The Stovebolt Site Forums The Shop Area Driveline Questions updating axle / drive shaft / transmission on 1952 3100

I've read many threads on this but feel like I'm still missing something. I have a '52 3100 - with '54 235 engine - 3 speed - I'm going to put a new rear axle / drive shaft / and possibly a transmission. Trying to keep it somewhat period correct but more driveable. I have a 60' Impala axle ready with choice of 3.08 or 3.36 gears. I realize replacing the axle the torque tube goes away and need a driveshaft. The big question is can I use the original 3 speed manual transmission with this setup? Or will I need to find a newer 3 speed transmission. Any special tips to doing this?

On a side note I bumped into a borg-warner 3 speed manual with overdrive that came out of a '65 Studebaker - at first appearance it looks like this might be an option?

Thanks for any help! I'm in over my head and these forums have been a huge help.

If I were in your shoes (I already have been with my '50 3100), I would get my hands on a t-5 out of a mid '80s s-10 with a cylinder. They bolt up to your '52 bell housing without much difficulty. Look up Lugnutz in the search area. He is our T-5 guru. Then look for a '67-'70 1/2 ton rear end. A 3.73 would be a good choice. You will be astounded by how this swap brings your 235 to life. It will make you wonder why people put v8s in these trucks.
Carl

No, you can't use the original transmission...at least not without some changes to it.

If you have a 3.08 rear end you can find a T5 set up so that your first 3 gears will match very closely what came stock in your truck. This will give you the benefit of still being able to use it as a pickup. In fact, driving in town will feel just like the old truck you're familiar with except for two things: it is synchronized and the fun doesn't stop with the third gear. When you get to fourth gear, you'll be in what (from the point of view of your original 4.11 rear end) will be your first overdrive gear ... that is to say 3.08 will be a 25% drop in rpm from what 3rd gear in your old 4.11 used to be. Then if you have the .86 fifth gear, your fifth will be your second overdrive and that will effectively make your rear end seem like a 2.65 ratio.

But yes, you can use a 3 speed with overdrive as long as it is compatible with your bell housing and clutch setup. Lots of people do that and it is a good alternative. Please make certain you pay attention to your 1st gear ratio in relation to your rear end ratio. What I mean is if your first gear in that three speed is a 2.85 then the 3.08 rear end won't work for you. It will leave you with a starting line ratio of about 8.8 and when you let out the clutch to start driving, nobody will be home up there under the hood. I think you need a starting line ratio of at least 10.5 with a 235 and a truck weighing this much and that might even be a bit on the light side. Your stock ratio was nearly 12 to give you an idea. If you used the 3.36 rear end, you'd need a first gear of around 3.1. Having said this, you can combat this with smaller tires. I'm supposing you're keeping roughly the same diameter tires going forward. And from a steering geometry standpoint, there are reasons this is a good idea...

OMG, Pa..............leeze.

Awesome info - thank you both. I didn't think about the first gear starting line ratio. I was hoping to keep it a 3 on the tree for sentimental reasons but maybe that isn't a good decision.

If I was to keep the original transmission what changes are needed to run it with open drive? I guess I don't really know how / what needs to be done to make the tranny accept a driveshaft.

"If I was to keep the original [enclosed drive-shaft three speed] transmission what changes are needed to run it with open drive?"

You will not be able to use your original (three speed) transmission with an open drive-shaft (oh, I guess you could, with a driveshaft adapter from specific 3/4 ton GM trucks)?

You can use the 3.55 R&P with the original enclosed drive-shaft 3-speed. First gear will be (might be) a little "high" for start-up on a steep hill. I will most likely go back to an enclosed drive-shaft in my 1954 Suburban that now has an enclosed drive-shaft SM420 (to regain the middle passenger front seat).

Put the 3 speed w/overdrive in first gear and count the revolutions made by the input shaft and output shaft to see where you are. I'm afraid you're going to find it is 2.66...at least if that transmission matches the data I have for Studebaker in 1965. If that is the case, your rear end ratio is going to need to be either 3.73 or 4.11 and 3.73 would require you to use slightly smaller diameter tires.

Like Tim said above, start-up on hills might be a challenge. Probably will be, if we're being honest. When Patrick Dykes was doing the work on the rear end 3.55 gears I went out and met with him on one scalding hot afternoon and discussed all of this. He was clear his plan was that people would at the same time convert to a 4 speed (using his closed driveline conversion piece) and use the 4 speed with the 3.11 first gear. He knew a starting line ratio of 11 was needed if you were going to haul anything heavy or pull a trailer, boat, etc and he also knew anything below that (with a 235) was going to be flirting with the low side. Where he lives, hills are not a problem.

Now there is another option that was sort of popular many years ago. You can blend a 3 speed Saginaw overdrive with a Saginaw 4 speed and make a 4 speed overdrive. You don't gain a lot but it is interesting. As I recall, the trick is to duplicate a hole in the 4 speed case (that is in the 3 speed case) which is the 3rd gear overdrive lockout provision. But given the lack of availability of those transmissions, parts and such I believe you'd be better off going with the T5 today.

Here is what I consider a really good combination:
T5 with these gear ratios: 3.08 rear end for final drive ratio of:
1st--4.03 12.4
2nd--2.37 7.3
3rd--1.49 4.58
4th--1 3.08
5th--.86 2.65

Compare your present ratios with the 4.11 rear end to the above
1st--2.94 12.08
2nd--1.68 6.90
3rd--1 4.11

You can see the first 3 gears are going to feel pretty much the same and depending on the tire size you choose, they might be a bit improved. Your 4th gear will be your first overdrive gear and in 5th gear (assuming 28 inch tires), your engine will be running 1900 rpm at 60 mph. If you choose 27 or 27.5 inch tires, your rpms will increase a bit, but I think cruising on the highway with a 235 is going to work much better if your rpm is more like 2000 or just a hair below.

Jon G - thank you. That helps so much seeing the actual ratios. I know so little about most of this stuff. If it wasn't for forums like this and help from guys like you I never would of bought this truck. I really would of liked to keep the 3 on the tree but it doesn't sound practical if I want a semi daily driver. So now I need to research how to install a T5 ...

Thanks 52Carl - I'll search out lugnutz.

You ever get an AD with stock suspension and brakes up to 70 MPH and have to avoid someone cutting you off forcing you to slam on the brakes and come to a complete stop?
I didn't think so.
It ain't pretty.
Unless one completely upgrades the drivetrain and brake system, one should think twice before increasing horsepower by a factor of 2 or 3..
I have a '50 with stock brakes, 235, 4.64 rear end, and a T-5, and a '49 with a mild 350 and an automatic transmission and a 3.08 rear end.
I can get both of them up to 60 MPH in a very reasonable amount of time. I can easily get the one with the 350 up to 100 MPH, but that is just stupid.
Therefor giving more meaning to my statement, "It will make you wonder why people put v8s in these trucks."
Don't make me drive all the way out to your ranch and show you how sweet the T-5 is behind a 235. Never mind, its too hot down there. I'll drive the one with the 350 and A/C. We can go for a 100 MPH drive and slam on the brakes. If we live through it, we'll report back to the rest of the folks.
Carl

I've been looking through threads regarding drive line conversions with specific mention of the drive shaft. I've come across a '54 235 in pretty good condition, a nice T5 and a 14 bolt 3.73 rear end out of a 2005 Suburban. If I'm reading this thread correctly I've got the right parts. Now all I need is a drive shaft. Is there anything in particular I need or will any GM open drive shaft work with the T5/14 bolt?

Joe

You will need to match up U joints at each end, as well as length, probably no driveshaft you find in a wrecking yard will match up all requirements, plus not be dented nor bent. Driveshafts are reasonably priced, it is worth peace of mind to get all new parts, balanced, correct length. Make sure length is measured in loaded condition.

Ed

You might need a two piece driveshaft. The expert at the shop where my driveshaft was shortened and balanced was very helpful.

Would a 1/2 ton non-torque-tube (converted) truck need a two-piece open driveshaft?

I've found a shop that is willing to do the whole job, remove the old engine, trans, and rear and install the new stuff and find or make the drive shaft at a reasonable price so that looks like where it's going. I've even found another shop fairly close that will do the sandblasting/powder coating of the frame so it looks like I'll be able to haul it from shop A to shop B. I'm going to have the flatbed frame blasted and powercoated too. I love it when a plan comes together. :-)

I have to remember to take photos.

Joe

I prowled the wrecking yards looking for a one piece shaft. The SM420 is a short transmission, so a one piece would be relatively long. Found some shafts on Dodges that would work, but the diameter of the shaft is too large. I found a long box GM truck with the 4 speed had the two piece shaft. Our 63 C10 had the two piece shaft. So I talked to the driveshaft guy and he recommended a two piece shaft; said I would be pushing it with a one piece.