pmhowe

Double Clutching

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In 1958, my first car was a 1928 Hudson Super Six. It had a non-synchronized three speed transmission. I never learned how to shift it properly, up or down. I have had several cars since. Most shifted better. Morgan in in the 1950s and 1960s had Moss crash box transmissions. They were reputed to be synchromesh. If they were, they were snail slow. Shifting upward was pokey, and downward required double clutching. I mastered the downward shift, but never the upper.

 

I'm guessing all 1920s cars and some 1930s cars require double clutching for smooth driving. It would be great to see a video and written description of how to do up-shifting and down shifting properly on old transmissions. I would appreciate it and - I think -  it would be  extremely valuable for colleagues buying old cars. So, here is a challenge for you experts to post. If you do, many thanks - certainly from me, probably from many others.

 

Phil

Hudson.tif

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Well, interesting question.

 

I've had a couple of guys drive my older cars, guys who were used to "modern" cars, even if that meant the 1950's.

 

Here's what I've observed.  On an older car, you don't rev it high in first, then try to shift. That was always their mistake.  These are low rpm cars, not sports cars.  The habit of reving  high before shifting got them every time.

 

First gear gets you moving, second gear gets you to 8-10 miles per hour, then shift into high. All in slow motion.

 

if you get in a hurry, worry about the  car behind you, try to push it, then you'll fail.  Take it easy, take your time before moving shift lever, you'll succeed.  It's difficult to slow yourself down, but do it....

 

 

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It's half science, half art, and every car is a bit different.  Trimacar is right about upshifting early, which you can do because these are long-stroke torque monsters.  I can always tell an inexperienced person by his revving above 1,500 rpm in anything but top gear,

Remember for downshifting that the plan is to bring the input shaft (i.e., engine rpm) up to its speed in the destination gear by a judicious blip of the throttle while in neutral.

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My 27 Dictator:

1-2 upshift 4 to 8 mph

2-3 upshift 6 to 14 mph

3-2 downshift let speed drop to 10 mph shift to neutral, release clutch, blip throttle, depress clutch shift to 2nd.

2-1 downshift, wait until car has almost stopped moving, shift to neutral, release clutch briefly, step on clutch, shift to 1st.

 

As tramcar pointed out, these are low speed engines, my Dictator's engine develops its maximum horsepower at 2200 rpm, so winding it up does nothing.  Don't worry about the car behind you.  Drive the car the way it was designed to be driven.  

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Quote

 bring the input shaft (i.e., engine rpm) up to its speed in the destination gear by a judicious blip of the throttle while in neutral.

 

Just wanted to add "with the foot off the clutch pedal" at the end of this.

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I only double clutch when I am in a hurry.  Usually I only use the clutch to start moving.  About 4 to 8 mph I float the shifter into second and then into third at 6 to 15 mph.

If I am merging onto a highway I will float the gears at 15 and 25 and then floor it.  I have never had any trouble merging onto a 50 or 60 mph highway.

Downshifting I once again float the gears down from third at 20 to 10 and second to first at 10 to 5.  If traffic is really heavy like coming of an interstate I would double clutch down from third to second at 30 and from second to first at 15.  Sure saves the brakes.

Floating the gears.....in first gear, push lightly on the shifter as you ease off slightly on the accelerator, move shifter through neutral while accelerating the engine slightly slip the gear into second.  Repeat going into third.  Going down ease the pressure on the gears so you can move to neutral sped the engine up so the gears match and slip into the lower gear.

After driving the same car over 400,000 miles I don't even think about whether I will use the clutch, double clutch or float the gears.  I just do it.  After having driven trucks with 4, 5 and 6 speed transmissions (some with two speed rear ends), 5 with a 4 aux and 8, 10, 13, 15 and 18 speed road ranger transmissions you just do it, just like breathing.

It has never bothered me going from an SAE shift pattern to an old Dodge or Buick pattern or from my Pontiac to a MCI 6, 7 or 8.  A Carpenter 5 speed pusher was always fun (non syncro transmission and shift rods that were too small and flexible for the length of the bus).

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Ok, here is what I was taught to be double clutching, but like other have said you don't need to do it unless you are in a hurry to shift gears with a non-synchro transmission or if the synchromesh is shot on a synchromesh transmission.

 

1.  If you are grinding when trying to get into first from a stop try this while stopped, especially if you had the car in neutral with the clutch out while at the stop. Push in the clutch and move the shift lever in to the highest gear first then in to 1st all while the clutch is in.

 

2.  Pull out in first gear as described above.

 

3.  When shifting from first to second push in the clutch and shift to neutral, leave out the clutch then push it back in before completion the shift into second where you again let out the clutch to complete the shift.  Hence the term double clutch, since you pushed in and released the clutch twice per shift.

 

4.  Whether you are up or down shifting you accomplish the same pattern by going to neutral and letting out the clutch prior to pushing it in a again to complete the shift.

 

 

Edited by Vila (see edit history)

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Another consideration is whether your car has a clutch brake, as my 1918 and 1925 are equipped.  The clutch brake engages when the clutch is fully depressed, and is used only when the car is at rest.  When the car is moving, avoid pushing the clutch all the way to the floor so as not to engage the clutch brake.

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When my Model "A" was my daily driver I took a couple of teeth off low gear (don't ask - I was young). I drove it for the next several months starting in second and in all honesty unless you are on a hill it works just fine - if on a hill you grab a bit of throttle before starting....that 40 pound flywheel (if memory serves) makes it relatively easy..

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Here is another thought.  Don't rule out a gear oil change

 

Lubricants have come a long way from the beginning of the start of the automobile.  Of course some of the very thick gear lubes, may not have a modern equivalent. 

 

1. From my own experience:  BMW early airhead motorcycles, have a great  transmission; but it likes to be shifted on-time (Revs), and torque load,  plus shifted positively. BMW uses an automotive type       transmission and dry clutch; not your typical motorcycle transmission  integrated with the engine. Synthetic gear lube really makes a huge difference. Better shifting, no crunching, just smoother.

 

2. 1990's Mitsubishi/Eagles and Chrysler/Talons, had a gearbox that was a cruncher and hard shifting.  I had  Talon 5-speed that while in warranty I had the synchronizers replaced to fix this problem.  The syncros made it better, but a technician recommended that we try synthetic gear oil. OH MY what a difference.  Smoother by a lot and positive engagement every time.

 

I'm not new to double clutching: Many 1940's thru 1960's commercial and Military heavy trucks.

 

Of course the transmissions of the very early cars had very thick lubricants; I'm not sure how to match them up to modern lubricants.  

 

intimeold   

 

 

  

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I think this guy's video does a good job explaining the process and why we do it. I use the clutch on every shift.

 

 

Edited by Buick64C (see edit history)
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6 hours ago, vermontboy said:

] Model "A"  if on a hill you grab a bit of throttle before starting....that 40 pound flywheel (if memory serves) makes it relatively easy..

My memory is that its a lot closer to 100 pounds.

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16 hours ago, Tinindian said:

A Carpenter 5 speed pusher was always fun (non syncro transmission and shift rods that were too small and flexible for the length of the bus).

 

Oh boy -- that fired a couple of synapses that have been dormant for decades!  I rode many of those buses to school as a kid.  The memory you sparked was in junior high school.  Our bus driver was a woman who was maybe 5 feet tall (and almost as wide), so her arms weren't very long and I remember her leaning to the right and stirring that floor shifter like she was mixing cake batter.  Every so often she'd miss a gear which was immediately punctuated with a chorus of "Grind me a pound!" from the back of the bus.  Those were the days...  ;)

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I used the old adage, "If you can't find it, grind it!"

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2 hours ago, EmTee said:

 

Oh boy -- that fired a couple of synapses that have been dormant for decades!  I rode many of those buses to school as a kid.  The memory you sparked was in junior high school.  Our bus driver was a woman who was maybe 5 feet tall (and almost as wide), so her arms weren't very long and I remember her leaning to the right and stirring that floor shifter like she was mixing cake batter.  Every so often she'd miss a gear which was immediately punctuated with a chorus of "Grind me a pound!" from the back of the bus.  Those were the days...  ;)

 

Em Tee,  interesting.  You may be on to something here.  I read this morning an interesting thought from a respondent to a drive time article in the local paper.  If all vehicle manufacturers were required to eliminate automatic transmissions and produce "only" 3 on the tree manual transmissions I wonder if it would save lives by eliminating or at least reducing texting time?".

 

Peter J.

Edited by Peter J.Heizmann (see edit history)
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6 hours ago, mrspeedyt said:

i find 'floating' works well for me with a non syncro trans. 

Yes, mrspeedyt

 

I thought that too; but didn't want to really confuse some.  The 13 speed Road Ranger trans, was ideal for that; but of course it has syncros

 

intimeold 

Edited by intimeold (see edit history)

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Interesting, my first Jags all had Moss gearboxes with a non-synchro low gear. So did an MGA. Got so I could downshift from second to first without a sound, just a matter of matching the speed. Back in the 70s I used to blow GM clutches quite often, usually the disk plate would crack and let one of the springs cock itself & jam. Good thing was it was locked solid. Once drove for three states with no clutch, just avoid stops and if needful stop, turn engine off, put in first, crank starter when time to go. Helped that my cars were tuned so tight they squeaked. What clutch interlock ?

 

For a long time the trans I liked best was a big shaft Muncie with a Hurst shifter. When time to shift just pull back on lever as hard as you can and just bat either the clutch or the accelerator (not both), shifts sounded like an automatic. Helped to grind every other tooth off the synchro rings.

 

Have a Crossfire with a Merc six-speed. Most positive and fastest shifting gearbox I've seen. F&F shifts are easy. Only problem is a really fast 1-2 near red-line and the traction control gets upset.

 

ps with a non-syncho low the trick is to declutch then pull back to 2nd for a moment & go into first.

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1 hour ago, padgett said:

Once drove for three states with no clutch, just avoid stops and if needful stop, turn engine off, put in first, crank starter when time to go

Amen!  Lost a clutch in my 1975 Datsun pickup at the west (SF) anchorage of the SF-Oakland Bay Bridge during the evening rush hour.  Got 20 miles home to East Bay as you describe, shutting off ignition at multiple stops, going to 2nd and 3rd via float.  Changed clutch in driveway over the weekend.

 

I was double-clutching into 1st in a friend's XK-120 55 years ago and surprising the hell out of him on what the car would do when driven that way.  By that time, I'd been double-clutching 1920s cars for several years.  It's funner when you have a 4-speed with straight-cut gears! 

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Out of financial desperation I drove a VW for a month with no clutch whatsoever. Luckily it had a strong battery and started in gear quickly. Back and forth to work. Happily I could do the drive with minimal stopping.

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1 hour ago, Restorer32 said:

Out of financial desperation I drove a VW for a month with no clutch whatsoever. Luckily it had a strong battery and started in gear quickly. Back and forth to work. Happily I could do the drive with minimal stopping.

Ha! I did the same thing.

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And we tell Corvair owners the same when their clutch cable breaks.  Easy to start and drive without a clutch!:)

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Broke a clutch cable in my Chrysler TC Maserati once about twenty miles from home.

Very busy stop and go traffic, I made it alright. Got better at it as the day went on.

I am a manual tranny guy and lately have been manufacturing hydraulic actuators on my four speed hot rods.

Not much fun pumping the clutch but I have had to do it.

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This has been a fascinating thread. I have learned a lot. I am most impressed with the number of people able to shift smoothly without using the clutch. If you can do it, I can do it (maybe). I wish I had my old Hudson with its non-synchronized box to work on. (As an aside, my Hudson was a 1928 model. In 1962 I had a chance to drive a 1931 Pierce Arrow roadster part way from the PA Society meet in Staunton, VA to PA. It had a synchromesh transmission.  Hudson is nice, but it is not a Pierce Arrow. What a thrill it was to drive that car!) 

 

Once the weather clears (we had snow today, and I am sick of it) I will give clutchless driving a try - with the Morgan. If I succeed there, I will try the 1935 Cadillac.

Many thanks for all of your inputs. 

Phil

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22 hours ago, Peter J.Heizmann said:

If all vehicle manufacturers were required to eliminate automatic transmissions and produce "only" 3 on the tree manual transmissions I wonder if it would save lives by eliminating or at least reducing texting time?".

 

As an added bonus, it further complicates the 'self-driving car' problem.  ;)

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