The Stovebolt Site Forums The Parking Lot Big Bolts help with 2 speed axle

Im trying to identify my 2 speed axle in my 59gmc.
Here are the only numbers I can find on it.
3711468 GM this number is cast into the housing of my diff

I also found what looks like GL109 that is stamped into the same housing.

Ive been trying to find out what axle this is and how to look it up. I'm looking for an exploded view of the diff assembly. I havent been able to find anything except EATON stuff and it doesn't look the same.

My questions are what are my gear ratios on this axle. I pulled the diff cover off and I found 5.32:1 stamped on the ring gear. My data plate in the glove box has it marked as a 6.40:1 and 8.72:1. This axle has a electric shift motor for the 2 speed operation.

The axle is inoperable right now so I cant turn the wheels and count the driveshaft turns.

My bigest problem with the axle is what I think is called the shift collar (splined gear roughly 4" in diamete) is busted in several pieces. (PIC IS ATTACHED)
So for this reason my axle has no function the driveshaft just turns and the wheels dont.

I want to know if there is a way for me to manipulate the diff in a way that I can just lock it into high gear with out this gear. If not how difficult is it to replace this gear? And what is the right term for this gear? Thank you all for your help

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bcgmc,

You have a 1959 rear, check your numbers again and see if it is really 3711483 (not 3711468).

The ring gear numbers are tooth counts, not gear ratio 32-5T = 6.40:1 ratio.

Take another look at GL 10 9, I believe it's CL 10 9; CL was used from 1955-59.

CL = 15,000 pound 2-speed rear with 6.40/8.71 gears.
10 = Day
9 = Month

The broken part is called the "Double Reduction Shifter Sleeve". It's found in in the parts book under Group 5.492...p/n 3762911...used from 1955-65.

Your 2-speed electric shifter is not original to the truck, ALL Corporate Rears were vacuum shift at that time, the first electric shift on the Corporate rear didn't happen until 1962 in Diesel model trucks.

My guess the shift motor failed and the rear got stuck between gears which broke the Sleeve. Not knowing what else is broken it might be simpler and cheaper to find another Corporate 2-speed pumpkin and swap them out.

Hope this helped,

Mike B

Yes mike that helps. The gear broke as I was told by the previous owner by someone shifting the 2 speed incorrectly. I looked and it still looks like 3711468. Here is a pic.

It could be cl109.
is the parts book on this site?
Can I lock the rear in high without this gear?
How can I look this axle up? Does it have a generic name...I.E. gm 14 bolt

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I rechecked the casting number and the parts book gives a range (I only looked at the last number). The range is 3702244 thru 3711483...sorry I missed that on the first go-around.

Three different parts books on my desk...

I think you need that gear, unless you break out the big welder and fix it forever with no hope for repair.

If you're OK with HI only, look for a single speed 6.17:1 and swap pumpkins...very easy.

I've always known this rear as the "1955-59 15,000 pound Corporate (GM) rear". The other axles used at that time were made by Eaton.

Hope this helps,

Mike B

Where would I start looking for the 6.17? I've checked the for sale forum. And did some searching on the web. What did this axle come in? Did it come in SRW and dual?

You are looking for the single speed rear that matches your 2-speed rear housing (Corporate GM 15k). They would be on most 1-1/2 and 2 ton farm trucks (1955-59 Series 4, 5 & 6). Find your local big truck junk yard and start looking!

Place a wanted ad here in Stovebolt and see what turns up.

Mike B

While you are searching, might want to think about anticipated use, freeway, rural roads, short or long trips, etc. 6.17 with a direct trans. Will take a while to get there, be a road block on freeway, OD trans. Would help some, otherwise might want to consider higher ratio rear gears.

The 6.17 single speed rear will give you a slightly higher speed top end than the 2-speed in high range, but an OD 5 speed would definitely be a help with either one of those rear axle ratios.
Jerry

Fire trucks are a good source of single speed rears because many firemen weren't able to shift a 2 speed and they didn't want a dilemma on the way to a fire like you have. What size GMC with what engine do you have anyway?

My intended use for this truck will be, around town, car shows, and some extended freeway use. I would lke to be able to do at least 70-75 rpm in the 2k range. I know I wont get that with either rearend setup. I will swap the trans to a 4l85e automatic. 4th gear is .75:1. I really need to get a lower gear set in the rear end. If I pull the 2 speed out and replace with the single speed are there other ring and pinion sets available aftermarket?

My truck is a GMC 350. The original engine has been removed and replaced with a 383 stroker.

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You would probably need to go to a much newer axle housing and a considerably higher gear (Maybe 4.56 or a bit higher) to get that kind of highway speed without making your 383 sound like a bumblebee on steroids. You'll also need to do a major upgrade on brakes, ditto on steering, before those speeds would be safe. These trucks were intended for top speeds in the 50-55 MPH range. Getting 50% more road speed is an exercise in irresponsibility unless the handling and braking is upgraded as well.
Jerry

My fire engine and tow truck will both run 65 mph (the sweet spot is about 63 mph) and both have 2-speed rears. Rolling down hill I've hit 70 mph, but that's scary and something I avoid as that's exceeding the limits on EVERYTHING...me and the truck!

If you really cruise above 70 you should concider a modern chassis swap, maybe a Topkick, Isuzu or Freightliner...

Mike B

There is no original type rear that will work for your needs, however you are in luck. D-60's come with your bolt pattern with normal ratios up to 3.54. Look on airport buses, similar small buses.

LOL! Thats to funny I got a crazy mental picture of that happening. "As the brake pedle goes slowly to the floor" GEZZZZZ...

Thankfully that never happened...

Mike B

"I looked out the window and I started countin' phone poles- - -
Goin' by at the rate of four to the seventh power- - - -
I put two and two together, added six and carried five- - - -
And came up with forty-two thousand telephone poles an hour!"

C.W. McCall
"Wolf Creek Pass"


Jerry

I've pulled the diff out of my rearend and i'm dropping it off at the shop for repair. I'm going to replace this rearend with a dana 80 from a p30 stepvan. Once I get this axle repaired and get my new dana 80 I would like to sell my 2 speed axle. Is there a demand for these gm corporate 2 speed's? If so what would it be worth?

I wouldn't spend a dollar on repairing it unless you need and can use it yourself.
I suspect it's worth about scrap price unless the rest of the truck comes with it. The axle alone will be hard to sell.

I agree with Grigg...to heavy to ship and finding a guy in your area that needs one is pretty slim.

Scrap here is $1.00 per 100#, so that 100# pumpkin is worth a buck!

Mike B

Ok. So I will probably just scrap the whole rearend hub to hub.

Could post a for sale or free add in the swap meet section here. There is a small chance someone else can use parts, axle shaft, drums, hubs, or something before you scrap it.