Running generic 15w in my stock front end and it's working very well for me. 07 FXD.

 

I changed out to PJ1 20wt fork oil. No more bottoming out and she rides fine...
Eventually, I would like to work on the rear suspension. The potholes here are kickin' my *ss!!

 

I put heavy duty fork springs in my forks and I run standard weight fork oil 10wt i believe. The heavier weight makes my front end to stiff on these crappy NJ roads

 

http://racetech.com/articles/CartridgeForks.htm
This is a good article and I'm assuming the one you mentioned. So now in my case I see the advantage of the cartridge over the damping rod as it allows rapid flow through the system as opposed to the oil acting as a damper itself during quick compression/decompression like hitting a rut or etc. This allows the spring to do the work better and not add rigidity because of a failure to displace oil quickly. I see it now.

I talked with my indy guy this moring and he said the stock oil weight was 10wt. and what he changed it to was 15 wt. What I experienced in just a 35 mile trip home was the clanking was gone BUT it became more rigid, not to a fault, but more rigid. To dial it even further, I would need to go with a racetech springs system (utilizing the cartridge system, because now I'm sold) ...OR...perhaps bushings in the risers? I don't need perfect and I may be fine after I get used to what I now have. Maybe even softening up the rear springs to a lower setting with a spanner, also would help overall?
Thoughts?

Edit: just got off the phone with racetech and they have a whole kit to totally dial in my FLD front w/cartridge and proper spring for my weight at about $500 out the door with them doing the install. $300 plus oil if we do it ourselves and he said the install was easy...he said that HD did good by adopting the cartridge system but then put an inferior or not-ideally-matched-spring (which is more politically correct, lol) and then over tensioned it.
The racetech system provides and aligns all the components properly and then we would have a killer system. Me, personally? I'm going to go with this 15 wt. oil that i got yesterday for a while and see if I can live with it before going this route though. Going back to my riser bushing question; will that help at all?

 

I just changed out my lowers this weekend and I went by the Harley Shop to pick up some fork oil. I was going to buy 7-10 wt oil. The sales person told me I shouldn't use any less the 30wt on a bagger...we got into a discussion about it and then the HD Mechanic came in and said the same thing. So I bought the 30 wt. I haven't got back together yet but I bet it will be very stiff and will probably change back to a lighter wt. Time will tell.

 

Im installing my Burly front lowering springs today. Do i need to change the fork oil to a higher viscosity?? Also, Does the amount of fork oil need to be changed with the lowering springs??

Drew