Been considering upgrading to Race Tech cartridge Emulators for some time. I was waiting to order until I tore the forks down to see what else might need freshening up.
You are not supposed to hang your calipers like this...
Here's what I found:
Bottom of Fork Tube with inside bushing removed:
Piston
Inside and Outside Bushings
Spec says "replace if scored or more than 25% copper shows; do ya think???
Piston Ring
Sweet! Great content Brad, will make a dandy reference. Please do continue!
Did you get a chance to measure sag with the old springs before it came apart? Forgive me spending your money but you might ask RaceTech to send a spring kit too that's matched to your weight.
N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)
Did not measure sag. Thought about ordering springs. I am going to go this way; since I will be riding my prolink with fairing on and fairing off, i will need multiple spring sets to set the spring rate ( pre load) for the difference in weight. I have been told i can use various lengths of pvc tubing as a shim with the stock fork spring to vary pre-load as desired. According to race tech, the stock spring rate is .614 kg/mm. Their recommended spring rate for my 200lb rider weight is .951kg/mm (with fairing). There is a third spring rate (close to an early model i presume) for my bike without its fairing. I am going to experiment with varying shim lengths until things feel right for me depending on the bike configuration.
regarding fork spring preload; Race tech cites the stock rate at .6XX, and recommends .9XX. When you install the gold valve, that acts as a spring spacer tube, thus increasing spring preload by the height of the valve. Thats probably why the race tech replacement springs are shorter than stock springs.
/r
B
They are a lot shorter generally, for whatever reason, but that allows for more flexibility for fine adjustments of sag. Like, 6 inches shorter as I recall when I did my SV650. The note about the compensation for the height of the gold valve is useful though, for sure.
N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)
Quick update. I wound up buying the Race Tech "Motorcycle Suspension Bible". Wow some great info!! Well spent $35 for those wanting to improve their suspension knowledge.
Regarding the previous pix, after re-evaluating my bushings, the wear surface of the wide bushing is the outside surface. It really was not that bad. The wear surface of the narrow(er) bushing is the inside surface. Again it was not that bad. My thought was, if I was gonna rebuild to a race tech suspension, I wanted to start with a clean baseline, thus new bushings, seals, etc. to eliminate all variables.
In assembling the forks, the left assembly had a bind to it I had a hard time tracking down. At one point I thought the tube was bent. I tracked it down to the narrow, top bushing. The last time the old narrow bushing was pressed in (um, by me...), I'm guessing it got cocked, and the edge scratched the surface of the area it is installed in as I found a glob of soft aluminum protruding from the bottom of the scratch. Not noticing this, when I installed the new bushing, the gob, forced the new bushing to protrude in that area. This caused the tube to bind just a bit. i disassembled and found the issue. I used some 500 grit sand paper to smooth out the scratch. I followed that with a gob of mothers polishing paste to polish out the sanding marks. Lastly of course I thoroughly cleaned all surfaces to ensure no grit remained.
I found a 8" length of 2.5" PVC tubing works great as a slide hammer to install the new seals. Be sure to install the backer plate , then the seal, then the backup plate before hammering the seal in... (I now know the correct order from memory...). for fork oil level, (before installing the spring) collapse the fork tube. Fill with fork oil (I used 10W) to 100MM from the top. I crafted a dipstick and marked with 100MM and 130MM levels. Pull the tube all the way out before installing the spring. Otherwise the oil will overflow... I found this out too...
I took a short ride. First impression? WOW!! You should consider the Race Tech Fork Emulator upgrade. Significantly different feel! Much tighter (not harsher). The wheel stays planted to the pavement. Will need a much longer ride thru varied surfaces and curves for a better evaluation. More later.
Brad
