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Gold Valve Emulator

I did all the drilling during assembly the first time. I don't think I need to do any more.

Today I drained the 15W oil.
I also realized that there was a serious gap (1.5 inches) between the Race Tech springs and upper fork cap. I increased the PVC spacers and used 5W fork oil and the forks rebound as expected and feel much less stiff. (Stiction is OK)

I'm going to do my first ride tomorrow and who knows... I may end up using 7.5 or 10w oil.... but at least now i'm not afraid my arms will get punished from the stiffness.

I'll report back...
 
Maybe I missed it in your post but:
What bike are you working on?
Did you put RTGV's in both tubes?
Nice work. Thanks for sharing.
 
morning all, J_withers didn't follow race tech's instructions, they call for a 15 mm preload on the fork springs, which is one of your adjustments for how stiff your forks are. race tech also says you can use anywhere from 5wt fork fluid to 30wt, although anything over 15wt is probably for racing. also they make 3 different springs for the GV, which can each be set from 0 to 7 turns. I just put GV's in my 1990 R 100 GSPD ( different forks than you guys ) and am thrilled with the results. I put a GV in both sides, after some mods, yellow spring, set to 2 turns, 10wt fluid, this is probably stiffer than you would want for the street, ( unless you like to go fast ) but I am thrilled with how my bike handles now.
 
morning all, J_withers didn't follow race tech's instructions, they call for a 15 mm preload on the fork springs, which is one of your adjustments for how stiff your forks are.

You are correct, I initially didn't have the 15mm preload. I do now though.
Although, when i first put the forks together, the springs were at the top of the forks and I had to press them down to secure the upper fork nut. Perhaps it was how the bike was sitting.
Upon second inspection when i realized everything was so stiff, the springs were far from the top (on centerstand) and i had to increase my PVC size for the correct preload.
 
deburring damper rod inner wall

I'm still wondering how to clean out the inside of the damping rod thoroughly to make sure I have all the debris from the drilling. I don't have a parts washer and just spraying carb cleaner and WD40 through the center is not gving me that warm, fuzzy feeling of confidence. Any suggestions?

I used some small round files , reached in from outside to give the inside edge of the drilled holes just a bit of chamfer.

This was pretty good but not gt, so I superglued (sparingly) a little flag of 320 grit SiC paper to the plain end of a loooooong 3/8 drill bit.
As long as the paper didnt overlap itself, this Hone, Sweet Hone, fit down inside the rod just right.
Wood dowel would work probably even better.
Chucked the bit in a drill , dunked the business end in a bucket of water and gave it a few dozen twirls to deburr the inner walls.


If/when the paper broke off, it wasnt too hard to remove from the bore- its just a through-pipe with a single restriction.

There are bore brushes (gun / eng kits) that fit in there for the final scrub.

Aside from getting the swarf out, its not exactly critical to perfectly deburr the rod ports inside; with all the extra holes, the velocity (and backpressure) of the oil cycling through will be much lower, so the potential to cavitate is much reduced.




yeah I know this in ancient thread, but the internet is forever and this thread is worthy of pull back up top ! thanks colwell !
 
15W fork oil. It seems extremely heavy for a 1972 /5 BMW. -josh

Reading through RT docs; seems that fork oil would ideally be more viscous than the 5 or 10 wt OE spec'd ,
but an orfice-controlled damper rod system is subject to cavitation ( caused by back pressure, resistance to flow , oil piled up inside the rod/orifices so to speak) upon rebound motion.

Higher oil WT is even more susceptible to this effect, so lower viscosity oil is the less-than-optimal answer.

Simply enlarging the orifices in order to reduce the flow impediment will also reduce the dampening on compression stroke & lead to bottoming , lift-off, etc.

With the larger rod holes allowed / required for the emulator, the higher WT will work better without the cavitation drawback
 
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