The shocks on this Dyna are similar to the shocks on Sportsters.
Sportster shocks are usually 13.5 inches long. Installing shorter shock absorbers will slightly affect the part of motorcycle frame geometry called “trail.” Trail is the ratio of the distance from the axle to the ground on the back of the bike and the distance from the center of the steering neck to the ground on the front of the bike. Radical trail is one reason why the most extreme looking custom bikes usually don’t handle well. You should be aware of frame geometry if you replace your Sportster shocks with longer or shorter ones. Installing new shocks is a very simple job.
1. Remove any accessories, like saddlebags, that limit access to the shock absorbers. Raise the Sportster on a motorcycle jack just high enough so the bike is upright and not leaning left on the support stand.
2. Remove the lower shock mounting screw, washer and nut from the old, right shock absorber. Remove recent Harley shocks with an Allen wrench and older or non-Harley shocks with socket wrench and hex socket. Save the hardware for reuse.
3. Remove the upper shock mounting screw, washer and nut from the old, right shock absorber and save the hardware. Remove the left shock absorber the same way you removed the right one.
4. Paint the mounting screw threads with thread locker and bolt the new shock absorbers to the Sportster using the original hardware. Tighten the mounting bolts to 50 ft.-lbs. of torque with an Allen or hex socket and a torque wrench.
5. Lower and remove the jack. Sit on the bike, bounce up and down and check for binding.
6. Reinstall any accessories.