Here at Proshaft, we're starting to become known in the South Florida area for doing drive shaft conversions. It's not that we set out to do anything special. It all started when one customer came to us for help and we agreed to do our best.
When this job came in, we weren't exactly sure how to go about it at first. Our customer from here in Ft. Lauderdale had installed a Ford 9 inch rear differential in his Nissan. Apparently, the Ford was a wrecked donor truck and he just so happened to have the drive shaft left over from it as well. Knowing the 9 inch rear accepted the flange from the driveshaft, he brought us both the drive shaft from his Nissan and the one left over from the Ford. Since he kept the original engine and transmission in the Nissan, the drive shaft would stay the same from the transmission to at least the carrier bearing.
The driveshaft from the Nissan is on the left. The shaft for the Ford with the 2" female flange pilot is on the right.
We tossed around a couple of ideas as far as getting this conversion done. A one piece steel replacement drive shaft was out of the question since the distance from the transmission output shaft to the rear differential was too long. It would probably have been possible to build him a large diameter aluminum drive shaft but we still don't have the aluminum spool gun for our welder. A third option we considered was to build a replacement rear section for the driveshaft with the proper u-joint to connect to the Ford pinion flange. This would have been extremely difficult due to the difference in the original tubing and the parts we had available to us. After some consideration, we settled on a fourth option: to replace the rear weld yoke with one that could attach to the proper flange.
There was just one problem, the tubing diameter from his stock drive shaft was roughly 2.25" outer diameter by .093" wall thickness. The closest component we had on hand was a 1310 weld yoke made for 2" outer diameter by .083" wall thickness tube. There was going to be some machining involved to pull this off and get the drive shaft built properly for the customer.
The first step in the process involved removing the rear drive shaft section from the front section. Many American driveshafts have a handy splined slip yoke that allow you to simply slide the front section away from the rear section. This shaft was semi permanently attached with a u-joint at the midship yoke where the carrier bearing is installed. So, we had to disassemble the front and rear halves by removing the u-joint from the midship yoke.
Here is the front section of the Nissan drive shaft separated from the rear section. Notice that we've got a timing arrow marked on the front section. We marked a similar arrow on the rear section. Even though we're going to be cutting and welding on the rear section, reassembling the drive shaft with the same timing can still help with the balancing process.
With the front driveshaft section separated from the rear, we set the front aside to get to work on the rear. We machined out the old weld yoke and flange in the lathe. It's important in this case to try and leave as much of the original surface of the machined butt intact as possible so that we can take a direct measurement from it. In the case that the machined butt was destroyed during machining, we could always just measure the inner diameter of the original tube.
Here is a picture of the original weld yoke machined out of the Nissan drive shaft. Luckily, this yoke has a straight machined butt that we can measure and then duplicate on the weld yoke that we're modifying.
With the rear weld yoke removed from the Nissan shaft, we could then determine what the diameter of the machined butt of the 1310 weld yoke needed to be. Depending on the style of machined butt, there are two ways to do this. Some weld yokes use a sort of tapered machine butt that is difficult to get an exact measurement from (many old GM, Oldsmobile, and Pontiac yokes are like this). If the yoke is the tapered style, it's best to measure the inside diameter of the drive shaft tubing and machine the new weld yoke butt to be about .010" larger so we still get a nice press fit in the tubing. In our case (as can be seen by the picture above), the machined butt is straight and easy to get a measurement from.
This is a picture of the Nissan driveshaft tubing after the rear weld yoke has been removed.
As mentioned earlier, the weld yoke that we went with was for a 1310 Spicer type u-joint and designed for 2"X.083" tubing. The machined butt diameter was only 1.844" originally. On the original Nissan yoke, we got a measurement of 2.130". This left us with a difference of .286", or more than 1/4"! How would we get the extra material on the new yoke to fill in the difference?
After some thought, we had a plan. We decided to go ahead and weld the new yoke into the original intended tubing size (2"X.083" drive shaft tubing). This would not only help fill some of the gap between the new yoke and original tube, but it would also give us a nice clean surface to build enough weld on to machine down to the proper dimension. We made sure to weld the yoke into the 2" tubing as straight as possible so our new weld surface would be true. Then, we built up a series of welds that were +.300" or so above the tube diameter. The reason for this is that not only would we be machining a new butt on the yoke but we also needed a nice flat surface to weld onto that was 2.250" to match the tubing in the Nissan drive shaft.
In this picture we can see where we're both machining the butt diameter to proper size as well as machining a nice 2.25" surface to match our tubing. This 2.25" surface ensures that the weld burns in nice and even with the tubing that it is mating up against.
Once we'd machined the proper dimensions onto our new weld yoke, we simply parted it off from the tubing in the lathe.
Here's the completed, custom 1310 weld yoke ready to be installed and welded into our Nissan drive shaft.
With our new yoke complete, we welded it in nice and straight just as we would any other drive shaft. We used a 1310 to 1330 crossover u-joint (Spicer 5-134X) to mate the Ford yoke onto our Nissan drive shaft. Then, we used the original u-joint from the middle to reattach our front and rear sections of the shaft. With all that done, it was time to put it in our computerized drive shaft balancer.
Here is our Nissan to Ford conversion drive shaft mounted in the balancer. Notice we've cleaned off sections of the old paint in the middle of the rear section so that we can get a good ground with our welder. Additionally, you'll notice the shims under the carrier bearing. These are important during balancing because we don't want our driveline sagging in the middle. This can cause the shaft to run at too high of an angle putting stress on the joints and leading to unnecessary vibration.
Note about drive shaft balancing:
Our computerized driveshaft balancer can balance either one piece or two piece drive shafts. In the picture above, you can see the vibration sensor installed on the carrier bearing support pedestal. If you've seen our other blog articles, you may notice that we don't have the sensor attached to the pedestal when we're balancing a one piece driveline. The reason for this is, with this particular balancer, we program the computer to balance with either two or three balance planes. In the two plane mode, it only reads off of balance plane number one and number two. In three plane mode, it reads off balance planes one, two, and three. So, when we balance a two piece shaft, balance sensor number two moves to the carrier bearing support pedestal and a third sensor is plugged in and attached to the rearmost bearing in the balancer.
The driveshaft balanced nicely without much trouble. Then, it was time to tack weld the balance weights and take the driveline to the paint booth. Below are a couple of pictures of the finished product.
This picture is of the front section of our Nissan to Ford conversion driveline with the transmission yoke installed.
This is a picture of the rear of the driveline with the 2" pilot Ford flange installed.
This conversion shaft turned out great for the customer. We were able to save him a ton of money over building a completely new drive shaft that would probably be extremely expensive. You'll notice that we didn't alter the length of the shaft whatsoever. This was at the customer's request. Normally, when swapping transmissions or rear differentials, a different length is required. The customer got back to us a couple of days later and told us that the custom unit bolted right in place and is running as smooth as a factory original! If you have an idea for a custom driveshaft of your own, our contact information is below. We'd love to hear from you. Thanks for reading!
Phone: (954) 939-4415