Will the real GVWR please stand up?

[HomeMadeSin]

The 67 C20 I picked up had a SS plate on the door jamb that indicates 7500lb GVWR:



The 1967 Chevy truck "sales" book that lists the standard and optional equipment indicates that 7,500 is "Rating on standard GVW plate". but also lists that the 3,000 lb rear springs is required to achieve it. Seems ass backwards to list a higher GVW as default but you can only achieve it with optional equipment. Seems safer and more prudent to list the more conservative GVW of 5,500 lb. I'm sure there is some twisted bureaucratic BS logic to it. Or Chevy was too lazy to switch GVW plates as required.

My glovebox sticker only lists the auxiliary rear springs as an option but the 500 lb not the 3,000 lb:



So given the dual 3,000 lb (each) aux springs nets you an additional 2,000 lb in GVW, do my 500 lb (each) aux springs net me an additional 665 lbs? Or maybe a nice round 500 lbs NET and hence the stickers on the side of the truck that indicate 6,000?



If that holds water, then my payload is about 1,750 lbs (6,000 minus the 4,248 lb curb weight), although I have no clue if the curb weight is dry or full tank of gas.

Thanks,
Z

[special-K]

Don't over think it. Just load it up and go. It can take most anything you can throw at it. What it can't, it will let you will know. Numbers is just numbers. When do we ever know exactly what the weight of our load is, unless we runs across scales loaded then empty?

[Keith Seymore]

Learn this backwards and forwards:

https://www.gmheritagecenter.com/doc...olet-Truck.pdf

[Getter-Done]

Originally Posted by Keith Seymore

Learn this backwards and forwards:

https://www.gmheritagecenter.com/doc...olet-Truck.pdf

Cool info 😎
Thanks For Sharing

[Mike C]

I know on the 70 GMC 3/4 tons that I have owned, they switched to the max for platform GVWR and the as equipped GVWR on the door jam tag.

I was surprised at how much variance there was. My Sierra Grande was 7500# as equipped, the 127" wheel base long step 6 cylinder 3 speed was 6200 and the 133" GMC "Longhorn" with 350 and SM465 was 6600#.

[HomeMadeSin]

Originally Posted by Keith Seymore

Learn this backwards and forwards:

https://www.gmheritagecenter.com/doc...olet-Truck.pdf

Ok, it won't be the first time I've been called slow, but that was the document I was referring to above (excellent document btw). I didn't read past the C20 option info before I posted but did go back to read the later pages thanks to your hint.

So, I didn't really see a direct way to determine my vehicle specific GVWR but read the data and feel comfortable enough that given the optional HD springs up front and auxiliary leaf in the rear, it should be about 6,730lbs. This gives me about 2,612 lbs to play with.

Thanks,
Z

[HomeMadeSin]

Originally Posted by special-K

Don't over think it. Just load it up and go. It can take most anything you can throw at it. What it can't, it will let you will know. Numbers is just numbers. When do we ever know exactly what the weight of our load is, unless we runs across scales loaded then empty?

The reason I am trying to get this sorted and not wing it is that the plan is to utilize the truck for business purposes. So, I need to ensure that how I intend to use it (not haul for hire or moving goods for shipment) does not exceed the originally intended GVWR. Just trying to (over-)do the right thing so the texting idiot driver that causes an accident can't get off the hook because I had 2 lbs over the limit.....

It hasn't happened yet, but as a motorcyclist I may be more sensitive to it than others.

Z

[HomeMadeSin]

just for FYI:

Optional Coil, front, sprung cap: 1,152lb each for 2,304lbs
Std coil, rear, sprung cap: 1,713lb each for 3,426lbs
Optional aux leaf: 500lb each for 1,000lbs
Total: 6,730 lbs.
Truck curb weight: 4,118lbs
Net payload: 2,612lbs.

With the original tires, which should be easy to beat.

Z

[Coley]

The GVW plate rules the day for any grievance or traffic violation issue.
To make sure you don't over load the truck...you will need to specifically weigh your truck. I recommend a relatively empty weigh in (log this) ....and then a full load weigh in.
Note that every single one of these trucks weighs a little different so don't go by any stock or generic literature to 'guess' the truck weight....literally go weigh it.

Now, the GVW rating on the trucks encompasses more than just the spring options.
The tires play a role as well as the brakes, the frame, etc. The heavier trucks with the higher GVW got most of this stuff often built into them....such as the camper special trucks.

I have been through this cycle repeatedly on the half tons trying to figure out why the capacity never seemed that high based on the GVW plate (ie: 5000 lbs)....and I did this because I wanted to carry a small 8ft overhead camper. I did this successfully, but I was always over the original GVW of the truck.

Now, from GM's standpoint they are always going to under rate the trucks....always. This is their factor of safety to compensate for the guys who always overload their trucks....and you will never know that safety factor number.
However, in defining the GVW they would base it on the weakest link in and under the truck...and that is usually not the springs.
On the original 1/2 tons it was the tires. Those old technology bias ply tires were lucky to carry 1500-1600 lbs each...which would (on a good day) give you a maximum of 6000 lbs for safety...and of course GM would de-rate that.

Also, I'm pretty sure that the auxiliary springs did not bump up any GVW ratings...they simply were marketed as overloads to help with load stability and not necessarily increasing any rating numbers....at least this would be GM's safety/liability default point.
Why?....because you could remove them ...and then still claim you were within the GVW rating.
(I noticed this on a 1/2 ton I had that came with the overloads....and I too, was expecting a higher GVW plate rating...but there was no change in it)

Today, with modern tire technology the GVW rating of these original 1/2 tons would probably easily pick up another 500 lbs or so, given the fact that any 15" truck tire today has a rating above 2000-2200 lbs each...for a net safety/capability of 8000 lbs with 4 tires...although GM would never give you personally the benefit of that doubt relative to GVW.

The other thing to factor in is if your springs are original. If so, they have probably lost 500 lbs worth of ability vs. a new spring.
As a result if you want to safely carry bigger loads, get your springs redone and you really see and feel a difference.

My two bits.
Coley

[factorystock]

Originally Posted by HomeMadeSin

Or Chevy was too lazy to switch GVW plates as required.

Yes. Sounds pretty close to the truth.This ties well into a recent post about Chevy truck history, or IMO, lack of history. 7500 is the max. rating for a C 20 with all heavy duty options. If you don't have the optional heavy suspension, the rating is actually less than 7500. Period Ford pickup would show the actual weight rating stamped into door tag (6200 6700 7500 8100*) *new for '72.

[Keith Seymore]

Originally Posted by HomeMadeSin

Ok, it won't be the first time I've been called slow, but that was the document I was referring to above (excellent document btw). I didn't read past the C20 option info before I posted but did go back to read the later pages thanks to your hint.

So, I didn't really see a direct way to determine my vehicle specific GVWR but read the data and feel comfortable enough that given the optional HD springs up front and auxiliary leaf in the rear, it should be about 6,730lbs. This gives me about 2,612 lbs to play with.

Thanks,
Z

Well - I went back and dug into the document and....I now see your dilemma. It doesn't make sense to me either that we would affix a GVW rating to the vehicle if it doesn't have the option content to support it.

Unfortunately I can't think of anyone left here (who has not retired) that I can ask.

One comment, though - the GVW rating doesn't go down to a specific number (like 6730 lbs). GVW ratings are in "buckets" and a specific truck would fall within that range (ie, 5600, 6100, 7600, 8600, 10000, etc).

K

[HomeMadeSin]

I was going to first use my 2015 RAM 1500 Eco-diesel for my business use, but the stated payload on the B pillar is a measly 1,053lbs. So, barely enough for the "crew' in crew cab. I got excited when I saw the SS plate on the '67 indicating 7500lbs! That's something to work with, only it may not be legit. That's about how my luck goes.

[Coley]

Originally Posted by HomeMadeSin

I was going to first use my 2015 RAM 1500 Eco-diesel for my business use, but the stated payload on the B pillar is a measly 1,053lbs. So, barely enough for the "crew' in crew cab. I got excited when I saw the SS plate on the '67 indicating 7500lbs! That's something to work with, only it may not be legit. That's about how my luck goes.

...lol, that actually isn't too uncommon these days.
Once you add (4) people at say....650 lbs total...that leaves you with a solid 400 lbs worth of payload.
...just enough for some luggage and a couple of purses, lol.

That said, the tow capacity (not the payload) is probably pretty high...just keep the load behind the truck on its wheels and you are ok.

Coley

[Mike C]

I've towed and hauled a bunch with an older truck and the real concern is brakes. If you are going to drive that '67 for your business I wouldn't even think about getting behind the wheel (or having an employee!) without disc brakes put on it.

[HomeMadeSin]

Originally Posted by Coley

...lol, that actually isn't too uncommon these days.
Once you add (4) people at say....650 lbs total...that leaves you with a solid 400 lbs worth of payload.
...just enough for some luggage and a couple of purses, lol.

That said, the tow capacity (not the payload) is probably pretty high...just keep the load behind the truck on its wheels and you are ok.

Coley

Thanks, but I'm tipping the scales at 230 these days....4 fat bastards like me and some gear that 1053 is spent.

[HomeMadeSin]

Originally Posted by Mike C

I've towed and hauled a bunch with an older truck and the real concern is brakes. If you are going to drive that '67 for your business I wouldn't even think about getting behind the wheel (or having an employee!) without disc brakes put on it.

Most definitely job #1. I will not drive it w/o discs on it.

And the rear two stage springs are no longer multi-stage....

Z