How to Shift a Two Stick Transmission #peterbilt #twostroke #twinstick

One of the best examples here, I wish i was this good.

Going over the two stick transmissions again. These are spicer transmissions, Consisting of two separate transmissions instead of a married box design like the macks used. I only put a couple hundred miles on this truck before i took it apart mainly to make sure the drivetrain was sound or what repairs it would need. The spicer was a staple of the 60's often coming in a 4+4 configuration then came the 5+4 and 6+4 Transmissions. Mine are both overdrive which means both sticks are against the dash in high gear. When i am in 5x3 i get my 1:1 ratio or what a 6+4 direct setup would be in high gear instead of my .68 high gear. i have a spreadsheet with all the ratios mapped out which can easily be made by multiplying all 24 gear combinations together. a lot of the gears overlap so you really dont need to shift many times to get progressive shifts, in fact its kinda nice to be able to pick whatever gears you like to get to speed in as few or many shifts as you would like. in fact when bobtailing you can get in high gear quite quickly without massive skip shifts like in a modern 18 speed. Its a little harder to run sticks with the 2 stroke as the snappyness of the motor makes timing a bit harder and the auxilary is really unforgiving especially the 3-4 shift.

1978 Peterbilt 359
475 Silver 8v92 100 mil injectors
6+4 Sicer O\D

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[endtimeawakening]

This is a great example of how these transmissions work together. It really helps when you put the two graphics on the screen and show what upshifts and downshifts are taking place. This is the BEST twin stick tutorial I've ever seen. Great job, you have a great mechanical aptitude and teach very well! God bless!

[davepenn]

The old-timers had a word for getting stuck with neither transmission in gear because you let the connecting driveshaft coast down too far. They called it "double nothing." Experienced it a time or two, which is why I always shifted the transmissions separately.

Also, your Spicer set-up has little gaps between the gears in the main 6-speed box and big gaps in the aux box (sometimes called a "Brownie"). Most twin sticks I drove used Eaton/Fuller boxes up front with big gaps (usually a 5- or 6-speed) and an aux box with real small gaps. You had to figure out what combinations overlapped so you knew where to go for the next highest or lowest gear. I usually started in 2-2, then depending on how heavy I was loaded I'd go to 3-2, then 3-3, then 3-4, then 4-2, 4-3, and so on. The tricky thing was that on the 5-speed main box, 4 and 5 were pretty close together so I'd usually go 4-3, 4-4, 5-3, 5-4.

[iBackshift]

In the late 80's, when I was taught 5x4, ol' Kevin & Frank put 4 pieces of tape on the dashboard for me [depending on what truck i was in, another had a 6x4]. When i had my hand on either shifter, they made me point my index(first) finger out and touch the tape on the dash. The tape pieces were Main 2 and 5, Auxiliary 1 and 4. So, when I shifted gears, no matter if I took my hand off the shifter and I couldn't remember what gear I was in, all I had to do was put my hand on the shifter, point my index finger out and, voila....I knew where I was in the shift pattern.

[Nico-rdur]

This is by far the best tutorial I have seen on this subject. The way you show what gear each transmission is in while watching you shift is very helpful. Thank You for putting this together.

[jamesellis]

best video I have seen on the twin sticks, haven't drove one of those since early 80s!

[kevinmurphy]

That was a great video showing how this system works! Having the gear patterns imposed while actually shifting was fantastic.

[davewhite]

Sort of watched the video. I just turned up the volume and closed my eyes. There is nothing more pleasant to my ears than the sound of a 2 stroke going through the gears. I more or less visualized it in my head and could follow your up shift and down shifts. I miss seeing these old girls on the road.

[marcharris]

This is the best tutorial I have ever seen on how to drive twin sticks.I have driven single stick heavy duty transmissions, but never twin sticks.After seeing these tutorials, I feel confident that I could actually drive a twin stick!This guy should be an instructor at a truck driving school!I hope he has tutorials of how to drive a 3 stick transmission in the future!

[wesleysmith]

Just wanted to comment on such a wonderful video. I learned to do that back in the sixties, my great grandfather on my right and grandfather in the driver's seat with me in the middle, using the twin sticks... I could never have had two better teachers ❤️‍🔥❤️‍🔥

[johnwatts]

Good video. Watch how this guy holds the sticks. He pushes them out and pulls them back in easy, never making a fist like he's mad at the truck. Probably rode shotgun a long time with the old man.

[scottfowler]

Wow, search after search I could never find an explanation that makes sense to me……until this video. Thanks for giving me a very good walkthrough.

[ericksoncraig]

Great job on explanation a d demonstration. I drove a 73 Pete cabover with a 4x3 and 8v92 detroit w/ J Brake . Loved it. The most difficult 2 stick I have driven was a Mack 5x4 married box with a Cummins.

[julianndavis]

I’ve heard this explained numerous times. First time I’ve understood
👍

[jsd]

If anyone finds themselves having to quickly learn how to drive a two trans. truck there is a much easier way. The shifting with one arm through the wheel and the other on the aux. isn't necessary. Say for example you are going from 3rd +3rd to 4th + 2nd all you have to do is pop your aux. in neutral after which the main will go in 4th with no matching of RPM( because since it is separate as far as it is concerned you are sitting still). Then grab your aux. and goose the throttle and when the RPM's match up the aux. will go into 2nd just like any other transmission. Downshifting is basically the same just backwards. Sounds like it would take too much time but once you get the hang of it you can do it very quickly all with one hand and no clutch.

[deanm]

Very cool, shifting a twin stick is definitely an art form

[kirkpalis]

Thanks for the excellent video, explanation and the overlays. This really answered several questions I had.

[carlwilliams]

Good job showing the aux box and drive shaft to help people better understand whats going on. That 92 Series DD sounds really good. My favorite sounding Detroit of all the models I have used!

[toddgittins]

With a Detroit, hauling a heavy load, you'd be a master at shifting in a day.

[xkuzu]

Great video and tutorial!! Love the gear ratios you showed!!

[climbingtrees]

This is by far the best example I've come across how to shift a spicer two stick. Well done!