30mm Fork Seal Replacement (quick how-to)

[Pep]

Here’s a very simple description of replacing a fork seal on a set of 30mm stock Hodaka forks. Not a complete rebuild/cleaning - just something that came up this morning on one of the bikes I’m prepping for Diamond Don’s. Might be of use to anyone that has not changed seals on a Hodaka. There might be a smarter way to do it, or some ‘Hot Tips’ out there, so please add any suggestions or advice along to this thread.
First: tell-tale sign that you have a leaky seal. In this case, these seals have been in a couple years on a race/trail bike.

If this was a complete disassembly, you should pull the front wheel, and remove the drain bolt to empty the forks - this will also allow the damper unit to slide out for inspection/cleaning. In my case, I just need to change the seal, and I’ll just drain the fork from the top.
*If the drain bolt is really stubborn or the damper unit is spinning with it (not allowing it to unthread), a little heat can help, and an impact driver. If the springs are just sacked out, not giving enough tension between the damper and bolt, you can remove the top nut and add a spacer to the spring (to increase the pressure on the damper)
While the fork is still clamped, loosen the top nut (easiest way to stabilize the upper tube). If the top nut is really tight, consider loosening the upper clamp, as it can relieve a little pressure on those threads.

Loosen the clamps, slide the fork out.
I put the lower portion (axle hole) in a vise, remove the dust seal, and use vise grips and inner tube to loosen the fork nut. Place your grips on the portion of the nut covered by the dust seal, in case it gets scratched. If the threads are rusty and seized, heat helps here.

Slide the fork nut off the top. I then removed the top nut, removed the spacer and spring, and emptied out the fork oil. In a disassembly, do the same (the damper rod will come out too) and remove the upper tube (plus the metal and plastic bushings).
Here’s the nut with the seal. There’s also an o-ring in there - remove it and clean/inspect - if it’s stiff or torn up, replace.

I heat the nut up pretty good, and either drive it out with the end of a socket or just use some seal pullers - don’t damage the inner surface of the nut.

Clean everything really well, grease and replace the o-ring, then drive the new seal in - a flat board works well to get the seal flush, then drive it in with a bearing driver (or something flat and with a broad surface) until it seats.

Grease all your threads, re-assemble in reverse. Add 148cc of fork oil (flavor of your choice) - time to ride!
Shouldn’t take more than 15 minutes.
Hope this helps some of our new Hodaka owners out there.
-Laurie

[Dale]

Good info and pictures Laurie. I will add that I not only loosen the top nut before removing the fork tube from the bike, but I also use a rubber strap wrench to break loose the seal carrier nut as well. I do both of these steps before removing the axle. No vise is needed this way. Then after pulling the axle, I use the strap wrench to hold the lower fork and a T-wrench to break the lower damper units loose. Everything is now loose and ready for dissasembly on the bench.
Dale

[Pep]

Excellent point Dale - and definitely a better way to do things if you're trail or trackside - that's a more streamlined approach.
Thanks for contributing!
-Laurie

[Zyx]

For what it is worth:

Since the top nut is aluminum and the fork tube is steel, always loosen the top clamp bolt before attempting to remove the top nut. The tension on the nut from the clamping bolt is intentional.

Seals for these bikes used to have exposed metal bodies so that when installed, the seal was metal to metal on the outer perimeter of the seal. Seems that these seals are either beyond scarce or no longer available, probably due to lack of demand. 30mm forks are rare these days. Today, the widely available seal is rubber body over metal core, which means that when installed, the seal is rubber to metal, not metal to metal. Rubber seals are intended to be retained by a snap ring. Hodaka obviously does not have one of these. This makes the use of a rubber seal technically inappropriate. But, since the correct seals are not readily available, we use what we have. Problem is that if the rubber seal is installed wet (oil, grease, or anything slick) the seals will not stay in place. Internal pressures will pop the seals out in as little as four or five strokes. However, driving a dry rubber seal into a dry metal fork nut can damage the seal due to excessive friction.

One solution is to install the rubber body seal with Locktite, which makes the seal slippery on installation but then dries completely, leaving the seal tightly in place. The same result may be achieved with Windex, but Locktite is probably better.

The correct solution is to use seals designed to install press fit into metal holders, which means metal bodied seals. If you can find them, use them.

Another thought on leaking seals - unless subjected to heavy doses of dirt, seals rarely leak due to wear. More often, they leak due to debris clinging to the seal lip. This can be remedied easily on Hodaka forks because the seal is in the lower nut, which is removable. Take the nut off, clean well with whatever you have, from light solvent to dish soap, and reinstall. The seals on my 43 year Hodaka were still serviceable when installed on new tubes. That is, the leaking was due to damaged forks, not leaky seals. Point is that although they showed wear, they still did not leak when installed on new tubes, so inspect what you have. They may just need to be cleaned. Same goes for the o-ring in the fork nut, as this ring only keeps the nut from leaking and does not run on a moving surface. If it is clean, it will very likely work just fine.

Perhaps with some searching we can find a seal maker who will run off a batch of the correct seals. I have the specs, and the correct seal profile is still shown on several seal maker's charts. Perhaps all it will take is a co-op sized order to make the cost reasonable.

[racerclam]

Here is a tip for keeping dirt out of the seal I have done for many years. cut a piece of cloth , old t shirt or piece of felt long enough to wrap around the fork tube and install above the seal before you slide the wiper in place .

Rich