Chevrolet truck gear shifting question

Buddy of mine just got an '85 Chevrolet C70 truck with a 5 speed transmission and a two speed rear. That said there's no sticker or anything in the cab showing what the shift sequence should be, so he asked me this evening. Personally I've owned my share of vehicles, but nothing with the two speed rear, so I have to admit to being lost here when it comes to what to tell him. I asked my Dad as I knew he had one in his service truck about 80 years ago. He said best he remembered he kept his in high range all the time and never even used the low range. I've always heard you could do that unless you were towing a heavy load, etc and then you would probably need the low range to get going if nothing else.

All that said, what would be the typical shift pattern for an unloaded truck, medium loaded, and heavy (ie-towing around 15,000 lbs)? I figure there will be a variety of different ways to do things depending on the amount of load, road conditions, etc, and that ultimately it'll be the driver making the command decisions, but where would be the best place 'to start'? Thanks for any help ya'll can offer.

Depends on the brand and style of transmisson you have. for light loads or when empty you can start out in 2nd hi and run thru the gears in the hi side to 5th hi. loaded you can start out in 1st hi or 2nd low, then split each gear until you get to 5th hi. above sequince will all depend on the type of terrian you are on.

1 l-h, 2 l-h, 3 l-h, 4 -l, 5-l, 4-h, 5-h. Shift into low in neutral. And shift into high by letting off gas, push clutch and shift to high. I think I explained it right, much easier to do sitting in the truck. Make sure you check the oil in the two speed.

Someone who actually knows will soon be here to set this straight, here's what I think I recall.
lots of those trucks had a trans. with what was called a working 4th. I think you split the first three, then low 4th, low 5th, high 4th and then high 5th.How you are loaded will determine how many of then you can skip.It's been a long time since I was around one so this may not be correct.

(quoted from post at 21:23:13 02/06/14) 1 l-h, 2 l-h, 3 l-h, 4 -l, 5-l, 4-h, 5-h. Shift into low in neutral. And shift into high by letting off gas, push clutch and shift to high. I think I explained it right, much easier to do sitting in the truck. Make sure you check the oil in the two speed.

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this is how mine is setup different 5spd may split high gears differently

Here in the flatlands of Iowa I always went through all five in the low side and then shifted into the high side last, like going into overdrive with the old overdrive cars. But this was with only two trucks, a 69 IH CO something or other with an electric over-under and a 66 Chevy C60 with a vacuum. When I was a kid the 54 Ford school bus had a four speed with two speed axle the driver only shifted after he was in the top gear. He had the knack with it but if there was a substitute driver he'd grind the two speed into the top side. Jim

Don't know about a 5 speed, but all our 2 ton trucks had 4 speeds with the two speed. Still have a C60 and F600. Some two speed were Vac, and later ones were Elec. I use the two speed all the time. Low then high in each gear. Shifting up I change the button to low before shifting. Shifting down I shift down then change the two speed down. Shifting down you have to be careful that the two speed doesn't kicks out. If I have a heavy load I don't take that chance on a steep grade. Drive a lot of 8-15% grade.

We had several 60's/70's IHC and GM single axle grain dumps with 5+2 transmissions. All were geared similarly. Good chance yours is the same too. Here's how they shifted -

Full load (uses all possible gears used in sequence):
1-Lo
1-Hi
2-Lo
2-Hi
3-Lo
3-Hi
4-Lo
5-Lo
5-Hi

Unloaded: Leave the rear end in high and shift 2 > 3 > 4 > 5

NCWayne, I have Ran the Shi# out of a 72 C60 and a 74 C65 Tandems with 22ft Midwest beds with 18in highrisers! Both had 366 Big Blocks with 5 speed transmissions the 72 had a different pattern from the 74 model. R & 1 were reversed to each other. In the Plains of Texas we call them 5 speed with a Working 4th & 5th!
the shifting pattern is....................
1Lo
1Hi
2Lo
2Hi
3Lo
3Hi
4lo
5lo
4Hi
5Hi
This shifting sequence will keep you in the power band with no Lugging!
I have personally crossed the scales at 40,000 lbs total wt carrying Wheat, both trucks weighed in the neighborhood of 17000 empty!
Real hard to get over 36000lbs carrying Corn.
Anyway the above pattern will be what you need Loaded. Empty, Depending on how the truck likes taking off in 2nd whether you need to use 1st. But stay in the Hi side empty. Hope this helps.
Later,
John A.

This is what worked for me. No Chev, but Ford & IHC.
Empty: 2-3-4-5 all in the lo side, then 5 hi at road speed. Less torque load on u-joints, the weakest link in the chain, than using the hi side.
Med load: 2,lo,hi-3,lo,hi-4,lo,hi-5,lo,hi.
Full load: start 1,lo then split all the way up.
A few units had what we called a "long 4th". To find this out, drive in each of the top 4 gears at the same tach speed, make a note of road speed, see where 5 lo falls relative to 4 hi.If between 4 lo & 4 hi, 5 lo comes after 4 lo, then 4 hi & 5 hi.
85 model should be elec shift, but some heavier axles had elec control, air shift, drive the same.
With a little practice, can make smooth lo to hi shift in 3, 4, & 5 by release the throttle & pause, no clutch.
Downshift rear without shifting trans in 3, 4, or 5 by quick release & stomp on throttle, again no clutch.
Splitting upshifts: trans to next higher & rear lower- shift trans first then rear, get on throttle quickly, need tospeed up driveshaft to match axle speed.
Splitting downshift: shift rear up first, then trans down.
Uphill, soft ground, or loaded: if it won't pick up the load at idle speed without slipping the clutch, need a lower gear. Extreme conditions in 1 lo might need about 1000 rpm to get moving.
In over 40 years never hurt a trans or rear, lost 1 clutch due to engine rear main seal leak, clutch got oil soaked.
In a stage coach: road test for new recuits- set a paper plate with a tennis ball in it on the floor. If the ball rolls out of the plate when starting, braking, or turning, you are giving the passengers too rough a ride.
Willie

Make it easy and simple. If you are not heavily loaded there is no need to split. If you are loaded and have a good running high torque engine you can experiment with what combinations you need. I usually did not split the lower gears. My last C-60 with a Clark, high fourth was higher than low fifth. I started in 1963 but was out a few years and quit in 1994. When I first started I split all of them to show off my foolish (?)skill. Too much wear and tear on clutch for no use.

Hmm. It shouldn't take but a short drive, running it through all the gears and axle splits to figure out what the sequence is. I haven't driven a lot of vehicles with two-speed axles, but with most of them it was a simple 1L-1H-2L-2H-3L-3H-4L-4H sequence if you used all the gears. The exception was a mid-sixties Chevy that used 3L-4L-3H-4H.

If your friend hasn't driven a two-speed axle before, there is a trick to it. It's been twenty years for me, so I'm not going to explain and get it wrong. Also, it's important to always park in low axle, otherwise your truck is likely to pop out of gear and roll away.

(quoted from post at 21:58:21 02/06/14) We had several 60's/70's IHC and GM single axle grain dumps with 5+2 transmissions. All were geared similarly. Good chance yours is the same too. Here's how they shifted -

Full load (uses all possible gears used in sequence):
1-Lo
1-Hi
2-Lo
2-Hi
3-Lo
3-Hi
4-Lo
5-Lo
5-Hi

Unloaded: Leave the rear end in high and shift 2 > 3 > 4 > 5

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That;s how I did it on Dodge, Ford and GMC trucks back in the day.

Listen to your Dad,

The only time I ever use that low rear end is if I get into some really soft dirt and heavily loaded.

The shift pattern should be on a sticker on the back side of the driver's sun shade. However, trying to shift thru 'all' those ratios is a recipe for a snapped axle.

Allan

You can either be a cowboy or a truck driver.4th High is usally the same ratio as 5th low.I always listen to the motor or go by the rpm if there is a tac.Its not rocket science

jimmy

Its funny how those 5+2's and 4+2's have gone to the wayside, do they even make them anymore ?

I've always liked them and have driven many of them. Growing up we had a Dodge D700 5+2, 2 C series ford (cabovers) same 2 spd rear, + how many others I drove as a kid in between, Ford, Chevy, and IH. I currently own a '64 F600 4+2 it has a292 y block. I drove many IH's from the loadstar series with the 345 V8 to the newer S series, S1600-1900's at the lumber yard, diesel, all with 2 spd rears.

They are all different, at the lumber yard I ran 2 S1600's IH's, both v8 diesels, 5spd was an '84, the 4 spd was an '86, both geared differently. There really seems to be no smooth way to split shift each gear going up or down. However, the 4spd IH S1600, you could go from 3rd high to 4th low, then pull the plunger switch up in 4th, and it was smooth, no real need for it, was a box truck for shipping our millwork, and that truck would fly, had tall gears in it, so the ratios were still climbing from 3rd high to 4th low, others I drove were not like that. I think 4th high on this truck you shifted 4th into high at well over 60 mph, this truck would run 90 mph or more, been so long its now hard to remember.

My old F600, you don't want to play games with split shifting, start off in low til you get to 4th, shift to high and thats it. Or if you don't need 4th, 3rd high, but thats it.

It seems to me that if you listen out the window, with most of these, you will here that hang time because while you are shifting the trans, your foot is off the accelerator, so its seems like something is not coordinated, but when you are in any gear, pull up or push down the switch, let off the accelerator, then push it back in one fluid motion, they just shift nice and easy, like a 13 spd road ranger when you split shift. When you try that while also shifting the transmission, I'd say listen to what Allan, your dad says etc. Youll either get a nice thud, or you'll hear that eaton rear in limbo and it sounds like a grinding noise, not sure if it is. I know there are data stickers under the visor on all these trucks and it has instructions, makes you think this method of shifting the rear at the same time as the trans is supposed to work, I only experienced one truck in my driving career that would do it smoothly from only 1 gear in its transmission to another gear, and that was the IH S1600 V8 diesel, box truck we had at the lumber yard I described above for our millwork. Things change with a load on, I delivered hundreds of framing orders on flatbed IH's S series both gas and diesel, and the loadstar as well, all those had 5 spds in them, try splitting those and you may find yourself with a problem, go all the way to top gear, then just switch to high, when shifting down, its top gear, to low range in the rear,then directly shift the transmission down, maybe I have missed something, but I drove for that place 4 years straight 6 days a week, often times it was one of those IH's if the tractor trailer was not needed.

I just spit coca-cola out.lol economical and Chevy big block don't belong in the same sentence together. They run down the road nice, but are thirsty.

Google Eaton 2speed rear end.It will tell you all about them with a video.

Some 5 speeds you shift from 4th low to 5th low then to 4th hi and 5th hi. Then if you need to shift down you shift the stick from 5th to 4th not using the button. Saves wear and tear on the two-speed.

When you shift from the low 2 speed to high, you let off on the gas pull the lever to high at the same time, pause on your throttle until you feel the axle shift and then down on the gas. Shifting from high to low 2 speed, you shift the lever to low then let up on the gas and down on the gas with almost no pause. Doesn't take very long to get the feel of it. When you are in the field with a load on, stay in the low range until you get to know the truck. On the road go through your gears in the low range and shift to the high 2 speed once you are in high gear and rolling. Once you get to know the truck you will vary this somewhat under certain conditions, but that's for after you get to know the truck.

(quoted from post at 09:25:22 02/07/14)
I just spit coca-cola out.lol economical and Chevy big block don't belong in the same sentence together. They run down the road nice, but are thirsty.

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Have not you ever heard the word """fallaciously"??????????

instruction decal from my 69 C60 Chevy

Yes I have seen these stickers. I use to have a 1965 scout model 80 four wheel drive. When shifting four wheel drive to low four wheel you had to be stoped compeletly and engine out of gear to go to low four wheel drive plus you had to do the same to get out and in to high gear. What alot of work it was the chance of a quick shift was never there to do. My Scout if you did not watch it you could trun sharp BUT the wheels would lock in to the sharp trun postion and not let you steer out of it. So you never took a very sharp hard turn.The fun of haveing surprise when you are out in no where Yes I do know now why they made a Scout 2 it is out helping those who had the Scout.L.O.L

You need to google a working 5th transmission. Check the vin and see if it has one. I wish my current grain truck had one. A working fifth makes your two speed rearend change a whole gear in fifth without moving the shifter. Usually the button is only half a gear meaning you have to shift more on hills. Working fifth has the button shift a whole gear. They are nice with smaller engines, heavy loads, or hills.

Every school bus I drove was either a 4x2 or a 5x2. I can make a bus do things that those folks with an automatic didn't think we're possible - as long as you play that rearend and transmission against each other.

Even unloaded I never start out on the high side. Regardless of whether it is a working 5th or not I usually split 3rd and 4th with a load. Without a load I run all the way through and then shift up the rearend.

I have owned several C50 and 60 Chevys and Dodge D600 and D800s and all of them had Clark 5 speeds and Eaton 2 speed rear ends and drove them all the same. Empty trucks I leave in HI axel and run them that way. Loaded truck from a stop, Low axel and run through the gears, Once in 5th in low then push the clutch in pull the nob for the 2 speed let the clutch out and go and its like shifting another gear. (This works the best for cold temps as the rear end oil is cold and takes more time to shift). In the picture this is what my Dodge D600 (Clark trans and 5&2) says to shift the axel with the gas peddle , Sounds crazy but it works. Just another way to do it. Bandit

John A has it right-the same as i was taught ! Mark

If you drive a truck with a 2 speed enough, you will figure out what works best for your area.

In my area we have alot of hill/mountains and you might end up using/splitting gears more often than someone on flat land.
To me the 2 speeds are bullet proof. In my line of work, County road dept. 35 years, we never had one fail other than the electric motor that shifts the two speed. Plowing snow with 8 ton of salt and anti skid on board is hard on any truck.

Drove a Ford 2 speed axle for Toledo scale inthe late 60's. Buddy was sleeping beside me. Just followthe dirrecions overhead at that time. He never woke up til later then bawled me out cause nobody was supposed to shift the axle. Dave

I have driven several Ford and GM 60's, 70's, and 80's trucks with 2 speed axles. All of the Ford and GM were gas, but I did drive an 80 something Interntional diesel with a 5+2 setup. We have a 67 F-600 with a 4+2 and our fire department has had several with 5+2's, currently an 80 model c-70 with a 427. I have gone through all the gears splitting them in our Ford with no problem, but never really saw a need to, even loaded to the point with wet sand that the ticket would cost more than the truck is worth. To split the gears, I would just push the switch down while the clutch was down between gears and the rear end would shift by the time I let the clutch back out. I would then pull the switch under load and let off the throttle till it shifted. If the axle is slow to shift or something is not right, you will get a grinding noise due to the axle not fully shifting and have to stop to get it into a range. Almost everyone in this area keeps it on the low side till they are in high gear and then shifts to high range by pulling out the switch with the throttle down and letting off. When you feel it change, drop the hammer and go. In cold weather or if a truck has been sitting up, it can take longer for it to shift. It is rare to need to drop to low range because we don't have many steep hills, but the way I've always done it is to keep my foot on the throttle, push the button, and rapidly "kick" the clutch. People usually laugh at the split-shifting guys as show offs and I have seen a guy break an output shaft doing it wrong. When we bought our F-600 it didn't have a switch on it because a previous owner got tired of hired hands tearing things up and left it on the high side.

We have two of these trucks in our fire department. One, an 87, and the other a 78. They are the same except for the 4th and 5th split. One of them, when full of water, has to be shifted 4-L 4-H 5-L 5-H. The other one has to go 4-L 5-L 4-H 5-H. I know it's not normal, but the sticker on the roof has it that way. I usually stay in low until I get to 4-L, then I go 4-H and 5-H. Unloaded I stay in hi range. Both of these trucks have a 366 gas engine, one is a C65 and the other is a C70, don't remember which is which as they are almost identical in appearance.

As a side note, the 78 model has 13,000 actual miles on it. No telling how many hours pumping water though. It was bought new by our department. We carried it in to the Chevy dealer for it's 12,000 mile checkup (as recommended in the owner's manual) and while the guys there had a good laugh, they did do a few things for us, got it detailed and it looked pretty good. It's a pretty solid old truck.