The Stovebolt Site Forums The Parking Lot Big Bolts Auxiliary Transmission Ride Along

I'd like to invite you for a ride along with me in my '46 2-ton. Just a short hop up the road to get the oil splashed up where it belongs. Yes that's a "crash box" 4 speed paired with a spicer 5831C. Both boxes are not synchronized. Its not as easy as it looks, but its also a skill that can be learned by anyone. A little practice will gain big confidence. I don't recommend downtown San Antonio for your first test drive out of the garage though.

I've often seen posts debating the usefulness and drive-ability of such a setup. Having a truck with the setup, I can say that it is a good combination. The under drive is useful for quite a few situations. The ability to split shift is useful when hauling a load and trying to get it moving. The overdrive can mean you almost make the speed limit in a few more speed zones lol (Although I agree that brake system upgrades are a must if you want to push more than 50 mph in a truck of this age much less with a load). A lot of the time, running without a load in traffic, and on relatively flat ground, I make three shifts to get up to speed: 3rd under, 4th under, and 4th over. If theres no traffic, i'll start in 2nd under as its easier on the clutch.

With a HEAVY load, starting in 1st under, then 2nd under, 3rd under, 3rd direct, 3rd over, 4th under, 4th direct, and finally 4th over works out ok. Unloaded, I have fun with the people in parking lots with 1st under, 1st direct, and 1st over. On most surfaced roads starting in 2nd under is not that difficult even with a substantial load along.

Running empty its fun to shift through all 12 gear combinations when giving someone a ride for the first time Wait how many times did you shift?

If anyone would like details on the setup i'll be more than happy to answer any questions.

In the video, I miss a shift and recover it, can you spot when?

Ride along on YouTube

Thanks for sharing the video. Looks like you've pulled those levers more than a couple times.

Awesome ride along . Truck sounds good too.

Thanks, it definitely runs better than it looks, although its not in that bad of shape.

Cool truck, real interesting set-up. Love the whine of the Trans as well.

I understand the Spicer 5831C, but tell me more about the "Crash Box" 4-Speed.

Bill

That is why I am a firm believer in believer in leaving the original sliding gear boxes in the old girls. The whine of the gears is part of the character of these machines. I learned to drive almost 60 years ago, and that was still a common transmission, and we had to learn the technique. Its been a little over 50 years when I had to deal with 2 sticks.

Its a good video and looks like south of Hyy 90 where my wife grew up at. Missing a gear and recovering isn't easy. We used to call it getting lost in the gears and I have had to stop and just start all over before.

Transmission with no synchronizers which was used before the SM420 came out in about 1948.

"Crash Box" is a term that could be applied to any transmission without synchronizers

Thanks Grigg.

I've never driven one that old.

Now a Crash Box to me is one that you can shift with no clutch (like on my Wrecker Boom). That wouldn't be true with those Pre-48's too, would it?

Nice ride! Had to make sure my seatbelt was fastened!

Finally,a TRUE video,on the use of an auxiliary transmission! First part of video demonstrates how to shift,with a light load. The second part of the video demonstrates how to shift with a heavy load/up-hill/rough terrain. Excellent! Once you miss a gear with 2 un-syncronized transmissions,it's a LUCKY man that can "catch" a gear,without having to come to a complete stop. Thanks for the video!

It is possible to shift these without the clutch. I find that because of the way the sliding gears move over a relatively long distance in the main transmission, its easy to start loading up the gears before you get them completely slid into gear. That runs the risk of breaking something. The Spicer has dog clutches in it and the shape and distance those have to move lends to them being able to slip all the way into the engaged position quicker. The Spicer shifts pretty similar to many relatively modern over the road truck transmissions.

I tend to use the clutch on this truck most of the time. The clutch pedal effort is pretty light. I haven't grown one leg bigger than the other. Easier on the driveline and transmissions, and I can replace a clutch with a trip to the parts house. The transmissions get to be a bit more interesting to source usable repair or rebuild parts.

I agree, the whine is pretty cool. The sound on camera doesn't do it that much justice, and the truck wasn't loaded in the video. The music made by a long loaded acceleration through 3rd gear in the main transmission generates a smile every time. I find that the noise around town turns heads to see whats coming before i get to them. Its not something that just about any car or truck makes anymore, save a few reverses in some of the imports.

You are also correct in your geography, I'm a little over 50 miles south of hwy 90.



You're welcome. I have missed a few in traffic. Most of the time I get it back in after a couple of attempts. Managing to get both into neutral at the same time while moving down the road is a big problem though. Thats almost always going to end up with a brief pause on the shoulder.

The B-73 Mack I learned to drive big rigs on only needed the clutch for starting and stopping. It had a 5X3 setup, with both transmissions in a common case. Mack called that a Tri-Plex. Of course, that one had a Cummins 262, but the RPM range was very similar to a stovebolt engine, and doing the RPM matching to slip the gears in and out of mesh isn't all that difficult- - -just don't rush the shift!
Jerry

I just can't get into the habit of using a clutch. Its gotten a lot easier with modern transmissions. All of our trucks have FRO16210C transmissions and they almost fall into the next gear. I visit relatives in Europe 2 or 3 times a year and I always rent manual transmissions. The reverse whine on them isn't near as pretty as the whine of good old USA sliding gear boxes. But there is a difference. I grew up near a creek. When I was a kid, I could tell if a GM, Ford, Dodge or IH was climbing the hill out of the creek from my house. I don't use a clutch on European rent cars either. Some of them are 5 speeds and some are 6 speeds. Kinda puts the fun back into driving.

Amen,Kenneth! I attended Semi Truck driver Training School,back in 1980. The instructor told us how to "double-clutch" a '73 "Freightshaker" with a 335 Cummins,and a Fuller "Ranger" RTO9510. He said that "double-clutching" was "By-The Book". Under his breath,he told us to use the clutch only for starting and stopping,and only depress it halfway,(between shifts),if you do use it.Since then,I've driven all kinds of 4,5,6,7,8,9,10,and 13 speeds,plus a couple of 4X4 Spicer's,and some 5X3's,and 5X4's.I never used the clutch in any of them. It's easier on the drivetrain,and you achieve slightly better fuel economy.If you push the clutch in too far,the clutch brake (on the older models,anyway), is actuated,and then you have a heckuva time getting your R.P.M.'s to match back up again.

Just to make it a little more clear, I wasn't actually asking if you can shift one without the clutch, as I believe just about any trans can be shifted without one, but was asking if it was anything an actual "Crash Box" where you can just about shift it anytime you please by just jambing it into gear (why I mentioned how I can engage my Wrecker Boom Cable). I believe Nascar also run actual "Crash Box" Transmissions.

But I believe I have kind of answered my own question, lol. I'm sure if you just jambed a pre-'48 Trans into gear, it would be in pieces in no time.

Now talk about shifting with or without the Clutch, I "always" use the clutch on all my Transmissions (3-Speed to 15-Speeds, lol). I find that I can shift faster and smoother with one, especially downshifting. And the GMC 9500 I used to drive, sure required a lot of it, lol.

Bill

I find my clutch use varies by what I'm driving. The 46 seems to prefer that I do use it, but there are times that I don't. The Kenworth we move our equipment with usually is a clutch only for starting and stopping ride. It has a 5x4 two stick setup. If I was driving that 46 on a weekly cross country freight run you can bet the clutch petal would become lonely in a hurry.

Nice Job on the video.
Look like you know what your doing.
That 49 looks to be in Great Condition!
Sounds good too.
I have a 64 C80 5+3 and Just sold my B61 Mack with
A Quadreplex.
That was a work out!!
Tom

I used to drive my '71 9500 in city traffic mostly (delivered Lumber locally).

...Double-Clutched every gear up and every gear down (that was necessary), everyday (10-Speed Road Ranger).

I just love to shift, lol.

(You can probably guess that I hate Automatics, lol)

Bill

was an auxiliary transmission a factory option in 46?

They were not installed from the factory.

There were a few aftermarket manufacturers offering auxiliary transmissions at the time, probably the most well known was from the Brown-Lipe gear company. The Spicer in my truck is a descendant of the Brown-Lipe, from a decade or two later.

There's a Ruckstell over/under box for a Model AA Ford truck on Ebay right now.
Jerry