Shifting to Reverse at Speed

[SonicHKS]

Been thinking about this, and theoretically it should work?


Ok, to get into reverse with a manual trans you typically have to be stopped, correct? Now, what if you were driving along at highway speeds and you locked up the drive wheels, could you get into reverse?

I'm thinking that if its a RWD car, you can just lock the rear wheels with the e-brake and then double-clutch into reverse? That begs the question though, what happens when you release the e-brake and just pop the clutch? Transmission grenades? The other way would be revving it up and dumping the clutch so it'll break traction, then the rear wheels would be spinning backwards while you're going forwards? Otherwise if you didn't apply power and just let the wheels "hook up" in reverse it'd blow the trans?

[theholycow]

Release brake and pop clutch: Engine stalls and turns backwards.
Rev it up and dump clutch: Something breaks (transmission, clutch, CV joints, driveshaft, axle mount), or if you're lucky you burn off your clutch/tires and nothing breaks.

[Rope-Pusher]

eye wons put an slushbox into Park while skidding forward....On Porpoise!


I wanted to see if it could be done in the brief moment that the front wheels locked up before the antilock kicked in.

With the park pawl resisting the torque of the skidding tires, I had to wait until the skidding stopped before I could pull it out of reverse.

Remember kids: Don't try this at home!

BTW, Reverse is generally not designed to take the peak torque or time at torque that a forward gear would be expected to endure.

[Shadow]

Try to shove a modern automatic into Park or Reverse while at speed and nothing at all will happen. Ask me how I know....

[potownrob]

Try to shove a modern automatic into Park or Reverse while at speed and nothing at all will happen. Ask me how I know....

how do you know??

[Rope-Pusher]

Try to shove a modern automatic into Park or Reverse while at speed and nothing at all will happen. Ask me how I know....

So what's a modern automatic? Even the latest and slushiest aren't all SBW.

[Shadow]

Try to shove a modern automatic into Park or Reverse while at speed and nothing at all will happen. Ask me how I know....

how do you know??

Glad you asked. A friend rented a new Toyota Camry. I bet him $20 that if he tried to put it in Park while driving forward at 30 mph, nothing would happen. He thought for sure that it would at least cause a nasty grinding sound, even if it didn't destroy the transmission. I was in the car when he tried it. Nothing happened. Nothing at all.

BTW, the guys from Myth Busters tried it with two different cars (neither one was new) and got the same results. That's why I was so sure that nothing would happen to the rented Camry.

[potownrob]

BTW, the guys from Myth Busters tried it with two different cars (neither one was new) and got the same results. That's why I was so sure that nothing would happen to the rented Camry.

and here i thought you knew it from being an automotive engineer

[six]

Glad you asked. A friend rented a new Toyota Camry. I bet him $20 that if he tried to put it in Park while driving forward at 30 mph, nothing would happen. He thought for sure that it would at least cause a nasty grinding sound, even if it didn't destroy the transmission. I was in the car when he tried it. Nothing happened. Nothing at all.

By "nothing at all" did you mean that you can still drive the car like normal while in Park? Like as if it stayed in "Drive"? Or did it act like it was in Neutral? Also, if you came to a complete stop afterwards, would Park engage by itself?

[bk7794]

Try to shove a modern automatic into Park or Reverse while at speed and nothing at all will happen. Ask me how I know....

how do you know??

Glad you asked. A friend rented a new Toyota Camry. I bet him $20 that if he tried to put it in Park while driving forward at 30 mph, nothing would happen. He thought for sure that it would at least cause a nasty grinding sound, even if it didn't destroy the transmission. I was in the car when he tried it. Nothing happened. Nothing at all.

BTW, the guys from Myth Busters tried it with two different cars (neither one was new) and got the same results. That's why I was so sure that nothing would happen to the rented Camry.

Mythbusters tried it even in a stick. I think it just made a very nice grinding noise. I wonder if reverse would work.



Nice CRX to restore.

[SonicHKS]

This has less to do with automatics, and more to do with technique of shifting a manual into reverse at speed. My theory is that the drive wheels just have to be stopped for you to select reverse, and locking them up while at speed is the same as having them stopped? So if you were driving a RWD car on the highway doing 70, yanked the e-brake and it locked the rear wheels, you'd be able to double-clutch into reverse?

And on the off-topic topic, I've looked into it and plenty of people have shifted a slush into park at speed. Usually the parking pawl clicks loud until it locks into place and the car slams to a halt. Other time it shears off completely and then Park is just like neutral. I also don't think shifting an automatic to reverse does much, pretty sure the trans just spins opposite and nothing locks up.

[theholycow]

I also don't think shifting an automatic to reverse does much, pretty sure the trans just spins opposite and nothing locks up.

Yup, it's anticlimactic, if you do it at speed the engine gently and quietly stalls but otherwise pretty much nothing of interest happens.

[daleadbull]

This has less to do with automatics, and more to do with technique of shifting a manual into reverse at speed. My theory is that the drive wheels just have to be stopped for you to select reverse, and locking them up while at speed is the same as having them stopped? So if you were driving a RWD car on the highway doing 70, yanked the e-brake and it locked the rear wheels, you'd be able to double-clutch into reverse?

What about AWD cars?

[theholycow]

What about AWD cars?

Get manually lockable differentials for all 3 differentials, then when you apply the parking brake it will BRAKE ALL THE WHEELS


(Or just disable ABS and lock the regular service brakes into a 4 wheel skid.)

[Shadow]

Glad you asked. A friend rented a new Toyota Camry. I bet him $20 that if he tried to put it in Park while driving forward at 30 mph, nothing would happen. He thought for sure that it would at least cause a nasty grinding sound, even if it didn't destroy the transmission. I was in the car when he tried it. Nothing happened. Nothing at all.

By "nothing at all" did you mean that you can still drive the car like normal while in Park? Like as if it stayed in "Drive"? Or did it act like it was in Neutral? Also, if you came to a complete stop afterwards, would Park engage by itself?

Car just kept going like nothing happened. Not sure what would happen after you stop the car because we didn't leave it like that....