Suspension tuning advice

[SS109]

Sorry, I have confused you. I read the base valve stack wrong and figured the 28 was against the piston. The stack is very strange that it tapers a lot of bleed and then clamps on the 28.. Are you certain you recorded it correctly?

Ah, ok. Had me really confused there. Yes, that is exactly how it came out. The other side matched exactly.

I also looked at your stacks again and don't think I would change the mid comp stack too much. It only has 2 x 20.1's already..

Hmm, is the mid comp the stack on the other side of the piston with the rebound stack?

Did you mention what the float clearance is?

No I did not. I honestly don't know what that is or how to measure it.

 

[Jakobi]

The damper rod has the piston attached to the end. One side is rebound, the other compression. With it assembled you'll notice that the compression side can float between the piston and its stopper. You can use feeler gauges to measure it up, or physically measure the amount of post without any shims and then subtract the stack.

 

[SS109]

Ok, I understand that. What is it's significance?

 

[Jakobi]

The more float, the more the mid valve compression stack can move away from the piston face, the less initial damping you have.

Tight float tends to feel firm and sharp with feedback through the bars; but not necessarily harsh.

Opening it up gives a plusher kind of ride.

But it's just another variable in the whole setup.

However, the mid valve is constantly displacing large volumes of fluid in both directions. Comparatively, the base valve which is a larger piston only has to flow the oil displaced by the damper rod entering the inner chamber/cartridge. As such changes in the mid tend to be more noticeable.

 

[Jakobi]

I feel like a base valve change would be the quickest and easiest though, and given that the comp adjuster is just a free bleed past the base valve it would be the best place to try and get your clicker centered again. The problem being your base stack already has a lot of free bleed and I don't think adding more to the stack is the right way to go.

For comparison my 2013 had this as its stock stack.

BASEVALVE/Piston
12x.10
32x.15 (2)
26x.15
24x.10
22x.10
20x.10
18x.15
11x.20 (2)

I ended up with this.. but it was more of a build a whole new stack vs modifying the existing.
13x.1
32x.10 (3)
24x.10
32x.10
32x.15 (1)
30x.10
28x.10
26x.10
24x.10
22x.10
20x.10
18x.10
16x.10
14x.2
11x.2 (2)

 

[SS109]

Thank you so much for the info and advice. Your explanation of the mid valve stack and it's float made it where even I could understand the concept. It takes me a while to grasp how some things work but once I do it's like an "ah ha!" moment.

So, what I'm thinking for what I currently have...

piston
11 x .3
11 x .3
18 x .1
20 x .1
24 x .1
13.8 x .1
31.8 x .15
31.8 x .15
28 x .1
2.5 spacer

...and going to...

piston
11 x .3
11 x .3
13.8 x .1
18 x .1
20 x .1
28 x .1
31.8 x .15
31.8 x .15
24 x .1
2.5 spacer

...then, if needed, I can play with the float by removing the 11 x .10 from it's stack or maybe moving it between the two 20 x .10 shims.

Does it sound like any of this might work? I think I'm about at that point I might have to send it to LTR or ZipTy. I wonder if either sells stacks so I don't have to ship my forks?

 

[Jakobi]

No float on the base valve. The stack is clamped against the piston.

The mid valve is different.

Have a read here: http://www.racetech.com/page/title/Fk Mid-Valve Float

 

[SS109]

Yes, I understand the float is only on the mid valve. That's why I said I could play with it and it's stack after playing with the base valve stack.

 

[Jakobi]

Understood now
Your alterations to the base valve will be softer than how it is now. Give it a crack and see what you think if you have the time.

It will be quite a bit softer likely though, given that you're changing the clamp from 28mm to 24mm. This may not be a bad thing.

Good approach changing one circuit at a time too. Always easier to evaluate the change.

 

[SS109]

With my compression all the way out it was really good on the MX track we raced on so quite a bit softer would probably work out.

Thanks again! Your insight has been invaluable!

 

[Jakobi]

Good luck and looking forward to the next update.

 

[SS109]

Did the re-valve this past week and took it out Sunday on our work day for our race. Didn't really get to hammer it much but I did get some idea of how it feels now.

I figured this was going to be a lot softer but it wasn't. I set the clickers at full out so I could compare it directly with what I had been running. Seems to soak up trail junk now but I was having some sketchy moments of it. Had to slow the rebound by 3 clicks to get it under control. So, PFP full out, compression full out, rebound 23 clicks in. While I am at extremes, it feels pretty good. This coming weekend I'll be back to my normal testing ground so I'll get a better feel for how it's actually working..

 

[kenfm2000]

Ah, ok. Had me really confused there. Yes, that is exactly how it came out. The other side matched exactly.

I am a newbie when it comes to working on suspension. I am curious about the Compression stack and orientation of the compression valve. On all the pictures I can find the large opening port side of the compression valve is on the shimstack side. In your youtube video it shows the small ports on the valve against the shim stack. With your current shim stack are you still having to run with the compression adjuters full out? The other thing I noticed is your compression stack is the opposite direction of everyone else's stack. Could it need to be using the smaller valve ports? Then also with the larger ports they are against the check plates. Could this cause it to flow more oil in the rebound direction? To me this could explain having to turn in rebound more and turn out compression more and backoff pfp to 0.

Hopefully someone with more knowledge will chime in. Unfortunately if you flip the compression valve over and reverse the shim stack you may have to start at ground 0 and then revalve from there to your liking.

I have watched your video several times as I am having issues of my own. I had a shop replace seals, bushings and they revalved as well. It feels like there is some kind of binding or hydro lock going on in mine. The first inch or so seems to take alot of force to start moving the forks down in the stroke. I have removed some compression shims that they put in but the issue persists. My forks were also shortened 30mm beforeaI bought them so it may complicate my issue. Although I used them for 3 years and they seemed to work much better than they do now.

I'm not sure what my next step will be with my forks, but the deflection I'm getting now is taking the joy out of riding my dirt bike.

 

[SS109]

Like I mentioned on Youtube, I'm not sure which direction the base valve should sit. I just put it back in the way I pulled it out. Yes, hopefully someone with more knowledge will chime in and confirm whether my setup is correct or not. I have another set of the 48 PFP's but haven't disassembled them yet to take a look.