Subject: FAC dampers, part II
Author: Greg Field
Date: Sep 15, 2004, 5:08 PM
Post ID: 1717535985
As promised, here's the harder method (the one I used) for putting FACs
on a disc-brake Eldo, a possible method for converting from drums to
discs using FACs, and a possible method for converting drum-brake bikes
to having damper rods.
The Method I used
This procedure assumes you've already disassembled the forks by
removing the old dampers, springs, and damper adapters from the tubes.
1) Affix the extender rods to the dampers and pull out to full
extension.
2) Measure damper and extender. Write it down.
3) What you have to do then is make a spacer that inserts between the
damper and extender to get a total length of XXXmm (I don't have it
handy but will get it later today). I made mine from a 5/16-18 coupling
nut by simply running an 8x1.0mm (uncommon fine thread, but most tap
sets include this tap) tap down the center of the nut (which left
surprisingly good threads. Get some 8x1.0mm all-thread or longer
8x1.0mm bolts and make short studs to thread into the bottom side of
the spacers and two 8x1.0mm lock nuts, one for each spacer, to clamp in
the stud to the spacer and take load off the spacer's imperfect
threads. With the FAC-included 8x1.0mm nut above each spacer and one of
the 8x1.0mm nuts you bought, firmly affix each spacer between a damper
and an extender. I JB Welded the studs into the spacers. Measure to
confirm overall length and correct as necessary.
4) Make spacers for the springs. If you do not want to add preload to
the springs, these spacers will be the exact length as the previous
spacers plus the width of the added 8x1.0mm locknuts. If you want to
add preload (I added 18mm), the spacers should be legthened by the
amunt of preload you add. I made mine from some 3/4-inch aluminum
tubing I found at the hardware store. OD was perfect; ID was slightly
under, so I opened it up slightly with a Dremel and grinding bit.
5) Assemble springs and spring spacers on dampers.
6) Insert spring-damper-spacer assemblies into tubes and tighten the
FAC top caps into the tubes. Be careful; you are threading the aluminum
top caps into the steel tubes. It's very easy to damage the aluminum
threads. Note that the bottom four threads on the FACs may need to be
dressed down with a file for the caps to insert fully. Dress them if
necessary
7) Assemble rest of forks per normal procedure.
A Possible Method for Converting to Disc Brakes
Wondering how to convert a drum Loop to discs? Here's a method I
thought of while doing the above procedure. You'll need a bunch of
parts before you begin. The best way to get them is to buy an old T- or
T3-type front end. This gives you the sliders, damper extenders, bottom
caps, wheel, disc, caliper, and master cylinder you'll need.
1) Buy FAC dampers and the shorter springs for the T3 (else there'll be
a large gap between the top of your fork sliders and the bottom of the
fork shrouds, or get the longer disc-brake fork shrouds). You could use
the ones from the donor forks.
2) Center-drill the the bottom of each of your stock drum-brake fork
top caps for an 8mm tap. (I'm 99 percent sure the FAC top cap is
threaded 8x1.25, but measure to make sure it's not 8x1.) Drill a blind
hole (one that does not go all the way through) deep enough to tap
threads for a short stud or bit of all-thread.
3) Tap the threads and insert the short stud. JB Weld it in place.
4) Measure the depth of threads into the top of the FAC damper. Cut off
stud to just under this measurement.
5) Then, on a lathe or with files, turn down the FAC top caps so they
slide into the fork tubes. This is easier than it sounds; they are just
soft aluminum.
6) Screw together the drum-brake cap and dampers.
7) Affix the extender rod to the damper's slider and assemble springs
on dampers.
8) Insert spring-damper-top cap assemblies into tubes and thread the
top caps into the tubes to hand-tight.
9) Assemble rest of the forks per normal procedure for disc-type forks.
10) Make adapters to affix the fender to the fork sliders.
There may be more involved. I'm gonna try this and let you know.
A Possible Method for Adding Dampers to Drum-Brake Loops
I really think the fork action of drum-brake Loops could use
improvement, so I'll be soon trying to adapt FAC dampers to them. The
FAC top cap will thread directly into the Eldo fork-tube top caps (or,
depending on length requirements, you could affix the FAC top caps to
the stock fork caps, as in the previous procedures), so it's no problem
affixing them at the top. And you could keep the external fork springs,
saving fuss and expense. I still haven't solved that problem but I'm
gonna give it some thought. Anyone have any ideas?
GF