|The first in a series of articles gathered from SLM group mail providing membersí perspectives and thoughts surrounding particular subjects. Guy Beaudette stepped forward to provide much of the content for this study of straight axles and leaf springs, and how-to-do-them. Mike Morgan put together an excellent walk through on scratchbuilding your own rod ends from aluminum tubing. We thank Guy, and everyone else who shared their techniques for putting together leaf-sprung front suspensions. Perhaps you have a particular project in mind that isnít specifically mentioned here. Donít fret! The principles are the same wherever straight axles are used. Simply adapt the techniques featured here to your needs.|
Pictured here is the front axle to the Groundshaker Jr. altered, before paint. It replicates a 2" diameter straight tube axle. If you have a printer, print this picture out so you will have reference to what I'm explaining here. The only difference on this axle from the standard type, is the bellcrank mounted on the top right hand side of the axle. Look at the bellcrank. Notice how this operates? Thereís a center pivot point mounted into the axle. On the left hand side of the bellcrank, a hole exists for the draglink. On the right hand side of the bellcrank, a small tie rod is attached, which continues on to the top of the spindle on the right. When the car is steering to left, the draglink will be pushed forward, which will pivot the bellcrank, small tie rod, and finally, the spindle.
The materials used for this axle were a piece of straight plastic from a kit, which was then sanded to the proper 2" scale size diameter (.080"). The axle ends, (which the kingpin will slide through), is .080" Plastruct plastic rod, or scrap plastic rod a shade smaller than the axle tube diameter. The tie rod tube, tie rod ends, and spindle hubs are .035" Evergreen plastic rod. The spindle hubs are where the wheels will be attached to. The rest of the flat pieces, which include, spindles, shock mounts, and bat wings (the mounting points for the radius rods, that will extend back to the frame), is .015" sheet plastic. Finally, common pins were also used.
The tools used are: a modeling knife, a modeling saw, a small rat tail file, wire snips to cut the common pins, sandpaper, a pin vise with a #73 drill bit, and glue of your choice. I use tube glue, (I'm probably the only one left that uses it), and Crazy Glue.
To assemble the axle, first determine the width you'll need. After that is done, cut your axle tube to the proper length. Make sure the cuts are straight. Don't want any misalignment. There are two ways you can attach the .080" plastic rod on each end of the axle tube. You can just glue it to the ends, and fill with putty later, or you can do it the way I do. The later is done by using the rat tail file on each end of the axle tube, and file approximately a third of the width of the .080" plastic rod. Once achieved, the plastic rod should nestle into the axle tube. I hope I'm not confusing you here. What we're building is a "H." The axle tube is the horizontal line, and the .080" plastic rod is the vertical lines on each end. Once the glue is dry, sand down the .080" plastic rod the width of the axle tube. make sure the sanded surfaces are flat. Now, using the #73 drill bit, drill straight down the center of the .080" plastic rod. Make sure your drilling is straight vertically. Part of this will determine your camber angle. When done, test fit one of those common pins. It should fit fairly snug. Also check to see if you did the drilling correctly. Look at it from the front, and the sides. If this checks out, that's cool.
|Next to do are the spindles. Using the .015Ē sheet plastic, cut a strip a shade wider than the .080" axle ends you've installed, and about an inch long. OK, this may become complicated, so I'll try to explain it the best I can. From that strip of plastic, cut a piece approximately 1/8Ē long; if it's a little longer, it's no biggie we'll sand it to size later. This piece will be for the top right part of the spindle. Now, take that piece, and drill a hole a third of the way from the edge, and on center. Now, round off the corners of that piece closest to the drilled hole with the sandpaper. Just for the hell of it, run a pin through the hole, and insert the pin into the top right axle end. Does it sit flat atop the axle end? If so, that's super! Does it pivot OK? You're getting there!|
Now for the top left spindle section. You have to remember that a draglink will need to rest, or be attached to this section. Get back to that .015" strip of plastic. We're going to make it the same as the right upper spindle section, except we have to include an extended area for the draglink. Let's say about a 1/4 inch long to be safe. We can always sand down the draglink side later. Take the top right spindle section you've already made, and align it on top of the 1/4 inch piece you just cut. Mark where the hole is, and drill out the 1/4 inch piece. Now with the left upper spindle section you just drilled, you can either just round the corners for the draglink side, or bring it to almost a point on the end, and then round it off. I prefer the later. OK, now install the left upper section with a common pin, and check as described earlier for the right upper spindle section. OK to move on? Great!
OK. Still with me? I know it sounds really complicated, but once you get the hang of it, it's a piece of cake. You'll be doing these puppies in your sleep, and you'll be in search of new missions to take on.
The lower sections of the spindles will be like that top right one you made, except we'll have to include extended areas for the tie rod ends to be attached. These two lower sections will be shaped somewhat like an "L." Take that top right spindle section, and lay it down on a sheet of .015" plastic. With a sharp pencil, trace the outline of the piece onto the sheet plastic, and also include the drilled hole. Just stick the tip of the pencil into the hole. It'll leave a mark. Drill where the pencil mark is. Look at your tracing. With the rounded end on your left, draw a line straight down from the outer most edge, oh about a 1/4 inch long. Now, from the rounded edge, to the outer edge on the right, measure about two-thirds the distance, and draw a line straight down from the bottom line about 5/32nds to 3/16ths long. connect the two lines with a horizontal line. Kinda looks like an "L" right? Now, measure up from that horizontal line about 1/32nd. Find your center, and drill a hole. Once this is done, cut that out from the sheet plastic. Clean it up some if needed, and then take that piece and place it down onto the sheet plastic, and trace it out. That piece will be for the other side. Once that piece is traced, drilled, and cut out, you can either round off the corners of the tie rod area, or again, bring it to almost a point. Just leave enough strength area around the drilled hole for your tie rod. Cool. Now grab a couple of common pins, and install all those pieces on the axle ends. Again. Do all your checking. Happy?
Ah. That's better. Notice the compactness of the axle ends, and spindles? Notice the bellcrank mounted to the front of the frame? This pivots, as well as the draglink all the way up to the pitman arm. This front end set-up was quite common on most Logghe, and Don Hardy funnycar frames.
|Hold up a strip of the .015" you've cut, and put it up against the outer edge of the spindle pieces you have pinned. What you're looking for is an air gap of approximatley .010" between the axle end, and the inside of the strip of plastic you're holding up. Sand the upper and lower sections until you achieve the desired measurement. Make sure your spindle top and bottoms are flat, and tight against the axle ends. Now, place the axle up on its end, against the strip of plastic, and draw a line on the outside where the upper, and the lower spindle sections are. Cut that piece from the strip. Do the same for the other side.|
For the hub area, we'll use .035" plastic rod. First, drill a hole in the center of each piece of plastic strip you've just cut, to accept the .035" plastic rod. Cut that plastic rod in two pieces about 3/16ths long. Take the plastic strips, and CAREFULLY glue them to the upper and lower spindle sections. If you need to, let the glue set up. Once the glue is dry, install the two pieces of .035" plastic rod you've cut, into the drilled holes in the spindles. Glue as needed, and MAKE SURE they are straight! remember, we're striving for zero camber.
Once the glue is all set up, check your work by pivoting the pieces back and forth. Should be fairly snug. You're almost there, man!
We'll use that .035" plastic rod for the tie rod ends, and tie rod tube. Use the #73 drill to drill into the end of the .035" plastic rod. Itís not necessary to drill too deep. Approximately 1/8Ē will do. Carefully cut off the drilled end in two pieces about .035" long. That's the thickness of your plastic rod. Pass the common pin through those pieces to make sure they're fairly free. Now, with two common pins, pin those two cut pieces into the tie rod area on the axle. I would suggest pinning them from the top downward. That will give your tie rod a place to rest.
OK, now for the final piece, the tie rod tube. Looking straight down at the axle, make sure both spindle hubs are straight inline with the axle tube. This should give you zero toe. Measure the distance between both tie rods, and cut a length of .035" plastic rod, and glue it to both tie rod ends. Let the glue dry. Check for operation. If youíre happy with it, cut all that excess common pin, and carefully file the ends almost flush with the pieces they attach to.
Man, you did it! No smoke, no mirrors! Just patience, and determination. Congrats!
One more little trick. As I said earlier, most drag cars run positive caster. Here's how to do it. Hold your new straight axle looking at it from the side. The front of the axle will be on your left. Now pivot the axle clockwise until the kingpin points at one o'clock. This is postive caster. I wouldn't go more than that. With the axle still pointed at one o'clock, mark dead center at the top and bottom of the axle tube. This will give you a reference point for the vertical line when mounting the axle on the frame...Guy Beaudette
|This is a scratch built car. The front axle is from the MPC Garlits' first rear engined dragster. It's just been modified to pose (steer). Since he used the same front axle as he used on Swamp Rat 13, I figured I'd do the same. Notice the bellcrank centered in the frame, and both tie rods are connected to it, along with the draglink...GB|
|This is a scratch built dropped front axle. I used Plastruct plastic coated wire for the axle itself. It took me four attempts at this before I was finally satified. The parts were then shipped out to Chrome Tech USA for chroming. Notice the positive caster?...GB|
|This is a dropped front "T" beam axle. "T" means that, if you look at the axle from the side, it is shaped like the letter "T". It was first drawn out on a sheet of .015" sheet plastic, cut out, and thin strips of .015" sheet plastic were applied to the top and bottom of the axle. I didn't think this was going to work, because that thin sheet plastic is pretty flimsy. But, once the thin strips were applied, it reinforced it pretty well. Notice the slots in the axle? Those are what are called "lightening holes"...Guy|
Guy also provided this commentary on his Mr. Norm car (seen above) regarding leaf springs:
To get the arch in the spring, the first thing you need to do is determine the mounting points on the frame. Once that is done, install the eyelets in the mounts with the mounting pins you're going to use. On this model, I used .030" plastic rod.
Next, attach the first plastic strip to each eyelet, making sure it matches the desired spring arch. Do the same thing to the other side, making sure the strips are of equal lengths. Once that's done, the base spring is in place. Now, begin installing the rest of the leaf springs to the base spring. Once that is done, remove the retaining pins from the eyelets, and paint them.
And, regarding the Mr. Norm frame and floor pan, Guy adds, "yes sir, it's all scratch built!"
This shot is a little dark. Had all kinds of light on it too. Anyway, this is the kit front axle drilled out, and made to steer. The front tires? They're 1:1 scale Chevrolet brake caliper "O" rings.
I made the leaf springs on my 55 Chevy from the printing plate aluminum I use for most stuff I make. The perches were made from same stuff...Mike Morgan
|The photos to the left illustrate a couple of tools that Mark Brown devised for leaf spring work, The photo on the left is a spring arching tool made from a small piece of hardwood, should you prefer to use kit parts. For more information on it, see our tips page. The photo on the right illustrates Markís spring eye tool. The eye tool is made from a ground down pair of needle-nosed pliers, and is used where metal springs are preferable.|
|Take a length of aluminum tubing (size depends on application); using a hobby knife, clean out the inside of the tubing. Use sandpaper or a sanding stick to de-burr the outside.||Roll the end of tube using a smooth and fairly solid oject (I use a tweezer handle), and rolling it back and forth while applying force on it with your finger. Roll|
it only enough to form a nice, snug fit to the rod youíre using in this application.
|Cut tubing by rolling it back an forth until it seperates. Determine what length to use based upon your application. Leave it a little long; it's easier to remove than to add on!||Not a very good shot, but if you do it correctly, you can almost close the end completely--Iíve made overflow tanks and shock absorbers this way.|
|Check fit to rod. It should be nice and tight. If itís too loose, roll it more closed as shown in step 2.||Using a pair of smooth jaw pliers, squeeze the end flat.||Drill the appropriate sized hole to fit your application--I use a lot of plain old straight pins for connectors. They come in a few different sizes, so look around and see what you can find. This is also a good place to use pieces of plastic hex rod to create bolts.||Using sanding sticks, sandpaper or small files, form the rod end to the desired shape.|
|After the rod end is partly smoothed out, you can polish it out to make it purty. Just be prepared to make another one after this one flies across the room! (Seems to me that safety glasses may be in order for this step!...ed.)||Now, if you spend more than the five minutes I took on this one, you should have a reasonably good looking rod end without spending much, and without driving all over town looking for ready-made stuff...Mike Morgan|