The big trucks got cool paint jobs too

[87 V20 Scottsdale]

These are probably the cleanest medium duty trucks I've ever seen with the special two-tone package that they offered in the 70's.
http://www.truckpaper.com/listingsde...x?OHID=2480128
http://www.truckpaper.com/listingsde...x?OHID=2480096

[77gmcjoe]

It's pretty cool that those trucks seem to have some type of up-level door panels in them. We used to have a C70 tractor that had the Silverado interior with a headliner and the deluxe door panels with brushed aluminum trim and storage pockets.

[irishman999]

Anyone in here know how your supposed to shift those things? I've always wondered. Never could drive those trucks!!

[Big Port Jimmy 6]

Originally Posted by irishman999

Anyone in here know how your supposed to shift those things? I've always wondered. Never could drive those trucks!!

Are you talking about the rear axle? The trans shifts normal, could be a 4 or 5 sp. The axle has high & low range, you can split the gears 1 low, 1 high, 2 low, 2 high etc, but it would have to be a heavy load to warrant it. Most of the time we would use Low range in the yard high on the road. But I only drove flat beds and short dumps, and never got close to max GVW. It has been at least 15 years since I drove any thing bigger than a ton with a manual. To shift the axle run up some momentum in gear, clutch it pull up or down on the axle selector for the range. Some of the trucks did better if you pulled the trans into neutral first and then the axle.. I always wanted to practice on a twin stick, but just never found time. I almost put a brownie in my 48 GMC but couldn't find a good one so I went with a 5 sp instead. Jay

[87 V20 Scottsdale]

We have a C65 427 with a 5+2. Even when the truck is grossed out it's sometimes pointless to split the gears, especially say from 3 HI to 4 LO. To upshift pull the selector knob out and let off the accelerator, pause, and then accelerate again. To downshift you push the selector in, and rapidly release then depress the accelerator. If you are splitting the rear end down while shifting the tranny up then I usually push the selector in while I'm shifting the transmission, or before I let out on the clutch pedal. Some trucks shift faster than others, depending on how much wear they have.

[irishman999]

I got thrown in a 4k gallon water truck just like the ones in the pictures and flat out could not drive them. So its not like the regular commercial transmission where you go through the l range and then switch to high, you keep switching between hi and lo.

[77gmcjoe]

To throw another monkey wrench into split shifting, I remember some of them having a pattern that was 4 low to 5 low to 4 high to 5 high. It just went against what you were used to doing.

[77gmcjoe]

Originally Posted by 87 V20 Scottsdale

We have a C65 427 with a 5+2. Even when the truck is grossed out it's sometimes pointless to split the gears, especially say from 3 HI to 4 LO. To upshift pull the selector knob out and let off the accelerator, pause, and then accelerate again. To downshift you push the selector in, and rapidly release then depress the accelerator. If you are splitting the rear end down while shifting the tranny up then I usually push the selector in while I'm shifting the transmission, or before I let out on the clutch pedal. Some trucks shift faster than others, depending on how much wear they have.

That sounds like the way I always did it too.

[irishman999]

Im glad i asked you guys since there is a c-60 dump truck in my dads shop with a fresh 454 and I should probably haul some gravel with it some time.

[foamypirate]

I saw a Suburban body with medium duty front end sitting on a medium duty platform at a car show not too long ago. It was a sight to behold! It even still had the 2-speed rear axle in it.

[irishman999]

WOA!!

[87 V20 Scottsdale]

Originally Posted by 77gmcjoe

To throw another monkey wrench into split shifting, I remember some of them having a pattern that was 4 low to 5 low to 4 high to 5 high. It just went against what you were used to doing.

I've driven two like that, one is in a Topkick we have and the other is in a GMC 6500. The Topkick has a CAT 3208 and the 6500 had a Detroit 8.2. I figured maybe they were only offered behind a diesel engine.

[77gmcjoe]

Originally Posted by 87 V20 Scottsdale

I've driven two like that, one is in a Topkick we have and the other is in a GMC 6500. The Topkick has a CAT 3208 and the 6500 had a Detroit 8.2. I figured maybe they were only offered behind a diesel engine.

All of the medium duties that we had (5 or 6 of them, one had an Allison) were gas engines. I can't remember how many of them had that same pattern.

[Shawn5488]

You guys are making it way to hard, there is a button on the shifter, when it is down you are on the low side, when it is up that is the high side.

All you do is drive it like a normal 5-speed without clutching, when it revs all the way out in 5th you simply pull the lever up and put the shifter back in 1st gear and shift through all the gears again.

Same to shift back down through the gears. Super simple!

[foamypirate]

Originally Posted by Shawn5488

You guys are making it way to hard, there is a button on the shifter, when it is down you are on the low side, when it is up that is the high side.

All you do is drive it like a normal 5-speed without shifting, when it revs all the way out in 5th you simply pull the lever up and put the shifter back in 1st gear and shift through all the gears again.

Same to shift back down through the gears. Super simple!

Yeah....no?

[irishman999]

Originally Posted by Shawn5488

You guys are making it way to hard, there is a button on the shifter, when it is down you are on the low side, when it is up that is the high side.

All you do is drive it like a normal 5-speed without shifting, when it revs all the way out in 5th you simply pull the lever up and put the shifter back in 1st gear and shift through all the gears again.

Same to shift back down through the gears. Super simple!

So it works exactly the same as an Eaton 10 speed with a high and low range selector?

[bikes&bowties]

Thats not how they work. You have to shift the axle from high to low everytime you shift a gear in the tranny. first low. pull switch into high shift to second while pushing switch to low. pull switch to high etc.. 1 high is wayyy lower than 4 low

[Shawn5488]

Hell I thought they were just like the semi's trans. my bad!


So 1st low to 1st high then 2nd low to 2nd high and so on then?

[irishman999]

So say your in 3 high, about 3k rpms and you accidentaly bump the switch down before you get to neutral? It seems very easy to accidently bump into low.

[cayoterun]

Nice color combinations posted. Sure like the color combo on both the tan/white truck, and the monster truck. Food for thought for the truck I'm working on now.

The 4or 5 spd tranny with the 2spd axles have been a mainstay in that size grain trucks since I can remember and that's over 60yrs.
They used to take them into the soft fields at harvest and dump the combines on the go. They were always overloaded for their rated GVW.
Now semis, grain carts and 30' combines have replaced the little machinery.
Sometimes you still might see a 50-60-70 model sell at farm sale with no more than 30,000mi or so. Only used during grain harvest.
Cayoterun

[JCampbell]

Looks like the tan and white one is A/C equipped, too.

Wish my old C60 had A/C.

[87 V20 Scottsdale]

Originally Posted by Shawn5488

Hell I thought they were just like the semi's trans. my bad!


So 1st low to 1st high then 2nd low to 2nd high and so on then?

Transmissions in road tractors are completely different animals. The medium duty 4 and 5 speeds are synchronized, unlike semi transmissions. The two speed is essentially an auxillary unit placed on the axle, between the driveshaft and the pumpkin.

[87 V20 Scottsdale]

Originally Posted by irishman999

So say your in 3 high, about 3k rpms and you accidentaly bump the switch down before you get to neutral? It seems very easy to accidently bump into low.

It won't shift until unless you release your foot from the accelerator, and it won't engage until you press the accelerator again. Say you go from 3 HI to 4 LOW and you don't accelerate right away. The two-speed will probably rattle and make noise until you give it gas, depending on what kind of condition the truck is in. If the two-speed is in HI and you want to go to LOW or vice versa and you switch it, it will not change until you release the load on it. For example if I am in 5 LOW and flip the switch to HI, it will not change gears until I lift my foot from the accelerator.

[irishman999]

So you change between high and low using your throttle the same way you float gears in the big trucks, Makes sense now.