1/2 ton Vs. Heavy Half

[mtnsackett]

can anyone tell me the difference between a regular half ton truck and a heavy half? I'm not sure which mine is.

thanks

[Jonboy]

The main difference is the rear leafs. The heavy half will have 8-9 leafs.

[MalibuSSwagon]

Didn't the heavy half have larger front brake rotors as well?

The rear springs cross reference to 3/4 ton rears, so they are easy enough to get.

[Jonboy]

Originally Posted by MalibuSSwagon

Didn't the heavy half have larger front brake rotors as well?

The rear springs cross reference to 3/4 ton rears, so they are easy enough to get.

I think that is after '81. I was told pretty much all trucks before '81 had 1.25 rotors.

[Tx79chevy]

Originally Posted by Jonboy

The main difference is the rear leafs. The heavy half will have 8-9 leafs.

My 79 has 8 leafs and is not a Big 10.
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[THE "10" SILVERADO]

Originally Posted by Tx79chevy

My 79 has 8 leafs and is not a Big 10.
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They also came with a tow package, don't know if that one was mentioned. My 77 has the large 56" springs (8 leaf) and heavy duty rear brakes but is not a big 10 because it didn't come with a tow package.

[Keith Seymore]

From another website:

"You are correct about the Big 10’s being the same as Heavy Halfs. In fact, the Heavy Half was the GMC equivalent to the Chevrolet Big 10. Both were identified by the option code “F44” and contained equipment allowing higher GVW’s than those of the regular Chevy C10/GMC C15.

The 1979 model year F44 package included a choice of 1,625 or 1,700 lb front springs (1,475 and 1,550 lb front springs were commonly used on standard C10/C15’s), 2,000 lb capacity rear springs (1,550 lb rear springs were standard on regular C10/C15’s), heavy duty power brakes (manual and light duty power brakes with smaller rear drums were offered only on standard C10/C15’s), larger tires in a choice of 1,790 and 1,905 lb capacities (several smaller capacities were also listed for regular C10/C15’s) and the 305 V8 (the 250 six was standard on regular C10/C15’s). With the exception of the 1,700 lb front springs, all of the F44 components shown above could be ordered separately on the regular C10/C15. Depending upon the equipment selected, the regular C10/C15 offered GVWR’s of 4,900, 5,300, 5,400, and 5,600 lbs. However, by selecting the F44 package, the buyer received all of the above equipment, plus the bodyside decal designating the C10/C15 as a Big 10/Heavy Half, offering GVWR’s of either 6,050 or 6,200 lbs (depending upon the tire and front spring capacities selected). (You can determine your Big 10’s rating by checking the label affixed to the driver’s door frame.)

A few other notables should be mentioned. For 1979, the U.S. EPA established fuel economy standards for trucks up to 6,000 lb GVW. To meet these standards, GM equipped the standard C10/C15 with a special hood seal and underbody air dam, and also offered a selection of rear axle ratios biased in favor of economy. The Big 10/Heavy Half GVWR’s exceeded the EPA’s 6,000 lb threshold, and accordingly, those models were not equipped with the hood seal and air dam. Also, the F44 package allowed the purchase of lower axle ratios, and the 454 V8 engine option. In contrast, the 350 was the largest engine available on the regular C10/C15.

Prior to 1979, the EPA considered all trucks under 6,000 lbs GVW to be light duty emission class vehicles. With few exceptions, these vehicles required undesirable catalytic converters and the use of unleaded gasoline. The F44 option was introduced to allow buyers the possibility of buying a heavier duty ½ ton truck that could use cheaper leaded gasoline. However, for the 1979 model year, the EPA expanded the light duty classification to include all trucks up to 8,500 lbs GVW. Thus, the Big 10/Heavy Half (and all ¾ ton Chevy C20/GMC C25 trucks, as well) lost this particular advantage. Only 1 ton C30/C35 series remained exempt from catalytic converters and unleaded gas.

Excepting the differences discussed above, the Big 10/Heavy Half was identical to the standard C10/C15. A 3.14 section modulus frame, 3,750 lb rear axle, and 15 inch wheels were common to both. These components were much more robust in the ¾ (20 series) and 1 ton (30 series) models."

I didn't verify for accuracy before posting but can follow up if you have any specific questions.

Here's an earlier thread with some discussion: http://67-72chevytrucks.com/vboard/s...d.php?t=369184

K

[Keith Seymore]

Originally Posted by mtnsackett

can anyone tell me the difference between a regular half ton truck and a heavy half? I'm not sure which mine is.

thanks

If you are referring to your '85: the "Heavy Half" package was not available in the '85 model year (1980 or '81 looks like the last year to me).

K

[mtnsackett]

Originally Posted by Keith Seymore

If you are referring to your '85: the "Heavy Half" package was not available in the '85 model year (1980 or '81 looks like the last year to me).

K

Keith, this is a truck that I was given the other day as a parts truck it is an 80 Chevy big ten or at least it says it on the box it has a 350 in it and a turbo 400, but the guy who gave it to me had it sitting at his storage business for years and could not sell it at an auction for what ever reason. so I have no title and a bill of sale, so it is basically a parts truck. but I was thinking that maybe I could change over some parts if it was worth the effort. I think the engine is ceased but I am going to drain the oil and refill it and over by hand and see

[Keith Seymore]

Originally Posted by mtnsackett

Keith, this is a truck that I was given the other day as a parts truck it is an 80 Chevy big ten or at least it says it on the box it has a 350 in it and a turbo 400, but the guy who gave it to me had it sitting at his storage business for years and could not sell it at an auction for what ever reason. so I have no title and a bill of sale, so it is basically a parts truck. but I was thinking that maybe I could change over some parts if it was worth the effort. I think the engine is ceased but I am going to drain the oil and refill it and over by hand and see

Ok, good - thanks for the follow up.

Does it show RPO F44 on the SPID?

Go to the Heritage Center link I gave you earlier and pull up the packet for 1980. It will give you the detail.

K

[gchemist]

1.25" rotors are common for them. 1/2 ton trucks mostly use 1" rotors.

[88Jimmy4x4]

Rear leafs will also be 56" versus standard 52" for 1/2 ton, alot if these options are part of towing packages too so VIN is best way to determine heavy half or big 10
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[GM-power]

Check the vin and if the 5th digit is a 4 than it has the f44 option.
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[MalibuSSwagon]

So I want to upgrade my C10 to Big 10 specs, I do use my truck for towing often. Besides the obvious rear spring change, what else is worth upgrading to factory F44 parts?

[mtnsackett]

the SPID is missing but the vin's 4th and 5th digit is a 4 the Vin starts off CGM44A7

[Old School Low]

If you werent 3,200 mi away I's swap for coils and leafs from my 78 short HH. I,m going for about 5-7 drop. (your last post was in May, did u make any changes?) Pretty sure gas filler is larger for reg gas nozzle on HH/B10. Can anyone verify this? Check out New Old Guy thread I started for pics.

[RoughKuntry]

I could say that my 1980 Chevy is a Big 10 the only problem is I do have the 4 in the 5th Digit. (VIN: CCD14A117900) Right now she sits with 33x14.50R15 Mickey Thompson's in the rear. I tow alot with this truck including logs. My truck also has been converted from a 350 5.7 back to the 262 I-6. I love this truck however, with the problems from my 1973 2500 Super Custom, All Original except for the 3/4 ton axles. I slapped Original Dana 60 FF under her. She sits now without a Motor. I traded my 3/4 GMC High Sierra Jimmy 4x4, for this 1980 Chevy Truck. Turns out that truck came from Canada, You Can still see the Forestry Logo's in the paint. My Photo shows the Face Lift I gave my truck. Made her look like my 1973 - 1976 because I really didn't like how the full square Lights looked. The previous owner loves the new look. I about to pull the 292 out and replace it with a 383 Stroker.

[cory d]

i always thought the heavy half thing was funny. heavy duty 3/4 tons make even less sense

[LuckyLightning]

Reviving this one to understand if the frames are any different between half-ton, heavy half-ton, and three-quarter-ton? I'm looking at purchasing an '80 heavy half ton, even though I was searching for a 3/4 ton for better towing capabilities over a half ton. I didn't even know the heavy half was an option, so I'm not very familiar with it at all.

Thanks!

[LuckyLightning]

Forgot to mention, this is 4x4. Thanks!

[Jonboy]

Frame is different on 1/2 ton vs. 3/4 ton. 3/4 ton is taller.

[nekkidhillbilly]

Originally Posted by Jonboy

Frame is different on 1/2 ton vs. 3/4 ton. 3/4 ton is taller.

iirc the 1 tons are the only one with a taller frame in squares

[LuckyLightning]

Thanks Jonboy. What about heavy half ton frames? Same as regular half ton frames, or taller like 3/4 ton frames?

[Old School Low]

Im sure its the exact same frame as any 1/2 and shares nothing w 3/4t. I have a short 78 GMC Heavy Half. Only real differences are 8 rear leafs. Then it could be rated over 6,000 GVW and not b required to use unleaded. That was the rule back then. 77-81 I think then some new rule made it so it didnt help anymore so they dropped them. (And check fuel fill nozzle, it should be larger dia for reg gas spout) Then there is the 4th digit vin # being a 4, this is pretty proof positive its HH or Chev Big Ten. (My 4th and 5th digit are 4's) Something else I've found. Truck is factory 350/350, now stroked to 383, and it has 34t ring and 10t pinion for a 3.40 open rear ratio. Some even real sq body experts just arent sure to believe this or not because they've just never ran across one. But I counted every tooth 5 times myself. (Remember Lonnie?) And u half to really dig to find replacements. I think its about a perfect ratio for my set up anyway. Havent been on here for months. The GMC is hauling ass whenever I ask it too. Running good. TH350 is begging to be rebuilt though. I moved couple of months ago right next door to a bigger MH w 2 CAR GARAGE! Getting filled up w wood working tools but this winter I'll make some room and finally C-Notch. (what are good tire dollies so i can push the truck around in garage? any suggestions?) Swear I only have 3/4in rear travel now. Big busted girlfriend will appreciate not having to hold on anymore when she sees bump coming. And hey. Would you guys suggest taking bed off when I c-notch to make it easier and clean it up and replace bed bushings and bolts? or is that just not necessary and ALOT of extra work?

[bnoon]

Originally Posted by Old School Low

Im sure its the exact same frame as any 1/2 and shares nothing w 3/4t.

I believe this to be correct, at least for 2wd. Both half ton frames have both sets of holes already drilled for either 52" or 56" rear spring shackle/hanger installation. I'm picking up another '76 this weekend that I believe is the regular half ton and will be swapping the rear springs over to my Heavy Half '74 for a better ride. I will compare the two side by side if you like.