It’s kind of cool realizing that my Chevy 350 small-block and TKO 600 trans are finally getting close to hitting the open highway. But wait, I may be overlooking something – oh yeah, the driveshaft. If the shoe fits, wear it, right? Well no, you spent good money on that V-8 you just hopped up and that new upgraded transmission may end up a different length than the stock three speed.
My question is this, why would you overlook the weak link? It’s true that the tiny stock driveshafts that came with the straight-six trucks were not made to handle the power of a V-8, let alone the higher rpm’s. Worn U-joints will most likely hold up with straight-six engines, but put on some sticky tires, drop in a V-8, or do any performance driving and you will be asking for trouble.
Ever do a burnout on a back road thinking everything was OK? Now imagine that same burnout ending with a bang because your U-joint broke or driveshaft twisted like a pretzel. I’ve seen what happens when a U-joint gives way, and not only could it damage your tailshaft housing, but it could also crack the transmission case. Not good! On the other hand, a replacement driveshaft, or possibly a longer or shorter driveshaft to fit the new concoction under the hood, may be the only thing you need.
First thing I did was print...
First thing I did was print the instructions off the Inland Empire Driveline Service website www.iedls.com. Then I decided that a one-piece driveshaft would work best for my application. Transmission, rearend, and engine horsepower all play into how big the driveshaft needs to be and also what material it is made out of. Make sure that you measure the vehicle at ride height, or if the vehicle is too low then place jackstands under the rear axle.
On the left is a long piece...
On the left is a long piece of driveshaft material that is thin walled. On the right the wall thickness is much larger and will withstand more horsepower.
Inland Empire Driveline Service...
Inland Empire Driveline Service has the ability to make just about any driveline application. Just name your material and horsepower.
To free up some of those ponies,...
To free up some of those ponies, IEDS recommends an aluminum driveshaft. The lightweight aluminum shaft reduces rotational mass and can help get the vehicle moving along quicker than a heavy steel shaft. We started with a piece of 3�x.125 wall driveshaft tubing that is straighter than regular tubing.
Rocky took the driveshaft...
Rocky took the driveshaft length I gave him and cut the tube to his specifications. Rocky made sure to leave a little bit extra material so he can trim later. But how did we get to this point you might ask?
I measured the rear pinion...
I measured the rear pinion yoke at the point where the U-joint would sit inside of the pinion. I came up with 35⁄8 inch wide for the first measurement. I then measured the pinion at where the U-joint cup would sit or half-moon looking area. The second measurement was 13⁄16 and if I check the IEDS website I would come up with a 1350 U-joint. The 1350 U-joint is overkill for a street truck, but since I will be doing a lot of performance driving the 1350 U-joint will hold up better than a smaller U-joint.
OK now you know what size...
OK now you know what size U-joint is used on the rearend. A good rule is to use the same size U-joint on the transmission side. If you already have a yoke for the transmission that has a smaller U-joint than the rear pinion yoke then you could use an adapter U-joint like this one. The U-joint can be used for a transmission yoke that has a 1310 U-joint and a driveshaft that is 1350 or vice versa. For me, if money was tight I would match the rear U-joint (1350) to the driveshaft (1350) and replace the transmission slip yoke (1310) later down the road to the larger 1330 or 1350.
A tape measure was used from...
A tape measure was used from the tailshaft housing end to the pinion yoke. Then I measured from the input shaft to the pinion yoke and subtracted the numbers to get IEDS’s Y number and X number.
A tape measure was used from...
A tape measure was used from the tailshaft housing end to the pinion yoke. Then I measured from the input shaft to the pinion yoke and subtracted the numbers to get IEDS’s Y number and X number.
A Splicer-style slip yoke...
A Splicer-style slip yoke for my Hurst Driveline TKO 600 was used. The slip yoke for the TKO 600 is a 31 spline with 1350 U-joints or you could just use 1310 or 1330 U-joints with a different yoke.
Rocky used non-greaseable...
Rocky used non-greaseable 1350 U-joints on the driveshaft ends. Rocky says he likes the non-greaseable U-joints because they have less vibration issues.
A large arbor press was used...
A large arbor press was used to press the U-joints in the weld on the driveshaft ends and TKO 600 slip yoke.
Don’t forget the C-clips on...
Don’t forget the C-clips on the U-joint ends.
The driveshaft is measured...
The driveshaft is measured again and the ends are chamfered to get ready for the weld on the driveshaft ends. “This is also a good time to get the driveshaft length perfect,” Rocky said.
Special adapters are used...
Special adapters are used to match the slip yoke and the opposite U-joint ends.
Rocky uses the driveshaft...
Rocky uses the driveshaft machine to press on the ends of the driveshaft. A shot filled hammer is used to keep the ends from going crooked. A skilled driveshaft guy like Rocky made it look easy during this process.
The same process is repeated...
The same process is repeated on the pinion yoke end until the desired length is achieved. Rocky is also watching the driveshaft-to-driveshaft end gap to make sure the welding process will penetrate the shaft and ends.
The driveshaft is then removed...
The driveshaft is then removed from the lathe to clean the layer of oxidation off the aluminum. Rocky uses a large wire wheel that is only intended for aluminum driveshafts.
The driveshaft is then measured...
The driveshaft is then measured again to make sure it is correct.
A special fixture and a micrometer...
A special fixture and a micrometer are placed on the lathe to measure the driveshaft. This step is very important to make sure the driveshaft is as close to perfect as possible. If the driveshaft is too far off after welding it could be unusable, thus having to start over.
The next step was to weld...
The next step was to weld the ends on the driveshaft tube. Rocky uses a hand controller to start the MIG welder and watches under his welding mask.
The next step was to weld...
The next step was to weld the ends on the driveshaft tube. Rocky uses a hand controller to start the MIG welder and watches under his welding mask.
The driveshaft is then turned...
The driveshaft is then turned with the lathe and this is where training and experience come into play because this is no simple task. The machine will tell Rocky where the driveshaft is unbalanced, but it will not tell him how much weight to add. Rocky has to take an educated guess at how much weight to add and retest the balance.
The same material as the driveshaft...
The same material as the driveshaft is used as a counterweight. Before welding on the driveshaft Rocky used coat hanger to attach the counterweight and retest.
The counterweights are then...
The counterweights are then welded on with the MIG welder. Rocky can add weight on the driveshaft weights just by adding an extra spot weld on the weight itself. The harder part is to remove the weight, so Rocky starts with a slightly smaller counterweight.
After welding the counterweights...
After welding the counterweights on, Rocky spun the driveshaft at a higher speed simulating highway speeds and rechecked the balance on the machine.
The last step was to polish...
The last step was to polish the driveshaft with sandpaper and Emery cloth.
Once the driveshaft was back...
Once the driveshaft was back at the shop I checked to see if it would fit. It did, but it looked too close to the TKO 600 transmission, so I called IEDS and explained what I thought was wrong. Turns out the TKO 600 input shaft is inside the tailshaft housing more than other transmissions. IEDS likes to have the slip yoke as close to the input shaft as possible to reduce the chance of vibration and transmission issues. They also stated that the outer seal is a dust seal and that the transmission seal is about an inch inside the tailshaft. I then checked the driveshaft during full drop and ride height and the slip yoke was 5⁄8 inch away from the input shaft at its closest position.
A common problem that causes...
A common problem that causes failure of rear U-joints is overtightening the U-joint nuts, thus crushing the U-joint. I use red thread sealant and lock washers to tighten the nuts. You will know when the nuts are tightened when the crush washer is flat on the nut and yoke. Give another 1⁄8 turn and stop tightening the nuts.
With the driveshaft in and tightened down it really completes the drivetrain. Looks, performance, and drivability all in one driveshaft.