rebuilding old (1984) FX 39mm fork tubes : V-Twin Forum: Harley Davidson Forums

rootercycles · 07-19-2008, 07:44 PM

All,

I bought, at a swap meet, a set of 39mm fork tubes for my next project. It appears to be out of a 1984 FX or XL. I am not sure if they are complete inside, and worth rebuilding, so I need a complete schematic of what the guts look like. I am a little baffled, because there are grease nipples on the lower legs where I thought should be drain plugs. Am I missing something or did someone else F#*K it up?
If someone could post a good schematic of what should be in this narrow glide front end, I can make a better assessment of what I need and if its worth keeping.

cat5752 · 07-20-2008, 09:27 AM

Look at Bike Bandit for exploded views. I can't remember when they went from 35 to 39mm. (I want to say 88?)My 75 Sportster has 35mm SHOWA forks. The Sportster and the FXR shared a lot of frond end components. Look at the inside of the fork lower, right above the axle boss, and it might have showa (or other name) there. There should be small phillips head screws with a washer in the bottom holes, not grease fittings. The re-build kit will run you about $25-40 and it is an afternoon project.

cat5752 · 07-20-2008, 09:32 AM

Did some quick checking, 1988 was when the Sportster and FXR got 39mm forks. The older forks that I couldn't rememebr the name of were Kayaba, but I believe they went away in 75. Hope all this rambling helps. It really is an easy job. One thing, make sure you have access to an air wrench. The main bolt that holds upper and lower together will spin and spin and spin if you do it by hand. Blast it with an airwrench and it comes right apart. It is an allen head bolt (3/8"???)

springer- · 07-20-2008, 09:34 AM

At the top of the fork tubes is there are a tapper or is it straight? In 84 it would have 35mm tubes with the tapper not the 39mm tubes.

cat5752 · 07-20-2008, 09:59 AM

Quote:

Originally Posted by cat5752

The main bolt that holds upper and lower together will spin and spin and spin if you do it by hand. Blast it with an airwrench and it comes right apart. It is an allen head bolt (3/8"???)

After thinking more on this, I am fairly certain that the allen is 6MM, not 3/8. These are Japanese forks.

rootercycles · 07-20-2008, 01:57 PM

Oh crap, I just mic'd the fork tubes and you guys are right, they are 35mm. Unfortunately, I had a set of 39mm triple trees polished so I don't think I can use these thinner (35mm) tubes in them. Anyone need some tubes cheap?....

rootercycles · 07-20-2008, 01:57 PM

They are Showa by the way.

springer- · 07-20-2008, 02:23 PM

39mm front ends or just fork assemblies are pretty cheap on eBay. I have purchased a couple and have been real happy with them. In particular I purchased a 2000 FXDX sport front end. They have adjustable rebound, dampening and preload as well as dual disc and 4 piston late style calipers. I purchased that front end complete with polished trees, polished lower legs and polished calipers for around $300. New from the dealer and nothing polished that front end is over $1200. The earlier style 39mm front ends are even cheaper. It would not surprise me if you could find one in the $100-$200 range. It does require being patient and waiting for the right deal.

Here are a couple examples .....
http://cgi.ebay.com/ebaymotors/ws/eB...m=270257388738
http://cgi.ebay.com/ebaymotors/ws/eB...m=150272036294
http://cgi.ebay.com/ebaymotors/ws/eB...m=220258637081

Note the late model front ends (2000-up) use a different brake caliper and also don't use a front wheel drive speedo. The 87-99 front end use the front wheel drive speedo and older caliper.

Y2K · 07-21-2008, 12:09 AM

Quote:

Originally Posted by rootercycles

They are Showa by the way.

Correct,my '84 FXRS had 35mm Showas.

hardluk1 · 07-21-2008, 09:48 AM

Springer , can't buy the sport type front end any more ,only parts.
rootercycle , buy a set of springs from works and you won't believe how well that 35mm frontend works. Just check your stock spring width hd had two tube thicknesses . It will take a 25mm spring or a 23mm spring. My 86 was the 23mm . My bike now rides better than any 39mm front i have had, so the right springs do help.And the sport front end as nice but for the more than average rider you will never find one setting that works for two up ,one up, just cruise'n, or gett'n with it. Hell most sport bike riders get all screwed up when tune'n front ends.

rootercycles · 07-22-2008, 12:09 PM

The problem with these forks and tubes, is that I have already had some 39mm triple trees polished. I only have a few bucks into these legs and would love to make them work, but I am afraid they will be too narrow (35mm) for the trees.

hardluk1 · 07-22-2008, 01:45 PM

If you are died set on useing them Kedall Jonson customs had some 39mm trees on there ebay site cheap. Not sure but i think they wear 20 something bucks. You will still want a spring kit .

rootercycles · 07-22-2008, 04:31 PM

Funny you mention that, I bought the trees from Kendall Johnson! They were in good shape but needed to be polished. I sent them out and they look like chrome now. I have a lot less in the triple trees than I would with "billet" aftermarket ones and they look great. The fork leg outer diameter is too small to fit tight enough in the trees. If someone has a way to negotiate them in without slop, I would like to hear it. I have thought of having some "spacers" machined, but I might be better off just getting some 39mm forks.