Coupling Rods

   
PRODUCT INDEX  
 
  • Fit the remaining bronze bushes in the ends of the coupling rods by following the same procedure as the motor mount bushes (soldering). Thread lock could be used if prefered.
  • Before drilling the two holes as described below, lightly grind or file a flat spot in the areas where you are about to drill. this will remove the hard steel left from the laser cutting and will make it easier for the drill bit to drill where you want it two.
  • Drill two 3.3 mm holes in each crank, as shown in the diagram to the above. Using a 4mm tap thread both the holes. The larger hole is to fix on to the axle end while the slightly smaller is for the rod supplied.
  • Drill down the centre of the crank pins with a 3.3mm drill bit.
  • In one end of the crank pin tap a 4mm thread. This is to hold the 4 penny washers in place which in turn hold the coupling rods on the pins. The supplied 4mm bolts need to be trimmed down leaving a shank length of around 10mm
Oiler cups and channels can be drilled in to the top of the cranks. File the tops flat before drilling a small hole (2mm max) straight down and trhough the upper half of the bronze bearing. Then using a larger drill bit (5mm) form a dish on the top of the crank.

Right - section through a crank end - 2mm channel and 5mm cup.
       

DO NOT FIT THE COUPLING RODS AT THIS STAGE

Fit after test running

1. Turn the chassis on to its side and fit a pair of cranks to the ends of the two axles. Fit the coupling rod onto the crank pins and secure with the M4 penny washers and two M4 bolts. The bolts will need to be cut down to a shank length of around 10mm.

2. If the penny washer clamps the bearings then undo the pin grub screw and move the pin out slightly.

3. Align the first coupling rod with the bottom edge of the side frame. This can be done be eye. Tighten the grub screws to secure to the axle ends

4. Fit the cranks and coupling rod to the other side but at a 90° to the first side. Do this by putting the first coupling rod horizontal then the second has cranks going straight up or straight down.
5. When tightening up the grub screws make sure you use a good quality allen key. Cheap sets will result in bent keys and loose screws. On final fit of the coupling rods apply thread lock to the axle ends to asist in fixing the cranks.
                   

   

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