What Would Happen If You Put Your Automatic Transmission Car In Reverse While Driving?

People are always susceptible to some brain-dead moments, the ones we would attempt in the heat of the moment but would sorely regret afterward. One of the key contenders would be attempting to shift the gear from drive to reverse. The prospect is tempting enough; after all the answer is merely a couple of clicks away!

Of course, do that, and you can seriously wreck your car to a grinding halt, or would you? In theory, you should never reverse the car unless it is completely stopped. But what does happen if you put the car in reverse while cruising forward?

Watch the video by AutoVlog below and find out as the YouTuber actually attempts this on his automatic vehicle!

So you didn’t get to see gear splattering, metal churning action that your inner psychopath so richly desired. As it turns out, engineers are shrewd enough to anticipate these wild desires and already have placed safety checks in the cars. In automatic cars, putting the gear in reverse wouldn’t do anything thanks to a feature called Reverse Inhibit that detects the selection and considers it as a mistake when on high forward speeds.

Craig Renneker, Ford’s Chief Engineer for transmission, talks about this,

“Putting it into reverse [in modern cars] when going forward has no action at all, the car just ignores the request until you get down to a proper speed,” said Renneker, using Ford’s six-speed automatics as an example; “It’ll just say ‘hey, I know you want reverse pal, but I’m just not going to give it to you until the appropriate time.’”

What About Manual Transmissions?

As most of the manual transmissions drivers know, putting your car in reverse while coasting at great speeds is practically impossible, as the move is greeted by a screeching howl and grind. This happens thanks to the physical locks that come in the shape of lockout rings placed in the gear mechanism which helps hinder the move.

“The main problem you’re going to be fighting is what you’re trying to get the thing to do is something it really does not want to do,” Renneker continued.

If someone is still undeterred by the noise and continues to try and place the reverse gear, he/she will only bust the synchronizer mechanism of the car, which is needed for smooth engagement of the gears with the dog clutch.

Same Applies For The Older Cars?

Absolutely NOT! Modern automotive electronics are handled by well-designed architecture like Control Area Networks which allow them to control the entire car’s transmission automatically and falter such crazy attempts in their tracks. Same can’t be said about the older cars with less safe technology since they might not have the reverse-inhibit function.

Renneker did explain that there was hydraulic reverse inhibit system in the past so that the older cars wouldn’t turn into a hunk of junk just by an inopportune gear selection. He added,

“If the transmission was not designed with a reverse inhibit feature, engaging reverse while driving forward will, most likely, stall the engine,” Renneker said. “The car won’t lock-up or skid, but it will slow down a bit and act like the transmission is in neutral.”

Putting an old automatic car would lead to a loss in engine power meaning you might not be able to use power-assisted brakes or steering. Emergency steering would also become a pain in the backside and brakes without vacuum assist would also need significantly more pedal pressure.

In short, it’s best NOT to ever try this!



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