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Just want to make sure I put it out there to save someone else from a major catastrophe. I personally have driven my SS on highway conditions in the rain many times w/o issues. with that said that is until water was enough for minimal hydroplaning. I had traction control off when rain started with no issues of sliding or hydroplaning. Decided to turn traction control back on and within a couple hundred yards the rear locked up twice making very subtle but noticeable skid and rear then went under a underpass that was dry came out I have the underpass to wet surface and traction control went haywire locking up rear tire first then Front left didn’t matter after that point after it locks up in the rain hydroplaning your just along for the ride. Everything I did to counter continued to cause skating because of traction control putting brakes to one or more of the tires. So words of experience If driving in rainy conditions Turn off your traction control if you want to keep control.
 

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Good post to remind the ones who are going to the Smokey Mountains (leaving 8/14) and seeing the weather for the next week of RAIN....
 
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Hydroplaning is no joke. I've had an "off-road" experience due to hitting deep standing water and it was THIS close to a catastrophe. If one must drive in the rain, please slow down considerably and yes, disengaging traction/stability control is also a good idea. In my instance, it was the front tires that lost traction, turning me instantly across oncoming traffic and into the shoulder on the other side of the road. It wasn't a "skid" in the classic sense: the rear stayed hooked, it was the front that instantly moved to the left.

As a further caution: maintain proper tire tread depth and tire pressures. Overly-worn tires will massively exacerbate the tendency to hydroplane.
 
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Turning off traction control in the rain? I have never heard of that one. I have driven mine through rain and never had a problem.

Its interesting that RobS7 said he had the traction control off before it started to rain which I don’t understand. Then once he turned it on the SS started to hydroplane. I cannot believe that the traction control caused the hydroplaning. The only things I know that contribute to hydroplaning are worn tires and going too fast. No motorcycle or car traction control can eliminate hydroplaning. If you’re going too fast when you hit enough water you are on your own.

Remember the comments on this sight are not always accurate. (Including mine.)
 

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Here is why turning off traction control makes sense, at least to me. What is the one thing you do not want to do when a vehicle starts to hydroplane, apply the brakes, right? How does traction control work? It applies the brakes, and asymmetrically at that! So here is the result, the SlingShot starts to hydroplane, traction control steps in and starts applying the brakes asymmetrically to three wheels. The SlingShot is now being pulled this way, then that way and that's it, game over, you are heading for the tooly bushes out of control! This is what happened to me. Since that first incident if there is the possibility of standing water on the road today, first I slow down, second I turn off the traction control. If the SlingShot still wants to get up on it's tip toes, I let off on the accelerator, (keeping off of the brakes), and allow the vehicle to slow on it's own until it regains traction. Simple!

Oh, and one other thing, there are tires out there far better suited for wet roads than those original Kendas.

Bill
 

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Just want to make sure I put it out there to save someone else from a major catastrophe. I personally have driven my SS on highway conditions in the rain many times w/o issues. with that said that is until water was enough for minimal hydroplaning. I had traction control off when rain started with no issues of sliding or hydroplaning. Decided to turn traction control back on and within a couple hundred yards the rear locked up twice making very subtle but noticeable skid and rear then went under a underpass that was dry came out I have the underpass to wet surface and traction control went haywire locking up rear tire first then Front left didn’t matter after that point after it locks up in the rain hydroplaning your just along for the ride. Everything I did to counter continued to cause skating because of traction control putting brakes to one or more of the tires. So words of experience If driving in rainy conditions Turn off your traction control if you want to keep control.
I have found that if I keep my speed 55 mph or lower I have no problem with hydroplaning. So when I am riding in the rain I am at 55 all the way.
 

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Here is why turning off traction control makes sense, at least to me. What is the one thing you do not want to do when a vehicle starts to hydroplane, apply the brakes, right? How does traction control work? It applies the brakes, and asymmetrically at that! So here is the result, the SlingShot starts to hydroplane, traction control steps in and starts applying the brakes asymmetrically to three wheels. The SlingShot is now being pulled this way, then that way and that's it, game over, you are heading for the tooly bushes out of control! This is what happened to me. Since that first incident if there is the possibility of standing water on the road today, first I slow down, second I turn off the traction control. If the SlingShot still wants to get up on it's tip toes, I let off on the accelerator, (keeping off of the brakes), and allow the vehicle to slow on it's own until it regains traction. Simple!

Oh, and one other thing, there are tires out there far better suited for wet roads than those original Kendas.

Bill
Maybe it’s different on later models, but my 2015 SS does not have power brakes. Anti-lock, yes, but the brakes are activated manually. Therefore, the computer can’t apply the brakes, it can only release a brake (using the anti-lock function) on a wheel that’s not turning fast enough. Traction control only affects the engine. If the rear wheel is spinning faster than the fronts, TC will slow the engine down to stop what could become rear wheel spin. Therefore, traction control has virtually no role in hydroplaning; since all the wheels keep turning, it will rarely, if ever, kick in, and even if it did, it would just slow down the rear wheel. And since you’re not applying the brakes (I assume everyone knows not to do that), anti-lock won’t engage; all you can do is ride it out. I’ve seriously hydroplaned three times. Each time it was the front wheels losing it (things happened fast, so I don’t know if the rear lost it too, or not; my guess is that it did) and the car rotating. I also noticed that when you are approaching a hydroplane state the rear wheel (wider and more lightly loaded) will “skip” a little—you can feel the traction drop off for a fraction of a second. If that happens, back off on the throttle. Now I just keep it under 45 mph in the rain (& slower if there’s standing water) and haven’t had a problem.
 

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Maybe it’s different on later models, but my 2015 SS does not have power brakes. Anti-lock, yes, but the brakes are activated manually. Therefore, the computer can’t apply the brakes, it can only release a brake (using the anti-lock function) on a wheel that’s not turning fast enough. Traction control only affects the engine. If the rear wheel is spinning faster than the fronts, TC will slow the engine down to stop what could become rear wheel spin. Therefore, traction control has virtually no role in hydroplaning; since all the wheels keep turning, it will rarely, if ever, kick in, and even if it did, it would just slow down the rear wheel. And since you’re not applying the brakes (I assume everyone knows not to do that), anti-lock won’t engage; all you can do is ride it out. I’ve seriously hydroplaned three times. Each time it was the front wheels losing it (things happened fast, so I don’t know if the rear lost it too, or not; my guess is that it did) and the car rotating. I also noticed that when you are approaching a hydroplane state the rear wheel (wider and more lightly loaded) will “skip” a little—you can feel the traction drop off for a fraction of a second. If that happens, back off on the throttle. Now I just keep it under 45 mph in the rain (& slower if there’s standing water) and haven’t had a problem.
Very interesting observation. I have a 2017 SLR and it doesn’t have power brakes either. I think you have the right idea. If it’s raining slow down. Once you are hydroplaning you have no control wether you have your traction control on or off.
 

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Maybe it’s different on later models, but my 2015 SS does not have power brakes. Anti-lock, yes, but the brakes are activated manually. Therefore, the computer can’t apply the brakes, it can only release a brake (using the anti-lock function) on a wheel that’s not turning fast enough.
Copied from the 2015 Owner's Manual, page 21:

Electronic Stability Program (ESP) Switch
The ESP is active by default. This feature helps reduce the risk of accident by providing traction control and stability control. If ESP senses a loss of stability due to loss of traction (skidding) the ESP intervenes by automatically applying brakes to one or more wheels and reducing power to the rear wheel.


Bill
 

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Copied from my 2015 Owner's Manual:

Electronic Stability Program (ESP) Switch
The ESP is active by default. This feature helps reduce the risk of accident by providing
traction control and stability control. If ESP senses a loss of stability due to loss of traction
(skidding) the ESP intervenes by automatically applying brakes to one or more wheels and
reducing power to the rear wheel.


Bill
I guess I should have dug out my owners manual. Altho I don’t see how the computer could apply the brakes without a power braking system, so I’m a bit skeptical of this entry. I’ve seen other owners manuals (for other vehicles) with wrong info, apparently based on pre-production machines (the manual for my Moto Guzzi California advises using the center stand when changing oil. There is no center stand.)
 

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I guess I should have dug out my owners manual. Altho I don’t see how the computer could apply the brakes without a power braking system, so I’m a bit skeptical of this entry. I’ve seen other owners manuals (for other vehicles) with wrong info, apparently based on pre-production machines (the manual for my Moto Guzzi California advises using the center stand when changing oil. There is no center stand.)
Copied, (poorly), from the 2021 Polaris SlingShot Owner's Manual:

Electronic Stability Program (ESP) Switch


The ESP is active by default. This feature helps reduce the risk of accident by providing traction control and stability control. If ESP senses a loss of stability due to loss of traction (skidding) the ESP intervenes by automatically applying brakes to one or more wheels and reducing power to the rear wheel.


I am thinking that we can safely assume that over six years of production that Polaris understands how their ESP works?

Bill
 

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I guess I should have dug out my owners manual. Altho I don’t see how the computer could apply the brakes without a power braking system, so I’m a bit skeptical of this entry. I’ve seen other owners manuals (for other vehicles) with wrong info, apparently based on pre-production machines (the manual for my Moto Guzzi California advises using the center stand when changing oil. There is no center stand.)
I had an 850 Motto Guzzi in the 70’s and it had a center stand and a kick stand. I always used the center stand because the kick stand was very unstable.
 
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I think I can shed some light:

ESC comprises a combination of anti-lock and stability behaviors intertwined using stored logic routines. These routines are mostly built around mainting vehicle stability in hard braking and heavy cornering actions, such as would be encountered in collision avoidance maneuvers. In addition to wheel speed sensors, it also uses a yaw sensor which transmits vehicle attitude data when tuning left or right.

The issue with its use in potential hydroplaning conditions is that it will interpret sudden changes in wheel speed as an event for which is its intended to intervene. In the case of a hydroplane event where wheel speeds are suddenly no longer within the acceptable range as compared to one another, it will attempt to correct the imbalance via selective braking application. Bear in mind, it can't "slam" on the brakes. It can only apply light braking pressure and/or remove braking pressure as it deems neccesary to restore wheel speeds to the correct allowed differential. However, this is where things can get hinky:

While that light application isn't able to lock the wheels in typical operation, when you have zero traction in a hydroplane event it can seriously slow the wheel(s). Of course, it will then react to the major loss of wheel speed, but by then, the wheel's tenuous traction on water momentarily gets even worse as the wheel slows. Even that momentary worsening of prevailing traction can further unsettle the machine.

So now, you're only slightly in control if at all due to the interaction of hydroplaning and ESC. And yes, it will now get worse. If the machine makes a quick move to the right or left, the yaw sensor picks it up and further routines are engaged, further muddying your connection between driver, machine and road surface.

I personally have encountered this in a severe hydroplane event. I was cruising along on a two-lane highway at about 60. A torrential downpour erupted, and the significantly reduced visibilty from me crouching down behind the rain-spattered windscreen means I didn't detect standing water on the road ahead. When I hit it, the front of the Sling INSTANTLY veered hard left, across the oncoming lane. Of course, I didn't dare try braking, but I could feel oddness in the steering wheel as the ESC confusedly tried to intervene, quite in vain.

By the time I shot into the left-side ditch, I had the steering wheel cranked hard right. Before I could hit the trees in the highly-forested area, my LF tire dug hard into the ditch outside berm with intense force, violently pivoting the machine back parallel to the road. Were it not for my death grip on the wheel, it would have surely catapulted me out in the woods as it rotated. I was now heading down the ditch at about 50 MPH, but the worst had passed and I was able to get back onto the road surface. That LF wheel carved a furrow down the ditch a hundred feet long.

Needless to say, I was shocked, but very fortunate. Neither I nor machine were damaged, although we were both splattered with considerable mud and turf. Had there been oncoming traffic, or had the ditch not snapped me away from the trees, I'd likely not be here to write this today.

How my Sling behaved in this was a source of extreme fascination for me, as well as a real eye-opener. I've never felt the front end of any machine just shoot to one side like this. As in many cases, what I encountered was a mixture of hydroplane reaction peppered with an ESC system that was out of its comfort zone. Relating my experience and knowledge about the system here today is an attempt to help others out.

Take hydroplane danger VERY seriously. Slow down or stop altogether. And if you have to drive in the rain, it's best to disable the ESC.
 

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My 3 experiences (I know: slow learner) were very similar to Bill’s: sudden violent rotation (to the right in my case) and “correction” when the front wheels hit the rough berm with the steering wheel cranked all the way over. What no one has explained here yet is how the system can apply the brakes in a manual braking system. My motorcycle has ABS and traction control, but all the ABS does is release the brake when one wheel speed is lower than the other wheel, and TC just slows the engine if the rear wheel spins. I know I was not applying brakes when the machine lost traction, so I still believe that neither traction control nor ABS had anything to do with the events.
 
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My 3 experiences (I know: slow learner) were very similar to Bill’s: sudden violent rotation (to the right in my case) and “correction” when the front wheels hit the rough berm with the steering wheel cranked all the way over. What no one has explained here yet is how the system can apply the brakes in a manual braking system. My motorcycle has ABS and traction control, but all the ABS does is release the brake when one wheel speed is lower than the other wheel, and TC just slows the engine if the rear wheel spins. I know I was not applying brakes when the machine lost traction, so I still believe that neither traction control nor ABS had anything to do with the events.
I feel you, you view the ABS module as a regulator of sorts, which isn't untrue, but the current generation integrated with ESC can also apply. It's usually a short duty-cycle pulse burst as opposed to a continuous apply, used to discourage a "spinning" wheel. It's not unlike the old drag racer's trick of applying the brake to control wheelspin.

In the instance of hydroplaning, the ESC could operate in this mode: it sees the front tires spinning faster than the rear, so pumps the front brakes a couple-few pulses. How? Well, when one suddenly hits deep water, it's customary to lift off the throttle hard. The rear wheel may actually overdecelerate via engine braking due to slipping on the water. Suddenly the front wheels are spinning faster than the rear, and the ESC intervenes in an attempt to get all three tires back to the same speed. One bedrock aspect of ESC is wheelspeed, for in terms of stability, there no better tell. If all three wheels aren't in concert, there's a problem: something is akilter and stability can only be enhanced by suppressing the overspeed and restoring all three wheels to similar speeds.

ESC constantly tailors it even in normal driving, especially in hard maneuvers. If one or two tires are moving faster, it restores synchronization with a brake pulse or few to the speedy wheel(s). If you've ever done a hard enough cornering maneuver to break a tire free, it will often slow in relation to the others. So ESC will slow the others. The ESC "feel" in such an instance is a slight lurch as the brakes are pulsed and the car settles back into the groove when all wheels regain similar speed. We've all felt it on cars with ESC, and it's why we typically turn it off when doing spirited driving, as its interventions will interfere with the driver's intent.

ESC is mostly there to rescue lesser or surprised drivers from the worst results of avoidance maneuvers that, while they may well be able to initiate them, aren't always trained or experienced or even ready enough to follow through safely. ESC makes up the difference and helps keeps them from throwing it away.

There's so much more, even ESC and braking being used to enhance cornering and body roll, even turn-in. I do believe Slingshot has a fairly basic version though, just for safety.
 

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Not trying to be argumentative, but no one seems to know the answer to this simple question: on a car without power brakes, how would the ESC apply them? Is there a secret brake pump we don’t know about? Is there a connection to engine vacuum? What provides the power to apply the brakes, and how are the two front wheels activated separately? As far as I can tell, the master cylinder has a single output to the front (which powers both front brakes simultaneously) and a second one to the rear. I haven’t crawled underneath to look, but I don’t think there are two brake lines to each front wheel, one for normal and one for stability control. (You don’t need one on the rear, since engine braking can be used there.) And, if the car has the equipment to power-apply the brakes, why don’t they just make it a power brake system?
 
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Not trying to be argumentative, but no one seems to know the answer to this simple question: on a car without power brakes, how would the ESC apply them? Is there a secret brake pump we don’t know about? Is there a connection to engine vacuum? What provides the power to apply the brakes, and how are the two front wheels activated separately? As far as I can tell, the master cylinder has a single output to the front (which powers both front brakes simultaneously) and a second one to the rear. I haven’t crawled underneath to look, but I don’t think there are two brake lines to each front wheel, one for normal and one for stability control. (You don’t need one on the rear, since engine braking can be used there.) And, if the car has the equipment to power-apply the brakes, why don’t they just make it a power brake system?
Slingshot employs discrete contol of each of the three wheels' braking function, with three separate lines emanating from the ESC/ABS controller.

I believe you are conflating power brakes with ESC function, when in fact they are not synonomous. Within the ESC controller is the ability to solenoid-pulse braking force to each wheel independently as needed to restore wheel speed to match the remaining wheels. You can learn more about ESC at this link:

Electronic stability control - Wikipedia
 

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I’m not confused about how ABS works, I’ve already noted that ABS works by opening an electrically controlled bypass valve on the line out of the master cylinder to release the brake, which is why they can work on a manual brake like my motorcycle (and why you can feel the pulsing in the brake lever when it engages). And I‘ve already noted that ESC is the opposite: it must pressurize the hydraulic fluid within the brake line between the master cylinder and an individual wheel cylinder to apply the brake. I’m just asking what device pressurizes the hydraulic line to do that. The wikipedia article mentions in passing a “hydraulic pump” or a “vacuum booster“ to pressurize the hydraulic line when activated. These are normally present in a power brake system, but since we don’t have power brakes, I assume that there is a mechanical device of some sort (or two, actually—one for each wheel) somewhere in the brake hydraulic system that provides the necessary hydraulic pressure to apply one brake momentarily. Obviously, the brake lines do not go thru the electronic control module itself. You mentioned a solenoid, which could be used to provide a short pulse, altho the Wiki article does not mention that as a component (probably because it isn’t used in power brake systems, which all cars have these days). I’ll see if I can trace the hydraulic lines and find the actuators.
 
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I was merely addressing your mention that you felt actuation of the brakes would need be tied to some sort of power booster. Modern ESC actuation is a different animal.

This isn't actual engagement of the master cylinder occurring; the brake pulses emanate further downstream from the ESC/ABS controller (not control module) which is an electromechanical device containing solenoids that selectively pulse-actuate each wheel as deemed necessary by ESC logic, which takes into consideration a number of factors including wheel speed differential, yaw and lontitudinal attitude rate, and steering wheel angle.

You'll find the ESC/ABS controller under the master cylinder, attached to the chassis.
 
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