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Old 09-20-2010, 04:57 PM   #1
ryans69chevy
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1949 chevy 3100 rear end questions

hey, my dad and i are working on a 1949 chevy 3100 1/2 ton (or so we think). It was used as a grain truck on my great grandpas farm and nobody really seems to know much more than that about it. the front end has a 6 bold pattern where the back end has an 8 bolt. the rear end is jacked up so high also prob so the extra weight wouldn't effect it.

were wondering what rear end from what other vehicles we could get to fit under this pickup without any modifications? we want something that can do good on the highway since we aren't planning on towing anything with it.

Thanks!
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Old 09-20-2010, 07:26 PM   #2
raycow
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Re: 1949 chevy 3100 rear end questions

It sounds like a PO swapped in a 3/4 or 1 ton rear at some point. You probably wouldn't enjoy the gearing at highway speeds.

A few questions first. What kind of transmission does it have? When you look at the driveshaft how many U-joints can you see? Is all of the driveshaft exposed, or is any part of it enclosed in a tube so you can't see it turn?

Ray
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Old 09-20-2010, 07:36 PM   #3
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Re: 1949 chevy 3100 rear end questions

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Originally Posted by ryans69chevy View Post
were wondering what rear end from what other vehicles we could get to fit under this pickup without any modifications?
Can you post some pictures of how the rear axle is mounted. Somebody make some modifications to mount an 8-lug rear under the truck and suggesting a swap that does not require modification requires knowing what it looks like now.

Is the axle above or below the springs? Has the frame been modified?

If it still has the stock frame and springs you may be able to convert back to a stock type rear without too much trouble.
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Old 09-22-2010, 02:37 PM   #4
ryans69chevy
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Re: 1949 chevy 3100 rear end questions

here is some of the pics i took ill post some more here in a min if i can. the tranny we believe is a 4 speed, it was originally a 3-on the tree not sure why they changed it. when we got the truck it still had the 3-on the tree "workings" as well as under the hood. as far as i can see there is nothing around the driveshaft i got some pics of it and how weirdly angled the thing is...i don't know if thats how it is suppose to be or not...
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Old 09-22-2010, 02:42 PM   #5
ryans69chevy
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Re: 1949 chevy 3100 rear end questions

here is the rest of the pics of the rear end. i also took some of the inside of the cab. My dad and i are taking all the rust off and putting on POR 15 to protect the metal against future rust. I also have pics of the 216 cubic inch 6volt motor also if anyone wants to see those ill post them. hopefully someone can help us find a rear end that we could take out of some vehicle and put under this truck without any modifications if posible. thanks!
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Old 09-22-2010, 08:11 PM   #6
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Re: 1949 chevy 3100 rear end questions

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the tranny we believe is a 4 speed, it was originally a 3-on the tree not sure why they changed it. when we got the truck it still had the 3-on the tree "workings" as well as under the hood. as far as i can see there is nothing around the driveshaft i got some pics of it and how weirdly angled the thing is...i don't know if thats how it is suppose to be or not...
The transmission swap was a necessary part of the open drive conversion because the original 3 speed was set up for a torque tube. If you would rather have the shifter back on the column you could use a 55-67 3 speed.

It looks like the PO swapped in the complete driveline from a later 3/4 ton and shortened the rear driveshaft to fit the 1/2 ton WB. It's actually not a bad job, other than the angle on the middle and rear U-joints. You could help the angle by lowering the rear of the truck or going to a one-piece shaft.

Your best bet for a rear end would be one from a 63-69 1/2 ton. This would get you 6 lugs and better gearing while remaining approximately the same width as stock. Check 4WD Chevy rears or any GMC rears first, as they are already set up for leaf springs. You might have to re-locate the spring pads to match your stock spring spacing. Most 2WD Chevy rears in those years are coil spring, so those would need spring pads welded on anyway.

Ray
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Old 09-23-2010, 02:21 AM   #7
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Re: 1949 chevy 3100 rear end questions

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Originally Posted by raycow View Post
Your best bet for a rear end would be one from a 63-69 1/2 ton. This would get you 6 lugs and better gearing while remaining approximately the same width as stock. Check 4WD Chevy rears or any GMC rears first, as they are already set up for leaf springs. You might have to re-locate the spring pads to match your stock spring spacing. Most 2WD Chevy rears in those years are coil spring, so those would need spring pads welded on anyway.

Ray
Also look to the '73 and up 4X4, they were six lug also.
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Old 09-23-2010, 03:16 PM   #8
ryans69chevy
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Re: 1949 chevy 3100 rear end questions

Quote:
Originally Posted by raycow View Post
The transmission swap was a necessary part of the open drive conversion because the original 3 speed was set up for a torque tube. If you would rather have the shifter back on the column you could use a 55-67 3 speed.

It looks like the PO swapped in the complete driveline from a later 3/4 ton and shortened the rear driveshaft to fit the 1/2 ton WB. It's actually not a bad job, other than the angle on the middle and rear U-joints. You could help the angle by lowering the rear of the truck or going to a one-piece shaft.

Your best bet for a rear end would be one from a 63-69 1/2 ton. This would get you 6 lugs and better gearing while remaining approximately the same width as stock. Check 4WD Chevy rears or any GMC rears first, as they are already set up for leaf springs. You might have to re-locate the spring pads to match your stock spring spacing. Most 2WD Chevy rears in those years are coil spring, so those would need spring pads welded on anyway.

Ray

ya, it looks pretty good. i'm not sure if my great grandpa did the work himself or had someone else do it for him. But he has owned the thing from the beginning. we are going to change it up anyway. we want a 1/2 ton rear end. i actually own a 69 chevy c10 1/2 ton. I'm in the process of finding a rear end for this as well. So if i find 2 rear ends at a junk yard with around a 3.08 ratio I'm buying them! I have a couple questions on the driveshafts tho...

First of all could i get a rear end for the 49 from a 70-72 c10? Because 67-72 were all the same pretty much. I'm just trying to get a bigger window here so i can find a rear end easier. Ill try and get one that had leaf springs. If i was to get a rear end from a c10 1/2 ton would i need to get a driveshaft custom made to fit the 49? or could i take the driveshaft that i got the rear end from. I'm sure it will have a 2 piece driveshaft. and FINALLY...i want to get a rear end that i know has good gears still...so how do i know if they are good or not??

Thanks for all the help!
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Old 09-23-2010, 09:13 PM   #9
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Re: 1949 chevy 3100 rear end questions

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Originally Posted by ryans69chevy View Post
First of all could i get a rear end for the 49 from a 70-72 c10? Because 67-72 were all the same pretty much. I'm just trying to get a bigger window here so i can find a rear end easier. Ill try and get one that had leaf springs. If i was to get a rear end from a c10 1/2 ton would i need to get a driveshaft custom made to fit the 49? or could i take the driveshaft that i got the rear end from. I'm sure it will have a 2 piece driveshaft. and FINALLY...i want to get a rear end that i know has good gears still...so how do i know if they are good or not??
71-up rears (and some 70) are about 1-1/2" wider than stock. They will work, but you may have fender clearance issues if you run wide tires/wheels, especially if you are lowered.

I'm not sure what later stock driveshafts will fit without modification. If you look at newer trucks, the engine sits farther forward relative to the front wheels than yours does. This means that even if you find one with the same wheelbase as yours, the shaft may be too long for your truck. You best bet is to get everything bolted together first, measure for the shaft length you need, and then head for the salvage yard with your tape. I have had very good luck finding shafts that way, and have needed a custom shaft for less than 10% of my swaps

Buying a used rear is always somewhat of a crapshoot, although I have never personally gotten burned. Naturally you will want to take off the cover and inspect for obvious damage, but this doesn't neccessarily guarantee that it will run quietly. Fortunately, most honest salvage yards will give you some kind of exchange guarantee.


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Old 09-22-2010, 04:18 PM   #10
T Hilde
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Re: 1949 chevy 3100 rear end questions

Yes, that is a 1/2 ton frame. Loose the axle and the overloads and keep the main spring pack and you should be back to a 3100. Are you wanting to restore this or ??? Because you will have a number of options available to you for the rear axle.
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Old 09-22-2010, 06:26 PM   #11
ryans69chevy
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Re: 1949 chevy 3100 rear end questions

yes we want to restore this. we are actually in the process of that right now. we are prob gonna have the cab off by the end of the week. we want to have this thing be a good runner on the highway so maybe somewhere around a 3.08?? or what were you thinking as some of the options? we always like ideas! thanks
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Old 09-23-2010, 07:30 PM   #12
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Re: 1949 chevy 3100 rear end questions

71/72 C 10's have 5 lug patterns. Later 4x4 rear ends may be a bit wide for the truck.
I have put a 56 rear end under a 53 3100 by using a set of aftermarket spring pads.

From looking at the photos it appears that they may have just added the helper springs on top along with installing the 8 lug rear end although they may have also used 3/4 ton springs.

What I would do is find the rear end that I wanted to run, pull out the 8 lug rear end and helper springs and install the new rearend in the proper place on top of the springs with new U bolts. Buy U bolts long enough so that you can install lowering blocks if needed or trim off the excess if you don't need the length but that will save buying U bolts twice. Put the truck together and drive it a bit and see what the stance looks like and go from there. You could probably get by with running the 4 speed and drive shaft that is in the truck now for the time being if the truck runs until you decide what you want to do. If you switch to a column shift three speed I'd suggest the later full syncro trans from the mid sixties. I have had one in my 48 for years and it is a lot nicer to drive than the older ones.
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