- The internal springs support the weight of the motorcycle
- The shock dampers limit the speed that the wheel can move up and down, keeping the wheel on the road instead of it bouncing into the air
- The shock dampers dampen the natural resonance of the springs, so that the motorcycle doesn't bounce up and down repeatedly after hitting a bump
The shock dampers work by having fluid inside them. When the shock is compressed, the fluid is forced through a small orifice. This limits how quickly the shock can be compressed. On the Goldwing, the shock preload can also be adjusted. This helps adjust the amount of pressure exerted by the spring by pressurizing the shock with air, to adjust for different loads being carried.
The shocks require internal seals to contain the fluid and air, and as a result occasionally need rebuilding or replacing. One of the shocks on my Goldwing had started to leak fluid, always a good indication that a seal has failed. However, upon inspection, I discovered that there were actually two different shocks on my bike - so instead of rebuilding them, I decided to replace them with a pair of Progressive 416 air shocks.
Before starting, if you have saddle bags, you will need to remove your saddle (pannier) bags. For instructions on this, see:
How to remove and replace your saddle (pannier) bags
Also, you will need to remove both side panels, and if you have an air pressure system, use it to remove all air pressure from the rear shocks.
1. If you have a trunk, unlock the two locks at the rear holding the trunk in place.
2. Lift the back of the trunk slightly, and pull it to the rear to remove it from the frame, leaving the trunk frame exposed.
3. If you have an antenna, unbolt the antenna bracket from the trunk frame. You don't need to disconnect the antenna, it just needs to be removed from the frame.
4. Looking underneath the rear fender, you will find two long bolts fastening the fender and the frame together. Remove both bolts.
5. Locate the wiring leading to the tail/brake light and turn signal connectors.
6. This is the connector you are looking for.
7. Disconnect this connector and pull the harness free from underneath the frame crossmember.
8. Move the wiring to the back, out of the way.
9. Use a socket wrench to loosen the acorn nut holding the top of the left shock in place.
10. Remove the acorn nut and washer.
11. Pull the rear trunk rack frame off of the top shock mount stud, and pull it to the rear of the bike. Then pull the left rear crash bar off of that same stud, and gently move it forward to allow the shock to come off the stud.
12. Remove the bolt fastening the bottom of the left shock to the swingarm. Pull the bottom of the shock out of the saddlemount on the swingarm, then pull the top of the shock off of the mounting stud.
13. Now that the shock is free of the bike, the air fittings are accessible. It is possible - but extremely difficult - to remove the air fittings while the shock is still on the bike, so I recommend you do it after the shock is free. Be careful not to pull or damage the rubber air hoses too much.
14. Holding the fitting closest to the shock in place with a wrench, loosen the hose end of the fitting slightly. This fitting acts as a jam nut to prevent the main fitting from backing off.
15. Now that the hose end of the fitting is loose, use a wrench to remove the fitting from the shock.
16. The shock is now free of the bike and can be removed. You can see that this shock is leaking fluid rather badly, as the shock boot is covered in oil.
17. You can use a standard tire valve cap on the shock fitting to keep the oil from leaking out when you set it down.
18. If you have aftermarket shocks, the fitting might not be mounted directly to the shock, and instead fitted with a separate air hose. The same procedure applies - loosen the hose end of the fitting first...
19. ...and once loosened, remove the hose fitting. In this case, a second wrench is being used to hold the shock side of the fitting in place.
20. Remove the upper and lower acorn nuts and washers from the right shock. Pull the rear trunk rack frame off the upper mounting stud, and then gently pull the right rear crash bar up and off the stud. Pull the old shock off of the mounting studs. Unlike the left shock, the right shock is mounted with two studs - the upper one on the frame, and the lower one on the final drive. If the shock is tightly stuck to the studs, you may need to wiggle it back and forth a bit to convince it to come off.
21. This is one of the new shocks I will be installing - an aftermarket Progressive 416. These shocks are far better than the original OEM shocks, give a better, smoother ride, and can handle a higher load.
22. The Progressive shocks come with several sets of bushings, for different applications. We will be using only one of them - the thickest one, which will be inserted into the rubber bushing in the bottom of the left shock.
23. Push the metal busing into the rubber bushing in the bottom of the shock. You may find it easier to insert if you lubricate it slightly first.
24. Use some solvent to clean all of the mounting studs, and lubricate them lightly with some light oil.
25. Place one of the washers included with the Progressive kit onto the mounting stud.
26. If you are reinstalling your original OEM shocks, you would at this point reconnect the air fittings. However, being that the Progressive shocks have the fittings on the rear of the shock body, making it easy to connect after they are installed, we can do that later in the process. Gently push the top of the left shock onto its stud.
27. If it is difficult to get onto the fitting, you can use a socket and a hammer to lightly tap it into place. Make sure the socket is large enough that it touches only the metal portion of the shock mount point, not the rubber bushing inside it! Leave the bottom of the left shock disconnected for now.
28. Place a washer over top of the shock.
31. Move the crash bar back onto the stud, followed by the rear trunk frame, and finally the original washer and acorn nut.
32. Snug the acorn nut so that the washer flange fits into the frame, but don't tighten it at this point.
33. Clean and lubricate the right bottom mounting stud on the final drive as well as the top mounting stud.
34. Place a washer on the upper stud.
35. Push the top of the shock onto the top stud, followed by another washer, just like the left side. Pull the right rear crash bar up over the stud, followed by the rear trunk frame, and snug the acorn nut with its washer, all like you did on the left side.
36. Chances are, the bottom of the right shock will not be turned correctly to fit onto the stud.
37. Use a socket extension to gently rotate the bottom shock fitting to line up with the stud.
38. You may need to use a piece of wood under the rear wheel to lift the swingarm into place so that the rear shock will fit onto the bottom stud on the final drive case.
39. Fit a washer onto the bottom right stud, then push the shock onto the stud.
40. Follow this with another washer, and the acorn nut with its split washer.
41. The bottom of the left shock should be close to lining up with its saddle fitting at this point.
42. Use a socket extension to gently center the left bottom shock bushing with the mounting hole.
43. Insert and tighten the bolt. Now tighten ALL four shock bolts to 25 ft-lbs.
44. Installing the air lines for the Progressive 416 shocks is relatively simple - but the fittings and lines are plastic, and will break if they are torqued. Hand tighten all fittings only!
45. Progressive states that you need a special adapter kit in order to connect the Progressive shocks to the existing air hoses, and you can buy this extra kit and do it this way if you wish. However, you can just as easily remove all the rubber hoses and plumb the Progressive shocks directly into the three-way valve without having to purchase the kit. To do this, disconnect the rubber hoses from the three-way valve on the right side, just behind the rear brake master cylinder. Note: If you do not have the on-board air compressor, and pressurize your shocks manually, you may have to use the Progressive kit.
46. Here is a close-up look at the three-way valve.
47. Disconnect the air hoses from the distributor at the top (if installed) and remove the hoses from the bike.
48. Using the Progressive-supplied plastic air line, fit the threaded connector, the compression fitting, followed by two rubber washers onto the line. Leave approximately 2mm of line sticking out the end.
49. Lubricate the rubber washers with ATF or light oil, and insert the assembly firmly into one of the three-way valve fittings.
50. Hand-tighten the threaded connector onto the fitting. Cut a second line and fasten it to the other three-way valve fitting. Progressive supplies about four times as much plastic line as you will need, so don't worry about making a mistake - leave the lines long, you can trim them later.
51. Route the air lines up through the same rubber bushings as the old rubber hoses used to run. They need to be kept tidy, so that they cannot rub against the rear tire.
52. Route the air lines through the clip on the top of the fender.
53. Cut each air line to fit, and terminate them with the same threaded connector, compression fitting and two lubricated rubber washers. Fasten each line to one shock. Make sure the air lines are routed neatly with no sharp turns, and won't rub or snag on anything.
51. Using the compressor, pressurize the rear shocks.
52. Spray soapy water on all of the fittings to check for leaks. Any leaks will cause bubbles to grow.
53. Route and reconnect all disconnected wiring.
54. Reinstall the antenna, then reinstall the trunk.