Question about Forks

[He Man]

Just reading up on forks and have some questions.

Between Damping rod forks and Catrdige type forks, which one do we have? Are USD forks Cartridge type only?

Going to a heavier oil wieght on the fork will do what?

While watching Dave Moss Unsprung, there is an example of a catridge type USD fork that has gunk all over the compression piston from the spring action scraping metal off the side of the fork. How often should this be cleaned out (and do are our USD forks the same way?)

one last question is, whats an alternative to Race Tech Ultraslick US2 Medium oil (the current oil in my fork)?  Theres a lot of oils out there that are cheaper, but im not sure if they have the same performance.

right now, i have my preload all the way clockwise in and the fork will bounce once when you push it down and let it travel.

[suzyj]

I've not seen any damping rod forks in all my reading - I think they're all cartridge ones.

Heavier oil will increase damping.  The more viscous oil resists flowing through the valves more.  Dezmonster went from 7.5wt to 10wt oil in his ST2 forks to increase damping.  Bear in mind oil weight affects both compression and rebound equally, so if you're just after an increase in rebound damping, you'll want to wind out the compression damping screws a bit to keep compression damping unchanged.

Your preload adjustment won't affect damping.  It just changes sag.

AFAIK, there's no appreciable difference between different brands of fork oil.  I plan on using Motul, mainly because it's easy to get here and I like their motor oil.

[He Man]

So whats considered "medium" theres no weight on racetech bottle. Im thinking its around 10weight.

I need to edit what i said. i meant my REBOUND is dialed in all the way. Which i dont think is a good thing since its maxed out. The rebound  damping is what sets how fast the forks come up right?

[Speeddog]

All OEM Monster forks are cartridge style.

RaceTech US2 oil is approximately same as Maxima/Spectro/BelRay 10wt fork oil.

Did you talk to the shop that did the mods on your forks?

[He Man]

All OEM Monster forks are cartridge style.

RaceTech US2 oil is approximately same as Maxima/Spectro/BelRay 10wt fork oil.

Did you talk to the shop that did the mods on your forks?

I did. But I didnt ask them these questions, just what kind of oil they used. Aside from that, I still dont know enough about my suspension ask them the proper questions.

that link cayman s linked has loads of good info. so im reading on how my suspension should behave.

[Cider]

right now, i have my preload all the way clockwise in and the fork will bounce once when you push it down and let it travel.

I'm trying to picture this.  Are you saying it rebounds so fast that it bounces off the top-out spring?  If so, that sounds pretty fast if the rebound adjustment is as slow as it will go.

[He Man]

i dont know what a top out spring is.

But it rebounds, over extends and then settles. No bouncing around, just settles after it over extends. if i backout the rebound screw, it bounces around.

[Cider]

I'm not a suspension guy, but that sounds pretty fast to me.

[suzyj]

I'm not a suspension person, but I have done heaps of control theory at uni.  An underdamped system will overshoot a little.  If suspension dynamics are like any other control system (and I'm sure they are), then your objective is to damp the system to the point where the overshoot just goes away.

http://en.wikipedia.org/wiki/Damping_ratio

Obviously if your rebound damping is all the way in, then the only way to do that is to change to a more viscous oil, or to change the valves.

[cokey]

Good stuff to learn

[He Man]

I went to clean up my garage today and started playing around with the suspension.

somethings to note, i may actually have to send them out if there is something wrong with them...

1) When i hold the brake and pump the forks theres a distinct clicking sound. Normal?
2)It will overextend only about 2cm. Is there suppose to be absolutely no rebound at all?

[ducpainter]

I went to clean up my garage today and started playing around with the suspension.

somethings to note, i may actually have to send them out if there is something wrong with them...

1) When i hold the brake and pump the forks theres a distinct clicking sound. Normal?
2)It will overextend only about 2cm. Is there suppose to be absolutely no rebound at all?

The click on Showas is pretty normal IME.

Are you confusing me with terminology?

What exactly do your forks do?

[He Man]

I pump the forks to see how much it rebounds. It compresses then it comes up, then it goes back down and settles without coming back up again.

i dont know the technical name for it... its rebounding too much? its not bouncing around, it just comes up and then it goes back down to settle.

[Ddan]

It sounds like you have essentially no rebound damping.  The fork shouldn't top out and then settle.  Try going through the full range of adjustment on the damper to see if there is any noticeable difference in damping between full out and full in.  There should be.

[He Man]

if i backout the rebound screw, it bounces around.

you mean this?

Shouldnt i be able to over dampen the system and my rebound damping should be in the middle range?

i can do this with my rear shock. if i over dampen it, it will come up very slowly. if its under dampen it will bounce around and come up very quickly.