Over rev ?????
Burning Brakes
Joined: Sep 2014
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it depends, if you miss a shift and hit the rev limiter "over revving", nothing should happen. If you hit second gear when you were trying to go hard from 3rd to 4th "mechanically over revving"... all kinds of $hit will happen. Its one of those things where you will know if you broke it
Last edited by jdmdohcpower; Jul 7, 2015 at 03:04 PM.
Race Director
Joined: Feb 2008
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From: Alexandria VA
Happened to me. Going for 3rd, went right back into 1st. Motor screamed. Its un-nerving, but as long as nothing let loose, you should be alright. If it did suffer a catastrophic failure, GM would probably tell you to pound sand for a warranty. Since it didn’t, no harm no foul, just make sure to not let it happen again.
Team Owner
Joined: May 2005
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From: NY
St. Jude Donor '26
It has a rev limiter, you're like fine. Unless you grabbed second instead of 4th and engaged the clutch you'll be A-ok.
I missed a shift once and did exactly that in my old Taurus SHO, spun the motor to like 10500 and never had an issue. That was an OHC motor, OHV motors will sometimes bend a push rod.
I missed a shift once and did exactly that in my old Taurus SHO, spun the motor to like 10500 and never had an issue. That was an OHC motor, OHV motors will sometimes bend a push rod.
Last edited by RJ-92; Jul 7, 2015 at 03:11 PM.
Thread Starter
Instructor
Joined: Aug 2012
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It has a rev limiter, you're like fine. Unless you grabbed second instead of 4th and engaged the clutch you'll be A-ok.
I missed a shift once and did exactly that in my old Taurus SHO, spun the motor to like 10500 and never had an issue. That was an OHC motor, OHV motors will sometimes bend a push rod.
I missed a shift once and did exactly that in my old Taurus SHO, spun the motor to like 10500 and never had an issue. That was an OHC motor, OHV motors will sometimes bend a push rod.
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Thread Starter
Instructor
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it depends, if you miss a shift and hit the rev limiter "over revving", nothing should happen. If you hit second gear when you were trying to go hard from 3rd to 4th "mechanically over revving"... all kinds of $hit will happen. Its one of those things where you will know if you broke it
Safety Car
Joined: Aug 2012
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With the A8 you couldn't have created a serious over-rev via a missed shift 
It won't allow a paddle shift into too low a gear, you will get a shift denied message if you try to shift into a range that will result in excessive RPM and the same is true if you try to select a range that results in RPM being too low. If you neglect to shift while accelerating the rev limiter will simply prevent you from going faster.
I am not sure what the transmission will do if you are on a very steep downgrade and have manually selected a range where the engine will exceed safe RPM if you don't use the brakes to keep speed in check. That is a programming choice and I would not advise testing how it behaves
With the A8 you haven't hurt anything except maybe your pride if you were racing and didn't shift quickly enough and lost.
It won't allow a paddle shift into too low a gear, you will get a shift denied message if you try to shift into a range that will result in excessive RPM and the same is true if you try to select a range that results in RPM being too low. If you neglect to shift while accelerating the rev limiter will simply prevent you from going faster. I am not sure what the transmission will do if you are on a very steep downgrade and have manually selected a range where the engine will exceed safe RPM if you don't use the brakes to keep speed in check. That is a programming choice and I would not advise testing how it behaves
With the A8 you haven't hurt anything except maybe your pride if you were racing and didn't shift quickly enough and lost.
Track Rat
Joined: Oct 2006
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Sounds like a non-issue for the OP since it was an upshift in an A8. However, I have had the experience of "upshifting" from 4th in to 3rd instead of 5th on the back straight at Road Atlanta. This was in my C6Z and the data showed I hit 8200 RPM. Nothing broke but I was smart enough to park the car after that.
I called Katech and Jason told me to change the valve springs as they were likely weakened from the overrev. I did and you could tell that some of them were because they were special pains to get out. If you keep running the motor the odds are the spring will fail, you will drop a valve, and then it gets expensive. In my case it was an easy fix because I didn't just keep going.
Just a word of warning should it happen to someone else.
I called Katech and Jason told me to change the valve springs as they were likely weakened from the overrev. I did and you could tell that some of them were because they were special pains to get out. If you keep running the motor the odds are the spring will fail, you will drop a valve, and then it gets expensive. In my case it was an easy fix because I didn't just keep going.
Just a word of warning should it happen to someone else.
Team Owner
Joined: Aug 2011
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From: GREER SC
I really doubt that you hurt anything. I went from top of 2nd at 6500 looking for 3rd and went right into 1st rear tires squalled like hell and the car's rear end went all over the track, but I saved it and it didn't hurt a thing.
Race Director
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From: Camp Verde AZ
C1 of Year Finalist (performance mods) 2019
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If nothing broke, then nothing happened. You would know.
I missed a shift in my 308 once, which has a 7500 redline motor; I watched in horror as that tach finally peaked at about 10,500-10,800, and started coming back down. Time seemed to in be slow motion.
Nothing was hurt.
Doug
I missed a shift in my 308 once, which has a 7500 redline motor; I watched in horror as that tach finally peaked at about 10,500-10,800, and started coming back down. Time seemed to in be slow motion.
Nothing was hurt.
Doug
Track Rat
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I disagree. An overrev will weaken springs. They may not fail immediately but if sufficiently weakened they will fail.
Somewhere around here there's a thread where JD dropped a valve at VIR. Jason went back and looked at his video from a previous session and found where he overreved on an early downshift.
All I'm saying is just because it seems fine I would take the precaution of swapping the valve springs and make sure everything else looks ok. It's not a big job.
Somewhere around here there's a thread where JD dropped a valve at VIR. Jason went back and looked at his video from a previous session and found where he overreved on an early downshift.
All I'm saying is just because it seems fine I would take the precaution of swapping the valve springs and make sure everything else looks ok. It's not a big job.
Le Mans Master
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From: Ontario
Drifting
Joined: Aug 2002
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From: MI
No issue, you just hit the rev limiter. The car is programed to keep you from over reving it. Even on downshifts, the automatic will not let you go to a lower gear if it would result in the engine over reving.
The only way to over rev a Corvette engine is with a manual transmission car. It will not over rev via the throttle as it is also rev limited. The danger is shifting into a lower gear and over reving.
The only way to over rev a Corvette engine is with a manual transmission car. It will not over rev via the throttle as it is also rev limited. The danger is shifting into a lower gear and over reving.
Last edited by Boiler_81; Jul 7, 2015 at 07:58 PM.
Thread Starter
Instructor
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No issue, you just hit the rev limiter. The car is programed to keep you from over reving it. Even on downshifts, the automatic will not let you go to a lower gear if it would result in the engine over reving.
The only way to over rev a Corvette engine is with a manual. transmission car. It will not over rev via the throttle as it is also rev limited. The danger is shifting into a lower gear and over reving.
The only way to over rev a Corvette engine is with a manual. transmission car. It will not over rev via the throttle as it is also rev limited. The danger is shifting into a lower gear and over reving.
Pro
Joined: Jan 2014
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You were lucky, unless the LT4 has lighter valves and better springs than the LT1.