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70mph in 1st gear

I was hoping to get some confusion cleared up. I have a 2010 Honda Accord and as I was driving about 70mph on the freeway, I was approaching a steep downhill. I wanted to slow the car down by downshifting the transmission into 1st gear. However, as I did this, I noticed that this car did not slow down at all. In fact, I stepped on the gas and I noticed that the car was still able to gain more speed. I was wondering why this is the case. I know that the first gear in my car only goes up to about 15 mph. Thus, I thought that by downshifting to 1st gear the car would slow down dramatically to 15mph. As I downshifted into 1st gear, the engine speed increased and that was about it, the car did not slow down at all. I was still able to accelerate albeit very slowly but the car was still running at 70mph. Keep in mind that I have an AUTOMATIC transmission and I simply moved the gear lever to the bottom position. Can somebody explain to me what is going on inside my transmission during this process and why the car didn’t slow down when I downshifted to 1?

Before you do anything else, I would suggest that you take out your Owner’s Manual and read it–particularly the section dealing with the transmission.

The highest speed at which your car is designed to operate in 1st gear is probably ~25 mph. By shifting into 1st gear at 70 mph, you may have done some serious damage to the transmission, simply because it is not designed to operate the way that you wanted to operate it.

If you want to slow down from 70 mph, you should first apply the brakes and bring the car’s speed down considerably. Then, you should shift down by one gear–i.e.–depending on the transmission, from 5th to 4th, or from 4th to 3rd. Once your speed has decreased further, if you still want to slow down, then you can shift down one more gear, to either 3rd or 2nd, depending on the transmission.

It is very possible that the electronic controls of your transmission overrode your decision to shift into first gear, and instead placed the transmission into the proper lower gear. If the transmission had shifted into 1st gear at 70 mph, you would have over-revved the engine–possibly destroying it–as well as doing damage to the transmission.

Electronic controllers nowadays will frequently prevent a driver from doing this type of bone-headed drastic downshift in order to prevent catastrophic damage. However, the fact remains that you abused your transmission by attempting to do what it is not designed to do. I strongly suggest that you never attempt this type of maneuver again.

Read your Owner’s Manual!

The auto trans in a 2010 Accord has electronic controls. Whatever gear you select the trans won’t downshift into a gear that would over rev the engine to the point of blowing up the motor. When you shifted to 1st the car’s computer said to the trans, downshift but only to a gear that won’t ruin our motor. Your trans shifted down perhaps 2 gears. If you have a 6 speed auto, that would mean down to 4 or possibly 3rd gear.

It is a good thing for you that such built in safe guards exist. Putting your car in 1 at 70 mph is simply nuts. IF the trans had shifted in to the gear you selected your motor would have been subjected to about 15,000 rpm. At that speed the pistons would detach from the rods and some would have come out the bottom of the motor. There would be a loud thunk and once the car stopped you’d see a trail of oil on the road behind you. The fix would be an entirely new motor, it wouldn’t be covered by your warranty, and you’d spend about 3 to 4K dollars.

Don’t do that again, and don’t go for R at 70 mph either. If you want to slow down there is a big petal to the left of the gas petal that is designed to slow you down without harm to the car.

The electronically controlled transmission won’t shift into first gear at 70 mph. It probably won’t even shift to second at 70. This is to protect the transmission and the engine.

I usually find that disengaging the overdrive is sufficient to maintain a reduced speed on a downgrade. Second gear would be OK if the hill is really steep and you’re not going fast, but selecting 1st gear at 70 is asking for trouble.

This explains it perfectly. The only thing I’d add is that this safety feature isn’t present in a manual transmission, so hopefully the OP never tries this trick with one of those!

Throw the car in reverse if you’re not convinced what everyone is saying is true. It should stall the engine and roll to a stop. That is if everything is in working order, you have the courage, are in a safe area and have the money for repairs if the computer decides to take some time off when you do it.

Want to slow down? Your car comes standard with an amazing device called a “Brake”. It is located to the left of the gas pedal. Try it sometime–mine works great!!!

Here’s your sign.

4th gear would be more appropriate than first. First is only for 0-20 mph or so. You’d be in for a quite unpleasant surprise if the Accord’s computer didn’t override your decision.

As we become farther removed from generations that were weaned on the manual transmission, we get farther removed from even the safer way of using an automatic. Manufacturers then have to compensate by using computer over rides and making operating manuals more legible. I would suggest they offer a DVD with the Lady GaGa doing a presentation on the most important operating instructions…like the entertainment system and the transmission thrown in for good measure.

Repeated for emphasis:

[i][u]Putting your car in 1 at 70 mph is simply nuts.[/i][/u]

Buy a car with a manual transmission and learn how to drive it.

“If you want to slow down there is a big petal to the left of the gas petal that is designed to slow you down without harm to the car”

Instead of conventional power brakes, does this car have Flower Power brakes?

I just couldn’t resist this one.


It is drivers like this that make buying a rental car somewhat risky…Perhaps this WAS a rental car…

It could have air brakes.

Are you trying to kill this car before it’s only 1 year old? The computer prevents you from doing some really stupid things like shifting into 1st gear at high speed. Why did you think this was a good idea?

It’s pretty frightening that you are driving when you understand so dangerously little about cars. If you had succeeded in engaging first gear, you not only would have destroyed your engine, but very likely crashed. I don’t have a problem with that in itself - chalk it up to Darwinism - but you might have hit me during the event. The US needs much stricter licensing standards!

Unless this is a long downgrade, use the brake and wear the brake pads a little, rather than the engine and drive train.
Doubthathe transmission would ever down shift to that low a gear at that speed. If so, it could self destruct.

Read your owner’s manual a little and learn how not to destroyour nice vehicle.

This forum had beat it to death about downshifting instead of rolling down hill in neutral. Mission accomplished. But the part about downshift just enough hold a downhill speed is left out.

I don’t know for sure but a 1994 Honda Accord 4 speed AT had grade logic. Head downhill, push the brakes, and the computer would downshift automatically. I think a 2010 Accord would do likewise.

Are you seriously blaming sound driving advice on this forum for rendering the OP so car-illiterate that he didn’t know 70 in 1st is a really, really stupid thing to do?


Actually, I am beginning to think that this thread was created as a joke.

I am now of the opinion that the OP is yanking our collective chains in order to see how extreme our reactions are.

Is it really possible that someone could be this unsavvy when it comes to operating a car?

What is next?
Will somebody ask if he/she should always drive with the e-brake engaged, just in case he/she encounters an emergency?