This was the old post from years ago with some thoughts added, things learned along the way. What have you learned?
There were three guys working on this kit. We talked and looked,
and looked some more.
First stage, strip down forks to one
fork stanchion, one slider, one steel bushing with clip to retain,
one high hat bush, one seal and one seal retainer assemble dry
at this point. Check travel, got six inches plus with no dampener tube,
valve, rod or springs.
Ok second stage, add stock dampener tube
with valve supporting rod, tube cap, spring, stock spacer, jam nut.
No fork cap nuts or fluid so when you slide this back and
forth the spring assemblies are coming in and out of the top of
the fork stanchions tops. The travel was four and one half inches.
Note that in this state the springs are loaded against the top of
the dampener tube cap and are trapped by the jam nuts and the
spacer on the other end so the dampener valve is tight up to the cap.
Until the bike is full assembled with the dampener rod jam nut
tight to the fork caps and the weight of the rider is felt the
valve is always going to stay there up against the cap.
The stock length of the rod is limiting the distance the
sliders can move. Do the same test with two inch longer rods and
an extra set of springs for preload and you get back the
six inches of movement. The true limit, the max to be had,
is when the top of the steel bushing hits the bottom of the
high hat bushing.
Now you don't want to ride the bike in this state with
the two bushes tight to one another there's just not enough
support and the front tire will bounce back and forth at
stop lights. So we came up with the two inch longer modification
for the one and one half inches of travel gain so that under
no circumstances could the dampener valve be used
to limit the travel. For this we wanted a fluid stop and not a
one and one half long loose fitting bushing between the two
bushings as used in the the covenant kit.
The springs that come with the kit are from ford tractors and are
the same O.D. and I.D. as Norton and progressive springs.
They start with a two and nine sixteenths free length and have
a bound length of one and nine sixteenths for one inch of travel.
From what we know the stocks springs have one half of an inch to go with
the slider bottomed out, that is the bottom of the stanchion hits
the bottom of the slider. We add one and one half of travel
with longer rods and the extra spring adds one inch of travel and
the old springs had one half inch to go so the springs should
bottom out just as the fork stanchions do.
Now for the fluid control if things were ideal one would have full movement with hydraulic stops at each end that is nice and slow acting right at the
ends of travel.
The best we have come up with so far is using ATF "F" type for fluid and leak proof brand seals. it works on fifty bikes so far with no adjustments needed not that there are no adjustments. I have one bike with stock springs and one with progressive springs and I have to say
that I find the progressive springs better but the stock springs work
well too.
On the center stands these modified bikes don't
lift the wheels of the ground any more but still work for me. Some bikes need a shim welded onto the center stand contact area.
The idea is to get the bike to go down from your weight
at least one and one half inches. Than ride around with four
and one half potential inches for bumps and the
one and one half for pot holes. Norbsa48503
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Some things that make sense learned over time as of 2008.
The dampener caps will be worn on your old bike, and need replacing. They are a big part of how the system works. If you’re using the aluminum dampener rods you should be running bronze caps, they can be had from Clubman Racing. Leak Proof seals and full rubber gators with a little filing of the top hat bushing will provide long lasting non sticking seals it needs to be part of the package with the kit. JMO though.
You are doing your own work here you have to make choices about how the work is done.
In the directions with a kit is a method that works for me and has worked on many bikes.
If you feel the need to omit or change the modifications spelled out you are on your own.
Nothing wrong with that you do the work and thinking with this simple kit anyway.
I encourage you to play with this on your own and please report back to me with your thinking and results. This kit may evolve from your testing. If you would like to do some testing on your own regarding the fluid stops at each end of the travel assemble the whole thing on one side with ATF and without the springs and test away slow and fast by hand.
Beware of fork tubes and bushings that are out of speck they can cause you to do fitting that requires machine work, you may not have a lathe near by. The inside of the bottom of the legs can bind on the taper on the dampener tube check this before assembly. I don’t use a bushing between
the stock ones provided nor a modified longer top bushing to limit travel I rely on the weight of the rider and the oil or ATF F type to allow the bike to sink to the normal ride height .
So you will have issues with brake lines that are too short sometimes, I sell a kit to deal with this it is a one inch longer S.S. brake line and a new one inch taller support bracket so you can use your new upgraded hose. Or just buy a new hose one inch longer hose if you haven’t yet
changed out the brake line. The extra travel seems to make the whole system work better than other alternatives.
I use ATF “F” type and change it often. Twice a season at least.I use Quick fill fork caps made by Bruce Chessel.Bruce can machine your good fork cap bolts or build you stainless ones. I use alloy ones he modified for me.
This is important, if you can renew your fork fluid in ten minuets for a dollar you will do so as you feel the ATF stiffen over the season. If you run expensive synthetic oil and have stock caps your much too likely to put off this 30 minute project to a time that will have you wearing out the parts by grinding them with metal paste. Less is more in this case.