How to Build a Square Driveshaft

This will give you a step by step on how to build a square driveshaft, including the tools you will need, and techniques to perform the task.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Some type of saw (Sawzall, Portaband, hacksaw)
• Grinder
• Bench Vice
• Welder
• 2" Square Tubing
• 2.5" Receiver Tubing (seamless)
• Driveshaft
• Marking Device (black marker, chaulk)

1. 
    
   1985 Toyota Driveshaft

   First you will need to find a driveshaft, preferably the one from the vehicle you are making this for.

2. 
    
   Driveshaft Seperated

   Next you will need to seperate the drive shaft peices by pulling them apart.

3. 
    
   Driveshaft soaking in Solvent

   While the driveshaft is out, you might as well clean it. You can use a bucket of solvent or Simple Green

4. 
    
   Using a Portaband Saw to make the cut

   Mark you driveshaft 3/4" from the u-joint and cut the shaft

5. 
    
   Shaft Cut Down to 3/4

   Cut off one end of the driveshaft with about 3/4" of the original shaft remaining behind the u-joint.
   
   You can also cut the factory weld and pull out the u-joint in tact.

6. 
    
   Metal Shavings in Shaft

   You will notice there is some metal shavings and dirt inside your shaft, clean it out now.

7. 
    
   Shaft Cleaned Out.

   Nice and clean!
   Now it's time for the other side...

8. 
    

   Cut down the other end of the driveshaft as well, try to keep as much of the u-joint as you can.

9. 
    

   You can see in the picture I was only able to keep about 1/2" on this side

10. 
     

    Using a saw (Dry Cut saw in picture) cut off a slice of the small tube to make the cut marks on your smaller u-joint

11. 
     

    Using the slice of square tubing you cut off, mark the round section that remains on your driveshaft for the cut.
    
    You want to make sure it is as square as possible with the u-joint so that it balances out well.
    
    Cut the shaft all the way down to the top of the u-joint, making as much flat surface as possible.
    
    Test slide the square tube slice that you cut off over the newly cut u-joint.
    
    Make sure the fit is tight but goes all the way to the bottom

12. 
     

    The inside of the square tubing may have a welded seam inside the tube.
    
    You may need to file this down, or groove your joint so the tube slides over the joint easily.

13. 
     

    I like to file the tube and find it easier than grooving the joint

14. 
     

    You can see here the joint won't slide over all the way, so more filing needs to happen.

15. 
     

    This is how your tubing should fit over your (now square) u-joint.

16. 
     

    Once you know that the joint fits smooth and tight and is square, then clean the tube for weld preperation.

17. 
     

    The u-joint end should be clean from the cutting and grinding you did, but make sure.

18. 
     

    Using a welder tach weld the joint to the tube.
    
    Make sure everything is square and stays that way.
    
    Double check your work and then proceed to welding...

19. 
     

    For this I used a stick (arc) welder.

20. 
     

    Weld only a little and check the squareness of your shaft again.
    
    You weld only an inch at a time on oposite sides, and check it after each weld.

21. 
     

    Make sure you fill in any gaps.
    
    The weld needs to go all of the way around the tubing.
    
    Do NOT grind your welds to make them look pretty, it's just a driveshaft, grinding will weaken the welds.

22. 
     

    At this point you may want to drill a small hole on the differential side square tube to let any water out that may have seeped in.
    
    On the outside tube you can also put a grease fitting along the tube to grease the inner shaft.
    
    You are done with that side, feel free to paint!

23. 
     

    The other side will be exactly the same just with the larger tube and the other joint.
    
    Once you have both sides together you will need to figure out what length to cut the tubes to.
    
    Here is how to do the front:
    1. Imagining your spring is flat; Measure the distance from your front hanger to the spring pin (measurement A)
    
    2. Measure the linear distance from your spring pin to your differential flange (measurement B)
    
    3. Measure the distance from your front spring hanger to the front transfer case output flange (measurement C)
    
    4. Add measurements A and B
    
    5. Subtract that answer from measurement D
    
    6. Your answer is the maximum length your driveshaft can be (measurement X). In a formula it will be X=[(a+b)-d]. I would subtract 2" from that just to be safe.
    
    Once you know your maximum length cut the tubes (just the tubes) equal length to acheive the maximum amount of travel.
    
    When you bolt up the driveshaft make sure it is in phase (both bearing caps on both joints facing the same direction
    
    THE END, have fun!

Tips & Warnings

• Wear Safety Glasses
• Clean area before any welding
• Double check squarness of tubing as much as possible
• Do not cap the end of the tubes, debris gets in there and can cause your driveshaft to lose compression
• This driveshaft will not be able to be balanced, if by some miracle you manage it, let me know how...