CARCENTRIC's conversion of a '79 Honda CX500 Custom into a 1F2R trike . . .

If you've been here before, press Ctrl-R to make sure you're seeing the most recent update. . . .

 SPECIFICATIONS

TIRES

tire W

tire A%

wheel D

tire D

FINAL DRIVE

DIFFERENCE

Stock CX500-C FRONT

3.50"

90

19

25.30"

IN OVERALL

 D

ring/pinion

D 

GEARING

Stock CX500-C REAR

130mm

90

16

25.21"

3.09:1

Roxinante

235mm

75

15

28.88"

14.5%

3.545:1

-12.8%

0.2% lower**

Stock CX500-C

Roxinante

3567

rpm @ 40 mph in 5th

3572

4458

rpm @ 50 mph in 5th

4466

     5350     

rpm @ 60 mph in 5th

     5359     

6242

rpm @ 70 mph in 5th

6252

7133

rpm @ 80 mph in 5th

7145

TRIKE CONVERSION
MECHANICAL DETAILS
 

REAR SUBFRAME MOUNTING POINTS.  The Honda frame has three pairs of points that are suitable for mounting the subframe (see drawing to the left, and parts in  BLACK  in the drawing below):
   • (A) the top mount for the bike's coilover shocks,
   • (C) the top crosstube of the main frame member (not used on the bike), and
   • (E) the main foot peg locator crosstube.

The bike's swingarm pivots (D) and passenger footpeg mounts (B) are not used on the trike.

REAR SUBFRAME FASTENERS.  Solid steel cylinders (whose ends will be drilled and threaded) will be pressfit and welded inside both CX500-C crosstubes (C and E). Neither bearings nor bushings will be needed at these mounting points since the rear subframe is not designed to move relative to the CX500C's frame. 

REAR SUBFRAME.  The new rear subframe (in  RED ) will be fabricated from steel tubing:
   • Upper [U] rails - 1" x 2" x 1/8" wall (vertical orientation)
   • Lower [L] rails and Lower rail extensions [L2] and Front and Rear crossmembers - 1½" x 1½" x 1/8" wall
   • Middle crossmember - 2" round x 1/8" wall
   • Stabilizing crossbar [X] - 1" x 1" x 1/16" wall
   • Package tray support (in  YELLOW ) and all other tubes - ¾" x ¾" x 1/16" wall

REAR AXLE.  The rear axle assembly from a 1981 Datsun 210 (aka B310) will be used. That assembly has mounts top and bottom, originally for four locating links. (Datsun parts are  TURQUOISE  in the drawing to the right).

REAR SUSPENSION.  The Datsun's two upper links are angled enough that a panhard bar is not needed to locate the axle left-to-right. A 1974 Volkwagen SuperBeetle's front swaybar (shown in  MAGENTA ) will replace the two Datsun lower links. It offers the added benefit of resisting the trike's tendency to lean outward during cornering. Initially, the stock CX500-C coilover shocks will replace the separate Datsun springs and shocks, but a second shock per side may be added if the rear proves to be too bouncy.

DRIVESHAFT (or propshaft for UK visitors, shown in  BLUE ). I intend to bring a CX500 driveshaft and a Datsun 210 driveshaft to a driveshaft speciality shop, supply the necessary dimensions, and pay them to provide me with a balanced, custom part ready for installation.

BRAKES.  The CX500-C's rear brake foot pedal will be connected by custom linkage to a small Wilwood single circuit master cylinder (5/8" bore, 1.4" stroke) which will actuate the stock Datsun 210 rear brakes (8" drums, 1.378" wide linings, 13/16" wheel cylinder bore). It should be fairly simple to hook up the Datsun's emergency/parking brake linkage, too.

OVERALL GEARING.  The Datsun differential has a 3.545:1 ring/pinion ratio that, with the significantly larger diameter 235/75R15 rear tires, will require Roxinante to turn only nine rpm more than a stock CX500 Custom at 60 mph - essentially a negligible difference.