Misshifted but didnt hit redline


#1

Hi all! I was just wondering, if one were to shift into 2nd instead of 4th at about 35mph, would there be any damage? Well, it happened, and the rpms jumped from about idle to 4500 (car redline at around 6500). I know it should be fine, but there was a thud noise when it happened and the car jerked quite noticeably, as if it was gonna stall. That’s what worries me. I do not see any difference in the way the car drives though. Misshifts are bad because you can overrev the engine, but in this case I’m worried about the shock that was caused to the engine, even though it wasn’t overreved…


#2

There should not be any problems because of this and you should not worry about it one bit. A severe lurch with something like this is normal. :slight_smile:


#3

A ways back, I managed to downshift from 4th to 1st at 40-45 mph in an 83 Mustang GT. The rear tires locked up and things got interesting but the car was not damaged. Not something to make a habit of though.

Ed B.


#4

Without knowing the car’s details like year, make, model, engine, and mileage it’s hard to give a solid opinion however I doubt the car has damage, the lurching was probably because the fuel was cut when the RPM approached the limit.


#5

The abrupt shift won’t hurt the motor. You did send a major shock wave through the entire drive train and that could finish off a worn out part somewhere, like a CV joint etc. If all seems well, then all is well. If there was damage you’d have noticed it immediately after the incident.


#6

I see, thanks. There were no fuel cutoff since it was a good couple thousand rpms until the redline. The car is a 2013 mazda3 skyactiv with 14000 miles on it. Never had a single repair (yet. Knock on wood).


#7

Don’t do that again, if you can help it. I’ve had 3 friends mis-shift cars at track days. All 3 hurt the engines. One OHV V8, one DOHC 6 and one DOHC 4. The V8 was mine, being driven by a friend. (Yeah, we are still friends). Bent valve(s) all. All were downshifting into a turn, all were forced to over-rev by the connection to the drive wheels. None of the rev limiters did or would work! One was fixed under warranty when the cute, redhead lady owner batted her eyelashes in ignorance (she was at the track driving but her husband popped the motor). The ugly guys had to fix their own mistakes.


#8

Yeah, I know about the bent valves and stuff, but my car redlines at around 6500, but in my case rpms jumped only up to 4500. The engine was not overreved, I am more worried about the jerk and the accompanying thud. Kinda sounded and felt like as if you forgot the car was in first while standing still and let out out the clutch (I assume it happened to everyone at least once :))


#9

The jerk and thud were most likely caused by the engine trying to quickly spool up to 4500 RPM. The engine most likely also leaped up on the motor mounts when you did this, causing the thud. I doubt you did any harm this time. Just try not to do it again.