupants looking at where they came from Vs where they are going.
Wet smooth concrete is one of the slippiest surfaces there is to drive on so if the highway is old the pavement is probably polished smooth from thousands of tires running over it day after day for year after year. The fact that you didn't end up spinning into the weeds indicates the rear tires weren't near exceeding their friction circle so you probably had plenty of rear tire grip.
When the front tires run into puddles they tend to pull suddenly toward the side that hits the puddle. Driving on an interstate (even concrete ones) you can run into puddles in the grooves that trucks wear into the pavement over a while. Driving when visibility is low it can be very hard to see these puddles. I have run into them many times with each side of the car encountering them intermittently with the car pulling back and forth across the lane. When I run into that situation I pull the driver's side wheels up onto the left side lane paint stripe so the wheels on both sides of the cars are out of the grooves. Since the C7 has the Weather Drive Mode it is a good idea to turn the control **** to weather. It gets a lot easier to control the car with Weather engaged. When I took the new owner school they had us on a wet skid pad driving a figure 8 attempting to spin the car and it was difficult to get it to spin even though we were trying to spin it.
Did you see any lights on the instrument panel when this was happening?
Remember the rules when driving on low-grip surfaces: Never make sudden moves with the steering, throttle, brakes (or gears). Every driver input should be smooth and gentle even when your heart is in your throat and your anus is puckered so tight you could snap pencils with it. In a lot of cases the brake if used incorrectly can become your enemy.
Bill
Last edited by Bill Dearborn; 12-20-2023 at 03:37 PM.
You noted that the dealership did an alignment; do you know if that included them adjusting the rear casters? I'm no expert in this and am not sure if an improper alignment would cause what you are experiencing, but I have read on the forums plenty about most dealerships not having the tools or understanding that when doing an alignment on these cars the rear casters must be set as well. Perhaps Bill can chime in on if this could be a factor in what you are experiencing.
When I had my 2017 Z06 A8 and drove it for the first time in the rain (Tour Mode) the handling was horrible. It felt like I was driving with 4 bold tires.
So I switched it to weather mode and it somewhat improved but not by much. I think switching to weather mode just made it tolerable enough to drive and
that was with MPS Summer tires .
Now my 2019 ZR1 stays in the garage when it rains !
I drove through a lot of fairly heavy rain to and from the track with my 2019 Z06/A8 with the Pilot Sport All Season 4 ZP. I did not notice anything unusual - I did slow down from maybe 80 to say 60 - 65, mostly due to visibility, but I would have done that with any vehicle.
You noted that the dealership did an alignment; do you know if that included them adjusting the rear casters? I'm no expert in this and am not sure if an improper alignment would cause what you are experiencing, but I have read on the forums plenty about most dealerships not having the tools or understanding that when doing an alignment on these cars the rear casters must be set as well. Perhaps Bill can chime in on if this could be a factor in what you are experiencing.
A recent alignment could be the difference but it would show up when driving in any weather. One of the key things I have found out about alignment techs (dealer or otherwise) is they don't tighten the lower cam bolts to the proper spec which can let the control arm move as various handling pressures are applied to them. When the control arm moves you get large changes in camber and toe with the caster being affected somewhat less.
Appreciate the feedback.
I admit I expected an improvement in wet weather handling with the AS tires which is why this is not just confusing, but scary. And to @Oskee point, was in weather mode. Actually never had a problem in wet weather previously, unless it was pouring and it would be a challenge in any vehicle. Growing up in the Southeast, all too familiar with hydroplaning and this isn't what's happening.
On the alignment piece, specifically went to JBA as they have the tools and (supposedly) expertise to align the rear end. Best thing I suppose at this point is to head back for an alignment check...
My 2017 A8 Z06 has been driven in the rain so many times my wife named it Stormy. I've not experienced what you indicate. I have all seasons as well. The only issue I have ever had is too much acceleration from a stop will break the rear free. The nannies and myself made the corrections. If I get caught in a heavy downpour (very common in FL), I put it in weather mode. My alignment is set between street and track.
Get the car back from the shop this afternoon, following a 4-wheel alignment- Significant improvement even on dry roads!
Not an expert by any means, but thinking the rear showing +2.36 toe out with the right rear the big offender, was a contributor! Most avoid driving their cars in the rain, but I'm looking forward to it!
My big question is what the hell would knock it so far out of spec? These cars are designed to take track curbs; figure that's more abuse than Maryland roads but could be wrong...
Glad to hear that you were able to get this resolved! If you don't mind me asking, how much did JBA charge for the alignment? I live in MD and am considering getting my alignment checked?
glad to hear that you were able to get this resolved! If you don't mind me asking, how much did jba charge for the alignment? I live in md and am considering getting my alignment checked?
Get the car back from the shop this afternoon, following a 4-wheel alignment- Significant improvement even on dry roads!
Not an expert by any means, but thinking the rear showing +2.36 toe out with the right rear the big offender, was a contributor! Most avoid driving their cars in the rain, but I'm looking forward to it!
Allen
I think it's safe to say that a total rear toe out of more than 2" is UNQUESTIONABLY the issue !!! I've driven a RWD sedan with an inch of toe in on one front tire (thanks to a AAA tow truck driver who chose to put a winch cable on a tie rod rather than crossmenber) in some partly snowy conditions, and the car was darn near uncontrollable at anything over 25 MPH.
not being an alignment tech I don't know how critical the mismatch left to right is as they are all in the green but you would think they would have been closer. Like Bill said wet smooth concrete is the worse. Here's my last alignment for reference and your numbers are pretty close to mine.
12-20-2023, 01:27 PM
Spooky handling on wet roads; PS All Season 4ZP - SOLVED
