Power-Shifting - Toyota Nation Forum : Toyota Car and Truck Forums

goooopher · 12-19-2006, 10:54 PM

Hey i was talking to a friend of mine today and the topic of power-shifting came up when he told me he blew out his clutch on his STI. I asked how he got home bc he did it on a major highway...he said he powershifted all the way home...i about more details and i decided to go and give it a try in the corolla lol It went pretty well considering i dont have a tach...drove arounf for like 15min using the clutch to stop and to downshift, but i got the hang of it going from 2nd-3rd, 3rd-4th, and 4th-5th...1st to 2nd was tough but aside from that it was fine. Didnt grind the gears except for the first shot at it from 3rd-4th, but anyway i couldnt downshift...upshifting was not an issue, but i was wondering if there were any tips for how to downshift...

ghost_ryder35 · 12-19-2006, 11:21 PM

when you pull it out of gear tap the gas and let the shifter fall into place as the rpm's fall to the right level. Its all about rev matching. but shifting like that is hell on the transmission. your wearing it down for no reason.

***toyomoho*** · 12-19-2006, 11:22 PM

You need to time when let off the gas and shift. The torque needs to be removed from the trans gears to allow them to disengage/engage freely. Might limit power shifting, it is hard on the syncro rings and will wear then out prematurely.

DoubleEdgedWomb · 12-20-2006, 03:02 AM

It's bad for the transmission. Why do it if you have a working clutch?

freakinbox · 12-20-2006, 05:04 AM

I did it on my car just to learn it just incase it happens

goooopher · 12-20-2006, 07:20 AM

exactly...im in need of a new clutch soon as it is and i just want to be able to do it if the clutch does decide to go on me...

ghost_ryder35 · 12-20-2006, 07:45 AM

Quote:

Originally Posted by goooopher

exactly...im in need of a new clutch soon as it is and i just want to be able to do it if the clutch does decide to go on me...

if i knew my clutch was on the way out, i would replace it before it did go out. just my .02

dgoodhue · 12-20-2006, 08:29 AM

I described downshifting in the 2nd to last post in this thread.

http://www.toyotanation.com/forum/t166083.html

Flashmn · 12-20-2006, 08:37 AM

I wouldnt even bother with it, unless it was a worst case scenario as in being stuck in the middle of nowhere, without a working clutch. Why fuck up the tranny more than just the clutch. A clutch doesnt cost much, a whole tranny does, in comparison.

Doing stupid things to your car without reason =

t_cel_t · 12-20-2006, 12:50 PM

um yeah shifting without using the clutch is NOT powershifting, powershifting is keeping your foot planted on the gas and slamming down the clutch and pulling the shifter into the next gear and slipping your foot off the clutch. whole process takes about .25sec. what you are describing is shifting without clutching, not all that bad if you know how to do it. hell when i drive any type of big truck/semi i dont even use the clutch for anything other than first starting out.

dgoodhue · 12-20-2006, 01:26 PM

Quote:

Originally Posted by t_cel_t

um yeah shifting without using the clutch is NOT powershifting, powershifting is keeping your foot planted on the gas and slamming down the clutch and pulling the shifter into the next gear and slipping your foot off the clutch. whole process takes about .25sec. what you are describing is shifting without clutching, not all that bad if you know how to do it.

I have actually heard people do that process w/o using the clutch. WOT clutchless shifts.

DoubleEdgedWomb · 12-20-2006, 03:26 PM

Semis have straight-cut gears though, so they can handle being shifted without using the clutch.

Flashmn · 12-20-2006, 04:38 PM

^ditto, your corolla doesnt. Trucks also lack synchros for most part, your corolla doesnt. You're hurting your gearbox alot. Dumb.

***silver04rollas*** · 12-20-2006, 04:49 PM

Bingo! if you want to destroy your transmission quickly and efficiently in order to accelerate faster, you found your answer.

Powershifting is the most awesome way to blow your tranny.

Electric Pi · 12-20-2006, 05:21 PM

Quote:

um yeah shifting without using the clutch is NOT powershifting, powershifting is keeping your foot planted on the gas and slamming down the clutch and pulling the shifter into the next gear and slipping your foot off the clutch. whole process takes about .25sec. what you are describing is shifting without clutching, not all that bad if you know how to do it. hell when i drive any type of big truck/semi i dont even use the clutch for anything other than first starting out.

Quote:

Semis have straight-cut gears though, so they can handle being shifted without using the clutch.

Perhaps someone with more expertise in transmissions can shed some more light on this, but my understanding is that the important difference is syncro vs. dogbox not straight cut vs. helical cut gears. As I understand it there is no significant difference in the strength of helical gears vs. straight cut gears, and the failure point is more likely to be the dogs anyway. In a dog box they are designed to take more abuse because there are no syncros to ease engagement. It is my understanding that straight cut gears are commonly used on dog boxes because they are much cheaper to make, especially in small volumes. This article seems to support my understanding: http://forums.nasioc.com/forums/showthread.php?t=665334

P.S. t_cel_t is right. we are talking about presure shifting not power shifting.