EvilRufusKay Posted December 8, 2003 Share Posted December 8, 2003 Not really tech but since there is no "How To Drive" forum I will post here. What does Double Clutch refer to and why would you do it? I have heard the term many times but never understood it. I eagerly await my education!! Thanks Guys!! Rufus Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 8, 2003 Share Posted December 8, 2003 Double clutching is something that you do with a non synchro straight cut racing transmission, or a REALLY old car that didn't have synchros. My friend used to have to double clutch his '40 La Salle coupe with 3 on the tree. I think lots of semis need to be double clutched too. Here's how you do it: when shifting (in racing trannys this applies to downshifting only), push in the clutch, take the tranny out of gear, let the clutch out. Push it in again, rev the engine to match the speed of the gears in the tranny, then push the shifter into the lower gear and let the clutch out. Some really good drivers can heel toe a straight cut trans instead of double clutching. One book I read, I think it was Driving Faster, had Danny Sullivan saying that he never double clutches, just heel toes on straight cut geared trannys, but he was the exception to the rule. It has the same effect as heel toeing, but is harder to do, and takes longer than heel toeing. If you don't have a full on racing transmission, don't bother. A good heel toe will suffice. It's nice to know how to double clutch just in case you lose a synchro, but that's about it for most of us. I've never driven a car that needed it, but this description is based on what I've read about double clutching. Jon Quote Link to comment Share on other sites More sharing options...
MY260Z Posted December 8, 2003 Share Posted December 8, 2003 Rufus, the term used to apply to big trucks or even old cars and pickups. You would push in the clutch shift to neutral, let it out and reapply the clutch and finish shifting. The pause in neutral was to let the gears slow down to match the speed between input and output sides of the affected gears. Newer semis have high tech trannys now so double clutching isn't always necessary. The time you paused was regulated by different factors. A cold tranny will slow down faster, if the engine had a 'Jake Brake' (you can hear it rumble between shifts) the pause was less because the brake brings the engine rpm's down faster to match the trans speed. So to make a short story long... Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted December 8, 2003 Author Share Posted December 8, 2003 Thanks guys, that makes perfect sense!! I was thinking more in terms of boosting pressure by "pumping up" the clutch but that makes no sense as a well bled system should not require additional psi. What an awesome forum this is. I have been wondering about this for a while but just decided to post about it. Five minutes later I have an answer. Thank You, Rufus Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 9, 2003 Share Posted December 9, 2003 I sometimes double clutch when I'm trying to downshift into 1st gear at 'high' speeds, like 25mph plus (at which speed 1st gear is something like 4000rpm). If I dont double clutch and rev the engine up I can't get it into 1st. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted December 9, 2003 Share Posted December 9, 2003 Ditto to what bastaad just said. I do the same thing into second gear usually, but not first gear, and only when downshifting. I used to drive an old truck that upshifted fairly well using the technique. Davy Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted December 9, 2003 Author Share Posted December 9, 2003 That is useful info for an emergency situation. Say you needed to get into first quick in a slide caused by snow!!! Quote Link to comment Share on other sites More sharing options...
Guest Grenade300 Posted December 9, 2003 Share Posted December 9, 2003 It's also handy to do if your syncros are going out. Happened to a buddy of mine and I showed him how to do it to keep from shredding his 3rd gear till he got it fixed. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted December 10, 2003 Share Posted December 10, 2003 That is useful info for an emergency situation. Say you needed to get into first quick in a slide caused by snow!!! AHHHHH!!! BLASPHEMY!!! You driving your Z in the snow?!?!?!?! J/K I dorve my first Z through 6 months of a HORIBLE winter and yes, first gear is quite helpfull for emergency braking, as long as you're ready for the 'tail whip' that's coming when you do it! My 81 280zx was in a few snow banks.. but never stuck for more than 2 mins. Once I was pulled out by a Mach Z snowmobile! Hee hee.. winter is fun... Quote Link to comment Share on other sites More sharing options...
Guest Nic-Rebel450CA Posted December 10, 2003 Share Posted December 10, 2003 I sometimes double clutch when I'm trying to downshift into 1st gear at 'high' speeds, like 25mph plus (at which speed 1st gear is something like 4000rpm). If I dont double clutch and rev the engine up I can't get it into 1st. That is because the synchros wont spin fast enough on their own. I do something similar, but not double-clutching. I just shove the clutch in, hold it in, rev the engine and then downshift and let the clutch out. This is good for downshifting, and it also sounds really nice. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted December 10, 2003 Author Share Posted December 10, 2003 AHHHHH!!! BLASPHEMY!!! You driving your Z in the snow?!?!?!?! J/K I dorve my first Z through 6 months of a HORIBLE winter and yes, first gear is quite helpfull for emergency braking, as long as you're ready for the 'tail whip' that's coming when you do it! My 81 280zx was in a few snow banks.. but never stuck for more than 2 mins. Once I was pulled out by a Mach Z snowmobile! Hee hee.. winter is fun... NEVEr I would NEVER drive it on the salt infested roads of Buffalo. It is alreadt a little rusty from some idiot doing that!! Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted December 10, 2003 Share Posted December 10, 2003 The link in this posting describes double clutching in excellent detail http://www.hybridz.org/phpBB2/viewtopic.php?t=28963 Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 11, 2003 Share Posted December 11, 2003 yep His original question prompted me to re-hunt down this link with some great double clutching and heel and toe shift techniques. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted December 11, 2003 Author Share Posted December 11, 2003 Thanks for the info guys. I have already started practicing. Man it is wierd to get used to. Question regarding "full race tranny." Why would a tranny have no syncro's? Is it simply weight? It seems that even if you were an awesome double clutcher, it would still take more time to shift gears than using a tranny that did have syncro's. More chances for mis-shifting as well? Rufus Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 11, 2003 Share Posted December 11, 2003 Helical cut gears are standard in production cars for noise reduction. Straight cut gears are easier to engage, but are noisy. So race trannies and motorcycles, and probably snowmobiles and ATVs often have straight cut gears because noise is not a factor. Anyone who has ridden motorcycles for awhile will tell you that you don't need the clutch to shift. Just slam the next gear. This is NOT good for the transmission, of course, but it helps to show that synchros are not necessary with straight cut gears, and it has saved my butt a few times back when I was riding dirt bikes. Slamming into the next gear is faster than waiting for the syncro to speed up the next gear cluster so that the helical gears will mesh. The price paid is double clutching on downshifts, or heel toeing, or as Nic does and I do too, just "heeling". Downshifts usually aren't going to make or break a race. Upshifts are. Jon Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted December 12, 2003 Author Share Posted December 12, 2003 Hey Jon, In the movie you posted are these guys doing what you called heel-toeing? Rufus Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 12, 2003 Share Posted December 12, 2003 Yeah. It should be called "ball of the foot side of the foot", but I guess in the REALLY old days the gas pedal was in the center and lower and the brake was on the right. So your heel was on the gas and your toe was on the brake. The name never got changed. That shot of the feet is pretty cool. You can see them doing some other things too. One guy is using the clutch to rotate the car coming onto the straight in one shot. Pretty cool video. The other one is good too, with the higher hp cars. Jon Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted December 12, 2003 Author Share Posted December 12, 2003 What the ...... Gas pedal in the middle????? Are you serious??? Man..are you kidding me or what?!?! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted December 12, 2003 Share Posted December 12, 2003 Never seen it myself, but that's what I've read. I think we're talking like 1910 or something. Jon Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted December 13, 2003 Share Posted December 13, 2003 that video is AWESOME!!!! Sux that I can't save it! All I can save is the link as a streaming link... WEAK. It's always a trip to hear how the japanese comment on stuff like that... they're competive but it's always this friendly, joking competitive-ness.... like they never taking anything too seriously. The end part with the AE86 smoking the GT-R thru the mountains was just icing on the cake... Is there any way someone can post or link to this in a way that we can save it not as a stream but just a regular video file? So you can skip around (FF and RW and stuff) and it doesn't have to be connected to the net to play. PLEEEEEEEEEEEEZ Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.