Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB

Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB (https://www.ft86club.com/forums/index.php)
-   Engine, Exhaust, Transmission (https://www.ft86club.com/forums/forumdisplay.php?f=8)
-   -   Misdownshifted from 3rd to 2nd and over the redline (https://www.ft86club.com/forums/showthread.php?t=120032)

krayzie 07-05-2017 02:35 PM

IIRC there was a post on Temple of Vtec a long time ago where somebody's Razo shift knob cracked and the dude money shifted into 2nd gear and hit 11,000rpm. The engine survived but the gearbox blew.

nikitopo 07-05-2017 02:37 PM

Quote:

Originally Posted by krayzie (Post 2940608)
I want to attend this Gforce school of physics.



I think now he will go back to school.
:lol:

Tcoat 07-05-2017 02:51 PM

Quote:

Originally Posted by krayzie (Post 2940615)
IIRC there was a post on Temple of Vtec a long time ago where somebody's Razo shift knob cracked and the dude money shifted into 2nd gear and hit 11,000rpm. The engine survived but the gearbox blew.

That can be a result as well. A lot depends on the clearances and some engines can take it better than others.
I just used the 1,000 rpm as a sort of place holder number. You could go over 1,000 or 10,000 a hundred times with no issue or you could blow things apart at 950 the first time you did it. It isn't an exact science.
I miss shifted a drag set up Pinto once. The engine survived fine, the tranny had some minor damage and the u-joints all but blew apart.


As far as the OP here goes he is fine.

FR-Sky 07-05-2017 03:42 PM

It is called money shift..sounds so Gangster....
I think you are fine if you don't do it all the time...
plus, it is very hard to mis-shift from 3rd to 4th....little more practice, yeah?

Ultramaroon 07-05-2017 03:48 PM

I believe, for the fa20, the weak link from an acute over-rev is between the wrist pin and piston. The holes stretch and give up the ghost. It has been covered here a few times.

Which astonishes me considering the floofiness of the valve springs. The valves must be super light.

Irace86.2.0 07-05-2017 04:01 PM

Quote:

Originally Posted by Tcoat (Post 2940596)
Did you even bloody well READ what I said before?



Yea. Even a thousand bro.


Sent from my iPhone using Tapatalk

Irace86.2.0 07-05-2017 04:12 PM

Quote:

Originally Posted by Ultramaroon (Post 2940682)
I believe, for the fa20, the weak link from an acute over-rev is between the wrist pin and piston. The holes stretch and give up the ghost. It has been covered here a few times.

Which astonishes me considering the floofiness of the valve springs. The valves must be super light.



Holes stretch? From force or heat/friction? Acute overheating would cause metal expansion, right, and lubricants to heat to dangerously thin levels resulting in metal on metal contact? If that is what we are talking about then could that much heat really occur in a second or two max? I can't see it happening.


Sent from my iPhone using Tapatalk

Tcoat 07-05-2017 04:20 PM

Quote:

Originally Posted by Irace86.2.0 (Post 2940700)
Holes stretch? From force or heat/friction? Acute overheating would cause metal expansion, right, and lubricants to heat to dangerously thin levels resulting in metal on metal contact? If that is what we are talking about then could that much heat really occur in a second or two max? I can't see it happening.


Sent from my iPhone using Tapatalk

You are stuck on heat. There is much more than heat involved in a miss shift over rev situation. The parts are simply not designed to move that fast and they hit things or shift and blow apart. Heat has nothing to do with that. We are not talking about sitting there with you foot on the gas at redline for an hour.

Tcoat 07-05-2017 04:29 PM

Quote:

Originally Posted by Irace86.2.0 (Post 2940696)
Yea. Even a thousand bro.


Sent from my iPhone using Tapatalk

Tell 'ya what. Why don't you just go out and make some videos of a few miss shifts at just 1,000 rpms over redline. Just a dozen or so would satisfy me that everything I have know and experienced about over revs is totally wrong. Hell you really want to convince me then do a couple at only 2,000 over since that should be fine as well.

topholney 07-05-2017 04:47 PM

Quote:

Originally Posted by skkk (Post 2940183)
I did not... cause it just hit like slightly above the redline and then it dropped under the redline right away. I'm just so worried about it.

Early on when I started driving mine I miss-shifted from 5th to 4th. I immediately hit the clutch to save it but definitely freaked myself out. I've driven probably 30k miles since then and haven't noticed any issues. If you know for sure something doesn't feel right, then get it checked out. Just learn from your mistakes and it should be fine.:thumbsup:

nikitopo 07-05-2017 05:08 PM

Quote:

Originally Posted by Tcoat (Post 2940715)
Hell you really want to convince me then do a couple at only 2,000 over since that should be fine as well.

I haven't figured out yet if this guy did it on purpose or by mistake. I was reading somewhere that he was trying that day to get used to the right-hand drive position:

https://j.gifs.com/LgE8x4.gif

On the other side, it is a bit bizarre to miss shift by accident and manage to make a lap record.

Ultramaroon 07-05-2017 06:04 PM

Quote:

Originally Posted by Irace86.2.0 (Post 2940700)
Holes stretch? From force or heat/friction? Acute overheating would cause metal expansion, right, and lubricants to heat to dangerously thin levels resulting in metal on metal contact? If that is what we are talking about then could that much heat really occur in a second or two max? I can't see it happening.

Peak linear accel. Casting yields.

Ultramaroon 07-05-2017 06:09 PM

Quote:

Originally Posted by nikitopo (Post 2940749)
I haven't figured out yet if this guy did it on purpose or by mistake. I was reading somewhere that he was trying that day to get used to the right-hand drive position:

His R8 which has a big ol' stepladder, gave out so he begrudgingly took out his backup vehicle which has a spring loaded centering mechanism. Forgetting about the spring, instead of allowing the gearshift to center itself for 4th, he nudged it across the nonexistent hard gate.

The rest is, as they say, expensive.

nikitopo 07-05-2017 06:43 PM

Quote:

Originally Posted by Ultramaroon (Post 2940789)

The rest is, as they say, expensive.



Or not so much for race cars ;)


All times are GMT -4. The time now is 08:34 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
User Alert System provided by Advanced User Tagging v3.3.0 (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.


Garage vBulletin Plugins by Drive Thru Online, Inc.