Square body mysteries

[Keith Seymore]

Originally Posted by special-K

I get what you are saying. I've sat down at a dealership and spec'd out a truck or two myself. It wasn't exactly like that. You couldn't "order down" on a trim level. In other words, while you could order the front end appearance pkg (dual headlights/fancy grille) on a base level truck, you couldn't get the single headlights/plain grille on a Silverado. Or, you could add carpet to a Custom Deluxe, but you couldn't get rubber floor covering in a Siverado. Many features you see in "most" Silverados are individual options not included in the trim level option

Correct. You can "opt up" but you can't "opt down".

K

[Keith Seymore]

Originally Posted by russgt

Why was the standard axle ratio for a "Trailering special" 3.08?

.

Base axle for '76 Blazer is 3.07.

I see that for 2wd manual trans it immediately jumps to 3.73 as base. This leads me to believe that for 4wd auto there was some thinking that you get torque multiplication from the trans torque converter (which you don't get with the stick) to help with launch. You can also drop into 4L in the transfer case to increase control during tight manuevering.

One of the requirements factored in to trailer rating is you have to be able to launch from a standing stop up the 16% grade at MPG, at GCW (Gross Combined Weight). This configuration with the 3.07 gear was apparently able to pass that test, and still offer some level of fuel economy when not trailering.

In any event, it's a simple stroke of the pen to opt up to the 3.73 when ordering the truck if a person wanted it and the added capacity that comes along with it.

https://www.gmheritagecenter.com/doc..._Full-Size.pdf

K

[Keith Seymore]

What I was looking for was this kind of option list with description. I had to bump to 1978 before they started publishing this detail.

Here's a few more words around what the Z82 package consists of and what is not available.

https://www.gmheritagecenter.com/doc...let-Blazer.pdf

K

[1976gmc20]

Originally Posted by Keith Seymore

.

Base axle for '76 Blazer is 3.07.

I see that for 2wd manual trans it immediately jumps to 3.73 as base. This leads me to believe that for 4wd auto there was some thinking that you get torque multiplication from the trans torque converter (which you don't get with the stick) to help with launch. You can also drop into 4L in the transfer case to increase control during tight manuevering.

One of the requirements factored in to trailer rating is you have to be able to launch from a standing stop up the 16% grade at MPG, at GCW (Gross Combined Weight). This configuration with the 3.07 gear was apparently able to pass that test, and still offer some level of fuel economy when not trailering.

In any event, it's a simple stroke of the pen to opt up to the 3.73 when ordering the truck if a person wanted it and the added capacity that comes along with it.

https://www.gmheritagecenter.com/doc..._Full-Size.pdf

K

We had a 1971 K10 with the 350/TH350/NP205 and presumably the 3.07 ratio because it came right off a dealer lot, not ordered.

It got terrible mileage solo or towing, and didn't do all that great at the latter. Oh, it would always get you there, but often going doing to 1st gear on mountain passes. Sometimes it would jump down to low on a hill even without a trailer.

From experience with manual pickups, my estimation was that the automatic sucked off about 35% of your power and gas mileage right off the top

[truckin 79]

Why did front fender wells like in a 79 truck got that little weird triangle patch with 3 bolts? I have seen a lot of trucks rusted out in just that spot.

Why didnt GM offer a fix for the hood flex problem?

I think the biggest question of all why is there Chevy and GMC trucks? Why not just one GM brand truck?

[Keith Seymore]

Originally Posted by truckin 79

Why did front fender wells like in a 79 truck got that little weird triangle patch with 3 bolts? I have seen a lot of trucks rusted out in just that spot.

It's an added reinforcement, to help with front end sheetmetal shake.

Originally Posted by truckin

Why didnt GM offer a fix for the hood flex problem?

Because the '81-'87 design was coming and would not have that problem.

Originally Posted by truckin

I think the biggest question of all why is there Chevy and GMC trucks? Why not just one GM brand truck?

To allow non-Chevrolet dealers to sell a GM truck. Said differently, Buick/Olds/Pontiac might not be comfortable selling Chevy trucks but would be ok with a GMC truck.

Additionally, GMC was seen as a little bit more "aspirational", meaning you might start with a Chevy and work your way up to the GMC. Just like a passenger car buyer might grow from Chevy to Olds/Pontiac to Cadillac as they matured.

I once heard it described this way:

The guy in the Chevy works at the job site.
The guy in the GMC is the foreman at the job site.
The guy in the Cadillac owns the job site (or the company).

K

[greg64]

Originally Posted by Keith Seymore

To allow non-Chevrolet dealers to sell a GM truck. Said differently, Buick/Olds/Pontiac might not be comfortable selling Chevy trucks but would be ok with a GMC truck.

K

I knew this was the reason, but it always seemed to me that GM gave up a big bragging right (marketing) by doing this. Ford has claimed to sell the most trucks (f150s) for years (decades), but technically this isn't true. GM sells under two brands, and neither one, by itself, matches the F150.

[Keith Seymore]

Originally Posted by greg64

I knew this was the reason, but it always seemed to me that GM gave up a big bragging right (marketing) by doing this. Ford has claimed to sell the most trucks (f150s) for years (decades), but technically this isn't true. GM sells under two brands, and neither one, by itself, matches the F150.

Yup. There were a few years where Chevy alone outsold Ford but Ford seems not to remember that.

K

[1976gmc20]

GMC used to be a bit different. They offered the V-6 which was a medium duty truck engine. Also, my memory is that the 1960s GMCs had rear leaf springs while the Chevy had coil springs and trailing arms.

When I worked for a Chevy dealer 1974/1975 we had a pickup come in on the transport that had a Chevrolet emblem on one front fender and a GMC emblem on the other front fender

They probably would have sold it that way if this "dumb kid" ferrying vehicles around hadn't pointed it out to the new car setup department

[Keith Seymore]

Originally Posted by 1976gmc20

When I worked for a Chevy dealer 1974/1975 we had a pickup come in on the transport that had a Chevrolet emblem on one front fender and a GMC emblem on the other front fender

Just one?!?

(lol)

I had a guy ask me one time, in a sort of surprised fashion: "you mean you built Chevys and GMCs down the same line?"

I said "yep. Sometimes on the same truck!"

It's really easy to mess up, if you understand the build process. The fenders (and hood) are all trimmed out on a remote line and are fed to the main line in sequence via conveyor. The guys back on the front end sheet metal line are looking at the manifest (all of the build sheets in one packet) and building the content specified (wheel opening molding vs none, chrome side trim vs black side trim vs none and, of course, brand) based on what the paperwork tells them. If they happen to miss a GMC then they'll put a Chevy emblem on out of force of habit. Or, they can misread the manifest and get out of sequence or off by one truck in the build.

Nobody sees the whole truck at the same time until later, when it all comes together on the final line, where most mistakes become very obvious. Somebody should have caught it immediately at that point; for it to get through three or four levels of inspection and get to the dealership is inexcusable.



K

[greg64]

Originally Posted by 1976gmc20

GMC used to be a bit different. They offered the V-6 which was a medium duty truck engine. Also, my memory is that the 1960s GMCs had rear leaf springs while the Chevy had coil springs and trailing arms.

Yup. My 64 GMC has leaf spring rear, but the Chevy had coil springs. The dash is also totally different, the grill is different, the wiring harness is different, and the interior seating is different (mounting).

[Keith Seymore]

Originally Posted by Keith Seymore

It's really easy to mess up, if you understand the build process. The fenders (and hood) are all trimmed out on a remote line and are fed to the main line in sequence via conveyor. The guys back on the front end sheet metal line are looking at the manifest (all of the build sheets in one packet) and building the content specified (wheel opening molding vs none, chrome side trim vs black side trim vs none and, of course, brand) based on what the paperwork tells them. If they happen to miss a GMC then they'll put a Chevy emblem on out of force of habit. Or, they can misread the manifest and get out of sequence or off by one truck in the build.

Here's a couple sample build sheets: one for a 67-72 pickup and one for a more modern vehicle.

The operator back on the sheet metal line (or cushion room, or tire bay, or axle line, or motor line) would receive a packet of these all strung together, encompassing all the vehicles to be built that day.

What you would do is come in early, before the line started (typical start time is 6am) and sit down at the picnic table with your manifest, cigarette, coffee and red crayon. Then, you go through that document and circle every time you see "Z88" (the RPO for GMC). After you've gone through the amount you will likely build for the day (anywhere between 480 and 600 units) then you are ready to begin.

K

[TKCR]

Working in an Auto Assembly plant, I understand the process of building on an assembly line. I had to chuckle about the GMC & Chevy Emblems on the same vehicle. It's easy to do, if the assembly worker isn't paying attention. Where I work, my job is inspecting the vehicles before leaving the plant. It amazes me sometimes of the mistakes that can be made in the assembly process.

As far as the comment about having a Chevy & GMC brand truck. I can speak from experience. I ordered a 1996 GMC S-15 Pickup Extended Cab (two tone paint) vs. a Chevy S-10. Same body style truck, but I just liked how the GMC looked better than the Chevy. It was a sharp little truck, wish I still had. I had it repainted years later. It looked better than the day I bought it. Many years after that, I sold it to my parents. And they totaled it!!

[Keith Seymore]

Originally Posted by TKCR

Working in an Auto Assembly plant, I understand the process of building on an assembly line. I had to chuckle about the GMC & Chevy Emblems on the same vehicle. It's easy to do, if the assembly worker isn't paying attention. Where I work, my job is inspecting the vehicles before leaving the plant. It amazes me sometimes of the mistakes that can be made in the assembly process.

Which plant do you work in?

K

[TKCR]

Originally Posted by Keith Seymore

Which plant do you work in?

K

I don't work for GM. My dad retired from there. He worked at a parts supplier in Ohio. I myself work for a Japanese Automaker. And they are very nasty about posting anything about them. Like what you do, I did this for late models on the appropriate forums for the make. I nearly lost my job over it, so I don't even say for who, even though I'm on this forum now.
So I went back to the GM Truck, which I dearly love. Iv'e had several over the years. Now I have the 86 Silverado.

[1976gmc20]

The dealer where I used to work was located on half a city block downtown so space was tight. They had an acreage several miles away where the body shop was located with a big field full of new inventory.

So the transports always unloaded at the body shop, but the vehicles were brought straight downtown for "new car setup" before being returned to the storage lot, unless it was to be immediately delivered to the customer. One of my jobs was ferrying new vehicles back and forth between the two locations, so I got to drive everything from Corvettes to C-60 trucks. A lot of those cars/trucks would barely run when they were unloaded, either because they hadn't been set right from the factory or because they were not set for the high altitude of Colorado (remember those days ???).

Anyway, I got to see a lot of interesting things regarding raw from the factory Chevys. The HEI had just come out, and one cold day I was sent over to pick up a new Blazer for delivery. It wouldn't start for anything and I told them it must not have any spark. They scoffed and said I had just flooded it and later somebody else got it started and it was delivered to the customer. A couple days later this same brand new Blazer came in "on the hook" because it wouldn't start. Turned out the ignition module had random failures. The customer probably wasn't very happy, all because they wouldn't listen to me.

There was one four speed C-20 that I remember: straight off the transport, it ran better than any pickup that I'd ever driven. The acceleration in traffic was amazing even if you didn't bother to shift down. I had to know what kind of huge V-8 had this kind of power, so the moment I drove it into the new car shop, I jumped out and popped the hood. It was a 292 straight six