The Roads Less Taken: Fork Seals and Give Me a Brake!

Let me say right here...Fork Seals are EASY. (If you do them correctly.)

Like many guys, I approached fork seals with some apprehension. So I read the procedure over a few times. I watched a bunch of videos...most of them two or three times. (Call me a slow learner. Fine.)

Here are the tips I found really helpful.

Protect the shiny surfaces. Tiny scratches cause seal wear and leaks. No vice. No Vice Grips. Cloth padding on the bench.

Photograph your disassembly along the way. (Carried over from the last blog.)

Strip everything off the forks. Suspend the brake(s) from the frame or bars. Don't let them hang on their hoses. Keep the front wheel safe after removal. You don't want to damage the brake rotor.

The fork legs are held by pinch bolts at the steering head (a.k.a. Triple Tree). DO NOT LOOSEN THEM YET. Here's the deal. For the things you need to do that require clamping a fork leg, the best, safest clamps available are the ones that hold the leg to the bike. Use them.

Each leg has two "hard to loosen" items...the cap on top and the plug on the bottom. (The bottom plug can be seen by looking up into the axle end of the fork leg. It is typically an allen head bolt that is recessed in a hole above where the axle passes through the fork leg.) Loosen them while the fork legs are still installed on the bike! This will save you a world of trouble.

Loosen the lower plug first. Just crack the seal then screw it back in gently so the oil does not leak out.

Different bikes have slightly different configurations. Removing your cap may require a socket or maybe a large allen head wrench, you can figure that out. But here's the trick... Loosen the UPPER PINCH BOLT first. Take the squeeze off the upper end of the fork leg first, then loosen the Fork Leg Cap. (Tricky, huh?) Then gently tighten the cap again to prevent any oil spill.

Now loosen the lower pinch bolt and slide the fork leg out.

There are lots of videos on how to drain, disassemble and clean fork legs, so I will not go over that here, other than to reiterate what everyone says, lay the pieces out in order as you disassemble. They are your bible for reassembly. Take particular note of the orientation of the oil seal. You do not want to put the new one in upside down. (And that is easy to do.)

As long as you handle fork legs by hand without a vice or clamping tools it would be hard to go wrong. They are very strong. Just don't scratch the shiny parts! Keep your inclination to go after them with steel wool or emery paper under control. Don't do it. Cloth, solvent and elbow grease are sufficient and recommended. And watch it with using a screwdriver to pry the bushings off or onto the fork leg...you don't want to scratch the shiny parts! (I mentioned that already, right?)

Your bike may be a little different, but on mine a fork leg rebuild requires a new O-ring for the cap, a Dust Seal, Oil Seal, Upper Bushing and Lower Bushing and the drain bolt Sealing Washer...and of course, fresh oil. (I recommend the factory stuff of correct weight, just to be sure.)

Draining all the oil out of the fork leg may require pumping the Damper Rod in and out of the Cartridge. (Getting it to re-fill properly requires pumping the rod too.) Check out some part diagrams of your fork leg to identify those parts.

Reassembly, after everything is clean, is very easy and will not require any high forces...at least until it comes time to drive in the Oil Seal and later, the Dust Seal. The size of my particular fork made it possible to use a 2 foot piece of 2" PVC pipe with a 2" to 1.5" adapter on one end as a Seal Driver. Your fork leg may be a different size that requires you to spend $50 or so on a Seal Driver. Don't screw up by trying to use a hammer and a punch to seat the seals. It is not worth it. It is a short trip to a ruined fork leg.

Seat everything as well as you can, as evenly as you can, by hand (with your finger tips) before you use the driver. The Driver is just for final seating.

When you insert the Cartridge / Damper Rod assembly, tie a bit of steel wire (not soft, weak copper wire) onto the end of the Damper Rod...18" or so of wire. When you turn the whole affair upright and start to fill it with oil, the Damper Rod will sink into the fork, out of reach. The wire will still be sticking out of the end of the fork tube. Pull on the wire to pull the Damper Rod back up. Now you can pump the Rod to re-fill it with oil, easily. You can push it down by hand or with a piece of wood and pull it up with the wire. (There is also a Damper Rod tool you can buy that threads onto the Damper Rod, if you want to be a real pro.)

Most forks specify a specific air gap from the top of the fork tube to the surface of the oil with the fork leg completely colapsed. The air gap plays a critical role in how the fork performs, so make sure you get the gap to spec. The most common approach is to over-fill the leg and then use a tube marked to the required gap length to suck the oil back out. As soon as the oil drains down to the end of the correct length tube, the gap is the perfect depth. I bought a cheap tool made by Bike Master. Other guys make one with a turkey baster or a syringe and a piece of hose. The options are endless. Go wild.

Anyway, with all that done, reverse the uninstall procedure to put the forks back in...and the key tip here comes back into play...get the legs clamped in with the LOWER PINCH BOLTS (to the correct torque) and then torque the plugs and the caps to the spec torque. Then torque the Upper Pinch Bolts. Then you can hang all the stuff put back on the forks.

So here is where, on my project, Dumbassery came out to play again. It turns out that it is much easier to get the calipers reinstalled if you remove the brake pads. Just back the pin out and they drop out of the caliper. Then, after the calipers are reinstalled, you put the brake pads back.

I recommend that you put them back correctly. I was assuring myself late one night as I was getting close to the end of the project, that brakes are easy. They only fit together one way. If it goes together, by definition, it's right...right?

Wrong.

The first (attempted) test ride produced a god-awful scraping noise from the front brake calipers. WTF? Guess what? You can actually install the pads backwards (so the pad faces the pistons and the back of the pad rubs against the disk. This was not my first pad swap...just the first time I got them backwards. (I chalk it up to the late hour...which only moves the dumbassery from the poor install itself to the poor judgement demonstrated by not calling it quits before my brain had called it quits for the evening.) In the end, it all worked out and STella is back on the road, happy as a (high speed) clam.