Been practicing my double clutch downshifts lately, first gear only non synchro. I understand the process, clutch in, neutral, clutch out, rev, clutch in, first gear. Match input shaft speed to output. Faster you're going the higher the rev.. I think I've been revving it too high for the speed I'm going. So who's the pro at it?
Safer to just not do it. We still have truckers that think it is a thing. Modern truck trannys hate it.
yeah, usually best not to do it...what driving conditions are you attempting it on? slowing for a turn, going up a steep hill, or ????
You're doing it wrong , when you let off the gas you should be able to drop it out of second gear silently , then tap the gas to bring the rpm up ,press the clutch & " feel" it into 1st .
Is it the bantam or the corvette? Going into non synchro first while moving is dangerous. That’s how teeth and or trans housings get broken....
But I believe the old semi transmissions had a clutch brake to stop the trans. I don't know why anyone would do it now. It was and is a feel thing. lol
Your right Mark. Just downshift to second and leave it in neutral till your stopped with the old three speeds. I can still feel the lever jumping around on my 55 chevy if I wasn't patient. LOL
The '56 Vette. OK, point taken, no more double clutch. There is an uphill hairpin on the way to my house, plus the occasional slow down/speed up traffic situation. '57 had full synchro 4 speeds, easy enough to swap one in but I actually like the 3 speed otherwise. I kind of thought it was a bit of a badge of honor among old timers. Thanks for setting me straight guys.
Man you guys ar pussy's !! Last summer with my broken left leg I drove my model A nearly every day with 1 leg, no clutch at all, shift like the big trucks. I have about half a million miles in big trucks, so its nothing new. Its easy in the big trucks because the diesel is running slower RPM's, and the shift dogs on the gears are near the shaft, and made for it. And, every gear is the same rpm split, And, you have a tach, so your ear gets used to it. The problem in the car is different split for each gear, and then for me I drive too many different cars to memorize the sound. Cars with brass syncro's don't like it when you miss, so those cars I would clutch. The A, no clutch all 3 gears. If you don't jam it, you are not going to hurt anything. In my v8 tranny's I have it memorized what speed it falls into 1st gear when I am slowing down to enter the barn. Do it every day. Sorry for the long rant, sounds like you know what you are doing, just need more practice. Doing at slower speeds/ RPM's will help
Lol,,,,,it does take a little effort,,,,,my Doug Nash Comp 5 speed can be difficult if you’re out of practice . It’s even more labor intensive using a V gate shifter,,,,,,manual dexterity. But with a little patience,,,,,you soon get the hang of it ,,,,,,then it down shifts like butter . Tommy
drive an old rambler with 3 on the tree, and a flaky carb, and you'll get good at heel and toe pedal action....
A common misnomer about big trucks and the clutch brake. The clutch brake is used only from a standing start to get it into low gear. It doesn't have any effect on normal gear changes.
The entire purpose of double clutching is to give the driver something to do while hes waiting for engine and trans speeds to match up. Its not neccesary
Paul , Get a 4 speed or Japanese 5 speed and practice clutch-less shifting [up and down] If the trans is old and flogged it is easier The wider the ratio difference the more difficult it is. So 5th into 4th is a lot easier than 2nd into 1st. After a while you get tuned into rev matching the gears Then after a while you can take on the synchro-smash [non-synchro] 1st gear shifts. The purpose of clutchless shifting is to rev-match and not chirp the rear tyres. And it is better to downshift too late than too early [the best rev limiter in the world won't save your engine if you downshift too early] I've been doing this for years now. Plus Left or Right foot braking Synchromesh actually slows down my shifting now. Left foot braking allows me to dive in deeper on corner entry [on the track] Left foot braking with an Auto-trans on the street is great for tailgating [I don't recommend this]
My first car was a 37 Ford Tudor, 85 hp with poor mechanical brakes. The only way I could get it to stop was by double clutching. I got pretty good at it and only had to dodge stopped cars a couple times.
I am drifting off a bit here, but will spew out some more comments. @BamaMav comments are correct about the clutch brake (big truck stuff here) . The clutch brake is to stop the trans from spinning so you can get it in gear at a dead stop. It only applies the brake effect at the very bottom of the pedal travel, so any clutch use while moving should never use the full pedal stroke. Many inexperienced drivers that think they should be using the clutch to shift will wear it out in no time if they push the pedal to the floor on every shift. Early cars use a "selective sliding" transmission design, which means the whole gear is sliding to engage the other gear desired. Later when syncro's came out, the gear stays put, and the syncro moves. Imagine , spin a bicycle wheel, notice the spokes around the outside are spinning like a mofo, and near the axle you can almost count them go by. The whole wheel is spinning at the same RPM, but the outside larger diameter travels more distance to achieve the same RPM. Big truck trannys take advantage of that fact by putting the engagement dogs close to the shaft so, its an easier target to hit. Later syncro trannys have the engagement dogs out further, near the gear teeth, assuming the syncro will make it work...which it does. Now, back on topic, anyone who has ever been inside an old tranny can see normal wear on the "selective sliding" gears, being 1st and reverse. That wear probably took 100k miles or more to do. The ones with broken teeth was the guy that forced it in. Listen....feel it....its not hard to do
We had a 46 Chevy truck with a non synchro 4 speed. My wife had no problem learning to double clutch up or down.. You also can easily double clutch a non synchro first gear three speed in low gear...If you can't, you need practice..
As mentioned, in big trucks the clutch brake gets engaged at the bottom of the pedal throw and is only used when stopped to get the trans into gear. When double clutching you don't depress the clutch to the floor. Doing so will wipe out the clutch brake in short order.
I had contemplated, after taking it on a trip last summer, going the other way, 3:08s. But I've gotten used to it spinning at 3k+ on the freeway, and the little 265 seems to love it. Seemed a little odd with everything modern having OD, plus sucking down gas at $6 a gallon (yes, that's what it is here). A full synchro 3 speed with OD would be the cat's meow, but the tunnel already hugs the trans, plus no floor shifter mount. A rear mounted OD might work, somehow, like the units that bolt to 9" Fords.
In the 41 G.M.C. - K-18 army truck I had in high school, it came with a 4 speed rock crusher, with a super low granny, and an ancient low geared rear end. I learned how to double clutch in that rig, but over time, I was lucky enough to put a Clark 5 speed with 30% over drive in it, and things got easier. As I got into driving the big semi rigs, the modern Eaton 10 speed Road Ranger transmissions were so much easier to shift. Imagine how the older trucks were, that had the 3 speed " brownies ", truck drivers back in those days, had to have skill and agility to shift properly back then. @BamaMav knows exactly what I am talking about!
Just be glad it's a floor shift, not on the column.... Practice the few situations where you really do need to downshift into low, and get used to leaving it in second, or waiting till you come to a stop, for the other times.
My concern would be how difficult (or not) its going to be to get parts if you tear it out or just chip a tooth. Whats available now may not be there later. I'd pull the tranny and save it for originality replacement if you ever sell the car. Then put a 4 or better yet, a 5 speed in it and enjoy driving it more. Just spent a $125 for gasoline this morning and that was regular with a $0.40 Kroger discount.
I learned to drive big trucks when I was 15. The truck had a 5 speed main box and a 4 speed auxiliary to compensate for not a lot of power for the task. You got a workout, especially on a long steep grade. Had to be smooth to keep the driveshaft in it and when split shifting both boxes don't get them both in neutral at the same time.
Did a good one yesterday, at the hairpin, which prompted this thread. I think I have been revving to high, spinning the input shaft too fast. A matter of timing seems to me. I push the clutch in just as I let off the gas, so it's spinning pretty fast. Less revs yesterday, barely a grind. Would a later full synchro 3 speed (Saginaw?) be a bolt in? I think the levers or the trans are different. And maybe no floor shifter mounts. Mine has them on the tailshaft, like a 4 speed. Truth to that. I've ridden many motorcycles home with broken clutch cables. Never tried to push the car out of second without the clutch. The last thing I want to do is break it with summer coming.. Happen to have an image of the hairpin I took awhile ago for another reason. Can't tell but it's very steep uphill right hander. I have chugged around it in second but it's much better in low, and sure don't want to stop and start.
The clutch brake is only used when the truck is standing still. It used to stop the input shaft so that you can get the transmission in gear when the vehicle is stopped. You engage the clutch brake by pushing the clutch pedal all the way to the floor. The back side of the throw out bearing squeezes it between the bearing and the transmission housing. Using it while the truck is moving will destroy it.
The Jalopy Journal
