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Today my rear left driveshaft gave up (lots of grinding noise while in Drive or Reverse, coming from the left side of the differential, and the car won't move).

One strange thing I noticed is that the car will not stay still when it's in Park. I have to engage the e-brake to stop it from rolling up or down.

Is this related to the broken driveshaft?

The car is RWD with automatic transmission.

  • Out of curiosity, has the car been going clunk-clunk-clunk around curves or getting more grindey for the last couple of years? – Harper - Reinstate Monica May 27 '18 at 0:28
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    ...wait, so you don't normally use the parking brake when parking? Because that's kind of its primary intended purpose... – Sean May 27 '18 at 0:40
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While the other answer is basically correct, it really doesn't tell you why it does this.

These two things are related because of the differential. The differential is made to allow either side to spin at different rates. There are three connections to the differential in a rear wheel drive vehicle: drive shaft (from transmission); left axle shaft; right axle shaft. If any one of these is not connected, this allows either of the other two to spin freely. Since one axle shaft is gone on your vehicle, this allows the power to go out through it the brokens side of the differential without moving the vehicle. Conversely, since this axle shaft isn't there, it allows the other tire to spin freely when the car is in park. It would work the same way if one tire was on a sheet of ice or was up in the air. There is an escape route for the power, or in your case, this allows the other tire to spin.

  • And your transmission is fine ; park has locked up the drive shaft. But as Paulster2 said, with the left axel broken , the right axel is free to turn. – blacksmith37 May 26 '18 at 21:32
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    Yes, if you put a healthy car on jackstands with it in Park, and spin the left wheel, the right wheel will go same speed opposite direction. That's the differential doing its job. When you're parked on a hill, both wheels are free to spin equally in opposite directions, but for that to work, the whole car would need to pivot around the front axle, and the rear wheels won't allow that. This weird dynamic flow of forces in 4 directions is what keeps the car from rolling away in PARK. Moral of the story: use the e-brake. – Harper - Reinstate Monica May 27 '18 at 0:25
  • There's also a grinding noise comming from transmission when shifting to Park, is this also related to the broken cv axle? – Marius Marusanici May 28 '18 at 8:19
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    @MariusMarusanici - The noise is most likely the parking spaul in the transmission. When you put it in drive the one side of the differential is spinning. This means the drive shaft is spinning. When you go to put it back into park, the driveshaft is still going round, so the pin in the parking spaul makes a noise until the pin settles and the driveshaft stops. Same thing if you tried to put the car in park while it's moving. Not good for the parking spaul, but if you don't do it often, you most likely will not have caused any damage. – Pᴀᴜʟsᴛᴇʀ2 May 28 '18 at 12:16
  • Yes, it was the parking spaul, now it makes sense. Hopefully there's no damage done to the transmission. – Marius Marusanici May 28 '18 at 13:20
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Yes it is related, both drive shafts (cv shafts) must be connected and in working order for park to work, use the e brake like you have been.

Replace the cv shaft and all will be working again.

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