The Stovebolt Site Forums The Shop Area General Truck Talk Jim G’s SLURP Project – Posting 4: Red steps on a scale!

Jim G’s SLURP Project – Posting 9: Red steps on a scale!

This posting is one in a series. If you have not yet read the earlier postings in the series, you’ll need to, as this posting won’t make much sense without having done so! Just do a search using the word “SLURP”.

In my last posting, I described the trip to pick up Red and drive him home, and the surprises that were revealed.

In this posting, we will see how accurate and honest GM was when they declared the weight of its 1955 trucks in its 1955 sales data, how close or far from factory stock “Red” has drifted over 53 years of use, and what the incredible potential could be if we “make some changes”.

Chevrolet had at least two fine sources of specific weight data for its 1955 trucks: the shop manual, and an intriguing black book (literally black in color) called “Chevrolet Truck Data Book –Specifications Catalog for Chevrolet Salesmen”. Both of these are available to us today – the shop manuals in physical printed form or as electronic images, and the data book in reproduction printed form.

In addition, Chevrolet will for free, if you call them to request it, send you a “restoration” documentation package, that reproduces key pages from the shop manual, as well as from other original GM documents, to guide you in your restoration or refurbishing efforts.

If you study the sections of these documents that apply to the 1955 1st edition model 3100 pickup, as I have, you could find the following data and summarize it as I have.

Chevrolet at the time defined “shipping weight” as the complete vehicle but without either engine coolant or gasoline in it – presumably because neither coolant nor gasoline could by policy be aboard a vehicle being shipped. The “curb weight” was defined by Chevrolet as the shipping weight with the weight of both engine coolant and a FULL tank of gas added back in.

Here is the predicted weight of “Red” using the weights published by GM at the time for the model “3104” (half-ton pickup):

3115 lb Shipping weight
+ 33 lb 4 gallons of coolant
+ 107 lb 17.5 gallons of gasoline to completely fill the fuel tank
= 3255 lb Curb weight for a 3104 with NO options

Chevrolet actually broke this down by front axle versus rear axle weight, and also did that for OPTIONAL equipment as well! Hence, the 3255 lb above was broken down as:

Front and Rear
1850 and 1405 (i.e. 57% on front axle, 43% on rear axle)

The (known) options on Red look like this:

Front and Rear
100 and 40 Hydra-matic automatic transmission in place of the standard 3-speed manual
0 and 30 Rear bumper

So, the new totals are:

Front and Rear
1950 and 1475 lb. = 3425 total with a full fuel tank

When I actually weighed Red 3 days after I bought him, the only convenient place to do so was the recycling center at Marble Falls, Texas! This center uses a drive-on scale to weight incoming trucks and trailers carrying recyclable material to get a gross weight, and then weighs them again as they leave after dropping off their recyclable material. I have no idea how precise the drive-on scale is, but since it was the only game in town, I went with it! Besides, the staff were so intrigued with Red (there’s those good looks in a “senior” coming out again), that they weighed him for free! Plus, I got ANOTHER “we had a truck just like that” story while I waited.

The recycling scale showed Red to weigh 3580 pounds.

So, it looks like Red did pick up some weight –about 155 pounds, but wait, there are explanations!

First, Red has that 261 engine from a 1960 model big truck, versus the original 235 engine. It turns out that the 261 engine weighs 21 pounds more than the 235 (625 lb. for the engine plus clutch on a 261, versus 604 lb. for the engine plus clutch on a 235). Remember these engine weight numbers later – they will be highly significant. Since the engine weight is concentrated over the front axle, our numbers become:

Front and Rear
1971 and 1475 – 3446 total

Next, we need to study those flashy chrome and rubber shoes that Red is wearing these days, which are not what he came out of the factory wearing.

The factory wheels and tires weighed 47 pounds each, and there were 5 of them on Red including the spare (Yes, the published curb weight includes the spare tire). So, the factory wheels and tires weighed a total of 47 x 5 = 235 pounds. Red’s flashy new Unique brand chrome wheels required some detective work to positively identify model and size, but they turn out to be Unique’s part number 298-5860P, and they weigh 28 pounds each. The Hankook tires took even more detective work, but I finally spoke to an actual Hankook technical resource, who looked them up and said they weigh 27.6 pounds each. That means each wheel and tire assembly weighs 55.6 pounds, which is 8.6 pounds more than factory stock! That adds 8.6 x 5 = 43 more pounds to Red. 17.2 pounds go on the front axle, and 25.8 go on the rear axle (2 wheels on axle plus the spare behind the axle). Note that the 5 wheels and tires weigh a total of 278 pounds of unsprung weight. Remember that for later.

That gets us to:

Front and Rear
1988 and 1501 = 3489 lb (57% front and 43% rear)

At the time he was weighed, Red also had only 14.5 gallons in his tank instead of the full 17.5 gallons, and the tank is located right behind the seat in the cab, and its weight is pretty much centered between the two axles, so we need to ADD 3 more gallons of gas, or 6.15 x 3 = 18.45 pounds to Red’s scale weight, so now we have 3580 scale weight plus 18.45 = 3598 pounds with a full tank of gas.

So, Red weighs 3598 minus 3489 = 109 pounds more than we expected. Weighing the extra floor mats that Carter had added, takes the 109 pound discrepancy down to just under 100 pounds. That’s not bad accuracy when comparing a 1 53 year old truck with unknown mod history to factory specifications. But, it turns out we DO know where a good chunk of that extra 100 pounds came from.

First, Carter added a dual exhaust system! So, we have a complete tailpipe plus a second muffler. I don’t know how to estimate their weight without removing them. 

Secondly, Carter put a LOT of Dynamat into the lower portions of the cab. Dynamat is noise reduction material, and it’s heavy!

It’s pretty easy to imagine the combination of dual exhaust system and Dynamat adding something close to that 100 pounds we are looking to identify.

So, was GM accurate and honest? Yup!

Now, remember that Red weighs 3598 with a full fuel tank, or 3490 with the tank empty.

Ok, you say, so what?

Well, for starters, that’s about 1150 pounds less than a Chevrolet SSR (Red’s “clone”) with no fuel in it. It’s also about 950 pounds less than a 2008 bare bones Silverado.

And, here’s the thing. Red weighs that while carrying the following major chunks of readily identifiable weight:

Engine withOUT clutch: approx 575 pounds
The cast iron Hydra-Matic: 235 pounds

That’s a total of 810 pounds for the engine and transmission ALONE – that’s 23% of the entire vehicle weight.

Thing is, a modern LS1 engine, clutch, and the HEAVIEST 6-speed Tremec version transmission altogether weigh 605 pounds. If we put that into Red to replace his engine and transmission, we would be removing 205 pounds. That would get Red down to 3285 pounds.I’m not saying that’s what I intend to do – I’m just saying “if” here!

Now, let’s just CONSIDER some of the other really heavy chunks of weight on Red. Like the front and rear leaf springs that could potentially be replaced by mono versus multi-leaf steel or fiberglass springs(yes, they are available). The steel leaves in the 4 factory multi-leaf springs weigh 142 pounds. Steel mono leafs total to 80 lb. Composite mono leafs total to only 32 lb. (8lb each!), cutting 110 pounds. See the potential?

And those wheels? Would you believe that inexpensive alloy forged wheels and carefully selected tires can take off 40 pounds of that 278 pounds of wheels and tires that Red is currently wearing (sort of like cement overshoes).

Are you beginning to see the raw potential here?

I sure am.

And remember, it’s still going to be a TRUCK. It will still be able to HAUL (in more ways than one).

Next posting, we’ll take a look at 1950s truck engine power curves, and the results of Red’s own dyno visit! (Scandalous)

Jim G

Jim, you ought to be submitting these to Stovebolt Sagas.

This is not fiction. It is real life technical reality! Wait til you see the Stovebolt dyno charts coming next.

Jim G

Look carefully at these photos I snapped at the annual custom and hot rod show in Austin, Texas yesterday, and you will see where some of the weight reductions on rthe AD trucks versus the SSR come from. Note things like:

- Amount of exterior sheet metal showing within the cab of the AD truck versus the SSR

- The single wall cargo box (all 4 sides), versus the TRIPLE wall construction of the SSR (exterior sheet metal, interior wall structure, interior liner)

- Note NO cargo cover on the AD trucks, versus the hinged and hydraulic-cylindered cover on the SSR

- The floor of the cargo area on the AD trucks is 3/4 inch Southern Pine, supported by 4 metal cross braces

Picture 1

Pic 2

Pic 3

Pic 4

Pic 5

In this pale green example truck:

- The V8 engine dropepd in actually REDUCED the weight

- The "modern" interior INCREASED it to more like the weight of an SSR interior.

Pic 6

Pic 7

Pic 8


The owner of the black ratrod pull all his weight and money into that engine . . . that is NOT an AD truck obviously

Pic 9


If you don't care about weight at all, you restore this: (see below)

Pic 10

Pic 11

Pic 12
Jim G

Interesting question. What about paint? Now if I remember right it has been repainted. I have no clue when it comes to painting but depending on the type the number of coats etc that could contribute to extra weight couldn't it?

I hope this study ends up with a discourse in the lightest, most efficient engine for an AD truck, let's say the 4 cyl Mercedes that they're placing in the Freightliner 3/4, 1 ton vans.

Cosmo: This project will indeed address "which engine", but the criteria that work for ME might or might not tickle YOU! I have been considering, and researching, a number of engines. I have also been computer modeling their performance in an AD truck, and you WILL hear all about the results of that. Then, hopefully, one of the engines will be the one that excites you. But, I imagine different Stovebolters will be excited by different ones. One thing I leanred early on this board is that everyone has a different, and interesting, perspective, and I try to hear as many of them as I can!

We do much better when we combine the brilliant thoughts of MANY. The engine discussion will be highly interesting, but needs to be preceded by some dyno data and measured performance data.

I try to be very thorough . . .

Jim G