One of the areas I had the most difficulty finding information was the steering shaft. I’ll use this post to go into detail about how I made mine work.
Stock Tacoma steering shaft
Earlier Truck/4Runner steering shaft without rag joint
Woodward U-joint Part # UA108100, .688"-34/36 spline to 3/4" weld
¾-¾ rod end
¾” round bar
Starting with the stock Tacoma steering shaft, I disassembled this section.
To get this
At first I tried pressing the joints out of the circular center sections, but ended up just cutting the center section off. That left me with this.
Then I cut the ball tipped ends off to get the standard “U” shape.
After pressing the joint out of the longer section I was left with this.
I put that in the press and used a 3/8” extension to press out the splined shaft.
And was left with this.
Then I reassembled the joint as a single U-joint without the center section. Disregard the splined shaft in this picture.
This is where my application got tricky. Apparently, the male splined section from the earlier steering shaft should fit directly into the female splined section of the Tacoma parts. Mine didn’t. The earlier shaft had a splined section of 17.5mm x 36. This was too large for the female section of the Tacoma shaft. I needed to bend my shaft around the coilover tower anyway, so I started looking for other options. I found the Woodward U-joint and decided to try it with a few other changed to the overall plan.
I took the ¾” round bar to a local machine shop and paid $20 to have them turn the last 2” of it down to fit inside the female spline section of the Tacoma steering shaft. It was well worth the money to ensure it was even and true. Then I drilled 4 holes in the Tacoma section for rosette welds, leaving me with this.
Then I welded it and cleaned it up.
I wanted to leave the female splined section of the Tacoma shaft intact because the outside diameter properly fits in the firewall seal. The ¾” round bar is too small for the seal.
The early steering shaft had to be significantly shortened to fit my application. This is how it started.
I cut the tube at the weld and pressed out the remaining tube section, leaving this.
I cut out a section of the tapered tube so that when reinstalled, the taper would be at the edge of the larger splined tube.
After test fitting, this was still too long. So I removed a section of the tapered tube. A section of the DD rod had to be removed as well to allow max insertion without interfering with the splined section of the U-joint.
The male splines of the early shaft fit the female splines of the Woodward U-joint. It was a tight fit that took a mallet to achieve full insertion. I attribute this to trying to match old, worn splines with freshly cut splines in the U-joint. The splined end of the Woodward U-joint also had set screws. I drilled a few shallow holes in the splined section of the early shaft to allow more positive engagement of the set screws.
More test fitting was done, and the ¾” round bar was cut to the required length. The Woodward U-joint is made to be welded to the ¾” bar or tubing. I couldn’t do that because I need to add a rod end to my steering setup to stabilize additional U-joint. Since one end of the round bar was welded to the Tacoma U-joint, the other end had to be removable to allow the bar to inserted into the rod end. I took the parts to work and used the drill press to drill a hole through the U-joint and the round bar. The hole is 5/16”, and the back side of the U-joint is threaded 5/16-18. At a 90° offset, I drilled 2 holes and threaded them ¼-28. The bar was dimpled at these holes for positive engagement of set-screws. The addition of the set-screws really made the assembly solid.
Here’s a shot of all the individually modified parts prior to assembly.
Here’s a picture of the complete assembly with a couple closer shots of individual sections.
For installation of the shaft, the rod end had to be loosely installed in the coilover tower. Then the ¾” round bar had to be slid through the firewall seal and inserted into the rod end. Once that was aligned, it took a bit of effort to get the splined at the footwell to mate up. I already had the Woodward U-joint installed on the splined section of the early shaft. Next it was connected to the ¾ bar with the 5/16 grade 8 bolt and a grade 8 nylock nut for extra insurance, followed by the 2 set-screws. Then with a nut on the end of the rod end splines, the rod end had to be pushed through the coilover tower towards the engine to allow enough play to get the end of the shaft onto the steering box splines. After the shaft was installed on the steering box splines and tightened, the nuts on the rod end were tightened to secure the assembly.
Here’s some installed pictures.
This is the location of the rod end.
I used a FROR firewall plate to seal the firewall. I had to enlarge the holes slightly to get all of them to line up, but nothing major. Notice that I installed the firewall seal backwards. After converting the Tacoma shaft to a single U-joint, the joint is so far forward that it would be inside the seal. Flipping the seal allowed everything to fit.