MG3 rear shock absorbers:
We set up the rear swing arm and shock absorbers using standard Moto Guzzi swing arm pins and bearings.
We use and recommend Hagon 350mm 60mm diameter shock absorbers with 200lb springs.
Top bushes are 12mm.
To locate the bottom of the shock absorber to the left hand side of the early T3 style (Tonti frame) swing arm, we originally set it up using a T5 shouldered bolt rather than use the original T3 style swing arm locating shouldered bolt. This bolt (T5) has a 14mm diameter shoulder and requires therefore a 14mm bush at the bottom of the shock absorber.
When you locate the original Moto Guzzi brake caliper plate to the lug on the LHS of the swing arm, the whole set up becomes very close to the Hagon 55mm diameter spring.
Most Moto Guzzis used socket cap screws to locate the caliper to the caliper back plate, however in view of the closeness, it is necessary to replace the top one with a rounded socket button head screw.
If you do not have a T5 shouldered bolt, it is feasible to use an M12 1.5mm pitch bolt, however, you will need a 12mm bush at the bottom of the shock absorber rather than a 14mm bush. You will need to shim accordingly.
Hagon shock absorbers have 60mm diameter springs as standard, and the whole setup works in this manner.
If you choose to use other types of shock absorbers including standard or later Moto Guzzi types, you will be far to close to the brake caliper back plate.
To facilitate different shock absorbers, we will be moving the LHS upper shock absorber mounting a minimum of 10mm to the left.
Below are photos illustrating all of the above points:
The centre bolt above is the T5 bolt. It measures 54.4mm long. The 14mm shouldered end is 21mm long.
The accompanying M12 1.5mm pitch bolts are 60mm & 50mm with 28mm &18mm shoulders respectively.
click on the above photos to enlarge: