This is written in the first person and work done by Bob Broussard. I have not
done this mod.
This is for mounting a 2001 gsxr750 front end
on a GS500. Doing this is really overkill for the street in my opinion so if you're going racing and /or you've smashed your
forks and need them replaced anyway here's what to do.
A) Take the steering stem from both bikes and have them pressed out. Press them out
the bottom of the triple clamp! I broke my press trying to go the wrong way. They have collars so they won't pull up out of
the lower clamp.
B) The GS stem is just a hair smaller than the hole in the gsxr lower. I took some aluminum
tape I had and put one layer on the bottom part that fits into the lower. Then I was able to hammer it into the lower. The
tape is aluminum with glue on one side. It's used for heater ducts. You could use some shim stock if you can get in .001 thicknesses.
The tape is extremely easy to use.
C) Put the bearings on and put the lower on the frame. Thread on the collar.
D) Now is the part where you have to make a spacer. If
you have a lathe, that would be perfect. I have a mini milling machine and rotary table. The spacer fits into the hole
on the top clamp. It is wider on top to sit on top of the upper clamp. Then it is the same size as the hole in the upper to
fit down into the hole. The part that fits into the hole should be the same length as the hole itself. The part that sits
on top could be 1/8-1/4 in. thick. The bottom of the spacer should be milled out to fit on the tip of the gs500 steering
shaft. Then drill a hole for the bolt to go through into the steering shaft. It is actually very simple.
I had a 97-gsxr front-end before and it needed a larger
spacer on the bottom to make up the difference between the gs shaft and the larger hole on the lower. The bearings from
the gs fit the 2001 shaft but the length is too long. Don't waste your time trying to make the gsxr shaft work. Just
use the GS shaft and make spacers.
Weight difference between the 97 and 01 front-end
is about 2 lbs. That's including wheel brake rotors and everything. Ive heard the gsxr1000 front-end is a little lighter
than the 750.
What you
end up with is a fork set that is probably 6 times as stiff, so all that flexing under braking and cornering on the race track
is virtually eliminated. You also get a wider front wheel to run the common sizes of radial race rubber. You also get rebound
and compression damping adjustments to make the bike behave on different tracks and of course bigger, dual disks, with 6 piston
calipers for better braking. Dual calipers/rotors are also probably overkill on the street (looks way cool though) but on
the track you'll need both since one alone will overheat at extremes.
A word
about pressing the steering stem:
I press them out cold, from top to bottom only. Heat won't help, because both members expand at same rate. and aluminum
galls easily at higher temps. There is no locking agent. However, things worth noting: 1) you can probably find a lathe that
will swing the clamp, and you can then do it between centers with a driver on the clamp itself to make it all go around, 2)
your top race should actually be a light press fit, about .0001" tight, 3) the stem is anodized and you will turn that off,
reducing hardness quite a bit, 4) a steel stem is going to be about thrice as stiff for the same wall thickness if you care
to make one, and stiffness is at a premium in stems. If you do make a stem your fit steel-to-aluminum should be about >.003"
tight; only fools do presswork like this w/o an anti-seize compound on both sides, and for this case some heat on clamp eases
the effort. If you want help, I do these swaps at rate of about 6-8 per year and will be happy to assist. And finally, I hope
people onlist here who have no experience in the matter will have the grace to not expose that through gripes or personal
comments. Bob Broussard can be contacted through one of his posts on GSTwin.com.
