Harley Davidson FXR Suspensions
Prorider and motorcycle instructor Alexander Andreev brought his new old motorcycle Harley Davidson FXR 1994 for customizing and extreme riding preparation. Iconic and unique, it's the lightest Harley with big twin and the most rigid frame. The engine has already been rebuilt, so it works well. The carburetor problem wasn't solved yet, it overflows while riding on the rear wheel for a long time. If we don't fix the carburetor, in the future it's possible to replace its engine with a modern one with injector, since the frame allows it.
The first thing we need to do is to replace the suspensions as they determine efficiency and comfort the most. Many things depend of them, such as the braking distance (the fork stability to push the wheel to the road), the dynamics during fast acceleration (shock absorbers compression when the rear wheel is loaded quickly), control when passing obstacles (bottoming out the suspensions can lead to an impact, wheels lifting from the road surface, losing control of the steering wheel), the motorcycle stability on high speed (the fork and shock absorbers shouldn't swing the motorcycle at speed or on bumps), stability in leaning when cornering (swinging suspensions can lead to the wheel unloading and fall).
Stock suspensions are not suitable for stunt riding as the fork bottoms out when landing after a wheelie. It's impossible to achieve effective emergency braking, because the fork instantly compresses and goes back when pressing the brake lever sharply. Shock absorbers don't provide an even loading on the rear wheel when drifting; they swing the motorcycle changing the load and grip of rear wheel. Jumps and flat tricks will quickly kill not only the suspensions, but the entire motorcycle, because the impact energy will be transferred to the rims, bearings, frame, and swingarm.
After test runs, Alexander chose 14-inch length for the rear shock absorbers, for the weight with the rider. This means the shock absorbers should be about 15 inches. The longer the shock absorbers are, the greater the travel and energy consumption. Also, long shock absorbers will increase the ground clearance, which will allow the rider to lean the bike more while cornering. Longer shock absorbers will at the same time raise the wing to prevent its rubbing against the wheel. Alexander messed up with the wing configuration, so it's impossible to put short shock absorbers - he didn't mention that in the video.
The only 15-inch shock absorbers we found were the progressive suspension 470 series. They fit on the FXR with some modification: the bushings must be shortened by 1 mm so that they can fit into the mounts on the swingarm - we didn't show this in the video. What's good about shock absorbers is that a floating piston is used instead of a rubber bulb in the reservoir - it's more reliable and easier to maintain. For compression, a separate valve with its own stack of washers is used - this allows you to simulate work for fast and slow compression regardless of rebound. The manufacturer gives a lifetime warranty on their products.
For normal use, we always recommend installing the shock absorbers 0.5-1 inches longer. This will practically not affect the motorcycle height and weight distribution, but it will increase the run and energy consumption of the rear suspension, which is very useful. The manufacturer doesn't really matter, the main thing is that they are monotube (oil under pressure due to a chamber with compressed nitrogen). On such shock absorbers, the oil doesn't foam, and it continues to work even under intense load. When air bubbles appear in the shock absorber, it's like an air-filled braking system: the lever becomes soft and the brakes stop braking. The same happens in the shock absorber when covitation occurs: the rod moves inside the damper without resistance.
Elongated shock absorbers require the fork to be lengthened, especially when doing a wheelie. For a wheelie, it's better to load the rear wheel as much as possible, that is, raise the steering column. This can be done by installing a wheel with a larger diameter or a longer fork.
We are fortunate to have Legend produce Axeo cartridges for a 39 mm fork with a high top cap, where a nitrogen pressurized chamber is. This plug allowed to lift the front of the motorcycle as needed.
In the video, we replaced the original fork with a Sportster 2004 fork because it has a caliper mount on both frok legs. In the future, we will install a double disc front brake. The cartridges were ordered specifically for this fork.
Even though all 39 mm forks are similar, they all have different lengths. Even forks with the same inner tubes can have different lengths and run, due to different cup depths at the bottom of the outer tube. Therefore, we recommend buying cartridges for a specific fork. Especially since the oil level is matched to specific cartridges and forks. Since in the manuals Legend doesn't indicate the oil level but only its volume, it's impossible to know how much oil we need to pour if the cartridges and fork have different models.
You can get Harley Davidson suspensions and get advice in our store. We are official dealers of Legend, Progressive Suspensions, Bitubo, Ohlins, Hyperpro, RaceTech, Drag Specialties.