STDWG
Custom Softail Frame Drawings.
Note that these drawings are
not intended to be a plan for building a frame. However, the dimensions, angles
and shapes are provided such that a competent motorcycle fabricator could
easily build a frame from the information.
Skill and knowledge of metal fabrication, welding and motor vehicle
engineering are required for the construction of a motorcycle frame.
The softail frame is
designed for late model Evolution style engines and 5-speed transmission.
Dimensions for a stoker engine of .200 taller has been installed in a frame
built from these dimensions without interference. Engine mounts and holes,
transmission mounts and holes and swingarm shock mounts are indicated on the
drawings. The frame backbone is shown for flat side stock tanks but can be
changed to any shape desired (as long as engine clearance is observed). The
frame uses 1.5” x .125 wall DOM steel tube for the backbone and seat post, 1”x
.125” wall for the seat wishbones and 1.25” x .125” wall for everything else. A
1”x2”x.125 wall tube is used for the seat post crossbar. The seat post may
require considerable dimpling to clear the transmission top cover and the rear
cylinder / exhaust when 1.5 diameter tube is used. The pivot stanchions that make up the rear of the frame and
provide the pivot point for the swingarm is cut from ½” steel plate. The
drawings include full-scale drawings for the steering neck, front motor mount,
rear engine mount, top engine mount, front transmission mount, side
transmission mount, rear transmission mount, oil tank bracket, and forward
shock mount. The rear pivot stanchions are 17-1/4” tall and hand traced on
oversize paper from a full size cutting template. There is a sheet for the side
view of the frame, a bottom view and backbone view showing angles and
dimensions. The down tubes connect to the backbone with the steering neck
connected to the backbone and gusseted for strength. This is an easy style neck
connection for rake modifications while building or for later changes.
Swingarm information is
not included since the swingarm is nearly as complex as a frame and can change
quite a bit depending on tire size used.
The frame can be easily
modified with neck rake and stretch in the front down tubes and backbone for a
more custom appearance.
Note that these drawings are
not intended to be a plan for building a frame. However, the dimensions, angles
and shapes are provided such that a competent motorcycle fabricator could
easily build a frame from the information.
Skill and knowledge of metal fabrication, welding and motor vehicle
engineering are required for the construction of a motorcycle frame.
The main purpose of these
drawings is to provide dimension information for engine and transmission
placement. The drawings also provide the basis for a rigid frame that uses late
model parts.
The rigid frame drawings
are designed to use late softail parts like Evo style engines, cast primary and
5-speed transmission with a belt final drive. The rear axle plates are spaced
10-1/2” inside-to-inside to center a stock width wheel with a 1-1/2” belt drive
pulley. The seat wishbones are straight until the bends inward for the
backbone. This makes for a wide seat area typical of west coast chopper styles
and simplifies construction. It may be possible to fit a 180 or 200 rear tire
with a chain drive depending on the brand of tire and type chain used. Of course, the rear section can be further
widened to provide for any size tire. The frame is entirely dimensioned for
1.25”x.125” DOM steel tubing. Drawings include the side view, bottom view,
backbone with seat wishbones, and front view. Full scale drawings include the
front engine mount with forward control mounts, rear engine and front
transmission mount, side transmission mount, rear transmission mount and rear
axle plates. Since all of the small parts that need to be cut out are full
scale, it is easy to trace on steel and cut to shape. The top engine motor
mount and neck gusseting is not included as there are too many ways to finish
these areas and anyone competent enough to build a frame should be able to
design and complete this area.
MechWerks also offers a
kit that has most of the parts required to build this frame. Check out the
frame kit section from the MechWerks home page for more details.