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over revved engine

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Old Sep 16, 2008 | 05:23 PM
  #1  
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over revved engine

hey guys, so at an HPDE (at laguna) i mis-shifted from 3rd to 2nd. i was probably going at least 70 (2nd max is 64mph) when i wanted to get 4th. so the mis-shift happened, the rear wheels lock up, and i immediately put the clutch back in. this is for a split second so i have no idea what the revs were. afterwards the car drives fine. i know our vq is not an interference engine, but im wondering how did the rear wheels lock up and is there a chance anything was damaged? ive put on a lot of miles after this happened and the car drives fine and sounds fine.
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Old Sep 16, 2008 | 05:26 PM
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Sam Rothstein
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Nah... You should be fine... Wheels locked up due to engine-braking...
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Old Sep 16, 2008 | 05:31 PM
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i might sound dumb, but by what mechanism does engine braking work by int his situation of overrevving? do all the valves close and prevent the chamber from expanding thereby causing wheel locking?
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Old Sep 16, 2008 | 05:41 PM
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Originally Posted by gshb
i might sound dumb, but by what mechanism does engine braking work by int his situation of overrevving? do all the valves close and prevent the chamber from expanding thereby causing wheel locking?
Hehehe... Nah maing... Hmmm, how can i explain this.... What happens is the engine is at around 3000 rpms in 4th gear at 60 mph (for instance)... When you downshift to 2nd gear going the same speed (60mph), the engine jumps to 7000 rpm.... Doing this slows down the car drastically and makes the engine actually "brake" (slow) the car faster... This is why the tires "locked"... Because the engine had to jump rpms so quickly and couldn't due to the tires preventing it from jumping rpms as fast as it wanted to... Has nothing to do with valves closing irregularly or anything... Hope i didn't confuse you... Is this your first MT?
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Old Sep 16, 2008 | 05:42 PM
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you should be fine...
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Old Sep 16, 2008 | 05:45 PM
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shouldnt be that big of a deal.. and +1 on the question is this your first manual?
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Old Sep 16, 2008 | 05:48 PM
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Originally Posted by gamedog
Hehehe... Nah maing... Hmmm, how can i explain this.... What happens is the engine is at around 3000 rpms in 4th gear at 60 mph (for instance)... When you downshift to 2nd gear going the same speed (60mph), the engine jumps to 7000 rpm.... Doing this slows down the car drastically and makes the engine actually "brake" (slow) the car faster... This is why the tires "locked"... Because the engine had to jump rpms so quickly and couldn't due to the tires preventing it from jumping rpms as fast as it wanted to... Has nothing to do with valves closing irregularly or anything... Hope i didn't confuse you... Is this your first MT?
heh it is, though not what i learned on. i was paranoid because i thought that at my speeds, going to 2nd would be way over the redline because max speed in 2nd is 64. i was most likely doing faster than 70 at least. probably 80 because i wanted to grab 4th. so that would put 2nd gear speed way higher than 8k? but i think i understand now. thanks!
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Old Sep 16, 2008 | 05:55 PM
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Sam Rothstein
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Originally Posted by gshb
heh it is, though not what i learned on. i was paranoid because i thought that at my speeds, going to 2nd would be way over the redline because max speed in 2nd is 64. i was most likely doing faster than 70 at least. probably 80 because i wanted to grab 4th. so that would put 2nd gear speed way higher than 8k? but i think i understand now. thanks!
No prob man... Glad I could help... Don't worry I've done the accidental 3rd to 2nd shift instead of 4th goin 85 mph on a freeway on an onramp... Kinda freaks ya out... Just don't make a habit of it...
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Old Sep 16, 2008 | 07:28 PM
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I would worry if you'd have gone into second at like 120mph. Then it may have over spun the motor. You'd probably know right away though.
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Old Sep 16, 2008 | 11:17 PM
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Just a question...were you pistol gripping the shifter?

Also, it was probably an instant but, did you manage to see where the rpm needle went up to before you pushed the clutch in? It can't hurt to get a compression test just in case if it actually did overrev.
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Old Sep 17, 2008 | 02:00 AM
  #11  
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You will definitely need to learn how to Rev Match. There is a guide on how to drive a manual so make sure you read through it. It is on the site so search for it.
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Old Sep 17, 2008 | 01:53 PM
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well this happened back in february. back then i used pistol grip, but since then i have used backhand. since its been so long, 5months at least, i assume theres no damage =/
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Old Sep 17, 2008 | 01:59 PM
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You are fine. Everyone with a manual has done that at some point.
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Old Sep 17, 2008 | 02:44 PM
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Originally Posted by gshb
well this happened back in february. back then i used pistol grip, but since then i have used backhand. since its been so long, 5months at least, i assume theres no damage =/

Ah, so in that case you were pistol gripping? Just to clarify.


If you haven't really onticed anything then it's probably all good..
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Old Sep 17, 2008 | 02:59 PM
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Who got pistol whipped? Why wait 8 months to say something
If it hasn't exploded by now and you aren't leaving a smog trail driving around town you should get another 10,000 miles out of it
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