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Subject: Double shifting unsynchronized manual transmission

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Brad    Posted 04-24-2020 at 09:14:57 [URL] [DELETE]        [Reply] [Email]  
  • Double shifting unsynchronized manual transmission
  • When I went to truck driving school years ago (before everything "shifted" to automatics, & now trucks are emerging that drive themselves lol) we were taught double shifting an unsynchronized, manual transmission: https://youtu.be/DGYuONwK7Nc?t=126

    Pretty much everyone has been made aware Ford 8N tractor has a manual, 4-speed unsynchronized transmission, and manual reads: "The tractor should be started in the same gear in which it is to be operated. Do not shift gears while tractor is in motion as the transmission may be damaged"

    This does leave me a bit puzzled, as I don't comprehend why double shifting would not function correctly with Ford 8N manual unsynchronized transmission?

    Kirk-NJ    Posted 04-25-2020 at 04:38:46 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • I'm sure it can be done. My email is open for gear replacement.

    Charles    Posted 04-26-2020 at 05:36:08 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • I do it all the time. Trick is sound of RPM of motor to about sense of forward speed. With a full load behind on any of my tractors 4 speed, I start out down the road in 3 rd-push clutch in- move hand throttle down to almost idle-put in 4th without grinding-let out clutch-move throttle for power.
    I would call it "seat of the pants feeling" instead of double shifting

    Bruce(OR)    Posted 04-24-2020 at 19:10:58 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • Take your tractor out and double shift it with the hand throttle.
    It's entertaining at least.
    I suppose if you get the foot throttle, it could get easier.

    Dean    Posted 04-24-2020 at 22:15:10 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • Tough to do with governor and both throttle and shifter on right hand side (yes, I know that the shifter is in the center but it is designed for right handed folks).


    Jack - Iowa    Posted 04-27-2020 at 07:21:01 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • Good Grief! I've been doing it wrong since 1939! There is almost nothing built in this world for us Leftys!

    I shift both my 2N and 860 on the fly. I also learned to drive trucks in the 1940's


    Dean    Posted 04-28-2020 at 08:07:52 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • So do I.


    Brad    Posted 04-24-2020 at 21:01:00 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • "if you get the foot throttle, it could get easier."

    With today's fake CGI videos, you could speed down a highway at 70 miles per hour, speed-shifting a Ford 8N tractor, slowing down, double-clutching to pick up a UFO alien space girl, and then go flying off into the sunset on your 8N tractor :-) lol.

    CGI is probably the only way you're going to see anyone speed shifting and double clutching a Ford 8N's transmission lol >8'-D

    8N wasn't designed for that :-) although... https://www.farmanddairy.com/uncategorized/1952-ford-8n-sets-land-speed-record-of-96-3185-mph/305627.html

    Now if I was going to direct one of those deep fake CGI parodies, instead of downshifting 8N to pick up a Space Girl, make mine a "Cherry 2000" lol ;-)


    Ultradog MN    Posted 04-24-2020 at 18:00:11 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • I think the issue is momentum.
    Take a truck transmission - 5, 9, 10, 13 sp - whatever, and start in 2nd. Run your rpms up and get the truck rolling to say 8 mph.
    When you go to grab another gear the mph may drop off to 7 but you are still in the range of 3rd gear at a lower engine rpm.
    On a farm tractor your mph (momentum) drops off much quicker than a road truck - faster than you can double clutch - or shift without using the clutch.
    So you just grind the gears.
    All 3 of my tractors have 8 speeds.
    I can shift from 7th to 8th on them pretty easily - and do so regularly,
    because in 7th I have built up enough momentum to catch 8th without grinding the gears. But 7 to 8 is the only gears I can shift that way.
    I do have foot throttles on two of them which helps too.

    Brad    Posted 04-24-2020 at 18:34:36 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • I can double clutch; also speed shift, both upgear/downshift in my Miata, but I don't, as everything has to be exactly perfectly timed and flawlessly executed, whereas, perfection's not my usual modus operandi, in my "good enough" world lol :-) Too much chance and opportunity for damage to the drivetrain imho.

    Timing is everything when you have to get RPMs matched exactly, you have to add enough RPMs when going to another gear to compensate for RPMs when you actually manage to complete the shift when the gears mesh.

    Doable, but takes a lot of practice and experience, which seasoned OTR truckers make it look easy but it ain't nothing of the sort.

    That's why for everybody else we've got automatic transmissions and synchronized manual transmissions.

    Most people are not professional drivers and they're not ever going to reach up to that level of experience & proficiency acquired through hundreds of thousands of miles on the road, 11, 12 even 13-hour + days.

    Not to worry, one of the "Ower-Operators" (as I refer to them) that I knew from back in the day tells me the "old Trucking firm" has purchased and is experimenting with it's first self-driving truck.

    Seems in future robots will have to deal with all of the Hazardous/difficult/dangerous/boring work of humanity.

    I'm hoping for The Jetsons and not Skynet terminators :-)

    Dean    Posted 04-24-2020 at 22:12:46 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • Speed shifting/power shifting does not require timing/matching engine/driven disc RPM.

    Indeed, that's the idea.

    Anyone around these days that has done it?


    Brad    Posted 04-24-2020 at 23:51:27 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • Dean,

    My bad, I'm not using the correct terminology, what I should have said instead of "speed shifting" is "rev matching." https://youtu.be/FnXLZg_O1rk?t=73.

    What I'm speaking of, is when one becomes good enough matching RPMs, to where no clutch input is needed, and transmission slips smoothly into next gear.

    I have often times heard other Truckers refer to this as "speed shifting" (since it's faster than using the clutch), but that's not the correct terminology and I'm sure there is a more proper term for this practice?

    Since a lot of people get these two terms mixed up, here is a complete guide to clear up any confusions what speed shifting is: https://youtu.be/LUE0Uq2hpEI?t=82

    "People often get confused when talked about speed shifting. They believe it is a technique of shifting by not using the clutch. But, they are wrong. In actual, speed shifting means changing the gears by not uplifting your right foot off the accelerator. This practice helps the racers to attain the greatest acceleration while driving."

    Anybody wants to understand the ins-and-outs of shifting, this engineer guy explains things pretty clearly: https://www.youtube.com/watch?v=zZBqb0ZJSwU&t=12s

    Dean    Posted 04-25-2020 at 07:39:48 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • OK. I understand.

    I rev-match shift routinely when driving my Fords but not under load.


    Ultradog MN    Posted 04-25-2020 at 05:08:53 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • "Rev matching" is a good way to put it. I always thought of it that you are trying to match rpms in the front and rear halves of the transmission for a clutchless shift.
    Very doable but as you say, it takes practice.
    Getting back to tractors, I think your momentum drops off too fast in a tractor to do that.
    I drove heavy trucks both local and otr for a couple of years back in the 1980s. I did not like it much.
    Must have showed as I was let go - twice. LOL. Only times I've ever been fired from a job.

    Brad    Posted 04-24-2020 at 15:32:27 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • When I'd had enough "over-the-road" double clutching & speed shifting, and decided on a local job, I needed personal transport and the more economical and smaller (I was way tired of driving huge trucks) the better I liked it.

    I was test driving 1993 NA Mazda MX-5 Miata with manual transmission and I simply could not make myself stop double clutching! lol You should have seen the looks on Miata PO's face! Especially humorous as I tended to buttonhook and swing wide around turns, while peering into my mirrors, looking for a non-existent 53 foot trailer! lol :-)

    It's not exactly clear what one would gain, nor why one would wish to double shift a Ford 8N tractor, but I feel better hearing from Bruce that it is actually possible (I prefer for things to make sense), as I couldn't comprehend why it wouldn't work?

    I wasn't about to give double clutching a go, when manual so blatantly stated "don't do this", HCooke, Oh! but my "curiosity bump" was sure itching! Can't say as I care all that very much for a mystery, because a challenging conundrum makes me want to find solutions! lol

    I suppose I should forbear asking (or thinking) about speed shifting, something else we did routinely in our big rigs. Some types of rigs, only time we ever touched the clutch was engaging into first gear, and when stopping (we always down shifted, too).

    Remainder of speed shifting was done by instinct and experience, knowing when speeds/rpms were right & how the engine acted, so no clutch was needed. Depending on load and conditions, skipping unneeded gears was also routine.

    If I start thinking about whether one can speed shift an 8N? I don't prefer mysteries, as it would bug me seeing as to how I couldn't figure it without a foot throttle, Dean. 'Course foot feed throttle's one of the projects I'm contemplating adding onto my 8N tractor lol (owing due to the need to have more arms/legs/coordination than I possess for conveniently running a front end loader) ;-)

    Thanks for your gentlemanly, scholarly inputs :-) Perchance I'd best watch "Unsolved Mysteries" or "In Search Of" so that I don't start thinking about more "Tractor what-ifs" lol ;-D

    HCooke    Posted 04-24-2020 at 12:36:37 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • No need to shift on the go. The tractor will easily start from a stop in any gear. But if you want to try it there are plenty of transmissions available on ebay from people that part out old tractors.

    Dean    Posted 04-24-2020 at 11:37:44 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Double shifting unsynchronized manual transmission
  • Double clutching has been the tried and proven method of shifting non synchronized transmissions in road going vehicles since the advent of such.

    How would one do this on a farm tractor without a foot throttle?

    More importantly, why would one need to?


    Bruce (VA)    Posted 04-24-2020 at 09:53:49 [URL] [DELETE]        [Reply] [Email]  
  • Re: Double shifting unsynchronized manual transmission
  • It's called double clutching.

    Get up to speed, clutch in, shifter in neutral, clutch out, shifter in next higher gear.

    That's how I shift my Model A Fords because at some point, you want to go faster than 10 mph in a car. And the transmission is geared accordingly.

    But that's not the case w/ a tractor. You can start in any gear easily.

    Yes, you can double clutch an N and shift while moving......and what does that get you? Because as you are learning how to perform an unnecessary task, you will be grinding the gears.

    Just like starting an N w/ a hand crank. Want to see how easy it is to break your wrist? ;)

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