The Stovebolt Site Forums The Parking Lot Big Bolts Identification Help

I just purchased my first stovebolt and actually haven't even recieved it yet. I've been doing a ton a research lately and can't wait to get started on the restoration.

What i know about the truck is this:

Its a 1954 GMC 5 window With a four speed transmission, two speed axle and the 270 motor. I Believe it has 5 bolt up front and 10 in the rear, but I can't see the rear axle clearly.
Here is a link to some pictures. http://www.hotrodgarage.net/54gmc1766.html

The owner of the truck didn't list the model and my head is spinning trying to figure it out with out the VIN. Hopefully someone on here can help identify which model I have.

I think I narrowed it down to a 350 or 400 today while I was waiting for this post to get approved..

Still an outside opinion would be great!

That looks pretty decent! What happened to your 6th wheel? I'm not as familiar with the GMC trucks quite yet, sorry. I don't see a shifter for a split rear, unless you have a dash shifter...

That is a sweet looking truck you got there!! As I said in your other post, probably a 2-ton. They had 10 bolts in the rear, same pattern in the front but only 5 bolts (same wheel used on front and rear that way).

Thanks guys! I'll post more pictures and hopefully start a build thread once I actually get the truck to my house.

pvfjr:

I noticed the wheel too, I figured I'd have to find one somewhere. Possibly from the owner. As for the two speed axle, i was wondering the same thing. I can't find much information on how they work. Maybe someone can chime in on that too?

I've been looking more into the two speed axle and there's not much info out there about how they function.

Is there a switch on the dash to controll it? Also what is the shift pattern? 1 through 4 in low, then 1 through 4 in high... Or 1 low, 1 high, 2 low, 2 high ect...

AdamK1500,

" . . . my head is spinning trying to figure it out with out the VIN"

What is your "VIN" - from the ID plate?
What is your registration ID/"code"?

I have a 1954 GMC 350 COE - it has a 1.5-year-only (Z-series GMC) vacuum-actuated 2-speed-rear switch. It is attached to the front of the dash to the left of the steering wheel.

This shows the hole in the 1954 dash for the 2-way-rear vacuum-operated/actuated switch

Here is a close-up photo of the switch

Selector switch
What attaches to:
- left line (to 2-speed diaphragm at rear end)
- rear line (vacuum line in through the firewall)
- needle line (line to speedometer 2-speed-adapter)

2-speed-selector on the rear of the speedometer

Lets see if this helps.
Modern heavy trucks with 2 or 3 speed splitters use the gears and splits together when they are under heavy load. ( light loads use less or no splitting)
That would be 1st low, 1st hi, 2nd low, 2nd hi, etc.
The trucks of this era, like your 2 ton, rarely split shifted because their ratios were so low to begin with.
On a paved road, you usually started in 1st (granny gear)high range and shifted normally.
If you were off road or starting on an uphill pull, switch to low range and shift through the gears until you reach paving or smooth ground. Then shift to high range and select gears as needed.

That is very helpful! It does have the switch on the dash, so that is solved. Thanks tclederman!

Jim, as far as shifting the axle goes, is it more like a transfer case high/low on a newer half ton pickup? What i mean by that is you pick either high or low range depending on the job and have to be mostly stationary to shift the axle up or down? or can you shift through the low range and while moving shift into high range?

I looked on the site, and saw the pictures. You do indeed have a 350 series 2 ton. Has the 350 emblems on each side of the hood. Good looking truck. just need to find yourself a original'54 GMC front bumper for it.

Adam,

You do what they call split shifting. Each gear has a high and a low, and you can shift the rear end between tranny gears so you can have a closer gear spread. This way you can keep the engine right in its power band.

Here's a video I found a while back. It's pretty much what you'll be looking at, except you control may be on the dash instead of the stick.
How to drive a two speed rear

That makes sense, I'm thinking of getting a service manual online to get a better feel for everything.

Check here, you'll find a lot of what you'll need:

54 Chevy Truck Manual

I'm not sure what all the differences between the Chevy and GMC trucks are, but there are bound to be a few similarities.

That's an awesome link, thanks!

I have a sister to your truck. It starts and runs, but I have too many of them to try to keep the brakes maintained.

https://plus.google.com/u/0/1126369...1091222818&oid=112636930370126476644

A lot of the body parts are the same on Chev as GMC as well as the transmission and rear. Engines are totally different. I would certainly buy a GMC book.

http://www.faxonautoliterature.com/Search.aspx?c=182016

I made a chart with the gear ratios in my SM420 along with the rear end so I could see final ratios. Both my 55.2 and 58 2-tons are the same, anyway, you would shift as follows:
1lo, 1 hi, 2 low, 2 hi, etc.... you may or may not need to use lo and hi, if you have enough engine and are not loaded and on the flat, you might get by leaving the rear in hi and just shifting the tranny. Final ratios are below, in order (1 lo, 1 hi, 2 lo, 2 hi, etc) my chart will not stay formatted when I paste it.



61.775, 45.184, 31.325, 22.912, 14.9625, 10.944, 8.75, 6.4

Very cool trucks crenwelge! Thanks for the ratios cuda. That was actually something I planned on doing. You guys are way more helpful that a lot of forums I've been on!

I'm gonna add one more question to this so i don't have to make a full new post for it...

does anyone know off hand if the electrical in this truck is 6v positive ground or 6v negative ground?

**Edit: I know that seems like a google question, but i'm haven't found anything. A few people make it seem like GMC was positive ground and chevy was negative ground so I don't really trust the chevy wiring diagrams to be correct. GMC stuff seems to be more difficult to come by.**

A 1954 USA GMC was 6v positive ground.

Purchased the manual tester so I can stop asking this questions, thanks for the answers!

No problem, AdamK1500,

Keep asking questions.

Bringing this back to the top because i got the title in the mail. The serial number on the title doesn't make sense to me using the decoder on oldgmctrucks.com

The VIN listed is PZ2546, 1954 GMC "Unknown" model... of course

Spanky: I'm not able to read the numbers on the emblems, you must have very good eyes!

Has anyone seen this style of vin?