"Park brake performance reduced on steep grades" -- new since 2023.50.01?

[emoore]

That would be interesting. @emoore is right that it is colder for me now than it's been. Of course, ice is more likely around freezing than well below freezing.


Yep, that makes sense, but that's not what the warning says. The warning doesn't mention temperature or slipperyness of the surface. Yet it appears possibly triggered by temperature. That's confusing.

It’s all based on incline and temp. There is no slip detection.

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[240vPlug]

That would be interesting. @emoore is right that it is colder for me now than it's been. Of course, ice is more likely around freezing than well below freezing.


Yep, that makes sense, but that's not what the warning says. The warning doesn't mention temperature or slipperyness of the surface. Yet it appears possibly triggered by temperature. That's confusing.

Agree it's confusing.

 

[SeaGeo]

True... Yeah I know about Jeeps.

What I'm talking about it what does it matter if it's only applied to two wheels? Unless your lifting/unloading the rear axles?

I mean you could chock all four wheels but if it's on ice it's not going to make any difference. It should say don't park on a hill in slippery conditions.

The brake is performing as designed, it's the surface that's the issue.

The effectiveness of the brake is decreased because you are more likely to exceed the frictional resistance of the two wheels holding it when the surface has a low friction coefficient (e.g. icy).

 

[usulio]

If I put a brick on the brake pedal, will the brakes still be engaged after the car turns off?

 

[usulio]

If I put a brick on the brake pedal, will the brakes still be engaged after the car turns off?

Someone must know the answer to this ... (and think I'm stupid for asking)

 

[mwexler2]

Well... lol... yeah.... if you are on ice, mud, slippery whatever, yeah... how many wheels are holding the vehicle in place matters. 4 wheels holding the vehicle in place is better than two... right? Now I think I must be missing something... "what does it matter..."? Four contact patches has twice the holding power of two with a given mu.

Physics says it matters...

Can’t you get a bigger increase in surface area by airing down to 30 PSI? The. Just use the compressor before you leave?
;-)

 

[Rivian312]

a bit confused here but is the risk of the vehicle sliding or rolling?

 

[R.I.P.]

a bit confused here but is the risk of the vehicle sliding or rolling?

Sliding.

 

[Rivian312]

Sliding.

Thanks. That's what I thought. Now I'm wishing i had paid more attention in physics because while I can see the difference in sliding risk with 2 wheels locked vs. 4 it seems marginal.

 

[R.I.P.]

Thanks. That's what I thought. Now I'm wishing i had paid more attention in physics because while I can see the difference in sliding risk with 2 wheels locked vs. 4 it seems marginal.

Double is hardly marginal lol. Two wheels literally have half the holding ability of four.

 

[emoore]

Thanks. That's what I thought. Now I'm wishing i had paid more attention in physics because while I can see the difference in sliding risk with 2 wheels locked vs. 4 it seems marginal.

Double the surface area will help a lot.

 

[Rivian312]

Fair enough. Although I feel like if i'm on ice skates and my dog's on ice skates we're both going to be sliding. Now maybe if we both weighed 7000lbs i'd notice the difference.

 

[Ahoymatey]

I got this warning all the time last winter too. Doesn’t happen when it’s warm. Never had an issue with it sliding down my driveway. How long have you had your truck?

I had mine slip about 3-4 feet on my driveway overnight on Friday. Front wheels on perfectly dry concrete with a rough finish and rear wheels on slightly icy asphalt. Put large rocks behind the rear wheels and it still slipped. Front parking brakes if applied are pretty useless.

 

[RivRyan]

I had mine slip about 3-4 feet on my driveway overnight on Friday. Front wheels on perfectly dry concrete with a rough finish and rear wheels on slightly icy asphalt. Put large rocks behind the rear wheels and it still slipped. Front parking brakes if applied are pretty useless.

Cripe! How steep is the slope? Did it flatten out after 4 feet, or are you lucky not to have it slide further?

 

[Ahoymatey]

Cripe! How steep is the slope? Did it flatten out after 4 feet, or are you lucky not to have it slide further?

Reasonably steep but flattens out quickly. My concern was if it gained enough momentum it would have gone to the very icy road and from there likely into the creek. Fortunately we were able to clear the driveway and the road in front of the house and make it home with nothing more than a little scare.

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