Just Curious
- Thread starter JBohannon
- Start date
Tom Wesenberg
Well-known member
The engine slows down as soon as you let of the gas, so when you let the clutch out in neutral it slows the ****** input shaft and gears on it to match the next higher speed gear. With a cold ****** and thick oil, you can usually just shift a little slower and not have to double clutch until the oil heats up and thins out.
Ron Kansas
Member
Having grown up on a '36 vintage truck, I learned to double clutch before I learned to drive! Just got my '29 Tudor running and double clutching it is a breeze. But, your question is just what does double clutching do?
When your are upshifting, I.E. going from first to second and then to third, when you depress the clutch after getting up to speed in first, the clutch disk and thus the input shaft to the transmission is turning at engine speed, while the mating second gear is turning much slower. If you try to depress the clutch and slide right into second, the gears will "grind" until the friction of the grinding gears slows the clutch disk and input shaft to the same speed as the mating second gear. Due to inertia, the clutch disk will take much longer to slow down than the engine. So, if you pull it out of first gear with the clutch depressed, then allow the engine to slow down and release the clutch, you instantly slow the clutch disk to engine speed, which should just about approximate the speed of the second gear. Then you depress the clutch pedal again and move the shift lever to second gear position. Same exact scenario going to third and for the same reasons. It takes a little practice "to get the feel" of of just when to release the clutch for going into the next gear, but after a few tries, it will become almost automatic.
Down shifting is the same situation except in reverse. (No, not reverse gear) If you want to shift from third to second and use the engine for braking, or if you are approaching a steep hill and will need to use second gear, if you pull the shift lever out of third and try to go directly to seconed, the clutch disk and input shaft will be running too slow to match the speed of the second gear. So, the solution is to depress the clutch pedal, pull the shift lever out of third then release the clutch pedal. At the same instant, you will want to accelerate the engine to approximately the speed the engine will need to be running in second gear. That speeds up the input shaft to approximately the speed of second gear, and at that point you will depress the clutch pedal and shift into second gear. Same exact procedure for shifting from second to first.
A lot of verbiage, but that is the gist of "Double Clutching."
Ron, Kansas
When your are upshifting, I.E. going from first to second and then to third, when you depress the clutch after getting up to speed in first, the clutch disk and thus the input shaft to the transmission is turning at engine speed, while the mating second gear is turning much slower. If you try to depress the clutch and slide right into second, the gears will "grind" until the friction of the grinding gears slows the clutch disk and input shaft to the same speed as the mating second gear. Due to inertia, the clutch disk will take much longer to slow down than the engine. So, if you pull it out of first gear with the clutch depressed, then allow the engine to slow down and release the clutch, you instantly slow the clutch disk to engine speed, which should just about approximate the speed of the second gear. Then you depress the clutch pedal again and move the shift lever to second gear position. Same exact scenario going to third and for the same reasons. It takes a little practice "to get the feel" of of just when to release the clutch for going into the next gear, but after a few tries, it will become almost automatic.
Down shifting is the same situation except in reverse. (No, not reverse gear) If you want to shift from third to second and use the engine for braking, or if you are approaching a steep hill and will need to use second gear, if you pull the shift lever out of third and try to go directly to seconed, the clutch disk and input shaft will be running too slow to match the speed of the second gear. So, the solution is to depress the clutch pedal, pull the shift lever out of third then release the clutch pedal. At the same instant, you will want to accelerate the engine to approximately the speed the engine will need to be running in second gear. That speeds up the input shaft to approximately the speed of second gear, and at that point you will depress the clutch pedal and shift into second gear. Same exact procedure for shifting from second to first.
A lot of verbiage, but that is the gist of "Double Clutching."
Ron, Kansas
newshirt
Well-known member
Is it a bad practice to simply hold the clutch petal in until the engine slows down enough to upshift?
I quit double-clutching on upshift because it seems to offer no advantage over the method above. Either way, I don't grind. And the owner's manual only recommends double-clutching during downshift.
I quit double-clutching on upshift because it seems to offer no advantage over the method above. Either way, I don't grind. And the owner's manual only recommends double-clutching during downshift.
BILL WILLIAMSON
Well-known member
On upshifting, I think double clutching is un-necessary BUNK! Think about it. Take off in first, push clutch down, in neutral, you're just waiting for the clutch disc & input shaft to slow down to the right speed to match second gear speed. I'll betcha' it'll slow down quicker than it would if connected to the engine with clutch out. Think about that GIANT flywheel, pressure plate, crankshaft, and other rotating stuff, it takes a loooong time to get it all slowed down!
I TOTALLY agree with double clutching on downshifting.
Upshifting REQUIRES you to be patient and WAIT. That's just the way the dumb thing was designed and it's kinda' fun to learn to master it!
I can downshift from high to second at 30 MPH, slickern' snot, NO GRIND! Yes, that takes double clutching and a LOT of practice!
Gear jerky, err, JOCKEY, Bill W.
I TOTALLY agree with double clutching on downshifting.
Upshifting REQUIRES you to be patient and WAIT. That's just the way the dumb thing was designed and it's kinda' fun to learn to master it!
I can downshift from high to second at 30 MPH, slickern' snot, NO GRIND! Yes, that takes double clutching and a LOT of practice!
Gear jerky, err, JOCKEY, Bill W.
Purdy Swoft
Well-known member
This is where a lightened flywheel really helps, Gear shifts are quicker and smoother plus better throttle response and quicker acceleration. I almost forgot, it helps the main bearings last longer. Its good to take a load off the babbit!!!!!