to my friend Ingelbert for transferring my plate designs onto a CAD program for me; and, oh yes, thanks to you Jim Wilson, for providing to the kustom bike world the most important (and influential) forum there is on the subject, bar none! Cheers Jim! John B. |
Click Here for a dimensioned drawing sheet which fits onto an 8.5 X 11" sheet from any ink-jet or laser printer. |
Click Here for a pattern sheet which you may print out for use as actual size templates for cutting and drilling parts. Cut the templates out from your 8.5 X 11" paper printout, and use spray adhesive to adhere them to your metal stock. |
Readers of our interview with Mr.Brain in our last issue probably found themselves asking: "Where does he get those springer forks for his choppers?" The answer, of course, is that he makes them himself. Now, he shows you how he does it, in complete detail. Happy Building! JimW. |
Introduction: Springer forks are one of the most highly desired of all kustom bicycle accessories. For years now, production spring forks like the "Schwinn" style units have been the first choice for many kustom builders. In the last year there has also been a great deal of renewed interest in long "chopper" style springer forks, like the kind once used on some kustom bicycles back in the late 1960's and into the 1970's. For those of you who would like to make a set of these "springer" forks (rather than buy a factory-made example for $200 to $700) we offer you the following example of how you might accomplish the task. This fork design does not require any specialized fabrication work (like laser cutting) to accomplish. If you have the means to cut straight lines in ¼" plate metal (as with a cutting wheel) and can get up to a 1-inch hole drilled, then this project is well within your reach. How much? The out-of-pocket expense to make this fork was about $70. It may cost you a little more, or a little less, depending on where you can save money on materials and welding; and, you will get the satisfaction of knowing you built it yourself. We start by gathering: |
Un-cut material, parts and pieces used in this springer build (yours may vary): Mild steel plate: (1) One: Plate ¼ inch x 3½ inches x 12 inches (spring plate) (2) One: Plate ¼ inch x 1½ inches x 12 inches (upper fork plate) (3) One: Plate ¼ inch x 1inch x 24 inches (spring pedestal bar& rockers) ---------------------------------------------------------------------------------------------------- (4) Two: Lengths of round mild steel tube (or rod) ½ x 12 inches (spring rods) (5) Two: Lengths of 5/8th O.D. mild steel tube 4 feet long each. (upper fork tubes) (6) Two: Lengths of 1 inch O.D. mild steel tubing 1/16th wall thickness 4 feet long each (lower fork tubes) (7) Two: Springs: 5 inches (Long) x 1 9/16th (Width). (Large compression springs) (8) Two: Springs: 3 inches (Long) x 1¼ (Width). (Small rebound springs) (9) Four: 1¾ inch car engine block "freeze plugs" (spring retainers) for the large compression springs. (10) Four: Nuts ½ inch (13 thread) (11) Six: Bolts, ½ inch (13 thread) x 1 ½ (4 rocker bolts and 2 for spring rod threads) (12) Four: ½ inch Lock washers (rocker bolt assembly) (13) Ten: Flat washers (small) with ½ inch holes (14) Six: ½ (13 thread) Acorn nuts, (15) One: Head tube 5 inches (16) One: Threaded steer tube 8 inches long. (17) One: Head set to fit 1 inch threaded steer tube. (18)-Five Chrome hole plugs: Three 1-inch plugs, and two ½ inch plugs. |
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Printable Specification and Pattern Sheets: We have provided larger versions of this specification drawing for more convenient use. |
Ingelbert Lievaart III |
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NOTES ON THE ABOVE MATERIALS: (Parts, prep and sources) |
Mild steel plate (below left) Was obtained from a local steel supplier, many steel retailers sell by the foot but will cut to length on request. It may be easier and more cost effective in the long run to have your supplier cut the plates to the basic outside dimensions (especially the large pieces). It is possible to cut any of these pieces with cutting wheels, band saws, or even hacksaws (on the smaller pieces). Use what you have available. (below right) Refer to the plate specifications (below left) and use it as your guide on where to cut and drill metal plates. |
Spring Rods These are made from two ½" O.D. mild steel rods (or tubes) that have a ¾" long threaded end. The spring rods are welded onto the spring pedestal bar, 2 ½" apart so that they slide easily inside the 5/8" holes in the spring plate during use. To get a threaded end onto the rod (or tube) you can weld on a threaded section cut from a ½" (13 thread) bolt . ½" O.D. tube may be harder to obtain than solid rod, again, use what you are able to obtain easily. |
Solid ½" rod can be bought from any steel supplier or hardware store. Final spring rod length is measured from where the rods are welded onto the "spring pedestal bar" to the top of the mounted spring assemblies (minus acorn nut). Cut the threaded length of spring rod accordingly. The top of the spring rods should be flush with the top of the mounted upper springs (left). When the acorn nuts are screwed on they will slightly compress the springs. Make sure you equalize the lengths of the two rods as closely as possible before welding. |
Springs. I obtained these springs at a "TSC" (farm, home, auto) store. These springs are also available at many hardware stores like Lowes and "Ace" hardware. The large compression springs are actually "porch swing springs" that have had the ends ground flat. (The photo below left shows the spring on left with its end ground flat, the spring on the right is untouched). The spring ends (on ALL springs) needed to be ground flat in order for them to seat properly in the spring retainer cups, and to equalize their height to each other. The small "upper rebound springs" (below right) are actually riding lawnmower (under-seat) springs from a Yardman mower (ask at the order counter to get some). Both these springs are the perfect size and strength for this application. It may also be necessary to weld a washer onto the open ends of the small rebound springs (to use as spring retainers) in order to keep them centered on the spring rods. Readily available flat washers (with a ½ inch hole) fit perfectly on the end of the Yardman seat springs. |
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Spring Retainers Retainers (right) keep your springs in place so they don't wander. The spring retainers for the large compression springs were made from auto engine block freeze plugs. They can be ordered in many sizes from auto parts supply stores. I bought 1 ¾" plugs to fit my "porch swing springs". Each one will need a ½" hole drilled in its bottom center (for the spring rod to go into). Make sure the hole is big enough for the retainer to slide easily on the spring rod. For the small rebound springs you can weld flat washers to each flattened (ground) end, this will keep the mounted springs in place. |
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Acorn Nuts These closed-ended nuts are used on the tops of the spring rods (above, top) and on the ends of the rocker bolt assemblies (left). They are ½ "-13 thread. It may be necessary to buy these from a specialty fastener supplier, as many hardware stores don't carry this large size. If you can't locate these nuts easily, you may substitute similar size lock nuts (but they don't look as good). |
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Head Tube This springer was designed to fit into a frame with a 5" head tube. To help in the accurate construction of this bicycle springer project I cut the 5" head tube off an old frame to use during the mock up. (right) It's much easier to construct your forks with a cut off head assembly. Used in conjunction with a threaded steer tube and "head set" it allowed for very accurate measuring and cutting of the other fork parts (especially fork tubes). Find an old frame with the same size head tube as the frame you intend to use, and cut it off for use during welding and assembly. |
Steer tube For this project I used a 1" threaded steer tube. I prefer them for this kind of project over threadless units. You will need to find a pair of donor forks with a threaded steer tube 2 or 3 inches longer than ones used on a stock 5" head tube frame. You need to cut the threaded tube off of your donor fork close to the base (only to be cut again later) You need the extra long threaded steer tube because of the way this springer is constructed. After cutting you will be left with a straight tube about 8" long with the thread on one end. |
Chrome Hole Plugs Hole plugs (below) are used in the furniture and automotive fields as decorative covers. They are available in many different sizes, and are available at fastener supply houses, and in the hardware departments of many large stores like Lowes and the Home depot. Use them to fill the open ends of the 1" and 5/8'" tubes. |
PREP AND ASSEMBLY SEQUENCE A: Gather all the raw material, parts and pieces together. B: Cut your mild steel plate according to the diagram, and then drill the holes. Drill all the 1" holes of the upper fork plate and spring plate together (if you can). Drilling with one plate on top of the other will help the 1" holes line up better when the fork tubes are inserted. Be as accurate as you can with cutting and drilling. --File the outside corners of all plates to round off the edges. |
Click Here for a pattern sheet which you may print out for use as actual size templates for cutting and drilling parts. Cut the templates out from your 8.5 X 11" paper printout, and use spray adhesive to adhere them to your metal stock. |
Click Here for a dimensioned drawing sheet which fits onto an 8.5 X 11" sheet from any ink-jet or laser printer. |
We hope this "springer fork" assembly guide will be helpful to you. A "Do-It- Yourself" article on this subject has been one of the things most requested from both the readers of Bike Rod & Kustom and from the many participants of kustom bicycle group sites on the internet. We want to say "thank you" to all those individuals whose interest and requests made this project come together, we enjoyed doing it for you. All the best, John Brain |
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M: REMINDERS --Make sure that your threaded fork tube will accept the handlebar stem you want to use; some tubes will only accept small stems. --If you want to use motorcycle style risers on these forks you will have to put a threaded bung into the 1" fork tubes and weld flat washers to the top of the upper fork plate to cover the fork holes, so you can bolt them together. This way you will have a firm enough mounting to use motorcycle style risers. The springer build as shown is designed for use with a handlebar stem as normally used on threaded fork tubes. --Finish by inserting the "chrome hole plugs" into the open tube ends on the fork tubes and steer tube bottom. -- The upper fork plate is removable so that the complete fork assembly can be taken off the bicycle frame (do not weld the upper fork plate on. |
L: FINAL PREP AND WELDING --With all the individual parts prepared and cut to length you can do the final welding of the upper and lower fork tubes. --Completely assemble all the springer parts including the steer tube and head assemblies (photo#19 )), This includes mounting a front wheel. --Put the fork assembly on top of a small welding table as shown (photo#20) --Assemble the springer so that the fork tube ends are flush with the tops of the plates they match up to. -- Use the 4 rocker bolts to firmly set positions by tightening(( photo#21 )). --The round ends of the 1-inch fork tubes should be flush with the upper fork plate top ( photo#22) --The 5/8" upper tube should be flush with the top of the spring pedestal bar. ( photo#23) --Adjust the forks until the wheel has perfect visual alignment in the assembly, along with tubes being flush mounted in their respective fork plates (photo #20). --Once you are convinced that the fork assembly is correct (not twisted) and the wheel has proper alignment, you can tack weld the fork tubes in place. --The welds are done on the sides of the plates that are facing the wheel. --Once tack welded visually check again for structural correctness ( photo #20 ). --Complete the welding of the 1" lower fork tubes to the spring plate, and the 5/8" upper fork tubes to the spring pedestal bar. --Readjust the rocker bolt assemblies (photo #10) so that they allow the rockers to move freely but with virtually no side play. The front wheel should feel tight and not move around because of play in the rocker bolts. |
K: CUTTING THE FORK TUBES --Disassemble (remove) the fork tubes --Bolt each matching pair together with a 1/2-inch bolt and washers --Cut the pairs together to the length you determined during the mock up (one length for the lower forks and another length for the upper forks). --By cutting pairs together they will both be the same length when measured from the ½ " mounting hole on the flattened end. |
J: UPPER FORK TUBE LENGTH Once you have determined the length of your lower forks you can measure the upper fork tubes for cutting. --With the Lower forks measured to final length on the bicycle, and the rockers tightened into final position you can take one of your 5/8's upper tubes and insert the round end in the hole on the spring pedestal bar. You then bolt the flattened end onto the rocker. --Mark the excess 5/8s tube above the spring pedestal bar for cutting. (see photo# 18) |
I: Determining the length of the 1-inch fork tubes --To illustrate this article we built these springer forks to fit onto the frame of an existing kustom bicycle. --The welded spring plate and steer tube assemblies were mounted onto the bicycle, along with the welded spring rod/pedestal bar, and complete spring assembly --The uncut Lower fork tubes were then installed ( photo#15 ) --The rockers were bolted onto the flattened fork ends with ½ " bolts. The front wheel was mounted to the forward 3/8" hole in the rockers. --The rockers are like levers, they push the upper fork tubes which in turn compress the large springs, giving you a spring-loaded suspension. Rockers connect the wheel to the fork legs. --The ½ " rocker bolts were tightened firmly at this point so that the rockers would remain in the determined final position. --(Photo#16 ) shows the unmoving tightened rockers on the end of the lower fork tubes. The front of the rocker is angled up slightly from horizontal. --The un-welded fork tubes can be moved up and down inside their 1" plate holes, allowing you to match the length of the fork with the frame you want to use ( photo#17) . -- Determine how long to make your forks so you have the look and pedal clearance you want. --Mark off the excess tube beyond the top of the upper fork plate (photo#15 ). |
H: FOURTH WELD --The spring rods are welded onto the pedestal bar 2 ½ inches apart (photo# 4 ) the same distance apart as the 5/8'' holes on the spring plate. The spring rods and the 5/8" holes "mate" so that the rods will slide easily in them. --When welding the spring rods onto the spring pedestal bar make sure the rods are welded perfectly vertical to the pedestal bar. |
G: Determine spring rod length. --Put one of your 12-inch uncut threaded spring rods through one of the 5/8" holes in your spring plate. --While holding the spring rod in this position mount both the upper and lower springs (and retainer cups) onto the spring rods. --Position the rod so that the top of the threaded end is flush with the top of the upper spring ( photo #5 ), at the same time press the entire upper and lower spring assembly together snugly. Mark off the excess spring rod at the bottom retainer cup, making sure that the threaded end is still flush with the top spring. --Once you have one spring rod marked cut both to the same length. --The length of my cut spring rods was exactly 9". |
F: SECOND AND THIRD WELDS --Weld a ¾ " long ½ " 13-thread section to the ends of your two Uncut spring rods. You can use a section cut off a bolt for this. --Weld a flat washer with a ½ inch hole onto the open ends of the small upper rebound springs to act as a spring retainer. |
E: FIRST WELD With the entire upper assembly together ((photo # 13 )) stand it up on end (steer tube "cap nut" down) on your welding table. --Hold the spring plate, and as you're pressing it down into what will be its final position you will feel when it seats properly on the bearing/steering assembly underneath. - The steering tube end should be flush with the face of the spring plate. --While holding the spring plate in this position (carefully like I did) have your welder tack the spring plate and steer tube together. --Double check this tack welded assembly to make sure that everything is aligned and sitting properly together. Adjust the head set to check for proper movement when tightened. --When you're sure that the components of the tack-welded assembly are |