My plan is to build a traditional Model A roadster AV8, with a flathead and a three speed top loader. Do people double clutch with this setup usually?
I assume you mean one of the types of '32-39 Ford sort of trans. They are all synchronized on second and third and can be shifted freely between those without any fussing. Picking up first while rolling does require double clutching or a skilled double move without clutch, but this is rarely done in normal driving...you have lots of low end torque and can pull almost anything in second. In a 2,000 pound roadster especially... One early '50's roadracer set up a 3 -speed Ford/Lincoln box as full synchro...the basics were published in Honk! magazine in August 1953, and Manning was planning to publish a set of plans. Basically, the trans got a 2-3 fork transplaneted to the 1-2 rail and a syncro tooth hub was transplated into the outer part of first, with other cut and welded syncro parts attaching into the former slider. I would need to be looking at the pics to discuss it coherently...it was actually pretty simple conceptually but took some really careful spacing, machining, and welding!
If you intend to use the A trans then knowing how to shift a crash box [no syncros] as in double clutching would help..A v8 trans has syncros for up shifting and down shifting between 2nd and 3rd gear but you will have to D'clutch if you try for first gear while moving....sorry type slow!!!!!
Reverse engineer the term, Clutch in - out of gear thru gate, clutch out, clutch in next gear clutch out. Some transmissions need to operate that way. My grandpa was a crane operator and was the only person who they would allow to drive one crane they had because it needed double clutched.
So if you're in first, you clutch to neutral, then clutch to second, clutch to neutral, clutch to third, etc.?
If ?........... You Have TWO GIRLS in Tha Back Seat.............. THEN, YOU "Double Clutch ! " Smoked up, In tha' Great Smokey Mts. of Tenn. Big Smile
Here's a good video (with poor quality) on how too double clutch: http://www.youtube.com/watch?v=Vlf09huxvHI I drove my "A" for a months accelerating up through the gears like a pro, but downshifting was a grinding mess, I even thought I had a bad trany. I couldn't get it, I drove sticks hard for years, so whats new about matching speeds I thought? Finally had an "A" expert show me the proper double clutch and now the pleasure is back in driving. Took a while to get used too but a skill worth learning if you have to deal with early non-syncro gears.
You aren't going to be using the A trans, huge thrash to keep an unsuitable part! Double clutch: In second (for instance) step on clutch, shift to neutral, engage clutch, step on gas to speed up engine to the faster RPM to maintain that speed in first rather than second. Step on clutch, shift the slider that is now spinning at right speed into mesh with first. Easier said than done...this and the following require some understanding of how the trans is arranged, a good ear/feel for the speeds of several things at once, and good coordination between ear, foot, and hand. Double no-clutching...when in gear and on the gas, the gear set in use is transmitting power to the wheels, take foot off the gas and the same set is transmitting power from wheels to engine in effect. Get the cogs spinning at the crossover point, gears are sort of in float with little load...you can now slide second (for instance) right into neutral. Rev the thing up to perfectly match what is needed and you can snick right into gear again with no clutch...or blow everything to flinders if perfection eludes you. With good feel, you can magically float up and down the scale while resting your left foot.
Sort of, like that. But you don't always go thru the neutral gate as in releasing the shift arm from the stick. That sound clip was lifted from some foreign sport/race car. Its not that mustang with a 4 speed running like that in bullet. There was a thread on hear a year or so about the soundtrack.
As I understand it, The synchronizers in a 1939 transmission are better than the earlier ones. I have the '39 trans in my Model A and I don't need to double clutch it. I also have a '35 and that one will shift o.k. if I take my time with the shifting but shifts smoother if I double clutch. It gets to where you double clutch the shifts and don't even think about it. Neal
The trick is to not shift to fast and force it in or wait to late and let the rpm get to low.With practice you can feel the gate when it will go in and get faster when you learn the sweet spot on your car/truck. no two tranmissions shift exactly the same so it takes some practice with your own car/truck.
The early trans didn't have synchro's in the lower gears, you have to get the speed of the gears so it will go into gear, harder to do when down shifiting
A good truck driver who is use to Road Ranger or eaton gearboxes will know exactly what it takes to double the clutch on shifting one of these gearboxes. Once you master the art its an intersting way to shift cogs and yes its a dying form of manual gearbox cog changing. Even trucks are going to syncromesh and auto style boxes.
And to clarify original connection here...top two gears on '32-48 Ford box, no double clutching needed up or down. First gear up, not needed, down, trickery needed. On the Manning conversion, he noted that with a bit more work he could have had full synchro reverse...but do note that various laws of physics would still apply to the operation.
Double clutching is not a big deal. Semi's are double clutched. I rarely do it, Simply relieve tq on tranny by releasing the throttle, then when the shifter falls into N, the push the clutch in into the next gear. The only time it becomes an issue, is if there is a clutch brake. Then dont depress the peddle all the way, Unless your stopped, and putting it into 1st gear....Or if you have a duplex or quad plex. aka: set of sticks, but those are rarely driven, and most people today cant drive them, old contruction equipment have um
I don't know what transmission that you are referring to but with the semi's that I have seen, you don't double clutch, you don't uses the clutch except for the 1st gear. But then, I also don't know what that has to do with the old Ford transmissions that the o.p. asked about. Neal
I have for years only touch the clutch when coming to a stop. I row up and down using RPM and a soft touch to feel the gears. after a while it just comes natural don't even give it a second thought
Richard you pop it into neutral then let the clutch out rev the engine and mash the clutch and slip it into gear. Basically it is a way of matching engine revs to transmission revs.
My tranny has no synchros at all, 1938 GM 4 speed. Therefore when upshifting or downshifting it requires a little something special. Double-clutch, i.e. push clutch in, take out of gear, push clutch in, put into next gear. (this is for upshifiting) You can also do this like a truck driver and not use the clutch, let off on throttle, pull out of gear, rev motor slightly, put into next gear as the rpms drop. (this works better on a big diesel engine as they turn at much lower rpm's and react slower) Down shifting, push in clutch take out of gear, with clutch still in rev up engine and push gently into the next gear down as rpm's start to drop. (this technique is caused from the tranny spinning at a higher rate than the engine when the tranny is taken out of gear, simple physics here, a body in motion tends to stay in motion, revving the engine allows it to spin faster and match the tranny speed) The simple truth is all you are doing is getting the engine and tranny rpm's to match close enough to allow entry into the next gear.
Double clutching is the same for any non synchronized transmission from a model a ,stovebolt or a peterbuilt. There is more to double clutching than pushing the pedal in and out .it is about timing ,getting it in and out of gear at the right time and matching gear speed and road speed.A Lot of people "float" the gears but when you double clutch it gives it a little relief if its not a perfect shift rather than breaking a tooth,grinding ,or making a box of pieces.
I laughed out loud. I double clutched the stock transmission with the 4 banger that's in the car now; I just wasn't that knowledgeable about the fact that it's the syncro rings that determine whether or not you need to do it. I need to read my Van Pelt book again. I'm going to build the transmission, starting from an empty '40 78 case. Thanks for the great info, guys!
We moved into town when I was 15, but we still had the farm and chores every evening. Had an old 50 Chevy pickup and I practiced my shifting without the clutch all the time, I was the one that had to go every evening. The comment on feeling the gears is spot on, I got so good at it, that I could slip it in to granny or reverse either one without depressing the clutch, and just chug off from a dead stop without ever grinding a gear.
These days they teach you to use the clutch on a road ranger or an Eaton I know all the old boys will say you dont but the new approach is to use the clutch to take the pressure off the gears as they come out of mesh - makes the 'box last longer. the same approach applies to early non syncro boxes - its a style to aid making gear changes easier and smoother in older less sophisticated manual gearboxes
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