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Old 05-15-2003, 06:52 PM   #1
GaTechWRX
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Default Double-Clutch + Rev-Matching

I am very new to stick shifting. My WRX is the car I'm learning on. I'm doing pretty well so far but I'm having trouble with the rev-matching portion of double-clutching. I have experienced an inability to shift to first gear and so I would like to double-clutch to shift into it. My problem is I do not know what to rev the RPMs to to match the car speed (gear and output shaft speed). Is there any trick to this, or is it just a practice type of thing? I did manage to double-clutch once while moving slowly (about 10mph) by revving to about 3000 and then pushing the clutch in and holding the stick against first gear gate while letting the RPMs fall into it slid in to gear. I'd rather not have to over rev the engine and wait for the RPMs to fall to double-clutch.

Thanks a lot!

Dan
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Old 05-15-2003, 07:59 PM   #2
meZoom!
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i suggest practicing double clutch-downshifting at 4th to 3rd gears because it's probably easier, and those gears are a bit more forgiving if you screw up.
as a rule of thumb though, when i double clutch and blip thr throttle, i raise the rpm's by approximately 800-11,000rpm for every gear dropped. of course i'm not sitting there counting the marks on the tachometer...it goes by the "vrooom" sound that the engine makes. after a while i think you get to "hear" if you've revved high enough or not.
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Old 05-15-2003, 09:32 PM   #3
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wow 11,000 thats alot j/k. Yea say your in 4th gear at 3,000 rpm and want to get into 3rd, just simply rev up to 4,000. You always go 1,000rpm more if your are going to one gear lower. 2,000 rpm higher for 2 gears lower, etc.... 10mph is pretty slow so you can pretty much get into first without double clutching. I also have the first gear grinding and so far the highest speed i've been able to get into it was 15mph. Today i double clutched and i still got the grinding while going 25mph. I was in 2nd, clutched in then put in nuetral, cluthed out then revved to 3500 then clutched in quikly and tried to slide into first. Just got the grinding... anyone have ideas?
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Old 05-15-2003, 10:48 PM   #4
xylem007
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Default Pushing too hard?

I don't usually need to down shift into first since its such a short gear but when i downshift into it at 15 to 20 mph i clutch in, bring the rev's up 1k over last reading, put the shifter in the first slot and when i feel contact i try to push it in gently and if it doesn't go at the force level i'm used to using i don't try soo hard that it grinds. I've had the grinding before and now i always associate that with pushing too hard.

I've found what they say at

http://www.spdusa.com/new_page_5.htm

to be quite enlighting...
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Old 05-15-2003, 11:04 PM   #5
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Practice...I've been practicing on this particular car for a little over two years and I'm still not able to perfectly match revs. I usually do what you are doing, over rev a couple hundred and wait for the gear to snick in when the revs drop to the appropriate level. The times I have done it perfectly have been so sweet, though. When you perfectly rev match you can just dump the clutch and you get no jerkiness at all because your right foot is already where it needs to be.
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Old 05-16-2003, 01:41 AM   #6
GaTechWRX
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Quote:
The times I have done it perfectly have been so sweet, though. When you perfectly rev match you can just dump the clutch and you get no jerkiness at all because your right foot is already where it needs to be.
Stanley, that sounds absolutely amazing. I cannot wait to accomplish such a terrific feat! :-)

Thanks for all the replies,

Dan
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Old 05-16-2003, 08:00 AM   #7
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It just takes practice. Soon, you'll have a feel for where the rpms need to be. There is not set rule such as 1k rpms per gear. Sometimes it's more, sometimes it's less. The higher the rpms are in the current gear, the greater the difference will be when you downshift. For example, downshifting from 4th gear at 2k rpms may only necessite 2.5k in 3rd gear (difference of 500 rpms), but downshifting from 4th at 4k may need 6k in 3rd (difference of 2000 rpms).

These numbers are just an example - you have to do it a lot to get the feel of it.
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Old 05-16-2003, 01:06 PM   #8
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There a big difference in 1st and 2nd gear. The rev match from 4th to 3rd is like Vrooom. The rev match from 2nd to 1st is like Vrrroooooom.

Also, find an empty parking lot and drive around in 1st gear making notes of rpms at 5mph, 10mph, 15 mph, etc. My old Nissan, i could tell you cold what rpm my car was at at a given speen and gear, I'm still learning the WRX gears. Also, always better to overestimate and have the engine spinning faster than the driveshaft this way you don't buck the car in a turn.
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Old 05-16-2003, 02:03 PM   #9
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When going into 1st from a higher gear, you need more revs when you blip the throttle than going into 2nd, 3rd or 4th.

Remember to put the shifter into neutral, clutch out, then blip the throttle. Then clutch in, and gently press on the shifter. Don't try to force it into first. Hopefully, you're pressing the shifter as the revs are coming down to match transmission speed. As they match up, the shifter will practically get sucked into first.

If your rolling 20 mph, rev to about 4500 rpm. Your speed will be around 15 when it goes into gear.
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Old 05-17-2003, 04:58 AM   #10
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I have found that it does help to rev match when down shifting but as far a double clutching I can't see why you would want to do it. The stock transmision has syncros there for a reason so unless you have upgraded to a syncroless gear set there is really no benifit from double clutching.
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Old 05-17-2003, 09:10 AM   #11
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Quote:
Originally posted by Silver_Bell_WRX
I have found that it does help to rev match when down shifting but as far a double clutching I can't see why you would want to do it. The stock transmision has syncros there for a reason so unless you have upgraded to a syncroless gear set there is really no benifit from double clutching.
I agree with you 80%. I rarely double clutch except when downshifting to 1st. Simple rev-matching is much quicker and just as smooth. However, my first gear synchros don't get the job done, so I always double clutch on those rare occasions I need to downshift to 1st.

Also, double clutching as a habit will prevent wear on your synchros.
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Old 05-17-2003, 11:03 PM   #12
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Your synchros will last longer, but even better is that the shifter will almost get sucked into the gear when you double clutch rev match. There's absolutely no notchiness this way and you can shift faster.
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Old 05-18-2003, 10:13 PM   #13
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From what I have heard, there are no sychros for 1st gear or reverse...
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Old 05-20-2003, 01:57 AM   #14
Tim Sanderson
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Yes, there is a synchronizer on first gear.
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Old 05-20-2003, 11:35 PM   #15
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I just recently bought a new '03 WRX and I'm really curious as to everyone's experience on double-clutching in this car. I mean, that flywheel has got to be enormous. How long does it take you guys to double-clutch or rev-match with the stock flywheel? The engine seems to rev extremely slowly for such a sporty car. I owned a Miata before the WRX and it just revved so much quicker with the stock flywheel. Granted, the Miata is naturally aspirated, but is that a factor?
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Old 05-21-2003, 02:57 PM   #16
kenchan
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hahahaha, AWD... needs more momentum to
get the drivetrain going. i have a protege5 as my commuter
and i know wat you mean, the flywheel spins up/dwn really
fast vs my wrx.

for street, the factory flywheel on the wrx is pretty good,
it takes a while to spin, but once you get the rhythm
its nothing...actually i feel the wrx is easier to drive than
the protege5 because you dont have to slide the lever
anywhere as fast. you can take your time shifting and relax
while you dust pretty much everyone around you....without
you even trying.


Quote:
Originally posted by CharT
I just recently bought a new '03 WRX and I'm really curious as to everyone's experience on double-clutching in this car. I mean, that flywheel has got to be enormous. How long does it take you guys to double-clutch or rev-match with the stock flywheel? The engine seems to rev extremely slowly for such a sporty car. I owned a Miata before the WRX and it just revved so much quicker with the stock flywheel. Granted, the Miata is naturally aspirated, but is that a factor?
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Old 05-22-2003, 11:48 PM   #17
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sorry to ask, but what the hell is double clutching? i can asume most of it from the name, but when it comes to my car, i try not to assume very much. so what is it and why? thanks.
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Old 05-23-2003, 01:22 AM   #18
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doubble clutch and rev match when you downshift! i just let my friend drive my wrx today (i just got it out of the body shop last night) and he downshifted pretty hard.. my tranny i ****ed up now. hard as hell to get into 1st to 2nd, 2nd to 3rd gets stuck. cars going back to the dealer tomrmow to get it checked out. i only have 960miles on the car!! 3 weeks old 1 1/2 weeks in a body shop. not sure if this has to do much about the topic but the tranny wont take abuse. downshift to help prevent a broken tranny
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Old 05-23-2003, 06:25 AM   #19
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Quote:
Originally posted by mtb_dude
Your synchros will last longer, but even better is that the shifter will almost get sucked into the gear when you double clutch rev match. There's absolutely no notchiness this way and you can shift faster.
Yep that's right... also downshifting can be a lot smoother since you're letting the lever be sucked into gear you can release the clutch at exactly the right RPM... no guessing like you're doing with just a plain rev match.
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Old 05-23-2003, 08:32 AM   #20
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Double clutching with Rev matching when downshifting you:

1. You push in the clutch
2. As you are moving the lever through neutral on its way to the lower gear you lift the clutch partway to get rotating assemblies in motion again in the transimission at the same time you want to raise the RPMs to match the lower gear (higher)
3. Then depress the clutch full again as you enter the shift gate of the lower gear and then you should be able to release the clutch with little to no lurch from the downshift.

If you combine this with heal/toe downshifting, you can really help the car stay stable entering corners at speed because you can keep even braking pressure throughout the shift.

(And all this from an automagic guy Don't worry my swapped Honduh is a manual.)
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Old 05-23-2003, 09:10 AM   #21
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I guess you could release part-way, but I do a full release in neutral. I don't think it matters much and I guess when you get really good and fast, it ends up being a part release anyway.

ellisnc: I totally agree, our cars shift like Hondas when you dbl clutch!
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Old 05-23-2003, 03:57 PM   #22
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wow! this week i've been double-clutching down into 1st when traffic crawls. I always double clutched into all my downward gears, except first because it seemed like after i blip the throttle, the shifter wouldn't suck right in so i'd just give up. I discovered this week that downshifting into first is a bit different than the other gears, in that it takes a second for the gear to get sucked in naturally. All the other gears, it's: vroom>immediately stick it into the next lower gear, but for first gear, it's: vroom>1sec pause>then gear goes in.

on a side note though, 2 days ago my first gear popped out (again) while decelerating in first. 2nd time this happened. "bonk" sound and next thing i knew, i was in neutral.
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Old 05-23-2003, 05:32 PM   #23
GaTechWRX
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I think it's taking it longer for you to make the suck into first because you aren't reving high enough, but because you have reved close, the synchros have an easier job and so can make the shift after the wait. Try revving higher and it should be like the other shifts.

Dan
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Old 05-23-2003, 07:24 PM   #24
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Quote:
Originally posted by GaTechWRX
I think it's taking it longer for you to make the suck into first because you aren't reving high enough, but because you have reved close, the synchros have an easier job and so can make the shift after the wait. Try revving higher and it should be like the other shifts.

Dan
i thought about this too, but i am quite positive i am revving high. the delay is almost as if the car's telling me "you've revved a bit high, there will be a 1 second delay as we wait til the rpm's have come down some."
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Old 05-23-2003, 08:47 PM   #25
dan avoN7
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oooo it worked i just tried again without forcing it in and i can now do it perfectly. Going from 2nd gear around 25 mph i clutch in, go into nuetral, rev to like 4,000, cluth in, slide into first. It goes in so easly.
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