The easiest frame to build is a traditional old-school style chopper since there aren’t any complicated bends or compound miters to cut so we decided to show the chassis fabrication process from A to Z as we do it. The process described here may not be the best way to build a frame and it certainly isn’t the only way. Others probably have different techniques. This system has worked for us over the past thirty years and guarantees that a first-time builder can create a good straight frame using a minimum of special tools or really fancy jigs. About half of the frame can be constructed without a traditional building jig being used so this is a good project to start with if you want to build a frame jig but you don’t have a frame to use as a mock-up.
As work progresses on the chassis you can fabricate a jig one piece at a time when it’s needed. The frame for this particular project is derived from the stock Harley Davidson 1948 Factory Rigid design that has formed the basis of every chopper ever made. We stretched the down tubes about four inches over stock, the backbone two inches and raised the rear axle plates one inch and shifted them rearward 2” to lower the entire frame one inch and create a straight line between the steering neck and rear axle shaft when the bike is viewed from the side giving it a classic wedge-like chopper profile without an extremely high neck. These instructions are actually part of the material that used to accompany our large-scale building plans and this is the first time we have published them separately.
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We’ve tried to make the small diagrams and photographs readable within the limitations imposed by the letter size page format but I am sure that some parts of the fabrication process will remain unclear without the prints. If you reach a stumbling block on your project larger format images of some assemblies, like mount dimensions for instance, are available in the appendix or on the website. The frame we’re going to be building here will accept Panhead, Shovelhead and Evo motors and all transmission types from early four-speeds to modern six-speeds. It is designed to use a 140 tire with belt or a 150 with chain and the budget is set not to exceed $1500 up to the point of having a complete rolling chassis. Part 12 In Part 11 we more or less finished up the major portions of putting a frame together but there is still a lot of work to do and in many ways the last 10% of frame construction will take up 90% of the time involved in finalizing a typical cycle chassis. Once I can put wheels on a frame, even if the forks have to be a set of wooden dummies, I like to take a few days and even weeks to consider what I've built and to decide on how I want the bike to look when it's finished.
I'll leave the bike in pretty much the same stage as you saw in Part 11 and if possible, weather permitting, I'll park it outside where I can see it from a distance and from a variety of angles over the course of several days and even weeks if need be. I'm not ashamed to admit that I sit on the frame and 'imagine' how she'll be to ride. I sometimes make mockups of the handlebars, foot pegs, shifter position and other 'control' types of features until I'm satisfied that I have a chassis that 'fits' not only my body but my riding 'style'.
In other words I try to fit the 'control' parts of the bike to fit my stature and posture. On the other hand I want the bike to have a certain 'look' but I won't sacrifice riding comfort for appearance so I make compromises back and forth for several days until I'm satisfied with both 'look' and 'feel' before I start to do any more welding. The mistake most first-time builders make is to simply bolt on a bunch of ready-made parts in a rush to finish the project and bikes built this way will show it. In photos they appear awkward, out of proportion and unbalanced with respect to the size and placement of the ancillary components. The human body comes in all types of sizes and shapes but regardless of the differences they are all proportioned in ratios that architects long ago recognized so when you're building a bike the shape of the human rider has to be a major consideration in the design and fabrication process and the best 'formula' to use in this endeavor is the real body of the rider that the bike is intended for. This is what real choppers are all about. They are created for an individual and this very fact is what makes them so distinct from mass produced cycles.
No matter how hard I try I can never give you any 'magic' dimensions for building frames or any 'secret' measurements for choppers that create the 'perfect' bike as each one will be unique. In fact if they weren't unique they wouldn't really be a chopper regardless of how they looked outwardly. Building a 'real' chopper is a lot like building a Rolex watch. You assemble a bunch of bits and pieces that you've pretty much 'standardized' on but as you put them together you deviate from the 'standard' and fine tune and fine-fit the various individual pieces until you have a unique creation that functions both mechanically, ergonomically and aesthetically. When you get aboard a truly custom built chopper you're not just a rider, you become a part of the machine and function as a single unit, which if you ever experience it you will come to understand, but very few people ever have this chance because they rush through the project believing mistakenly that the end result comes from just bolting on parts and components. Figure 6.97 below shows the Old School Chopper as it now stands in the shop during the 'think about it' phase of the project. We're thinking about a Sportster tank at this stage but we haven't decided whether to mount it low, high or in-between.
Figure 6.97 Modifications The Classic Old School frame project was intended to illustrate a simple way to build a relatively inexpensive lightweight chopper much as we did in the early sixties with a minimal amount of specialized tooling. Things have changed over the last thirty-five years, especially in the area of power plants and drive trains and if you’re planning on building a bike having much more than the stock 60 horsepower Harley-Davidson motor, or a bike that weighs more than 480 pounds there are some modifications you should make to the basic frame. One area that can be strengthened is the seat-post cross member. You can and should substitute the.120” wall material for thicker-walled stock. Conversely, keeping the original material specification you can drill an angled hole for the seat-post and weld it at each of the termination points, top and bottom.
Figure 6.98 Figure 6.98 illustrates a typical drilled-through cross member. To do this accurately does require the use of a good drill press with an adjustable table since the hole has to be drilled at the angle of the post. Figure 6.99 Figure 6.99 shows the seat post inserted into the cross member viewed from the upper side. Figure 6.100 Figure 6.100 depicts the cross member and seat post viewed from the bottom. Note that the bevels for welding have not been ground-in at this stage when the pictures were taken. The seat post will be welded along the top penetration point and around the perimeter at the bottom as well. This results in a very strong connection and has the added advantage of giving a completely open route for concealed wiring back down under the frame.
Unfortunately it entails a lot more fabrication work and if the bike is not intended to house a performance motor it isn’t really necessary. For a fairly hot bike you might also want to increase the wall thickness of the seat post from.120 to.134-inch but I would not increase the diameter of this member. For a high-performance frame you should also increase the wall thickness of the backbone from.120” to.134” or keep the same wall thickness and increase the diameter of the tubing to 1.375” in lieu of the 1.25-inch specification. For a frame intended for real high performance work you might also consider ‘drag-struts’ to tie the upper wishbones and lower rails together just ahead of the rear tire. This used to be common modification to stock frames and in effect what you’re trying to do is to simply reduce the lengths of unsupported tube runs and it can be done in several different ways.
Figure 6.101 Figure 6.101 shows a simple strut common on vintage bikes, in this picture located more towards the axle adjuster, but you’ll also see them reversed and running along the same line as the rear tire, more in line with the fender shown in this particular photo. Figure 6.102 that follows illustrates struts installed on an old Indian 640 frame. They don’t look like much but this simple modification more than doubles the stiffness of the rear tubes on a typical bike. Figure 6.102 Copyright © 2003-11, All Rights Reserved.
These plans are freely available from Crime Scene Choppers, they outline the construction of our frame jig as shown in Ron Covell's new 'Building a Chopper Chassis' video. Few of the dimensions or material callouts are critical.
The width of part #6, the frame rail fixture, is determined by the ou tside width of your lower frame rails. Typically, the inside width is 8 3/8', so the outside width is 8.375 + 2. the diamater of your frame tubing. Check the alignment of your parts carefully as you work, a warped jig is worse than no jig at all!
7 8 6 5 4 4 6 5 4 3 3 3 3 3 1 2 1 2 ITEM NO. D E S C R I P T I O N L E N G T H 1 2 T U B E, R E C T A N G U L A R 3. 1 3 9 6 2 2 B A R S T O C K, R E C T A N G U L A R. 5 x 2 F l a t B a r 9 6 3 5 T U B E, R E C T A N G U L A R 3. 1 3 6 4 2 T U B E, R E C T A N G U L A R 3. 1 3 2 3 5 2 T U B E, S Q U A R E 2. 1 3 1 0 6 2 B A R S T O C K, R E C T A N G U L A R 0.
2 5 x 2 f l a t b a r 3 7 1 T U B E, R E C T A N G U L A R 3. 1 3 2 4 8 1 T U B E, R E C T A N G U L A R 3. 1 7 9 10 5 3 8 8 6 1 3 2 1/2' thick plate, 6' wide x 7' long with 2' x 3' rect. Hole in center 6.000 7.000.750.750.500 Stitch weld 2' x.5' flat bar to 2' x 3' tube then set up in mill and machine a 1/2' slot for the length of the tube. P A R T N U M B E R D E S C R I P T I O N Q T Y.
1 N e c k F i x t u r e 1 2 S l i d e r M e c h a n i s m 1 3 B o l t P l a t e 1 4 H H N U T 0. 5 0 0 0 - 1 3 - D - N 1/2'-13 nut welded to top of #3 1 5 P i v o t P l a t e 1.75' x 1.75' square bar stock 2 6 N e c k P i v o t 1 7 a l l t h r e a d 3 / 4 ' - 1 6 t h r e a d e d r o d 1 8 N e c k C o n e 45 degree cone to hold steering neck 2 9 D K A - 1 3 R e i d T o o l 1 1 0 S D K A - 1 3 R e i d T o o l 1 I T E M N O. D E S C R I P T I O N L E N G T H 1 1 T U B E, R E C T A N G U L A R 2 x 3 x. 5 2 1 B A R S T O C K, R E C T A N G U L A R. 5 x 2 F l a t B a r 2 6.
Building a motorcycle in your garage or in a small shop with minimal tools is no small feat. But it can be done and hobby bike builders are doing it successfully, even on their first attempt. You can build a chopper frame on your own. The satisfaction you will get from building the frame alone is hard to put into words. In the article I am going to cover a lot of subjects that cover in detail what is required to build a quality chopper frame. I will cover:.
Jigs. Tools. Tubing. The Fabrication Processes. Welding, and much more!
If you want to build a motorcycle from the ground up you will start with the frame (or chassis). Some first time bike builders like to start with a pre-made from or rolling chassis and then piece the bike bit by bit from there. And that is a good idea because it will give you the experience you need when building from scratch.
But we want to build a chopper frame so lets begin there. Although it's possible to build a frame without a jig it's not a good idea.
A jig is a massive help in the frame building process because it holds your frame together as you do your mock up and welding. Without a jig it's very difficult, time consuming, and it's much more likely you'll get a bent frame. Commercial chopper frame jigs are very expensive. The beginning price could be anywhere from $5,000 upwards for an adjustable jig. The jig would have to be tailored to the bike design, or be infinitely variable. In either case, the cost would be prohibitive to the small shop or the individual builder. To build a jig yourself, and I mean all the machining and other work yourself, you will have to invest anywhere from $200 to $700 in materials alone.
If you tackle this job yourself, remember, it will always remain a 'work-in-progress' as you fabricate your frame. To the above right is an example of a builders Jig. Notice the adjustments that are available for the steering neck, rear axle plates and seat post. There are four leveling adjustments on the feet extending out from the parallel rails. As long as the jig base (parallel rails) and the vertical assemblies are perpendicular to the parallel base rails, accuracy will be achieved in the frame.
Many builders use actual major components such as engine, transmission, rear wheel and front forks to ensure accuracy of alignment. Just because you have a jig to setup the tubing for welding, does not ensure that you will have a perfect frame. The tubing should be mitered and fitted such that the junction fits easily together. If you have to force it, you have done something wrong. These tools come in all shapes, sizes and prices. One supplier for tube bending and tube notchers is Pro-Tools from Tampa, Florida. The link to their site is located in the RESOURCE section of this document.
Another supplier of tube benders is Williams Lowbuck Tools, Inc. In Norco, California. You will also find several other suppliers in the RESOURCE section. A common question is whether or not a pipe bender can be used to bend tube. The answer is.not if the inside diameter (I.D.), and tubing is measured by the outside diameter (O.D.). Another difference is the wall thickness. For our example projects, we are using tubing with a 1.25' diameter, and a 0.125' wall thickness.
Some tube bending machine suppliers emphatically state that you absolutely cannot use a pipe-bending machine for tubing. Don't be fooled into thinking that you can use a pipe or conduit bender for bending tubing. Tubing is tubing, and pipe is pipe, and never the twain shall meet! Yet there is a noted frame builder who states that if you are in near desperation and still need to have your frame tubing bent, you can use a 1' thick-walled conduit bender to do the job. The rigid electrical conduit is nearly the same as the outside diameter of ERW tubing. But don't plan showing the bike at some of the better shows. So there you have it.
If you have a choice, your preference should be to use the right tool for the job at hand. Other tools used for measuring include a decent tape measure, carpenter’s bubble level, a steel rule, a machinist’s square, and a nine-inch caliper. There are 3 types of tube used to build frames. They are Chromemoly, DOM, and ERW.
ERW = Electric Resistance Welded. This type of tubing is created with mild steel. The tube is created from a sheet of mild steel, and then it's rolled up. DOM = Drawn Over Mandrel. This type of tubing is basically the same as the Electric Resistance Welded tubing except that it has been put through an extra process to take out the imperfections which are supposed to give it more stability (strength). Chromemoly is a type of alloy that has both Chromium & Molybdenum and has more strength than the other two types above.
But it's a bit lighter. The most common type of tubing used for chopper frames is DOM. But ERW is nothing to scoff. Design Integrity By definition, design integrity is the quality, or state of being complete or undivided. This includes a singleness of purpose in the fabrication of a motorcycle frame. If the frame fails, EVERYTHING fails! Everyone involved in the process must have the same goal as the designer.
The materials must be of good, uniform quality. The miter joints must be done properly and the welds must meet established minimum standards.
Any compromise in frame integrity could result in premature failure and personal injury to the rider, or even death. The designer should define the standards to which the frame is to be made, and demand that those standards be adhered to. Standards would include definitions of all materials used plus the definition of an acceptable weld and overall workmanship.
In addition, all material standards that will be acceptable, and expectations of the overall design should be clearly outlined. Before any successful project fabrication starts, the designer must have a goal in mind, as well as product expectations or there could be chaos. Imagine a motorcycle cruising down the highway at 70 mph, and the frame suddenly comes apart because of poor design or quality of workmanship or materials! The point to be made is simple! Make absolutely sure that every aspect of the project has been carefully considered in detail. You cannot allow for any compromise. The standards do not necessarily have to be detailed data sheets, but should at least be considered and noted in writing.
Hopefully you wouldn't build a house without a set of plans and specifications. The same should be true in most other projects undertaken. Now comes the time to pull together the first union. Before you jump headlong into the project, you need to have a plan, or at least an idea of your finished product. A sketch will work if you dimension the drawing together with tubing angles.
Without at least this amount of detail, you will most likely have a misaligned and warped mess that you may as well schedule for the dumpster. Using your drawing as a reference, select the seat post where it joins the backbone. Cut the seat post to length according to your drawing. Leave a little extra space just in case you need it for final fit. If the final piece is too short, you just start the seat post over again. Clamp the seat post tubing and make the rough cut with a notcher.
To finish the miter, use a half-round file to form the miter for a good fit to the adjoining tube. This is one of the reasons for leaving extra length whenever possible. Notice that the mouth does not come to a knife-edge. This would produce a poor penetration of the weld, and therefore a weak joint. Now comes the fun part. Bending tubing!
This guide is not intended for step-by-step procedural instructions on how to bend tubing. That generally is supplied in the manual that comes with your bender. If there is not a manual there, contact your vendor. You will find, however, the pitfalls you need to watch out for in tube bending.
The biggest problem is inaccurate measurement, or selection of incorrectly sized tools for your bender. This could result in several problems such as overall length error, bend angle error due to failure to consider springback, bend deduction distance error for a given O.D. Of the tubing, etc. Another problem could be the measurement of the bend angle, or rotation of the frame tube in compound bends. Any of these issues could hamper the assembly of the frame. Bending tube comes with a unique set of problems that could cost a good sum of money in scrap material.
If the bend measurements are grossly incorrect, resulting in overall dimensional error, you have just created a piece of scrap. Now if the angles are correct and the final length is too long, you are probably okay, so just trim the excess. Material Preparation: Material should be thoroughly cleaned to remove all scale, grease or oil residue. Parts to be welded should be properly fitted to each other, aligned and maintained in position during the welding process. To maintain alignment and position, clamps, bars, tack welds or other means may be used during the welding process. Flat Welding: Flat welding is just as the name implies. Welding of horizontal or vertical planes can generally be termed as 'flat welding'.
Preparation is the key to any welding, but more so in flat welding. Butt-welding requires that the two pieces of metal be prepared with a recess or angle to permit better penetration of both ends being joined. Butt-welding generally refers to flat stock or pipe, but can also refer to tubing as well.
However, butt-welding of tubing for aerospace and medical applications is usually accomplished by use of computer-controlled orbital welding machines. Tube Welding: Since the focus of this report is the fabrication of Chopper Frames, we will concentrate mostly on manual tube welding as opposed to orbital welding. In our process, we can choose to use MIG, TIG or Stick welding. Some people insist that the 'wire feed' arc welders are better than the conventional 'stick' method. The argument for and against TIG, Stick, and MIG welding is almost as old as the first motorcycles ever built. The preferred method is TIG because it is a very smooth and strong weld. But then again, you can get similar results from MIG welding.
And Stick welding is nothing to scoff! I know welders in their sixties who have fabricated some works of art with an old 'buzz box' welder (an old stick welder). In truth, there is no difference in characteristics or quality of weld. The 'wire feed' systems are faster than 'stick' welding, but when using one of the 'wire feed' methods for welding tube, the advantage of the speed is lost. So, which one is really better? The opinions out there are as many and varied as the welders that use them. Whichever system fits you and your application, then that's the one for you.
So if you were to twist my arm I would say TIG weld your frame. But TIG welding requires skill and practice. It's not easy, and TIG welders are quite expensive. MIG welding and Stick welding is easy. MIG being is the easiest of the three. So if you are not experienced or your funds are limited, go with a good stick welder. You can buy excellent ones for under $400, and good ones under $200.
Buy a name brand like Lincoln or Hobart. Norther Tools and Eastwood make pretty decent ones as well. Welding is an acquired skill that borders on being an 'art form'. It takes practice to produce a good weld.
Don't think that a 'pretty' weld is necessarily a good weld! You see only the surface and not the depth of penetration. Don't be afraid to take a few pieces of scrap and weld them together. After the weld has cooled down, use a band saw or suitable type of saw to cut across the weld.
You can then see the degree of penetration (or lack of), which will let you know real soon just how your welding is! Below is an example of what I am talking about. The picture here is a TIG weld. Notice in the first photograph how the bead blends well into the metal without a lot of buildup of metal.
But you can't tell about the penetration between the tubes without an x-ray of the junction or cut the junction in two. Look close at the photo on the right, and you can see the penetration between the lower tube and the upper tube.
Generally you would not cut your frame in half to see how good your weld is! This is a practice piece. Non-Jig Assembly To be clear.it is possible to build a motorcycle frame without a jig. Various tools, crutches, and other 'insider' methods can be used, but unless the issue is one of cost, it would be very difficult to imagine anyone wanting to build a bike 'free-handed' when a jig makes the process so much easier. However, if you are intent on NOT using a jig or have no ther choice, lets get at it! Non-Jig Assembly As mentioned earlier, you need to have a plan, or at least an idea of your finished product before getting to started.
A sketch will work if you dimension the drawing, together with tubing angles. Without at least this amount of detail, you will most likely have a misaligned and warped mess that you may as well schedule for the dumpster. Frame Drawings There are several good sources for drawings if you don't already have a set. The main one that comes to mind is Custom-Choppers-Guide.com. They also carry plans created by BCC Orlando and offer extra stuff for ordering them. Okay, now that you have drawings in hand, lets work on getting the necessary tubing and other miscellaneous steel parts gathered together The tubing we're going to use is 1.125' x 0.120' ERW, unless otherwise specified in your drawings. If you don't have a source for tubing, you can find several under the topic of RESOURCES in this document.
Next you miter the various components of the frame and check for good fit. After you finish with this process, you can begin piecing the frame parts together as depicted in the example below. This section is somewhat akin to a jigsaw puzzle.
After you have bent and mitered the tubing, you need some way of temporarily holding things together. Lets assume that you have perfect measurements, angles and orientation.
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Since we're not using a jig, we need to get to as level a spot as possible in order to start the assembly process. The next figure show one method of holding the pieces together for tack welding. Frame Alignment: To align the frame during the assembly process, use the motor (engine), rear wheel and front forks to verify fit and alignment.
As you can see from all of this, you need four arms or two people to work together. You can imagine how the frustration can potentially build up. Place major assemblies into the frame to verify alignment. Of course if they fail to line up properly, you have some adjustments to do.
This is why the frame components are only tack welded. You still have a chance to salvage the hard work you have done on the frame. After you are satisfied with the parts placement, you can begin welding the frame together. Of course there are many other ways to assemble your frame without a welding jig.
This is only one way to accomplish the task at hand. You can see from the examples that there has to be a better way to get your frame together correctly and that is why we recommend a welding jig. If you want to build your own jig, there are numerous sources for the plans, including Custom-Choppers-Guide.com.
You probably already noticed that these are the same sources for frame plans. Buy them both at the same time and you just might get a discount. The welding jig must be mounted with all four corners level. The leveling platform should be elevated to knee height. This could be a series of blocks or a welded frame upon which you place the leveling platform.
Any suitable arrangement will work, just as long as the jig is level. After the platform is level, you can then place and mount the verticals to the platform. Picture 1: Frame with engine and transmission mockup is located in the jig for alignment adjustments and tack welding. After alignments are satisfied, the frame can be welded together. Picture 2: This frame has already been tack welded together, using the jig. This is by no means an exhaustive guide on the building of Chopper frames.
It does however give you a frame of reference for what must be done to build a Chopper frame. The skill level required is alluded to throughout this article. Familiarity with basic hand tools is a definite requirement, as is the use of welders and tube bending tools. It's up to you now to take the first steps. Get your equipment, plans, and start building! If you need any more help, resources, or encouragement please comment below:-).
Dick Allen Blueprint Frames Dick Allen and I had a couple of conversations over the course of two or three years about building 'custom' frames for chopped bikes. To be honest I didn't understand about 75% of what he was talking about because he was approaching everything about frame construction from the standpoint of going back and using stock factory frame geometry and then 'chopping' that stock geometry into a new configuration even though he was planning to do this using a completely new, built from scratch chassis. I had been taught a completely different work method by my old boss where we started with a clean slate, ignoring a lot of the factory frame geometry.
Using Dick's method, the frame builders main control point, where everything was measured from, was the intersection point of the backbone and the seat post. On the system I had been taught to use the primary control point was the intersection of the seat post and the seat post cross-member that runs between the lower rails.
His system worked from the 'top down' and the system I used worked from the 'bottom up'. Regardless of the method used, the objective was to basically build a new frame (or modify a stock one) so that it closely resembled a classic Drag Bike, at least in the profile 'stance' from a visual standpoint. Everybody wanted that 'wedge' look. There is no doubt that a ton of 'Chopper' design was done from the standpoint of building something that was visually appealing but there were practical engineering concepts embodied in these radical looking bikes gleaned from the drag strips. They were long with fairly well raked out necks for high speed stability.
The center of gravity was kept very low. Virtually all drag bikes are built around 'rigid' frames. The easiest way to get that 'look' was to modify a stock frame by 'raising the transmission' so to speak. On a chopper frame the raised tranny mod was a little more involved than what you'd do on a flat-tracker or hill-climber and involved 'chopping' the lower rails right behind the rear tranny mount and then bending the wishbones upwards until they aligned with the stock backbone tube. We did a separate article about this simple modification that can be found. This customization was probably one of the first things that most frame builders did back in the late fifties and early sixties. Most of us didn't start adding raked necks until around 63 or 64 and by 1965 almost everybody who rode a chopped bike wanted the 'raked' look.
Picture Frame Blueprints
Dick was from what I call the 'true old school' of frame hacking from back in the fifties while I was from the 'new school' of hacksaw wizards and there is a ton of difference between the two schools of thought. Dick's basic concept was to take the geometry from one of his modified stockers and then transfer that to a new line of production frames. Somebody nick-named these frames the 'Blueprint' series. Somebody said the 'name' came about because the first bike was going to be painted blue but I still think it was because Dick had actually had blueprints made of some drawings he had drawn or had somebody else draft up for the project. I distinctly remember him marking up a print for me at one time in 68 or early 69. I'm pretty sure I still have the dimensions stored away. Another alternative source of the 'name' may hark back to the old days when most shops had copies of the original Harley frame drawings sold by a whole host of blueprint shops as promotional items.
These were the old style prints where the line work was white and the background was dark blue. Most of us in the business just called these 'The Blueprint' when referring to the factory frame alignment dimensions for a project frame. Most folks are probably already familiar with this drawing as it's been reproduced by dozens of print shops over the years and some folks are even selling these 'recent' Xerographic versions on eBay that are barely readable and way out of scale. I 'redrew' the original of this print and 'modernized' it a bit for use with the old Hossfeld benders in 1964 using ink on vellum and a Leroy set to do the lettering and sold copies of my own to shops for several years and then in 1976 I converted it to modern CAD format using an old Auto-Trol system. In 1986 I converted that over to the Auto-Cad format.
I used to give these copies away for free until we started seeing them being sold on eBay so we took them down from the free download section of the site. This is still our most popular drawing and to a fairly large extent shops use it as a 'baseline' for doing their own custom work since the dimensions are extremely accurate but I'm getting off subject. The first 'Blueprint' bike was supposedly built for Freaky Fred Williams and was a big hit. The image below was taken from the Chris Kallas site and looks to be a scan from a magazine article about the bike in one of it's later incarnations. The bike looks much larger in this photo than it actually was and another snapshot taken at a show in it's original configuration gives a better idea of the proportions when it's seen viewed from a different vantage point. This bike is considered by many to be the first completely custom built chopper that used what was basically a mass-produced frame.
Unfortunately Allen never really went into full production. Some say that he only built three frames while other friends have told me that he built several dozen 'semi-production' frames in several iterations that were based on this original prototype. He did build three almost identical bikes to completion but I haven't found any pictures yet. Here's another photo I lifted from the motorcycle-art site and it shows Bruce Parrish in the process of preparing one of the 'Blueprint' frames for painting.
It's dated April 1973. Note that this is not Fred's frame from the previous pictures. William's bike had 'sidecar hoops' welded to the down tubes that were used for highway pegs. I've also seen one 'blueprint' frame that had the old original style down tubes that bent into the lower rails with two short bends instead of the single large radius bend seen here.
To be honest I never could get my mind wrapped around Dick's theory of frame building so I just trudged along for the next forty years building what I was used to. A few weeks ago however somebody pointed out that Irish Rich had run across a frame that is most likely one of Allen's early work. The complete story of his 'find' is on his blog located. Here's a snapshot taken from his site and it clearly shows all of the typical Allen frame 'hallmarks'. Note the stock style rear axle 'slots' and how high they are from the ground level. Notice that the motor mounts look to be on a 2-degree slant, one of Dick's favorite tricks.
The fabrication technique used on the mount plates are almost identical to that seen on the 'Blueprint frame as is the rear tranny mount. After seeing this I decided that I had better go back into some of my boxes in the storage shed and see if I could find my old original notes made back in 69 concerning Dick's frame building geometry. It suddenly dawned on me that after 45-years I was now smart enough to finally begin to understand what he tried to tell me long ago.
Update 10-24-14. I did find almost all of my original notes and sketches on Dick's frame concept. They're dated 1969 and I'll start working on a drawing to post in the next few weeks.
I'm completely convinced that the frame Rich now has is one of Allen's 'Blueprint' series but I don't know if it's an early version or a later version. The down tube braces don't look like something Dick would have built and the lack of a steering tube gusset is also something Allen would not leave out. Here is a drawing, as promised, taken from the notes I had made in 69. I didn't add a lot of details but did put in some of the major dimensions. It's very close in concept to the frame pictured above with some minor variations. Basically this ends up being a frame with an average of close to 2-inches of up-stretch, 2-inches of out stretch at the neck and another 2-inches out in the rear. The axle is moved up an inch over stock (lowers the frame's ground clearance).
The entire motor/tranny is canted 2 degrees over stock, measured from a point revolving around the crank center. In effect you get a 'raised tranny' frame.
My notes indicated that the material was.095 wall 4130 and I had labeled the original sketch the 'Easy Frame'. I can't remember if that's what Dick was calling it or just a note I made about it being an 'easy' one for builders in general. Also keep in mind that these old plans were designed around Panheads so no way would a modern Evo fit under the backbone. Copyright © 2003-14, All Rights Reserved.
Chopper Tech Hondachopper Garage Since most shops REFUSE to work on choppers, we've got to educate ourselves and build our skills in the garage. This will be the place to share your hard-won knowledge. Last Updated:.
(Some pages are available as an Adobe PDF so you can save the PDF to save or print out). Haven't found the information you're looking for?
Ssomeone there can often provide it. We look forward to seeing you there! The complete Garage on CD including the entire shop manual as well as download links for the ISO or standalone installer. General Info A nice beginning to a much need F.A.Q. (Frequently Asked Questions).
Many THANKS to Fixn2 for putting this together! This is also available as an. Chart showing engine differences between years and models OldMagic's Check it out.
Conversion table for SAE to Metric drill equvalents. This is also available as an. Old chop mag articles on performance tweaks, reviews, and other roadworthy reading. Article by Copperhedz on how to remove broken bolts, in particular cover bolts.
Also available as an. Frame and Chassis Thanks to G.O.T.F. Member MickD for putting this together! Available only as Adobe PDF. Frank Woslum used his AutoCAD skills and detailed a kick-ass CB750 frame that any aspiring frame builder can use. The pics are LARGE (in size, not file size) so make sure you view @ 100%, otherwise the drawing will appear distorted. 'How do I mount a brake on a Springer fork?'
Seems to be a frequently asked question. So here is an explanation of the principals involved.
MANY THANKS to Blackjack for writing this up! An excellent article on how to fit metal shapes, how and where to place different types of welds, welding sequence, and more. 836Rigid) A walkthrough put together by Sixshooter on how to 'Kong' a stock frame. This is also available as an. CSC's plans to build your own frame jig.
Available as PDF or zipped JPG download. Step by Step on how to shorten stock forks thanks to Olgraybeard and Bigmcgiv. This is also available as an. Wiring and Electrical Guide to troubleshooting the charging system done by CrazyCats. Wes Erickson was kind enough to throughly detail instructions for wiring up your Santee box.
Avaialable only as Adobe PDF. Um, the Stock K1 Wiring Diagram. This is also available as an. Simple to follow diagram adapting DOHC Reg/Rect to the SOHC system drawn up (literally!) by Rick. This is also available as an. You may find this useful too if you're in electrical HELL!! THANKS to RICK KEEVER for the addition of color and correction to the regulator & ignition switch.
( updated 8/14/04 ) This is also available as an. How to wire a Finch box thanks to Mr. This is also available as an. Simplified Dyna ignition wiriing diagram provided by Jaysco. This is also available as an. Here's a great article from the pages of an August 1975 Street Chopper magazine.
Thanks for the scanning! Many thanks to Keith Barnett for drawing out these simple diagrams! A scan of the original Santee chopper wiring diagrams. Big thanks to G.O.T.F. Member Paladin333 for sharing 'em! Complete ARD Magneto installation instructions and manual. Thanks to Boogieman we now have the FM version.
Martek 440 Electronic Igntion instructions (could use better scans) Dyna S Installation instructions in PDF format. Engine and Drive Train Static timing using a meter and strobe tuning. This is also available as an Oil Flow Diagrams (in both and sizes). This is also available as an.
Making lower end gaskets for the 750A provided by Hendrcs, but applies to any gaskets. There are printable templates included. If you're thinking about increasing your CB750's displacement to add horsepower, then you'll certainly be interested in how the porting process happens. PDF Only Excellent archive of CB750-related technical articles and tutorials!
HIGHLY RECOMMENDED! An old dog's collection of tips, tricks, and walkthroughs for those hated carbs.
Chopper Frame Blueprints
Also avaialbe as separate Adobe PDFs. A technical specification chart for Keihin carbs.
This is also available as an. Shots of various intakes systems used on the SOHC CB750 (POSA, Weber, etc.) An excellent introduction to the CB750 points ignition system by Wrenchbender. Sprocket gearing ratio chart. This is also available as an.
Free Chopper Frame Blueprints
Common Metric - Alphabetical - Inch tire charts and speed/load rating codes. This is also available as an.
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