HarleyMotorcyclePartsLow Rider S (FXLRS): When to Replace a Shock That Is Already Better
The factory unit here is not the base Low Rider's. Judge any replacement against that, not against a bargain shock.
A widespread assumption is that any aftermarket shock must beat the factory unit. That idea comes from cheaper bikes. The Low Rider S is the high-performance M8 Softail, and its shock differs from the base Low Rider's. Replacing it can be a sideways move, or even a downgrade. Know exactly what would improve, and why, before you pull a single bolt.
Tools
- Secure rear support
- SAE and Torx sockets
- Torque wrench
- Sag measuring tape
- Helper
- Notebook
- Correct adjuster tool
- Service manual
Audit what you have
Set sag correctly on the existing unit before anything else. Sit on the bike in your full kit, with a helper reading a tape from axle to a fixed point above. If you have never done this, your impression of the shock so far may be an impression of poor setup.
Next, go through what is wrong in specific terms. Note the road, the speed and the symptom. 'It feels rough' gives you nothing to shop against, whereas 'it kicks over sharp edges at low speed but stays composed in fast sweepers' gives you something to tell a suspension specialist.
How old is it and how far has it gone? Look for oil on the body and on the shaft, and notice if the rear keeps bobbing after a dip. Wear is a sound reason to act, and a leaking shock has made the decision for you.
Comparing like with like
Owners here pay for improved control and travel. So when you compare a candidate, ask if it holds on to both. A shorter or cheaper unit might fit perfectly and still leave you with less of what the model was built for.
Beware of reviews from riders of the base FXLR. They may well have been happy with an upgrade over a different stock shock, which proves little about yours.
Confirm fit for FXLRS and your model year specifically, along with the adjuster type involved. Should the supplier give only a broad Softail listing, ask them directly. Once you have clear answers about length, travel and spring range, compare them to whatever you can establish about your factory part, and treat any shortfall in travel as a cost you are choosing to pay.
Consider the cheaper first step as well. If your complaint is that the spring does not suit your weight, a shop with the correct compressor and the right spring may solve it. Ask them whether your unit can be serviced or re-sprung, because that keeps the mounts and adjuster your bike was built around, and it may leave you with what you liked about the shock in the first place.
Disassembly
Support the rear firmly and remove the seat. The workshop manual then lists what must come away next, and on many of these machines that means things in and around the battery tray, along with side pieces. Stick to the written order. Take pictures throughout, since you may want to refit this shock later.
That last point is worth acting on. Keep the factory unit carefully, with its hardware bagged. It holds resale value, and it is also your fallback if the replacement disappoints.
With mounts loosened per the manual and the rear held up, ease it clear without scraping. Do not dismantle it. Its spring is compressed and needs the correct compressor, which is shop equipment.
Examining the seat of the shock
A bike ridden with intent can wear its mounts. Inspect each bushing, then the bolt surfaces, then the frame and swingarm mount points. Watch for fretting dust or polished areas, which show movement that should not be there. Replace questionable parts, because a perfect shock on a slack mount cannot perform properly.
Installing and setting up
Before installing, compare both units side by side on the bench: length, mount eye, adjuster position, any hoses. Then route the new unit in, checking nothing is pinched. Start each bolt by finger, then use your torque wrench at the shop-manual specification for that fastener and year.
Rebuild everything you removed in reverse, and confirm electrical items work before you put the seat back. Set sag with the new unit, matching what you achieved on the old one to give a fair comparison at first, then make any further changes one at a time.
A fair verdict
Ride the road from your notes at the same pace, and be strict with yourself. New parts always feel exciting for a day. Does it do better at that specific sharp edge? Has it stayed composed through the fast sweepers? Has anything got worse, such as cornering clearance?
Check all fasteners after that first ride, and do so again after a longer one. If the verdict is that you lost something, there is no shame in going back. That is exactly why the old unit is sitting on your shelf.
Mistakes that cost money
- Assuming aftermarket automatically beats this model's factory unit.
- Taking advice from base FXLR owners at face value.
- Replacing the shock before ever setting sag.
- Selling or binning the factory shock before the new one has proven itself.
- Giving up cornering clearance for a lower seat without noticing.
When to stop
If you see fretting or cracking at a mount point, no shock decision matters until that is addressed. Leave the bike parked and get the mount inspected first.
Other Harley how-to guides
This guide covers procedure and judgement. Torque figures, fluid capacities, gaps and tension settings are specific to your model and year and must come from the factory service manual for your motorcycle — we deliberately do not print numbers we cannot stand behind for your bike. Independent aftermarket retailer, not affiliated with Harley-Davidson, Inc.