Has anyone built and run square drive shafts? I'm building up my '88 Ranger Truggy and need some long travel shafts but don't want to spend the big price for them. So does anyone have any ideas on how they would work and how to build them?

 

Square drive shafts wouldn't be as strong, would twist more, and would be just as expensive to build as standard round ones.

 

Thats not necessarilly true. If the wall thinckness were the same for both shafts then the round tube may have an advantage but only for torsional resistance. Like standing on a beer can. It can support some pretty killer weight unti something compromises the side. Once the forces are no longer equal, the can crushes like,,,,,,well,,,,,,,,,a can.
Consider that most square tube shafts are made from .250” X 2” ID tube as well as, .250” X 1.5” ID tube. Now consider that the inside tube can fit well into the outside tube and together you have twice the wall thickness that can resists quite a bit of abuse that a round tube would never even stand a chance against.
Most round tubes are only and 1/8 of an inch thick, and only single wall. Dent one and it crushes like that old aluminum can:




Kind of like that.
Now a square tube shaft will not be well suited for the street since it will be almost impossible to balance, so the round tube shaft takes the prize here, but a doubled up square tube measuring 1/2 inch in thickness can sustain rock hits and you can park the truck on a rock usiing only the driveshaft and you can bet that the shaft is not going to fail.
With a machined square to round insert you can actually get the things pertty well balanced and the amount of slip is about half of the length of the shaft. This would be very expensive to make with a long spline system. Keep them lubed up and they do a mighty fine job.
We run some high horsepower vehicles with square tube, and they work well. Cant knock them. (pun intended)

 

i agree with 75F350, they are great for off road only rigs but would be hard to get to work well at freeway speeds. The TV show Xtreem4X4 put square drive shaft in one of their buggies and worked out very well for them, doesnt mean its the best or even right but with all the money they have if it doesnt work why would they do it?

 

Thanks for all the info, where can you get square to round inserts to help build these shafts?

 

Most guys just weld the flange or yoke to the inside of the tube. This is because nobody makes such a piece. Should you decide that you want this insert, you will have to make it yourself.
The insert is not necessary, it just provides a little more surface area to weld against.
Again, not necessary, but does add a small level of added strength.

Also an important note. Since there is sooo much surface area making contact, it is a good idea to place a few grease fittings. You dont want this thing to bind up, so some grease is a good idea.
They do a pretty good job of extending and compressing when they are lubed well.

 

When I snapped a shaft on my E-150, I went to a truck shop and had it made of heavy duty round pipe. Worked great and didn't break it again. If you want cheap round pipe, you can always buy a lolly column at Home Depot, it is usually 1/4" wall.

 

Thanks for all the info now i just have to build them hope everything works out.

 

Alot of PTO shafts of tractor equipment is made of squareshafts.

 

Yes, but they are shorter and slower than vehicle driveshafts.

 

But they are under much higher amounts of torque and shock, and I beg to differ on shorter, the shafts on a tri fold shredder are pretty long, the center one is roughly 6 foot on ours, and I've seen longer.

 

Are there any theories about how to get a somewhat decent balance on these? What process do driveshaft shops use for round tubes?
I can buy scrap pieces of this at work for 25 cents per pound, so this would be a very cost effective solution for me when I swap in a NP205, and a D60 front.

 

Trying to balance the square tubes is difficult, not because of the shape of the tube, but because of the amount of slop between the inner and outer tubes. This is not a precise fit like a set of splines would be. This is a trail only type of deal. You will not want to run this type of shaft on the street. You will shake the bearings right out of the case, and the axle.
You can get them close to balanced, but they still have soome vibration, and highways speeds will result in failed components.

We have tried to balance square shafts with little success. The loose tolerances result in a shaft that moves slightly and this lack of tolerance throws the repeatability right out of the window.

 

Agree #13/75F350

>What process do driveshaft shops use for round tubes?

Sort of like a lathe then they weld the balance weights on. I did a quick Yahoo search for "machine balance drive shaft" and this is the type I am talking about

Drive shaft balancing machine balancing machine

 

Two real types of balancing, and the giant machine that is in the link is a dynamic balancing method, and is the most accurate. Different machies are to be used for driveshafts using a multi piece design.
Alright that is one way, but there is yet another, and many shops have used this method in years of past. The inductive light can also be used.
This requires a magnetic head / trigger and this is placed right at yoke by the the pinion. Then a light is placed directly under the driveshaft. Every time the shaft rotates one rotation, the light will flash after it is up to speed and it detects the heavy or low spot in the shaft. Just like a timing light, except instead of being triggered from a cylinder, it is triggered by the shaft itself. This is very repeatable.
Alright, then a chalk line is used to reference the bottom of the shaft, right where the trigger is making the light flash. This can be anywhere actually, this mark is only used as a reference to install a weight. With this method the heaviest part of the shaft will trigger the light, and if you pay attention to where that chalk line or mark is, you can add weight to the exact opposite side of the shaft. many use a hose clamp. This clamp can be loostened and rotated if the weight is not exatcly correct. Additional clamps may be required to eliminate the imbalance.
Once the balance is accurate, some permanent weights can be added to eliminate the hose clamp. Some leave clamps and others weld small weights, or washers to the shaft.
This method requires some patience and some large "huevos" because you are working under a vehicle that is running and secured on some sort of jack stands. Normal speeds are about 50 MPH.
I am not suggesting that one run right out and rig up this type of light to balance their own driveshafts. I am only sharing the idea and concept.
The rest is up to you and I assume zero responsibility for those that turn their garage into a drive thru!!!
Be safe, but this practice is still being used today.