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Discussion Starter · #1 · (Edited)
Probably going to be stopping by the dealership later this week but just wanted to get some opinions on what is happening to my 2011 5.7L Overland.

Was parked in a friends driveway that is decent incline, but nothing too steep. Up here in lovely Alberta so conditions were snowy/icy.

Put the Jeep in park to wait for said friend to hop in. Take foot off of the brake and the vehicle starts to slide backwards. Now this is the 2nd or 3rd time that this has happened in the last few months. Previously I wasn't sure if the vehicle was simply sliding due to ice or actually rolling backwards. I was always suspicious though as putting my foot back on the brake stop any motion.

Took the vehicle out of Park and drove forward a few feet to my original position. Back in Park, rolled down the window to watch my weels. Take my foot off the brake and observe that I am sliding backwards while my wheels are spinning. Again able to stop things by putting my foot back on the brake.

I know it's icy outside and I was parked on a decent incline, but the wheels should not be rotating while I am in Park regardless of the situation!?!?! Any insights here?

Cheers,

Chris
 

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Like "2012 Summit" suspected.

If you park the car and the left wheels are not firmly planted on the ground the car will roll.

This is common with AWD SUVs that I have owned. I almost had one roll off the jack when I was tightening the left front wheel and the parking brake wasnt set securely enough.

I would always suggest getting in the habit of using the parking brake to save the parking sprag/pawl thingy in the tranny.


Make sure that when you apply the parking brake it is still in gear so when it settles on the brake, you can get it out of park without that nasty clunk.
 

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Stop, parking brake on, foot off brake, change gear lever to 'park'.

Foot on brake, change gear lever to 'drive' (or reverse), parking brake off, foot off brake and you're good to go.

No rolling, no unnecessary stress on the gearbox, and no clunk. The parking brake is there for a reason. Never understood why so many Americans choose to ignore it.


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No rolling, no unnecessary stress on the gearbox, and no clunk. The parking brake is there for a reason. Never understood why so many Americans choose to ignore it.
So true, I use it every time I park. Mainly because I hate hearing that clunk out of park. There's just no way that's good for the long-term life of a transmission.
 

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Stop, parking brake on, foot off brake, change gear lever to 'park'.

Foot on brake, change gear lever to 'drive' (or reverse), parking brake off, foot off brake and you're good to go.

No rolling, no unnecessary stress on the gearbox, and no clunk. The parking brake is there for a reason. Never understood why so many Americans choose to ignore it.


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You are so right that it is an american habit, I can always tell when anyone has lived in the continetal US for a long time because they don't use the parking brake.


It is a must down here because alot of times you literally have to park on the side of a hill.
 

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Just as a point of interest: "49 C.F.R. § 571.114 Standard No. 114; Theft protection.
(b) Drive the vehicle forward up a 10 percent grade and stop it with the service brakes. Apply the parking brake (if present). Move the shift mechanism to the “park” position. Note the vehicle position. Release the parking brake. Release the service brakes. Remove the key. Verify that the transmission shift lever or transmission is locked in “park.” Verify that the vehicle, at rest, has moved no more than 150 mm from the position noted prior to release of the brakes.
ref §*571.114***Standard No. 114; Theft protection. :: PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS :: CHAPTER V--NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION :: Title 49 - Transportation :: Code of Federal Regulations"

BTW when the wheels were rolling were some spining backwards on the ice ?
 

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I have one answer to the question as to why "Americans" don't use the parking brake. My driver's education teacher told us not to use it as it can freeze in the on position in the winter. But that was a loooong time ago.
 

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I have one answer to the question as to why "Americans" don't use the parking brake. My driver's education teacher told us not to use it as it can freeze in the on position in the winter. But that was a loooong time ago.
Interesting.

In Australia you are legally obliged to apply the parking brake when you leave your vehicle to prevent runaway vehicles and theft. Doesn't get cold enough for anything much to freeze here though.


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Is also because it has been a while since I've had a real E-brake in a car, are now more parking brakes. Part of the issue is the 4 wheel disk brakes - there is none of the servo action that you get with a drum brake.

This why many 4WDB cars have an auxiliary drum brake in the rear just for the parking brake but that is expensive.

That said, in America the PARK position is supposed to hold a car. Years ago GM had a recall on the parking brake in Fieros that pretty much replaced everything - but only on cars with manual transmission. NHTSA agreed with GM that automagics did not need the upgrade because they had PARK.
 

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. The parking brake is there for a reason. Never understood why so many Americans choose to ignore it.
Historically parking brakes have been unreliable in that they freeze or rust up and fail to disengage. Although just about all my American friends use the parking brake, those that have been stranded by this (like myself) typically don't use them unless parking on a steep incline. Quite a few Cheby vehicles have parking brake components that break or lock up and repair technicians actually recommend not using them for reliability.

Just saying there is an understandable reason.

Perhaps most americans you know learned to drive automatics where the parking brake is not quite as useful as a manual transmission. Not engaging a proper gear when parked can easily result in a run away car.

Parking brakes are only installed on the rear, its pretty easy to park with rear wheels on ice and watch your vehicle slide away, best to also point your front wheels to the curb.... lock the transfercase into 4WD, and then use blocks :)
 

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Discussion Starter · #13 ·
Thanks for all the feedback guys. I guess I should be in the habbit of using my parking brake more often, especially when I am leaving the vehicle.

It just felt so odd to be sitting in the vehicle while it is in 'Park' and still have the vehicle rolling backwards. Maybe not headed to the dealership afterall!
 

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Discussion Starter · #14 ·
Just as a point of interest: "49 C.F.R. § 571.114 Standard No. 114; Theft protection.
(b) Drive the vehicle forward up a 10 percent grade and stop it with the service brakes. Apply the parking brake (if present). Move the shift mechanism to the “park” position. Note the vehicle position. Release the parking brake. Release the service brakes. Remove the key. Verify that the transmission shift lever or transmission is locked in “park.” Verify that the vehicle, at rest, has moved no more than 150 mm from the position noted prior to release of the brakes.
ref §*571.114***Standard No. 114; Theft protection. :: PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS :: CHAPTER V--NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION :: Title 49 - Transportation :: Code of Federal Regulations"

BTW when the wheels were rolling were some spining backwards on the ice ?

I only observed the drivers front wheel and did not note which direction it was spinning, but the friend who I was picking up said the wheels were rotating in the forward direction, going against the backward motion of the vehicle.
 

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Blaming it on open diffs is nonsense. Whether it is the Forester with open front and rear diffs and center LSD or the Legacy with 3 LSDs (manual transmission both), when you put the car in first gear and turn off the engine that is where the car stays. Yes - can it be pushed ? Of course but there are a lot of parts that need to move in order for the car to inch forward. And a lot of sweat.

Blame the parking pawl on an automatic transmission - when you place the trannsmission in Park, a pin should engage one of those notched wheels, therefore preventing it from rotating. Blame the electromagnets that should have engaged the pin; blame the driver for shifting into Park before coming to a full stop; or for relying on P to hold the car on inclines, putting pressure on the Pawl and/or its spring - but don't blame the differentials.

Owners of automatic tranny cars should use the parking brake at all times, unless parking on a flat surface. And the correct use should be : FIRST the parking brake THEN shift into Park.

 

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Blaming it on open diffs is nonsense. Whether it is the Forester with open front and rear diffs and center LSD or the Legacy with 3 LSDs (manual transmission both), when you put the car in first gear and turn off the engine that is where the car stays. Yes - can it be pushed ? Of course but there are a lot of parts that need to move in order for the car to inch forward. And a lot of sweat.

Blame the parking pawl on an automatic transmission - when you place the trannsmission in Park, a pin should engage one of those notched wheels, therefore preventing it from rotating. Blame the electromagnets that should have engaged the pin; blame the driver for shifting into Park before coming to a full stop; or for relying on P to hold the car on inclines, putting pressure on the Pawl and/or its spring - but don't blame the differentials.

Owners of automatic tranny cars should use the parking brake at all times, unless parking on a flat surface. And the correct use should be : FIRST the parking brake THEN shift into Park.
I have had two automatic SUVs (Chevy Blazer 4x4 and a Jeep Liberty). I haven't used the parking break in either, and destroyed both vehicles' parking breaks when someone else drove my car and put it on without me noticing and driving sluggishly before figuring it out, OOPS!

I have a new GC on order, and I plan to treat this one better than my last two. My question is what is the reason for putting the parking break on first before going into park?thanks!
 

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I have had two automatic SUVs (Chevy Blazer 4x4 and a Jeep Liberty). I haven't used the parking break in either, and destroyed both vehicles' parking breaks when someone else drove my car and put it on without me noticing and driving sluggishly before figuring it out, OOPS!

I have a new GC on order, and I plan to treat this one better than my last two. My question is what is the reason for putting the parking break on first before going into park?thanks!
So the brake is actually stopping the vehicle from moving, and not the parking pawl in the transmission. The parking pawl can, and does break sometimes if abused.:thumbsup:
 

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So the brake is actually stopping the vehicle from moving, and not the parking pawl in the transmission. The parking pawl can, and does break sometimes if abused.:thumbsup:
Gotcha, thanks, great to know!
 
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