[Z06] engine damage?!?!
Thread Starter
Racer
Joined: Jan 2008
Posts: 404
Likes: 0
engine damage?!?!
i was have a little fun with a C6 the other day on the highway. I was crusing in 6th when he decided to take off and i go to downshift to 4th gear. Clutch is engaged and WAM, i hear the rev limiter kick in twice before i depress the clutch again. I hit freakin second gear instead of 4th. Not sure my mph when i dropped to second but when it redlined i shifted quickly from 2nd to 5th and it then hit 3k rpm.
Car is running fine right now, cruising and WOT. but im wondering if i potentially damaged the motor?
Car is running fine right now, cruising and WOT. but im wondering if i potentially damaged the motor?
Pro
Joined: Sep 2008
Posts: 692
Likes: 4
From: PA
You'd likely know if you damaged the motor. Fortunately, 2nd gear goes to about 70 mph, so if you were under that when you were cruising and dropped to 2nd, you would have just hit the rev limiter which saved your ***.
If you were going faster than 70 mph and dropped it into 2nd, you may have over-revved the motor which can damage the valvetrain. When you downshift to a gear that would be spinning at > 6600 rpm at whatever speed you're at, the rev limiter can't help you.
How does your car feel/sound?
If you were going faster than 70 mph and dropped it into 2nd, you may have over-revved the motor which can damage the valvetrain. When you downshift to a gear that would be spinning at > 6600 rpm at whatever speed you're at, the rev limiter can't help you.
How does your car feel/sound?
Thread Starter
Racer
Joined: Jan 2008
Posts: 404
Likes: 0
You'd likely know if you damaged the motor. Fortunately, 2nd gear goes to about 70 mph, so if you were under that when you were cruising and dropped to 2nd, you would have just hit the rev limiter which saved your ***.
If you were going faster than 70 mph and dropped it into 2nd, you may have over-revved the motor which can damage the valvetrain. When you downshift to a gear that would be spinning at > 6600 rpm at whatever speed you're at, the rev limiter can't help you.
How does your car feel/sound?
If you were going faster than 70 mph and dropped it into 2nd, you may have over-revved the motor which can damage the valvetrain. When you downshift to a gear that would be spinning at > 6600 rpm at whatever speed you're at, the rev limiter can't help you.
How does your car feel/sound?
Thread Starter
Racer
Joined: Jan 2008
Posts: 404
Likes: 0
I VERY RARELY do anything on the street so i know lol. Oh and i dont believe in karma, i just believe that if you continue to do wrong things in life that it will eventually screw you over.....thats not karma is it? lol
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
That's a definition of something biting you in the a** eventually...
Burning Brakes
Joined: Feb 2006
Posts: 1,205
Likes: 5
From: Jupiter FL
That'll teach you not to do a 6-4 shift rather than a 6-5-4. 
Having done that sort of thing a few times myself, I know that "heart in the throat" feeling when the engine suddenly sounds like it's about to explode. As noted, if you did any serious damage, you'd know about it by now. You're okay, just chalk it up to "experience."
Having done that sort of thing a few times myself, I know that "heart in the throat" feeling when the engine suddenly sounds like it's about to explode. As noted, if you did any serious damage, you'd know about it by now. You're okay, just chalk it up to "experience."
Pro
Joined: Jun 2001
Posts: 721
Likes: 10
From: Irvine CA
I was a the track one time, Willow Springs, and a friend shifted from fifth to second at about 120. It locked up the rear wheels but caused no damage. The car, a C4-LT4, did wind up going south in the northbound lane.
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Thread Starter
Racer
Joined: Jan 2008
Posts: 404
Likes: 0
That'll teach you not to do a 6-4 shift rather than a 6-5-4. Having done that sort of thing a few times myself, I know that "heart in the throat" feeling when the engine suddenly sounds like it's about to explode. As noted, if you did any serious damage, you'd know about it by now. You're okay, just chalk it up to "experience."
Having done that sort of thing a few times myself, I know that "heart in the throat" feeling when the engine suddenly sounds like it's about to explode. As noted, if you did any serious damage, you'd know about it by now. You're okay, just chalk it up to "experience."
Instructor
Joined: Jul 2008
Posts: 150
Likes: 0
From: Chesapeake Beach MD
I think you are fine. I did this once in my GTO except I was shifting from 3rd to 4th and nailed 2nd. RPMs shot up very fast but no damaged occured. If anything you will cause velvetrain damage especially to the push rods but you would of known it by now. Next time get the jump on him so you arent paniced trying to find the right gear 
.
.
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 794
From: Longview Texas
Rev limiter cannot save you if you hit too low of a gear. 
Cutting ignition or fuel will not keep the RPM down if you are mechanically driving the engine.
Your engine is toast and you just don't know it yet.
Cutting ignition or fuel will not keep the RPM down if you are mechanically driving the engine. Your engine is toast and you just don't know it yet.
Burning Brakes
Joined: Apr 2007
Posts: 756
Likes: 22
From: OK/FL
I have at least 7 mech over rev (3-4 moneyshift) with 1 that accidentally had the clutch completely engaged (flatspotted all 4 tires, lost me ~10hp when I dyno checked it). But I've since swapped over the valvetrain to some stupid stout stuff.
Get the valvetrain checked out though. If it's a sewing machine you got a problem.
However, if you do it enough, you will smoke the bearings. I've seen that on a few cars where the driver thinks that you can downshift while at redline.
don't stress too much about it, just be mindful of it.
Get the valvetrain checked out though. If it's a sewing machine you got a problem.
However, if you do it enough, you will smoke the bearings. I've seen that on a few cars where the driver thinks that you can downshift while at redline.
don't stress too much about it, just be mindful of it.
Last edited by OKsweetrides; Nov 10, 2008 at 05:02 PM.
Burning Brakes
Joined: Dec 2006
Posts: 782
Likes: 0
From: Ga
I have done something similar to this in mine one time, thats all it took to learn from it! No engine damage for me, but you need to look under the rear diff and see if there are any leaks. When i did it my right rear diff seal built up too much pressure and started leaking. Its a much cheaper fix but it does happen.
Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
This is why I gas/clutch easy when downshifting multiple gears like that. You'll know right away you got the wrong gear as soon as you start feeding the clutch. So all ya gotta do is nail the clutch to the floor again before it overrevs.
Doesn't sound like you hurt anything.
Doesn't sound like you hurt anything.
Melting Slicks
Joined: Dec 2006
Posts: 2,186
Likes: 2
From: Woodinville WA
Practice, practice
This is why you should practice your downshifting. Get it down pat so you don't have to force it or think about it when you need to. I always downshifted to 3rd for anything below 80 mph as 3rd gear will run you up around 98 mph if you shift just b/f redline. Disengage the gear and blip the throttle the shifter will center in the 3-4 gate and when the engine revs are matched the shift will easily slide in place with minimal stress on the synchro's. With some practice you will be able to do this very quickly.
Drifting
Joined: Apr 2000
Posts: 1,390
Likes: 35
From: INDIANA
You would hear it already if you damaged the valvetrain. However, even if you didn't over-rev on the downshift, the abrupt change in rpm has been known to spin a rod bearing, and what would start out as a faint tick would progress to a knock in a few hundred miles.
I did that one time playing with the govenor springs in an auto. I thought it was pretty cool that it would downshift to first at 50 mph, until that time it did it from 3rd to 1st going from cruise to 6000 rpm instantly, with a soon to develop "tick" that ended up being about 1/8" clearance on the rod bearing, enough that the piston was hitting the head.
I did that one time playing with the govenor springs in an auto. I thought it was pretty cool that it would downshift to first at 50 mph, until that time it did it from 3rd to 1st going from cruise to 6000 rpm instantly, with a soon to develop "tick" that ended up being about 1/8" clearance on the rod bearing, enough that the piston was hitting the head.
Burning Brakes
Joined: Aug 2007
Posts: 880
Likes: 0
From: Bath PA
Suprising how many people forget under pressure that the shifter's default location is centered between third and fourth. Having said that I must admit to having grabbed second while H/T downshifting into a turn. I blamed it on g-forces! That was over two years ago. Engine was fine.
Advanced
Joined: Jan 2008
Posts: 87
Likes: 0
From: Clovis Ca
i was have a little fun with a C6 the other day on the highway. I was crusing in 6th when he decided to take off and i go to downshift to 4th gear. Clutch is engaged and WAM, i hear the rev limiter kick in twice before i depress the clutch again. I hit freakin second gear instead of 4th. Not sure my mph when i dropped to second but when it redlined i shifted quickly from 2nd to 5th and it then hit 3k rpm.
Car is running fine right now, cruising and WOT. but im wondering if i potentially damaged the motor?
Car is running fine right now, cruising and WOT. but im wondering if i potentially damaged the motor?
Thread Starter
Racer
Joined: Jan 2008
Posts: 404
Likes: 0
Are you using the stock shifter ? Since I installed the short shifter from MGW, my shifts are stiffer but much more positive. There is a distinct detent spring effect in second gear that discourages the 6th to 2nd, unless you force the shift in that direction. Using the shift hints from another forum member( Ranger, I think ), makes hitting the wrong gear a distant memory. The more miles I put on my MGW shifter, the easier the shifting gets, and the happier I am with the purchase.
I appreciate all of the input guys, so far all is well. I will keep checking her for the next few hundred miles to see if anything pops up