|[an error occurred while processing this directive]||Short Cuts|
By: John Nutter - 5/2002
Build Your Own Drive Shaft!
Don't be afraid! It's only metal. Shortening, lengthening and re-tubing your own drive shaft is not very hard, but you won't be able to balance the shaft at home. The methods shown in this article are geared towards trail Jeeps that rarely see pavement or trail repairs on any vehicle.
A drive shaft is just a piece of tubing with a yoke at each end to accept a U-joint or a CV joint. The yokes have a shoulder that is a press fit in the tubing to make assembly and alignment easier. The yokes also have a larger shoulder to act as a stop to prevent the tubing from being pressed on too far.
For the best performance and highest level of strength the shaft needs to be straight with the yokes properly aligned. The shaft should also be "in phase." When a shaft is in phase, the yokes at each end line up with each other. When the shaft is "out of phase," one of the yokes is twisted in relation to the other. To make a good drive shaft you need to build a shaft that is straight, has the yokes in phase, and uses appropriate material such as 2" by .120" wall DOM tubing.
In The Garage
You probably don't have any way to balance the drive shaft at home, so these techniques are best for use on Jeeps that are only used off-road and at slow speeds.
You only need a few tools to build a decent drive shaft in your garage. You'll need something to cut the tubing, you'll need a welder, and for best results you will need a dial indicator. You can cut the tubing with a hacksaw, band saw or angle grinder, but an abrasive chop saw works best. You could do the welding with a stick welder, but a wire feed welder will make the weld look better and leave you with less clean up work. The dial indicator will cost under $20 at many discount tool stores. You don't need an expensive instrument here. The goal is to reduce the run out on the shaft as much as possible, below .003" hopefully. Any cheap dial indicator should handle this job. A magnetic base for the indicator is nice, but you can make do by bolting the indicator to a piece of angle iron that is clamped to the vehicle's frame if you have no other way.
The first step is to separate the tubing from the yokes. I've found that careful grinding with a chop saw works very well. I try to grind away the intersection of the tubing and the old weld. You will want to avoid grinding too deep because this can damage the press fit shoulder on the drive shaft. If you are careful, observant and patient you'll see the tubing turn blue or brown from the heat as it gets close to being paper-thin. This is the time to stop grinding and separate the tubing from the yoke. Hit the yoke with a hammer or hit the tubing against the anvil area of a vice to separate the yoke from the tubing. If the metal at the bottom of the cut doesn't split with moderate force go back and grind a little more.
|Close the vice on the chop saw as much as possible while still allowing the tubing to rotate freely.||Rotate the tubing while lightly grinding down the old weld. It took several revolutions to grind this deep||Stop grinding when you see the metal at the bottom of the cut turn blue or brown.|
|Here's a better shot of the brown metal at the bottom of the cut. This area is paper-thin.||A light tap caused the thin metal to tear.||Tap on alternating sides to make the tube back off of the yoke.|
If you are re-tubing a drive shaft you will need to repeat the process to free the tubing from the other yoke. If you are only shortening a drive shaft you can cut the tubing to length and start re-assembling. To re-assemble, first drive a yoke into the tubing if you are re-tubing. If you are only shortening a shaft there should still be a yoke attached. Next lay the drive shaft with one of the yoke ears on a flat surface. Line up the loose yoke with an ear on the same surface and slide the two parts together. This will get the yokes into phase with each other. Drive the yoke into the shaft, being careful to keep the yokes in phase. I usually leave an opening about 1/8" wide between the tubing and the old weld so that the new weld will bite into the yoke as well as the tubing and the old weld.
|Cherokee front drive shafts typically have 2" by .120" wall tubing and a Spicer 1310 CV. These shafts make excellent donors.||This is a different shaft that was re-tubed. You can see the gap between the tube and the old weld.||The other end of the same shaft.|
|The Cherokee shaft going back together.||Note that the shaft is in phase and the tube was left 1/8" from the old weld.|
The easiest way to ensure the drive shaft is straight is to put it in the vehicle and spin it. This is also the best way to make sure the length is correct. The tube is a fairly tight press fit, so don't worry about it falling apart. Use your dial indicator to check for run out and lightly tap the tube near the yoke until the run out is as small as possible. I normally try to achieve .003" or less run out. Carefully remove the drive shaft and weld the tube to the yoke if everything checks out OK. If you have any excess weld on the shaft you can grind it down to try to help the shaft stay in balance as much as possible.
|Here's my dial indicator setup. It's simple to use the indicator. It is labeled in .001" increments. Try to minimize the movement of the needle. This is the same tool you need to check backlash when setting up ring and pinion gears.||Here's the finished drive shaft. It went into my friend Bob's CJ5 with an AMC 360/T18/Dana 20 drive train. We couldn't detect any vibrations at speeds up to 65 mph. We didn't test it at any higher speeds.||Proper pinion angle is critical to eliminating vibrations from the driveline. This shows the correct way to set the pinion angle for a CV drive shaft.|
On The Trail
You probably didn't bring your chop saw or dial indicator on the trail. Hopefully you have a welder and hack saw along. Some extra tubing and maybe some spare parts would be a good idea, too. If you have a length of the correct tubing for your drive shaft, you can try to follow the garage procedures and get it as close as possible. There are some other quicker and easier ways to make a new drive shaft on the trail, although they tend to result in a drive shaft that is not quite as straight nor well balanced as the garage methods.
If I'm going somewhere that's far from my trailer I usually carry ready-made spare shafts for my own Jeep and I also carry a "drive shaft kit" in case someone else breaks. This may sound generous, but it's really based in self-preservation. Dragging out a Jeep with a missing drive shaft tends to be hard on the vehicle that is doing the pulling, often resulting in two broken vehicles. Waiting around while someone takes hours for a simple trail repair is no fun either. I'd rather just fix my friend's Jeep and keep going.
The drive shaft kit consists of a length of tubing and a drive shaft with tubing that is just small enough to slip inside the tubing. Grand Wagoneers in the 1980s often had a front drive shaft that had a Spicer 1310 CV and used 1.75" tubing. A length of 2" .120" wall tubing just slips over the 1.75" tubing with a few thousandths of an inch of clearance. It's easy to cut the 1.75" drive shaft in half, cut the proper length of 2" .120" wall tubing, slip the 2" tubing over the 1.75" tubing and weld it up. The whole procedure takes only a few minutes. A similar idea can also work with the small "broom stick" front drive shaft often found on the front of stock CJs. You'll need some 1.5" tubing with a .095" wall for these.
|This is an old trail repair that has been dissected. It's an'80s Grand Wagoneer front drive shaft with 1.75" tubing. The 2" .120" wall tubing was slipped over the 1.75" tubing and welded in place to make a replacement shaft on the trail.||This is a small tube front drive shaft from a CJ with a piece of .095" wall 1.5" diameter tubing slipped over it.||The shaft in the background is a small CJ shaft that was cut off and had a piece of 1.5" tube slipped over for a pre-made trail spare. Drive shafts made like this are usually out of balance and best suited to use as a spare.|