Accidentally shifted into 3rd instead of 5th

[mercdank]

I was doing some spirited driving last night and took the car up over 5000 rpm in fourth gear (maybe more, not totally sure) and missed 5th in the upshift, going into third in error. The rpms went instantly to redline and I slowed down quite a bit. I quickly shifted to sixth after that and took it easy all the way back home.

The car didn't feel or sound any different, so I hope the rev limiter kicked in to save the engine in time. However I'm not so sure that the transmission was spared. Must have been around 100mph or so when I dropped it into 3rd. I will run the vehicle health report, hopefully nothing weird pops up.

Boomba bushings and transmission plate are next on the upgrade list after this little incident.

 

[Hijinx]

What's your redline?

 

[CanadianGuy]

I would not worry unless its a regular occurrence. The rev limiter would have saved everything.

 

[mercdank]

Definitely not regular, first and hopefully only time.

 

[Hijinx]

I would not worry unless its a regular occurrence. The rev limiter would have saved everything.

It's early, so I'm still getting my head on straight, but at 6500rpm 3rd gear is limited to 87mph on a totally stock car. Due to software limitations, I don't think he can physically shift into 3rd over 87mph... However, 3rd gear is capable of 100 with the rpm raised to 7500. So mechanically, everything would be sound.

 

[mercdank]

It's early, so I'm still getting my head on straight, but at 6500rpm 3rd gear is limited to 87mph on a totally stock car. Due to software limitations, I don't think he can physically shift into 3rd over 87mph... However, 3rd gear is capable of 100 with the rpm raised to 7500. So mechanically, everything would be sound.

Ok that's a bit of a relief.

Basically this is a step by step what happened:
In 3rd gear, 6k shift into 4th
In 4th gear, 6k (or so) shift back to 3rd in error, instead up to 5th.
In 3rd, car redlines and huge deceleration, quickly shift to 6th and coast for remainder of cruise.

I hope this makes sense.

 

[Hijinx]

Ok that's a bit of a relief.

Basically this is a step by step what happened:
In 3rd gear, 6k shift into 4th
In 4th gear, 6k (or so) shift back to 3rd in error, instead up to 5th.
In 3rd, car redlines and huge deceleration, quickly shift to 6th and coast for remainder of cruise.

I hope this makes sense.

I think you're fine... If you were like 105, 3rd would be mechanically limited (there's an ECU hard code around 8krpm), and you'd probably hear some crunching.

 

[CanadianGuy]

There is no physical prevention in the shifts like some other cars. You can slam in any gear from any gear including reverse if you disable the lockout. Yes in a pull 3 is limited to about 90 in stock. But the tranny and the engine easily handle a miss shift. I know ive done it more then once in many cars. Some were 3rd to 2nd instead of fourth. I personnaly think grinding the gears is worse then a bad but clean shift.

Im just saying based on what was described a one quick miss shift with a normal drive without any further sounds/ rattles or bad vibrations the liklyhood of damage is low. I could be wrong but i would tend to hope the tranny is not made of cheese. Especially seeing what rodmoe did to his car with only a clutch change.

 

[mercdank]

Thanks guys, I feel better now. No crunches or noises but I will keep a keen ear for a while.

 

[CanadianGuy]

I think you're fine... If you were like 105, 3rd would be mechanically limited (there's an ECU hard code around 8krpm), and you'd probably hear some crunching.

Interesting i never hit a mechanical limit yet and i caugh myself going from 4th to 1st did no relase the clutch i justnknow mybarm was in the wrong spot and corrected. Hmm may have to go play to figure some things out.

 

[Hijinx]

Interesting i never hit a mechanical limit yet and i caugh myself going from 4th to 1st did no relase the clutch i justnknow mybarm was in the wrong spot and corrected. Hmm may have to go play to figure some things out.

I used a "ould" word, which indicates a strong belief. There has to be a mechanical limit somewhere, as in, the gear will spin too fast, create a lot of heat and tear itself apart (or seize) at some point.

 

[CanadianGuy]

I used a "ould" word, which indicates a strong belief. There has to be a mechanical limit somewhere, as in, the gear will spin too fast, create a lot of heat and tear itself apart (or seize) at some point.

Ah should be that but i was thinking more a barier. In my aveo i could not shift into 1st if it was moving faster than 10mh had a mechanical lock out which near then end i crunched. The FiST surprised me not having one and i surged the first gear a few times while breaking it in.

 

[AMontgomery]

If you do too stupid of a shift the car has nannies and limp home mode. I've accidentally done a 3 to 2 shift redlining in 3rd coming up an on ramp. Revs jumped above 8500 rpm. Car went into limp home mode and limited boost to 7 psi. Got to work, shut her down and restarted abs everything was fine. It didn't even throw a code in diagnostic mode with the Accessport. Haven't had any trouble and that was 6 months ago. I just watch my shifts more closely now. This engine and trans is pretty tough.

 

[FORZDA 2]

I think you're fine... If you were like 105, 3rd would be mechanically limited (there's an ECU hard code around 8krpm), and you'd probably hear some crunching.

Just so folks know, the ECU can't stop you from severely over-revving the engine to ANY rpm on a downshift. Know that there is NO limit on a mechanical over-rev. Also, there is no mechanical limit on the trans shifting up or down with the clutch in. You can physically jam it into any gear, except reverse, with enough force on the shifter. Reverse gear literally rotates backwards from the forward gears so it will just grind the shift cone and the reverse gear engage teeth (not the actual gear teeth).

 

[Hijinx]

Just so folks know, the ECU can't stop you from severely over-revving the engine to ANY rpm on a downshift. Know that there is NO limit on a mechanical over-rev. Also, there is no mechanical limit on the trans shifting up or down with the clutch in. You can physically jam it into any gear, except reverse, with enough force on the shifter. Reverse gear literally rotates backwards from the forward gears so it will just grind the shift cone and the reverse gear engage teeth (not the actual gear teeth).

Yeah, I was trying to get that point across more or less.

 

[frankiefiesta]

I did a 1-2-1 shift at the drag strip. Ended up busting the passenger side motor mount bolt, and the transmission took a beating. Started making the infamous whining noise after the bad shift. Car is currently at the dealer having the transmission inspected.

You would know almost instantly if you broke anything

 

[techun]

Just so folks know, the ECU can't stop you from severely over-revving the engine to ANY rpm on a downshift. Know that there is NO limit on a mechanical over-rev. Also, there is no mechanical limit on the trans shifting up or down with the clutch in. You can physically jam it into any gear, except reverse, with enough force on the shifter. Reverse gear literally rotates backwards from the forward gears so it will just grind the shift cone and the reverse gear engage teeth (not the actual gear teeth).

This. People talking about the ECU limiting things...that is not what happened here. If you downshift to the wrong gear, you can break things.

 

[Hijinx]

This. People talking about the ECU limiting things...that is not what happened here. If you downshift to the wrong gear, you can break things.

We know.

 

[blurred]

4th gear at 6000 is 106mph, 3rd gear at 106mph is 7900rpm so that's the neighbourhood of what you hit.

stabbing 8000rpm in a mis-shift is certainly enough to have piston to valve contact, I would image these are severe interference heads and the valvetrain might be decent up to the 7500rpm range, but above that could float and kiss parts.

I have seen plenty cars that have a slight tap and slightly bent valves reducing compression slightly, so maybe a comp test to be sure if you notice a slightly lopey idle or slightly increased fuel consumption


To re-iterate the corrections... there is no such thing as a rev-limiter in a downshift situation, you can rev to 12,000 is you go 5th to 2nd for instance. Rev limiters are only to stop acceleration in gear.

 

[RAAMaudio]

Absolutely correct on the rev limit on down shifts, there is none.

The known rev limit, factory hard set, is 7,700 RPM and at least one working on this thinks it can handle 8,000 just fine so working on a solution to raise it

I am at 7400 right now and love the sound it makes, I can only imagine 8,000, must be damn fine indeed.

Of course this is not about the sound, it is above maximizing the output of the engine giving a wider powerband for those with a BT.

I want both, the power and the sound, of course