On the Beam: Old-Time Front Axle Restoration
The automobile evolved from the wagon and some cars and trucks used wagon type I-beam front axles until the early postwar years. Each wheel spindle typically has a yoke attached to it that fits over one end of the axle. The upper and lower ends of the yoke and the end of the axle are drilled so that a pin can be pushed through the holes. This king pin has a flat spot that allows it to be held in one position by a stake or bolt, so that it remains stationary once in place. Then the spindle can be swung back and forth on its yoke to allow steering.
The British call king pins "swivel pins," a term that actually describes their function more clearly. Whatever you call them, they need to be lubricated to prevent rapid wear and they need to be fitted just right so they swing smoothly. Lubrication of pins is accomplished by drilling holes in the yokes that are threaded on their upper (outside) end to accept a grease fitting.
If you're doing any job, including king pins, on a truck like this 1940 Dodge VC 1/2-ton pickup, you'll be wise to visit www.39-47dodgetrucks.com.
To give proper fit, bushings are inserted into each "branch" of the yokes and reamed to the right size opening. A too-tight pin would cause steering members to bind and a too-loose pin would cause vibration. The bushings also have holes drilled in them that line up with the lubrication holes in the yokes, so the grease gets all the way to the pins instead of being blocked by the bushing. There are some cars that left the factory with the king pins riding on needle bearings, rather than bushings, but these were usually repaired with bushings.
Before final installation of the pins, thrust washers with shims are placed at the bottom of each end of the axle, so that the pin goes through them before entering the hole in the yoke. These act as bearings so that the spindles swivel more smoothly. The shims are used to keep the up and down movements of the assembly within specs. Oil sealing plugs are also inserted at the top and bottom of the pins to keep oil in the spindle. These are staked in place with a punch.
In this article, we are going to discuss removing a beam axle from a 1940 Dodge pickup, breaking it down to component parts and the installation of king pin bushings. For veteran old car restorers, this is nuts-and-bolts stuff, but for the beginner or the mechanic with only modern car training, there's a definite learning curve. We read countless discussions of king pin bushing fitting on a popular hot rodding bulletin board and they were confusing. One poster would recommend using a machine shop to ream the bushings and the next would warn that his machine shop botched the job and say hand reaming was easy.
Another eye opener was a trip to the local parts store to see if they sold a king pin reaming tool. After initially answering the question with a blank look, the counterman called his warehouse and discovered there were two versions of such equipment available. One was $2,600 and the other was $5,600! We're guessing that the second quote included a hydraulic press that could push the bushings into the yokes. The first was probably for a set of hand reamers, because a commercial installer would need a set of different sized reaming tools to carry a variety of applications. There's no one-size-fits-all option here.
We were able to take the axle apart, push the old bushings out, put the new bushing in and hand-ream the bushings using equipment that we had on hand in our small shop, along with borrowing the proper size reaming tool from a very well-equipped mechanic who helps us a lot. We also found vintage reaming tools available on eBay at prices between $30 and $60, as well as a new one that Speedway Motors (www.speedwaymotors.com) makes for midget racing cars. The important thing with these tools is the size, not the specific application they were made for. Measure the diameter of your pins and look for a tool that can ream the bushing out to just a tad over that size. We have not run across a general spec for reaming. Apparently, mechanics of the day knew the right "feel," which is could be described with "as tight as possible with no binding."
As we said, taking the axle off the truck was a nuts-and-bolts operation, but some of those fasteners were huge. The fact that they may not have been loosened since 1940 didn't help either. We used a giant ratchet wrench set that we bought at Harbor Freight. It did the job, but we made a mistake using the ratcheting drive, because its bearings were not up to the job and we ruined it. We would have done fine if we used only the bar and the sockets.
The job starts by raising the front end of the truck. This was easy, as we were working with the stripped frame. With the rails supported on stand jacks, we took off the hubcaps, wheels and tires. Each end of the front axle was bolted to the frame with four heavy bolts. With these removed that axle came off the frame as a unit. Since the hubs, brake backing plates, brakes, bearings, yokes, spindles and steering linkage parts are all still attached, you have a heavy unit.
Removing four bolts on each side allows removal of front axle from frame.
The big sockets took off the wheel hub nuts and we carefully removed the wheel, bearings and brake parts, taking digital pictures of their relationships and putting each part in separate plastic bags. We made some hand-written notes and sketches and put them right in the bags and labeled each of the parts bags.
Steering linkage components do not all come off as easily as the axle and wheel parts. After taking out the cotter pins, a pickle fork removed one tie rod end, but it seemed like nothing except a sledgehammer would drive the other one out. The right and left steering knuckle support arms have socket balls. We used a 20-ton bottle jack press purchased from a body shop auction to push them out. The drag link had dust covers on each end that had to be removed along with grease fittings and cotter pins. Then, we unscrewed the plugs at each end, and pulled the drag link off the steering gear arm and steering knuckle arm.
Cotter pins are removed before nuts holding front end together come off.
Use a pickle fork to remove threaded tie rod end from steering knuckle.
Once everything was apart, we cleaned the parts of wet grease and loose grime with a wire brush and scraper. Then we bead blasted them in our media blasting cabinet and used a few coats of spray can black paint to protect them from rusting until we can get them to our powder coater. Some restorers we know — such as finned Mopar expert Jerry Kopecky — prefer using paint on suspension and steering parts and we're okay with that. However, the Dodge pickup is a customer's truck and we know that he wants powder coating.
Steering Yoke and Bushings
With everything disassembled, it was time to deal with removing the old king pin bushings from the spindle yokes, pressing new ones into place and fitting the pins in the spindle yokes once the new bushings were installed. The Dodge truck shop manual did not mention reaming the bushings and there were "full-floating" bushings that supposedly did not require reaming. However, the new old replacement stock king pin repair kit we purchased from Northwestern Auto Supply (www.northwesternautosupply.com) included bronze bushings that definitely had to be reamed before the pins would fit in them.
Axle fits between 'yoke' on back on steering spindle. The king pin holds these parts together and the thrust bearing and shims fill up any excess space.
King pins slide through bearings in upper and lower ends of spindle yoke (and through holes on ends of axle). Pins fit as tight as possible without binding.
A bolt or stake goes through axle end to hit the flat spot on each king pin and hold them in place. This allows spindle yoke to swivel on the stationary pin.
Final removal of old pin was done on 20-ton press using socket as spacer.
Finger points to old bushing being pushed out by socket seen on top.
While our 20-ton bottle jack press could easily have pushed the old bushings out of the spindle yokes, the job of setting the parts up in the press for a strong push seemed like it would be a challenge. The Dodge truck shop manual showed the factory tool for removing bushings and it looked very much like a universal front coil spring compressor tool we had purchased from J. C. Whitney (www.jcwhitney.com). We tried using our tool and it pushed the old bearings 90 percent of the way out. That made it possible to set the spindle yokes up in the bottle jack press for a gentle push to fully extract the bearings.
Universal coil spring compressor tool was used with large flat washers to push new bushing into place.
Before pressing on the bushings, we took out the screws that were threaded against the flat spots on the old king pins (the flats that keep them stationary). Then we used a small punch to remove the old oil seals. These are just thin steel discs and you actually poke through them with the punch and pry them out. The old king pin repair kits include new ones.
Next we configured our universal spring compressor to push inwards and ran it through some tubular spacers we had, then through the spindle yoke. The tubular spacers were just a little larger than the threaded shaft of the tool, but smaller than the holes on the spindle yoke. As we tightened the bolt down on the tool's threaded shaft, the tubular spacers moved against the old bearings and pushed them mostly out of the yoke ends. Then, we carried the spindle yokes to the 20-ton bottle jack press and using the proper diameter socket as a spacer, we pushed the bearings the rest of the way out of the spindle yokes.
By tightening bolt on top of coil spring compressor, the new king pin bushing is being forced into the lower part of the spindle yoke.
To put the new bearings in, we simply used the 20-ton bottle jack press along with the proper size socket that could push on the bearing, but not hang up on the hole. We used Liquid Wrench silicone spray to lube up the parts for the big push and we tried to carefully line up the lubrication holes in the bushings with the angled holes drilled into the spindle yokes. We got three lube holes lined up perfectly, but we thought we missed on the fourth one and carefully ran a drill bit down to test. It turned out we had just caught the hole and some goop had closed up the decreased opening. A piece of strong wire got the hole cleaned up.
We were kind of sloppy in pushing the first bearing in as we squashed the top of the brass piece a bit and we also pushed it down to where a small amount was protruding at the bottom. We were lucky our bearings had to be reamed, as this operation completely cleaned up the squashed down top rim of the bearing. A file took care of making the bearing fit absolutely flush at the bottom so the end of the axle could be placed in the spindle yoke without interference.
This shows the spindle yokes with new king pin bushings installed. The bushing on left was a little sloppy at top edge, but reaming cleaned it up.
Our mechanic friend measured the diameter of the king pin with a micrometer and brought what he thought was the proper size reamer over to the shop. At first, it seemed like the tool didn't fit, but he couldn't "buy" that because he had measured carefully. First, he disassembled the tool and carefully cleaned up all of the cutting blades. Then, he used a rat-tail file to clean up the bearings a tiny bit. Almost like magic, the tool then seemed to fit perfectly into the hole.
The talented hands of Vince Sauberlich prepare to twist the tool used to manually ream the king pin bushings.
We thought the reaming would take a long time, but it didn't. Actually, the phone rang and we went to get it. By the time we got back into the shop mechanic Vince Sauberlich had reamed all four bushings to the proper size. Now, we are ready to take the parts to the powder coater. Since this project is moving slowly according to customer wants, the final king pin install and axle/steering/brake re-assembly won't take place for quite awhile. When that day comes, perhaps we'll revisit the topic of old-time front axle restoration.