[Shaq74]

I bet you tires went SKRTTTTTT

[crunch527]

If the plan is to continue modding then none of this matters...

Not to be flippant, but if you can afford to buy a brand new ZL1 knowing you are going to mod it, and sacrifice the warranty, AND resale value, then why do you care about a missed shift?

If anything have the valve train checked...most likely its ok, but hard to say for sure...

But in the mean time rest easy...new LT4 crate engines are available...if this one blows, buy another engine and slap it in and go...

Either way, you are good to go...

[KyWildcats]

So I missed 4th a week ago smacked it in 2nd. It slung both belts off the car. But car is driving fine now.

[KyleL]

I care about the missed shift bc I'm just curious as to what safeguards are in place to minimize damage from missing a downshift. But If I do blow this one I wouldn't buy a crate motor, I'd build this one if possible

[dicebier]

Originally Posted by KyleL

I care about the missed shift bc I'm just curious as to what safeguards are in place to minimize damage from missing a downshift. But If I do blow this one I wouldn't buy a crate motor, I'd build this one if possible

There are really no safeguards against a downshift over rev, known also as a mechanical overrev..... it is possible to install stronger springs, rockers, etc.....however the computer itself cannot slow down the inertia going forward.
With that being said...most all failures due to this type of misshift happen almost immediately, not days or weeks later, usually it’s kaboom and fast.
How many RPM’s were you going while in 6th before the miss shift to 2nd? The reason I ask is that a downshift from high rpm to high rpm is MUCH worse than a downshift from a low RPM to a high one.

[FringBirdAloha]

Then study this video and adopt its teachings. Never will happen again!

https://youtu.be/ujTeX-LYmuo

[KyleL]

Originally Posted by dicebier

There are really no safeguards against a downshift over rev, known also as a mechanical overrev..... it is possible to install stronger springs, rockers, etc.....however the computer itself cannot slow down the inertia going forward.
With that being said...most all failures due to this type of misshift happen almost immediately, not days or weeks later, usually it’s kaboom and fast.
How many RPM’s were you going while in 6th before the miss shift to 2nd? The reason I ask is that a downshift from high rpm to high rpm is MUCH worse than a downshift from a low RPM to a high one.

It was a 5-2 instead of a 5-4....I'd say I was at about 3k, maybe a little less, in 5th.

[dicebier]

Originally Posted by KyleL

It was a 5-2 instead of a 5-4....I'd say I was at about 3k, maybe a little less, in 5th.

That sounds like you are ok...that red blinking was a shift light...keep us up to date but it seems ok. I have a friend that went from 6th to 2nd , 6th at about 1800 to 2nd for about as long as you did. Got his car dyno’d.... no sign of valve float 550 rwhp 556 tq 91 octane gas at 2200 ft above sea level. He was relieved lol. He’s over 2k miles now (was 800 when he over revved) and not a burp. Was a Corvette but supercharged same stuff...

[crunch527]

Originally Posted by KyleL

I care about the missed shift bc I'm just curious as to what safeguards are in place to minimize damage from missing a downshift. But If I do blow this one I wouldn't buy a crate motor, I'd build this one if possible

Ok, now I understand...

To take it further, it would be nice if there was a way to build in some kind of safe guard into the shift mechanism on downshifts...if GM can engineer the 1-skip 2nd to 4th on acceleration...then seems plausible they could design something to eliminate over-revving on the way down...

This down shift limiter could be designed to allow the car to be fully tracked within its maximum performance design envelope without losing any time on the track.

The manual purists will probably hate this and say it defeats the purpose of a manual.

Happy 4th!

[Gunkk]

Originally Posted by crunch527

it would be nice if there was a way to build in some kind of safe guard into the shift mechanism on downshifts...

Yes, they have done this. It's called:




Automatic.

[KyleL]

Originally Posted by crunch527

Ok, now I understand...

To take it further, it would be nice if there was a way to build in some kind of safe guard into the shift mechanism on downshifts...if GM can engineer the 1-skip 2nd to 4th on acceleration...then seems plausible they could design something to eliminate over-revving on the way down...

This down shift limiter could be designed to allow the car to be fully tracked within its maximum performance design envelope without losing any time on the track.

The manual purists will probably hate this and say it defeats the purpose of a manual.

Happy 4th!

Happy 4th to you as well

That's the same question I asked in here as well. These manuals have reverse lockout so you don't accidentally grab reverse while going forward, automatic rev matching, 1-4 cags, no lift shift, and even hill start assist!!! But they draw the line at a speed related gear lockout to elminate an accidental misshift???

I think if the manual purist wants to stomp their feet about anything on the manuals, they've got a few other reasons

[garfin]

Originally Posted by FringBirdAloha

Then study this video and adopt its teachings. Never will happen again!

https://youtu.be/ujTeX-LYmuo

^This!
Once upon a time, I went 3-2 (at redline in 3rd) on the dragstrip in 98 SS stock LS1. The car stopped dead in its tracks almost throwing me through the windshield! I finally got it started again and managed to drive home with the car bucking like crazy and raw gas dripping out the exhaust pipes.
I think all the pushrods were bent and there were definitely some smacked valves.
The engine was rebuilt at the dealer and I subsequently found out that they had done the rebuild USING THE ORIGINAL VALVE SPRINGS, which unbeknownst to me at the time, had been seriously weakened by the incident, This caused more grief later on with more bent pushrods when the engine spike to only 4500 rpm. I had the springs tested independently and there were a lot of springs measuring in the 40 lb.- 55 lb. pressure range where the stock pressure was supposed to be 70 lbs.
The engine ran just fine after the rebuild until that quick spike to 4500 rpm when I was getting used to rev matching after installing 4.10 gears from the stock 3.42s.

Best regards,

Elie

[BMWM.D.]

Originally Posted by dicebier

“100 percent directed at me” hmmmm not the link to the confirmed article? Well good to know you are 100 percent targeting me or my verified posts lol I’m out

No offense intended, but Road & Track was making their own assumptions based on what Al said. A missed shift and a "money shift" (aka mechanical over-rev) are two very different things. One can have safeties in place to prevent damage, the other does not. Al's point was that you can drive the car hard as it was intended, and not be worried about things like breaking an axle shaft on the drag strip. That is VERY different than jamming it into the wrong gear.

That said, I did this myself once on a supercharged LS1. Went from 3rd up at 6000 rpm, into 2nd. Thankfully, I felt the abnormal sensation as I was releasing the clutch pedal, and quickly pushed it back in. I wasn't watching the tach, but the whole car jumped sideways. So I'm guessing the revs shot up momentarily. This engine had a cam with aftermarket dual valve springs, titanium retainers, and chromoly pushrods. No damage occurred, and it was fine until I sold it a few years later. Can't say it would have been the same with a stock valvetrain. I guess I'll never know.

[Stephen12ZL1]

Originally Posted by BMWM.D.

No offense intended, but Road & Track was making their own assumptions based on what Al said. A missed shift and a "money shift" (aka mechanical over-rev) are two very different things. One can have safeties in place to prevent damage, the other does not. Al's point was that you can drive the car hard as it was intended, and not be worried about things like breaking an axle shaft on the drag strip. That is VERY different than jamming it into the wrong gear.

That said, I did this myself once on a supercharged LS1. Went from 3rd up at 6000 rpm, into 2nd. Thankfully, I felt the abnormal sensation as I was releasing the clutch pedal, and quickly pushed it back in. I wasn't watching the tach, but the whole car jumped sideways. So I'm guessing the revs shot up momentarily. This engine had a cam with aftermarket dual valve springs, titanium retainers, and chromoly pushrods. No damage occurred, and it was fine until I sold it a few years later. Can't say it would have been the same with a stock valvetrain. I guess I'll never know.

I've done the same thing in a 2002 Z06...felt funny on release and I immediately pushed the clutch in just as the rear tires were starting to protest. Scary but it happened on a 3-4 shift where I somehow managed to put it into 2nd instead of 4th.