I came to thinking that most of the time when I've mentioned this technique to people they tend to give me the deer in the headlights look:eek4:. So, I figured that I'd give a quick run down for all of your that might not be familiar with this technique. (yes, I know a ton of you already practive this) Why? I've learned to make my smooth shifting even smoother. I primarily use this technique during hard braking and downshifting. If you haven't learned it....you'll love it once you get it down. Especially for the owners that have syncro issues. :biggrin: Here's a simple overview I came across... http://en.wikipedia.org/wiki/Double_declutch The purpose of the double-clutch technique is to aid in matching the rotational speed of the input shaft being driven by the engine to the rotational speed of the gear you wish to select (directly connected to rotating wheels). When the speeds are matched, the gear will engage smoothly and no clutch is required. If the speeds are not matched, the dog teeth on the collar will "crash" or grate as they attempt to fit into the holes on the desired gear. A modern synchromesh gearbox accomplishes this synchronization more efficiently. However, when the engine speed is significantly different than the transmission speed, the desired gear is often unengageable even in a fully synchronized gearbox. An example is trying to shift into a gear while traveling outside the gear's speed or directional range, such as reverse while moving forward. Double clutching, although time consuming, eases gear selection when an extended delay or variance exists between engine and transmission speeds. When shifting up on a non-synchroniser equipped vehicle, the clutch pedal is pressed, the throttle is released, and the gearbox is shifted into neutral. The clutch pedal is then released. As the engine idles with no load, the RPM will decrease until they are at a level suitable for shifting into the next gear. The driver then depresses the clutch again and shifts into the next gear. The whole manoeuvre can, with practice, take no more than a fraction of a second, and the result is a very smooth gear change. Conversely, in order to downshift, engine RPM must be increased while the gearbox is in neutral and the clutch is either engaged or disengaged. This requires the driver to shift into neutral, apply throttle to bring the RPM up to a suitable speed, and finally shift into gear. This operation can be very difficult to master, as it requires the driver to gauge the speed of the vehicle and throttle accurately. Double clutching occurs if the clutch pedal is released while matching engine speeds in neutral and again engaged prior to shifting into the next gear.
I do rev match downshifting and heel toe daily, never this double clutch stuff for downshifting, isn't it the same as rev matching w/o touching the gas pedal??
i rev match all the time!! i love listening to kids in hondas that just down shift and let the cluth out without rev matching..i cant help but laugh..its just as funny listening to them ride the clutch from a dead stop!:laugh: REV MATCHING FTW!!
Rev matcher and double clutcher here. My 02 Bungeye was more sensitive to it than my 07. I can actually downshift into 1st at 30mph on my 07 doing this. My 02 would "zap" me for any such behavior above 10mph but double clutching still helped smoothness on all downshifts.
I rev match all the time on downsifting. And sometimes double clutch upshifting when it is cold out, makes the shifts smoother.
Double Clutching requires you to let out the clutch while in neutral and raise the engine rpm, then put the clutch back in and select the gear. It's almost the same as rev matching...with the exception that you are letting the clutch out while in neutral so the transmission input shaft speed increases. just one more step in the process
Yeah, I got into the double-clutching all downshifts habit this winter. My commute isn't very long, and cold gear oil doesn't help shifting.
I heal toe double clutch about 90% of my down shifts. If you're comfortable heal toe down shifting, it's actually a pretty easy transition to include the double clutch.
Actually, no. Matching input speeds with double clutching is going to be about the best you can do for your tranny.
that is correct sir! you can shift as slow as you want....the input shaft slows way down if the clutch pedal is in...lifting your foot off the clutch is the easiest way to increase the input shaft speed...making the shift smooth as butter
I have to say I've been rev-matching my down shifts since I got my car...I don't see why someone WOULDN'T...Anywho, I've just recently been working on heel/toe braking...it's kinda fun coming off the highway (100) to a stop light :biggrin:
Fair enough. Constantly heel/toe, double clutch down shifting etc is only adding excessive wear to yr throw out bearing no? It does however save yr synchroes that tiny little bit and helps you shift without throwing off the front to back balance of the car during a shift (on corner entry). That said, I do it daily and I'm sure it sounds like ass with the brake squeal followed by a rev blip and then some afterfire at every stop lol.
every time i try feels really uncomfortable/ I really suck at it. any tips. are my shoes to big? LOL!
I don't believe Double Clutching is neccesary with todays stock transmissions, 120k on my 02 5 speed with no trouble at all. And the clutch made it 100k miles and still had material left.
I guess it depends on whether you'd rather replace your clutch and throwout bearing more often or whether you'd rather rebuild/replace your transmission more often.
wait... are you saying that not double clutch downshifting etc puts you at a risk to blow yr tranny? Like Mike said, these trannys can stand up to a lot of abuse (shock loading)
me too. I pretty much have to....my 20 year old synchros don't like going into a lower gear unless you're going pretty slow without a double clutch. also, one of the reasons I love subarus, is the brake and throttle pedals are close enough to "heel-toe" without using your heel......the ball of your foot (for almost everybody....unless you've got freakishly small feet) can reach to both. just rotating your foot a bit will allow a throttle blip while holding the brake. much faster than moving your whole foot to reach both
Yeah, this is the technique I use to "heal-toe" as well. It's really more rocking down the right side of your foot.
I do it every day. When I testdrove GTI it was sad to realize that DSG gearbox was doing it better and faster than me (not fair comparison of course, since my car is different but still).
pictures: http://www.edmunds.com/ownership/howto/articles/45792/article.html video... turn the sound up: http://videos.streetfire.net/video/c8710573-fd48-4c11-8a2f-80db3f41d4d1.htm
I wear size 12 and do it daily in my boots. Practice shoeless with the motor off first maybe? If yr really clumsy, maybe try narrow shoes like some Puma speedcats/futurecats or something?
Alright I don't see the point of double clutching, rev matching yes but double clutching no. Also after a quick drive I have come to the conclusion that I more than likely will not be heel-toeing any day soon.
Shoe tech monkey!!!! LOL, it is way easier to do with narrow shoes. I wear big skate shoes and have taught myself to do it. I also own a pair of sparco driving shoes!!! FTW! they makes things lot more easys!!
just put the clutch to about the engagement point, then blip the throttle really fast and let it out slow from there and it will bring the rpms up to the needed point as your letting out the clutch slowly. just make sure your blipping it deeper the faster your downshifting.. easy..
...and for cold and/or stubborn Subaru trannies that were apparently adopted from a John Deere farm tractor. Why is it Heel y Toe - seems like the Toe is always on the brake before the heel blips the throttle. Toe and Heel? It also seems to be used primarily for progressive engine braking - multiple downshifts into the same corner.
