65 GMC questions

[DetroitDan]

Hi, just me again lurking around. Been thinking again about dumping the 82 to buy a 60-66, and I have some questions about what I want to do. I'm looking at a 65 GMC right now, I think it's a C10 but not 100% certain, it could be a C20. It's a longbed fleetside with the 305 V6 and 3 on the tree. I am using a K2500 Suburban for my daily driver, tow rig, and it will also be my plow truck next winter. So the 82 is a little redundant, however I do need a pickup truck jsut for dump runs and the occasional large item purchase. And oh yeah, I buy wood pellets by the ton 3-5 times a year, so I need a pickup capable of hauling 2000lbs in the bed. My duallies were overkill for this. I did it a couple times with my 1500 Avalanche which had a 1500 lb payload, it was a little light in the front but not too scary or I wouldn't have done it.

So, would a C10 be able to carry 2000lbs for a short haul? I would be running good radial tires and splitting the brakelines with a dual master cylinder swap. The only 305 I ever drove was in a 66 C50 firetruck, plenty of power to move that heavy rig, so I expect it would move the weight ok. I'm mostly concerned about rear suspension. Isn't the C20 a leaf sprung rear? What are the C10 coils good for? I kind of feel that an old truck is usually built far better than the new flimsy junk, so capacity should be fairly high, but idk.

I do know that 1/2 ton, 3/4 ton designations are not payload, so please don't bother pointing out a half ton truck can only carry a half ton, because I don't believe that to be the case.

Also interested in possible future upgrades. Did a lot of reading about swaps but didn't see what I was wondering about. How hard is it to swap the cab and bed onto a 73-87 4wd chassis? Be nice to get an OD automatic, 4wd and disc front brakes all at once.

[jonzcustomshop]

if it is 8 lug, then 3/4 or 1 ton, 6=1/2

better to keep the original frame, and swap the newer stuff to it, most is just a bolt on deal.

[padresag]

Originally Posted by DetroitDan

Hi, just me again lurking around. Been thinking again about dumping the 82 to buy a 60-66, and I have some questions about what I want to do. I'm looking at a 65 GMC right now, I think it's a C10 but not 100% certain, it could be a C20. It's a longbed fleetside with the 305 V6 and 3 on the tree. I am using a K2500 Suburban for my daily driver, tow rig, and it will also be my plow truck next winter. So the 82 is a little redundant, however I do need a pickup truck jsut for dump runs and the occasional large item purchase. And oh yeah, I buy wood pellets by the ton 3-5 times a year, so I need a pickup capable of hauling 2000lbs in the bed. My duallies were overkill for this. I did it a couple times with my 1500 Avalanche which had a 1500 lb payload, it was a little light in the front but not too scary or I wouldn't have done it.

So, would a C10 be able to carry 2000lbs for a short haul? I would be running good radial tires and splitting the brakelines with a dual master cylinder swap. The only 305 I ever drove was in a 66 C50 firetruck, plenty of power to move that heavy rig, so I expect it would move the weight ok. I'm mostly concerned about rear suspension. Isn't the C20 a leaf sprung rear? What are the C10 coils good for? I kind of feel that an old truck is usually built far better than the new flimsy junk, so capacity should be fairly high, but idk.

I do know that 1/2 ton, 3/4 ton designations are not payload, so please don't bother pointing out a half ton truck can only carry a half ton, because I don't believe that to be the case.

Also interested in possible future upgrades. Did a lot of reading about swaps but didn't see what I was wondering about. How hard is it to swap the cab and bed onto a 73-87 4wd chassis? Be nice to get an OD automatic, 4wd and disc front brakes all at once.

your going to hear it anyway. 1/2 tons are not rated to carry that weight. I am across from a lumber yard and see jerks overloading their trucks everyday, rear bumpers almost dragging the ground. and you just love driving towards these a/h's at night with their lights hitting you in the eyes.
you want to overload a 50 year old truck whose suspension is more than likely already worn out. good luck. and I guess that you want this for your dump run truck because it will more than likely be cheap
ron

[DetroitDan]

Originally Posted by jonzcustomshop

if it is 8 lug, then 3/4 or 1 ton, 6=1/2

better to keep the original frame, and swap the newer stuff to it, most is just a bolt on deal.

I know about the lugs, I just havent seen it in person yet and cant make it out in the pictures. Thanks for the other info, I was hoping for an easy answer, like it will drop right on a rclb or Suburban frame or something. More I think about it, I don't need another 4wd, and it would not be used on long trips, so the stock driveline would probably serve me just fine. Was just thinking how cool it would be to have an 87-ishk10 or k20 OD 4wd under it.

[DetroitDan]

Originally Posted by padresag

your going to hear it anyway. 1/2 tons are not rated to carry that weight. I am across from a lumber yard and see jerks overloading their trucks everyday, rear bumpers almost dragging the ground. and you just love driving towards these a/h's at night with their lights hitting you in the eyes.
you want to overload a 50 year old truck whose suspension is more than likely already worn out. good luck. and I guess that you want this for your dump run truck because it will more than likely be cheap
ron

thanks for your input, but I'm not entirely sure we're on the same page. I should have asked if anyone knew what the original payload rating was for the 10 and 20. I also see people overloading trucks at the landscape depot, etc, and I always shake my head. But they are probably carrying far more than 1000 lbs too, likely more than 2000lbs. A ton is just really not that much weight. And I appreciate your point about it being a 50 year od truck. Who knows what it's been subjected to in the past. Being that old, if it does have a pretty low rating, then I wouldn't carry a full ton in it.

What I was referring to was peoples mistaken belief that a half ton truck can only carry 1000 lbs in the bed. I dont believe that is what the term half ton refers to. For example, modern 1 tons have around a 5900 lb rated carrying capacity, yet they still call them 1 tons. My 2004 1500 "half ton" had a 1500 lb payload and that was with coil springs too.

So to rephrase my question, if the truck is not a C20, would one ton be too much for it? What would a C20 comfortably carry? Must be able to carry a ton on an 8 lug truck. Worst comes to worst, I can haul palletized pellets on my trailer behind any of my trucks.

If this is something I'm going to do I would certainly have all new brakes, brake lines, shocks and wheel bearings. I always replace all that whenenver I buy an older vehicle. Either way, I do have to own a pickup, because the town I live in does not have curbside pickup, so I have to bring my garbage to the dump every weekend, and I don't want to carry it inside my suburban. Any time Ibuy a washer/dryer or some other big item, I don't want to have to hook up my trailer.

[DetroitDan]

OK, I managed to find some data, it appears the max payload for a 1/2 ton would be only 1450. Considering they have to build in a safety factor, I wouldn't be afraid to exceed this number by 25% or so on a newer truck, but I think I'd go easy on a 65. Although my gut tells me a GM truck that was built to work wouldn't shy away from a few hundred extra lbs.
Interestingly enough, the 3/4 ton is 3550. 2100 lbs more?? Wow.

[lakeroadster]

Originally Posted by DetroitDan

OK, I managed to find some data, it appears the max payload for a 1/2 ton would be only 1450. Considering they have to build in a safety factor, I wouldn't be afraid to exceed this number by 25% or so on a newer truck, but I think I'd go easy on a 65. Although my gut tells me a GM truck that was built to work wouldn't shy away from a few hundred extra lbs.
Interestingly enough, the 3/4 ton is 3550. 2100 lbs more?? Wow.

Option 1:

Buy a C10 and put "heavy duty" rear springs on it, which are basically 3/4 ton springs.

Option 2:

Go with the C10 and buy an aftermarket overload spring set-up. Basically these are air bags that fit inside the coil springs. Here is a link: Rear Helper Bags

I think option 2 is the way to go. You end up with a nice 1/2 ton truck that doesn't have the harsh 3/4 ton ride. But for the occasional heavy haul you can pump up the air spring.

Hope that helps.

[DetroitDan]

yeah, I was actually thinking the same thing, but I decided against posting that because I was afraid it might upset Padresag. I had a 66 B-body with cargo coils in the back, so I know they must make them for trucks. And I had airbags in one of my 1 tons, worked very well for me when I carried sand/salt mix and the sander in the winter. Would only need small airbags or air assist to get to 2k I think. I just put airshocks in the rear of my 3/4 suburban to level it out when towing. Supposedly gives you another 1200lbs but not sure I believe that. It's going to be limited by the shock bolt hardware anyway. I had also looked at shocks with overload springs on them, but I like the adjustability of the air shocks.
Regarding the 1/2 vs 3/4 part of your post, aren't 65 3/4 tons leaf sprung in the rear? If not, I have no idea why I thought they were. In that case it would be very easy to swap it to 3/4.

[padresag]

your not going to upset me. been there done that. I run 3/4 t axles under my 1/2t 4 x 4 as I don't really appreciated the chicken/s rear axle brgs in a 1/2t. that is only one part of the scenario though. you also need tires to go with it.these old bodies take a **** kicking with loads to as usually everything is usually warn out.
no matter the capacity of the truck people will always tend to overload. iused to sell for IHC and Pacific trucks back in the mid 70's and spec them out. we had a customer for whom we were warrantying his 65,000 lb axles for bending. one day the people for Pacific were waiting for one of Dick's trucks to come over the scale with a log of logs on. he came across the scales netting 275,000 lbs. end of warranty, he was just a little over.
I can also remember when I pulled my first load of logs across the scale in my old 67 HD Hayes with just a tandem axle trailer at 104,000 lbs(that is what a "B" train carries.).
I was just a little over to maybe 50,000lbs, mind you this was off highway
ron

here was a pair of Pacifics that I sold in 74 on their first trip out

By rondavid at 2010-11-19

this pic was my pic on a Pacific brochure of one of the above trucks

By rondavid at 2010-11-18

[DetroitDan]

I'm not much into wimpy 1/2 ton stuff either, I've swapped in 3/4 stuff in the past, then my last truck was a 1 ton dually that was my daily driver for ten years. I've now got the 2500 sub and the 82 dually. I know what you mean. The way half tons are put together with little puny bearings, studs, axleshafts makes me nervous, especially when Isee big tires on them. I learned that the hard way like everyone else, lifting a half ton and putting bigger and bigger tires under it, then breaking everything and replacing it with stronger parts. You know what I mean when you look at a Jeep with 38 inch tires then look at those 5 tiny wheel studs!

Certainly not a fan of the 1/2 ton, but if it were to be just my weekend cruiser, and 2 mile weekend roundtrips to the dump with a half dozen bags of trash, I don't want to have to overbuild it. It wouldn't have to pull my big trailer or carry a sander, but it would be nice if I could make the wood pellet runs with it. If I can't, I can't. I'll just do it on the trailer, that's not a big deal for the few trips it makes. I just wouldn't want to have to hook up the trailer every weekend like I have been doing while my pickup was off the road.

[DetroitDan]

I have to admit I have never heard of Pacific trucks. Were they specifically an off-road rig, or something that stayed around northern logging mostly? I have an interest in big trucks, I used to drive heavy wrecker and we prided ourselves on having some heavy duty stuff. But 275,000?? How much motor do you have to have to budge that? Heaviest thing I ever hauled was estimated 170,000 behind a 44,000lb wrecker. Even with a turned-up N-14 Cummins making about 585 hp I could barely move it, I had to slip the clutch to get it rolling, then I couldn't get it over 35mph, and that was on pavement. Which was fast enough imo. Maybe if I'd had deeper reduction in the trans I would have had better luck.

[DetroitDan]

Whoa! I just found some more interesting data, I'm actually surprised it didn't come up sooner. According to a link in another post, a buyers guide for 60-66s, ALL GMCs in that year were leaf sprung in the rear, while Chevys, whether 1/2 or 3/4 were coil. That makes me like the GMC even more. Lot easier and more options to beef up the rearend imo.
Funny, at first I was considering swapping the grille, hood and other GMC specific stuff to make it a Chevy, because I am a diehard Chevy guy. But looking at them in pictures, (and knowing about the rear springs), I'm actually liking the GMC better. I still love the Chevy, but I gotta admit the 4 headlights makes a big difference.

[pmkrew]

I have a 65 Chevy c-10 that has factory "helper springs", I think maybe some type of a camper special set-up, haven't researched it. Anyone know the payload of that set up?

[padresag]

Originally Posted by DetroitDan

I have to admit I have never heard of Pacific trucks. Were they specifically an off-road rig, or something that stayed around northern logging mostly? I have an interest in big trucks, I used to drive heavy wrecker and we prided ourselves on having some heavy duty stuff. But 275,000?? How much motor do you have to have to budge that? Heaviest thing I ever hauled was estimated 170,000 behind a 44,000lb wrecker. Even with a turned-up N-14 Cummins making about 585 hp I could barely move it, I had to slip the clutch to get it rolling, then I couldn't get it over 35mph, and that was on pavement. Which was fast enough imo. Maybe if I'd had deeper reduction in the trans I would have had better luck.

Pacific truck and trailer came out of north vancouver, b.c.. they were shipped all over the world . they were used on highway and off highway. IHC bought them out in the mid 70's.
the one that I was talking about was a mod P12 and these were running 12v71s. there was also a P16 which were the granddaddies when it came to hauling logs. hayes and kenworth built similiar vehicles
ron

[padresag]

Originally Posted by DetroitDan

Whoa! I just found some more interesting data, I'm actually surprised it didn't come up sooner. According to a link in another post, a buyers guide for 60-66s, ALL GMCs in that year were leaf sprung in the rear, while Chevys, whether 1/2 or 3/4 were coil. That makes me like the GMC even more. Lot easier and more options to beef up the rearend imo.
Funny, at first I was considering swapping the grille, hood and other GMC specific stuff to make it a Chevy, because I am a diehard Chevy guy. But looking at them in pictures, (and knowing about the rear springs), I'm actually liking the GMC better. I still love the Chevy, but I gotta admit the 4 headlights makes a big difference.

either suspension was optional for both but were not common as such, so you could find a chev with springs or a gmc with coils
ron

[kieth]

This is how it works: GVW 5000 lbs (c10) - the weight of the truck with driver and fuel = Payload
5000lbs-3500lbs= 1500 lbs net payload

C20 gvw 7800lbs (ones without a full floating hub) 7800 - 4500 = 2300lb net payload

C20 8500gvw - 4900lbs = 3600lbs

C30 dual rear wheel 10,000lbs -6000lbs = 4000lbs net payload

next class GCWR gross combined weight rating

I own a class 8 truck dealership and I do know trucks all the way up to heavy haul stuff that moves 500,000 lbs....

each rating requires changes in tires, spring, brakes, frame, driveline, clutch, overall gear rario in rear axle and transmission.....

You may be able to get it to set level but u will have a hard time stopping it. Get a heavy 3/4 ton and save yourself a lot of trouble. Kieth ps no hostility intended.....good luck

[lakeroadster]

Originally Posted by DetroitDan

Whoa! I just found some more interesting data, I'm actually surprised it didn't come up sooner. According to a link in another post, a buyers guide for 60-66s, ALL GMCs in that year were leaf sprung in the rear, while Chevys, whether 1/2 or 3/4 were coil. That makes me like the GMC even more. Lot easier and more options to beef up the rearend imo.

"Easier...???" Not at all. The Chevrolet coil spring truck arm suspensions worked great in both the 1/2 ton and 3/4 ton trucks. It doesn't get much "easier" than replacing coils, it's a one man job. And compare the cost of springs and you will soon find out that the coil set-up is much more economical also.

[DetroitDan]

once again, I find out how much I dont know. I've owned a couple coil spring trucks but never messed with them, whereas I've lifted several leaf sprung trucks and thought it was pretty easy. Seems like it wouldn't be hard to slip a full floater and 3/4 springs under it. But the brakes are concern too, 4 wheel manual drums I'm sure.
Anyways, it's not going to be bought for hauling weight, I just wanted to know if I'd be able to have it fulfill all or most of my pickup truck duties, which generally consist of hauling 6-8 bags of trash to the dump on Saturday, I'm buying an aluminum 10' jonboat that i don't want to trailer, and then the 4-5 tons a season of wood pellets.