Frame vin and cab vin

[OJ1988]

With the recent talks of vin stamping on frame comparing to the cab, I thought I would bring this up.

I know the total history of my truck, its easy to track, the Air Force owned it for many years.

However, My frame vin is one number off from my cab.

These aren't the actual numbers but here is what i mean.

Cab abc12345

frame abc12346

Seems odd, but I doubt someone would have found another truck that was next in production and swapped cabs.

What do you guys think?

[no moa]

Thats weird. Maybe the stamper had to much pabst that day?

[fishingjred73]

Mine has the last number stamped out, it was a 6, and below it is stamped a 7 which matches my spid, vin tag and title.

[Keith Seymore]

Originally Posted by OJ1988

With the recent talks of vin stamping on frame comparing to the cab, I thought I would bring this up.

I know the total history of my truck, its easy to track, the Air Force owned it for many years.

However, My frame vin is one number off from my cab.

These aren't the actual numbers but here is what i mean.

Cab abc12345

frame abc12346

Seems odd, but I doubt someone would have found another truck that was next in production and swapped cabs.

What do you guys think?

Sounds like an assembly line mistake that did not get caught and therefore not fixed.

Originally Posted by fishingjred73

Mine has the last number stamped out, it was a 6, and below it is stamped a 7 which matches my spid, vin tag and title.

Sounds like an assembly line mistake that got caught and therefore repaired (properly).

K

[Longhorn Man]

My longhorn has a cab that is one digit newer than the frame. Title matches the cab/spid.
I figure a cab got damaged or was pulled off the assembly line due to not being up to GM's semi high standards and they just tossed the next one on.

[Keith Seymore]

Originally Posted by Longhorn Man

My longhorn has a cab that is one digit newer than the frame. Title matches the cab/spid.
I figure a cab got damaged or was pulled off the assembly line due to not being up to GM's semi high standards and they just tossed the next one on.

Perhaps - but we would restamp it with the correct VIN. Those repairs take place back in a heavy repair stall, not on the line.

Plus, grabbing the next one in line would through the rest of the line out of sequence. With all the proliferation in trucks (2wd vs 4wd, auto vs manual, A/C vs non A/C, cab styles, etc) there's a pretty good chance the substitute cab would not fit.

K

[Longhorn Man]

i've thought about that... but never came up with a better reason in my mind.

[Keith Seymore]

Keep in mind too that the VIN is not established until the body is through paint and starting down into trim (the first operation in General Assembly). If a cab is damaged beyond repair, then it is simply scrapped and a new one is built to replace it.

Since neither the original cab or the replacement cab made it that far, then the VIN has not been assigned or affixed to either of them, so it all happens behind the scenes and would not affect the VIN sequence at all.


K

[Keith Seymore]

I may be talking to myself at this point, but I have a couple more thoughts about VINs I'd like to capture somewhere, if I may (here is as good a place as any):

Vehicle Tracking During Build
First off, and it didn't register with me until the last couple years at the Detroit-Hamtramck assembly plant, but the VIN is not the primary tracking mechanism of the vehicle in the plant. The VIN (tag and etchings) is just another "part" to be installed, just like a tire pressure label or an engine emissions tag.

The way the vehicle is tracked through the assembly process is not intuitive: the dealer generates a dealer order and that "dealer order number" is sent to a particular assembly plant based on geography and/or model type and/or specific options. That dealer order number (a random looking sampling of six alpha-numeric characters) is the primary tracker until either (a) the PVI ("Primary Vehicle Indicator") or (b) the CSN ("carrier sequence number") is established. Once we have the PVI or the CSN those are the "names" we use to track the particular car/truck through cab shop/body build and through the paint shop - and the remainder of the build, too.

The reason for this is because (1) there are still a couple opportunities to shuffle the build order in the body shop and in the paint shop. Both of these areas have accumulators, or "mix banks", which allow cars to be cut in or cut out based on color, model, material availablility (or lack thereof), stop orders etc. Typically there are between 8 and 10 separate rows in the accumulator, and cars/trucks are pulled from one of the rows based on the earlier criteria.

And (2) as mentioned, the VIN is not yet established. The vehicle is not "committed" until it comes down out of paint and into Trim1 (General Assembly). At that point the VIN is assigned based on nameplate/division, check digit criteria (if any) and build sequence. Once the body hits Trim there is no turning back now. There is a couple hour lag time and then the corresponding frame/chassis build will also commence.

A couple additional points: VINs may or may not be in sequence, as some plants do not build in VIN order. VINs may not be in sequence as well, because usually the different nameplates will assign a different sequence. In other words, the first Chevrolet build will be 100001, but the first GMC would be 500001. As you build the different nameplate model mix (ie, six chevrolets and then one GMC) the sequence will increment up differently. Some plants simply do not build in VIN order regardless; for example, the Mishawaka plant builds in CSN order.

So basically the VIN does not even exist for about 3/4s of the time the build is in process.

VIN application:
The VIN "stamp" tool is a large, bulky hydraulic press that "squeezes" the number into the metal. The VIN is typically hit in two spots on the frame, and then manually indexed to the next number. My recollection is that there was one separate stamp machine for each nameplate (so one tool used for Chevrolet and a separate tool used for GMC, for example). So, you might imagine the operator lugging this huge machine around, hanging from the ceiling on balancers, methodically hitting each frame twice, manually indexing to the next number, then doing it again, all in a somewhat catatonic state for several hours at a time.

So what happens if he accidentally forgets to index to the next number, or unwittingly grabs the wrong machine (ie, uses the Chevrolet stamp on a GMC)? You've got a wrong VIN - but typically, it's not caught right away. It's caught several stations down, in either line side repair or in the inspection station. So now you don't have just one wrong VIN, you've got seven or eight or ten wrong VINs. AND - the line's not stopping for that. Now all of a sudden it's a mad scramble to get those VINs fixed, deploying one repairman or "quality man", using an X stamp and a hammer (and manually restamping the correct numbers), working your way back all while keeping the line running and fixing the regular level of lesser repairs, and not to mention while one or two of your guys are "out of position". It takes about a half hour of very harried, frantic activity to get the mess cleaned up. God forbid something else major happens while all this is going on (you'd be dead at that point).

I say all that to say this: although VINs are a federal requirement, and all due diligence was applied to make sure they were right, I'm not surprised that a mistake made it out every now and then.

Hope that helps -

K

[big_al_71]

I checked mine a while ago and they both match including the spid so I was relieve....

[RenoKeene]

Great info! Thanks for posting.

[29od1]

My Blazer VIN tag and frame are also off by 1 number sequentially. I had to go through a very thorough inspection by the Highway Patrol where they actually cleaned off the partial vin stamped on the top of the frame rail under the drivers seat. It matched the other partial vin on the frame by the steering box. After an hour of checking the trans, engine, databases, etc, he finally concluded that it was a mistake from the factory, but that it was a very rare occurrence.

[Keith Seymore]

Originally Posted by 29od1

My Blazer VIN tag and frame are also off by 1 number sequentially. I had to go through a very thorough inspection by the Highway Patrol where they actually cleaned off the partial vin stamped on the top of the frame rail under the drivers seat. It matched the other partial vin on the frame by the steering box. After an hour of checking the trans, engine, databases, etc, he finally concluded that it was a mistake from the factory, but that it was a very rare occurrence.

I agree - both that it was likely a mistake and that it should be very rare.

What year is your Blazer? Depending on when it was built I may have to apologize for that!



K

[RenoKeene]

^^

[29od1]

Maybe there was an odd smoke drifting through the Flint factory in 1972??

[Keith Seymore]

The California factories had more of a problem with that....

I'm clean on this one. Before my time -



K

[67basketcase]

I have one of these too. Frame number is one off. The last digit looks like it was struck several times with a "1" laying down to cover it. Then the right last number is stamped below it.