My '94 FLHTC no longer holds air in the front shocks.

There are really no front "shocks" on the 1994 FLHTC. The fork tubes are of conventional design. First things first - obtain a factory repair manual for your bike.

The suspension system of the FLHTC uses compressed air to stiffen the suspension components. For the rear, this additional air is added to the upper part of the shock absorbers. For the front, the handlebar is used as a storage chamber for compressed air. The level of air pressure is varied to suit the rider. Me? I like for a bike to be still so I use the maximum allowable air pressure.

Concerning the front suspension, there is a an "anti-dive" feature built into the circuit. For heavy bikes such as the FLHTC this circuit is controlled by a solenoid valve that switches to "closed" whenever the brake light circuit is made. This prevents the forks from unduly collapsing and maintains the geometry of the bike during hard braking.

The maximum amount of compressed air is small, and of low pressure, say from 10 to 15 psig. Over a long period of time it can leak out. Concering the rear shocks - if it leaks out quickly (four weeks or less) then it is probably due to a leaking hose fitting. There is one at the top of each rear shock absorber and some in the area of the valve stem (looks just like a tyre valve stem). I would check these first, and make sure the small hose is not damaged. These can be checked with a simple soapy water solution.

The front tubes can be a bit more of a challenge. Tube seals do eventually wear and leak oil and in the case of the FLHTC, air. I have a 1992 model whose front end I rebuilt at my shop this summer. This can be a bit of a challenge for most owners, so most would do better to take the bike to a qualified shop. But there are certain things that are very easy to check and repair before deciding to replace the fork seals and bushings.

The valve stem on the left handlebar uses the same internal components as the valve stem of a passenger tyre, and one can use soapy water to detect a leak here. At the bottom of the handlebar assembly there is a short piece of rubber hose that connects the handlebar to the solenoid valve. This can become dry and leak as well. The outer fairing and the radio must be removed to gain access to this hose. It can be checked for leaks the same way.

If the fork tube seals are leaking, there will be an undue amount of oil on the fork tubes and perhaps some on the outer sliders. Again, the servicing of these units is not something that a novice should tackle. I will say this - the factory manual describes a procedure where all tube components are completely removed from the bike and disassembled. It also describes that each fork tube assembly must be removed in order to fill it with the correct amount of fork oil. Neither are required when servicing the FLHTC provided one has access to a bike jack, a manual vacuum pump, and the ability to fabricate a couple of simple tools made from a plastic pipe coupling and a wooden dowel. But that adventure is for another forum.

In short - do the simple soapy water tests and hopefully the problem is easy to locate and cheap to fix. If not, you know what you must do next.

Kind Regards,
J

Air shocks are done when they no longer hold air, they'll need replaced. They can be rebuilt, (not sure why), but almost all places won't because it's cheaper to buy new ones, and not worth their time. You can also get a rebuild kit, but again, with the kit, specialty tools required, and the extreme pain in the arse that is involved, new ones are cheaper. So, with this said, buy new shocks, it's going to be cheaper and safer than rebuilding these.