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1966 F850 dump truck help needed

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helpless007

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Jun 6, 2022
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Location
BC, Canada
Please help. I got gifted a 1966 T855 tandem dump truck. I have no idea how to shift this beast. Has 2 shifters. First one is pretty basic, that second one is very strange to me. On the shift knob, lower left has a "U", lower right has a "D", upper right has an "O". Does anyone know what the who these stand for? Thanks in advance for any help.IMGP2590.JPG IMGP2591.JPG
 
willie59

willie59

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Most likely a main transmission and an auxiliary transmission setup, pretty common of trucks of that era. Main tranny is typically a 4 or 5 speed, 1st gear is typically a granny gear. The hog box, auxiliary, is typically 2, 3 or 4 speed. On yours, U, D, O, that's Underdrive, Direct, and Overdrive.
 
Junkyard

Junkyard

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Claremore, OK
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There are a bunch of ways to drive those old trucks. We had a grain truck with that setup. Best advice I can give is don’t get both boxes in neutral at the same time and keep it simple. You don’t need to run all the main gears through each gear in the aux. With some practice you can go something like this…..
Main in low, aux in under to start. Shift a gear or two in the main then shift aux from under to direct, run the rest of the main box to high gear then go overdrive in the aux. Once you’ve done this a few times you’ll start to figure out what gears it likes. You can also use direct and over in the aux to split each gear in the main. Under is generally to get rolling loaded or creep around in the field.

Our tandem grain truck would struggle in overdrive with a full load so keep that in mind.
 
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Jumbo

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I'm going to be the wet blanket on this party. You weren't "gifted" you've been stuck with it. The brakes are worthless on that truck, way too small.
 
H

helpless007

Member
Joined
Jun 6, 2022
Messages
7
Location
BC, Canada
willie59 said:
Most likely a main transmission and an auxiliary transmission setup, pretty common of trucks of that era. Main tranny is typically a 4 or 5 speed, 1st gear is typically a granny gear. The hog box, auxiliary, is typically 2, 3 or 4 speed. On yours, U, D, O, that's Underdrive, Direct, and Overdrive.
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Thanks. That helps.
 
H

helpless007

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Joined
Jun 6, 2022
Messages
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Location
BC, Canada
Jumbo said:
I'm going to be the wet blanket on this party. You weren't "gifted" you've been stuck with it. The brakes are worthless on that truck, way too small.
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Not stuck with it. Only going to be used on my property for a while then selling it. The truck could not be made legal again anyways, has copper air lines. So old school.
 
H

helpless007

Member
Joined
Jun 6, 2022
Messages
7
Location
BC, Canada
Junkyard said:
There are a bunch of ways to drive those old trucks. We had a grain truck with that setup. Best advice I can give is don’t get both boxes in neutral at the same time and keep it simple. You don’t need to run all the main gears through each gear in the aux. With some practice you can go something like this…..
Main in low, aux in under to start. Shift a gear or two in the main then shift aux from under to direct, run the rest of the main box to high gear then go overdrive in the aux. Once you’ve done this a few times you’ll start to figure out what gears it likes. You can also use direct and over in the aux to split each gear in the main. Under is generally to get rolling loaded or creep around in the field.

Our tandem grain truck would struggle in overdrive with a full load so keep that in mind.
Click to expand...
Thanks for the input. That really helps.
 
J

Jonas302

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Jan 4, 2015
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mn
Perfect truck for that job I bet it has some deep gears to crawl with
 
John C.

John C.

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Most I've seen had a Cat 1160 diesel engine and a 5 and 4 transmission set up. Still completely gut less but we drove up hills empty and came back down with a load. The only reason the cops ever pulled one of those trucks over was for a missing mud flap.
 
H

helpless007

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Joined
Jun 6, 2022
Messages
7
Location
BC, Canada
John C. said:
Most I've seen had a Cat 1160 diesel engine and a 5 and 4 transmission set up. Still completely gut less but we drove up hills empty and came back down with a load. The only reason the cops ever pulled one of those trucks over was for a missing mud flap.
Click to expand...
I am not a truck driver. Still trying to figure out the shifting. It is either a 3 and 3 or a 5 and 3 transmission. It also has a split differential. The dang linkages are missing for the differential and the shifting fork is messed up for the secondary. Using the beast though for some gravel relocation projects on my property.
 
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