DIY revalve of TC forks?

[PC.]

I've got some shim recommendations for the shock from a reputable builder if anyone wants to try them and give their feedback. They're for the 09' wr sachs shock.

I'm gonna tear my forks (50mm marz open) apart soon and try to get some recommendations on that. They absorb chop well, but they dont like big hits. Glad to see people talking about this stuff on here!

 

[ray_ray]

I think I will just start with what you suggested. Making the trail trash go away without getting all mushy is the goal so I appreciate the advice. If I don't like it it's not like it is hard to pull them back apart. The only thing I hate about the whole procedure is bleeding these things.

The bleeding is a pain ... Some of the notes I read on the process mentioned to work the air out as much as possible before putting the cap on the tube and this actually worked for me on one of the tubes ... no bleeding necessary ..

You'll just be removing the valve maybe to change the stack ... You have started with no air in the tubes at this point so the only air in the chamber will be in the valve itself and some in the top of the chamber ... so some work here in an effort to get some of that air out be capping. I.E... I dunked the valve in the chamber a few times in an effort to get the air out of it also before tightening it down.....

 

[NWRider]

Here is the rebound and midvalve. Once again I have lots of shims.

Starting from the nut on top I have:
11x2.5, 15x.1, 17x.11, 19x.1, 21x.1, 21x.1, 21x.1 (I assume this is the rebound).

Next there is the valve and what follows is what I assume is the mid valve:
22x.15, 22x.15, 13x.2, 20x.15, 19x.15, 17x.15, 22x.31, then the spring.


For reference here is my base valve:
12x.1
22x.1 (8)
21x.15
20x.1
19x .11
18x .1
17x .11
16x.15
15x 1.5
14x.2
13x.3
12x.2





I could not figure out what the float was so I did not measure it. If someone can explain it I can give it a try.

What changes do you think would work for the first try? I assume my base valve is on the stiff side. Is this midvalve soft?
I could not figure out what the float was so I did not measure it. If someone can explain it I can give it a try.

What changes do you think would work for the first try? I assume my base valve is on the stiff side. Is this midvalve soft?

Thanks again for the help!

 

[ray_ray]

NWr, how did the forks feel on a MX track ... ESP during UR jumping?

 

[MOTORHEAD]

NWRIDER,

Let's try this:

Base:
22x.1 x2
17x .11
22x .1 x3
20
12
21x .15
19x .1
18
16x.15
15
14x .2
13x .3

MV:
22x .15 x2
13x .2
20x .15
19
17
12x .2 ( From Base stack )
22x .31

Does your current set up seem to "Spike" over medium size hits? I'm assuming yes, most tend to. You seem like a pretty salty rider, so I don't want to get it too soft for you, but I do want to make the trash disappear. I hate trail trash myself, so I think I know what you're looking for, just not sure how stiff you need it overall. But, give this a try, see what you think and we can go from here.

 

[NWRider]

NWr, how did the forks feel on a MX track ... ESP during UR jumping?

I do not ride MX so I really do not know what is desired there. But for the times I get it in the air in the woods (generally just 5' or so with flat landings) it feels perfect. On a big slow hit they go through their stroke very smooth and progressive.

 

[NWRider]

Thanks Motorhead. I guess if I had to decide between too stiff or too soft I would rather lean towards too soft. Just for comfort and becasue of all the rocks littering our trails.

Can you explain the midvalve some for me? When I look at the base valve I can see how it works, oil comes in towards all the wide shims and they provide some resistence before bending. But the mid valve has 22mm shims on both ends of it. Is it providing damping in two directions? Or is it two stage, oil comes from one direction and when it overcomes the first set of 22mm shims it can move a little before it hits the other set?

Thanks for all the help.

 

[MOTORHEAD]

Yeah, that pretty much sums it up. In a multi-stage design the first set starts to deflect then comes in contact with the next stage, which starts to add resistance.

The rebound stack, on the left side as you pointed out, is off the face enough to allow oil to pass around it, into the ports and push open the face shims of the MV first stage.

As oil starts to file the chamber above it, it starts to do the same on the base valve and it's stacks.

Did that answer your question?

 

[NWRider]

Thanks. Is the midvalve modification you suggested (adding a 12x) softening the first stage or the second? Just curious.

Is the concept of float something to worry about? I see it discussed with KYB and Showa forks. The MV has a spring against it so I thought it might be doing what float does but that is just a guess.

I't interesting to learn how this all works. I know it would be easier to just sent the forks to someone but I like to do things myself when possible.

 

[MOTORHEAD]

It should soften both being at the base, but should have the most effect on the second stage.

That big spring behind the MV is a top out spring.

Some forks have a "float", but I don't think this unit does.

It's interesting, but can be argumentative. I think that has a lot to do with why you don't see much talk about it. It still has sort of a "black art" status about it, too.

Almost as bad as talking about religion.

 

[NWRider]

I definitly have noticed the "black art" status. When I used to be really into mountain biking wheel building was kind of the same. People talked about it like it was some high art that took years to master. Finally I decided to get some directions and try it myself and it really was not all that difficult to get good results. After tearing into my forks they do not seem all that mystical either. I think once I have modified some stacks a few times I will get the feel for it. I don't expect to get the results of a pro but it will probably be good enough and at least now I can modify things at will.

Thanks for all the advice and explanations. I'll repot back after I get a chance to try them out.

 

[ray_ray]

I do not ride MX so I really do not know what is desired there. But for the times I get it in the air in the woods (generally just 5' or so with flat landings) it feels perfect. On a big slow hit they go through their stroke very smooth and progressive.

Cool ... sounds good to me ... I'm retired here so I can play with all this stuff on a daily basis almost ... I almost wish I had 2 inner chambers and CMP valves so I could valve for trail & track n each specifically and not have to bleed the chamber each time ...

 

[MOTORHEAD]

I think once I have modified some stacks a few times I will get the feel for it. I don't expect to get the results of a pro but it will probably be good enough and at least now I can modify things at will.

Thanks for all the advice and explanations. I'll repot back after I get a chance to try them out.

I don't claim to be a pro, some are probable thinking I'm a hack, but I normally get desirable results. The neat thing is I can make myself and my friends happy, and have some control over how my bike works. I have to try different things, how do you know what's best for you if you just send it off and let somebody else make that decision?

 

[ray_ray]

I don't claim to be a pro, some are probable thinking I'm a hack, but I normally get desirable results. The neat thing is I can make myself and my friends happy, and have some control over how my bike works. I have to try different things, how do you know what's best for you if you just send it off and let somebody else make that decision?

Same here ... no pro rider or suspension guy but I do wanna do my own work and learn from it and I appreciate the help on this ...

Went to the track today and had a few side effects to report ...first, after closing the compression valves up, the forks seems to wanna hang and stick at the top of the fork... felt really strange going down the road as the steering would just lock and turning the bars was like I have a steering damper on it ... When sitting still, you can see the forks were almost stuck at the very top of the stroke ... Opening the CMP valves eliminated this issue ..


So I had to loosen the CMP back to about the default setting of 13 clicks out from the bottom ... At this setting, the bike jumped a little further but still bottomed out on the flat landings ... Felt OK except not enough bottoming resistant over jumps ... Seemed to be a firm stroke that went all the way to the bottom ...

The outer tube oil level is at 270ML .. this is about 5ML short of full ...

Not sure about that fork sticking ... I opened up the rebound valve to the MAX and it helped on the sticking issue but not 100% even though after I got going on the track, I could not feel the forks stick ... This did allow me to close up the compression value and the forks were better but still not enough bottoming resistance ... Pre-load not changed yet ... And very interesting day to say the least

PS -- If I can reach hack level, I'll be very happy ... I was once a hack programmer .. A.K.A. software tester

UPDATE (1/30/2011) ... Side effect I felt was sort of 2 fold and not specific to the stack .

1) Dirty forks and oils -- cleaning the tubes helped 100%
2) Bottom steering head bearing was also freezing up some and sticking the steering -- re-greased it and fixed this issue.

 

[MOTORHEAD]

When you say bottoming, do you mean they use all the travel, or that they bottom hard? Using all the travel on a vertical drop is going to happen and even bottoming pretty hard will be common, unless you build Freestyle type set up.

As far as the sticking, if you had both clickers closed that is possible. There is zero bleed in the system with the clickers closed and you are basically hydraulically locked, until you apply enough force to move the shims off the valve faces. That being the Mid and base valves.

When you change valving and start a test, you need to go to a base setting, like ten out on compression and rebound at the OE or best known setting. We are really not messing with the rebound circuit with these re-valves, so they can remain at normal settings.

You might add a couple of clicks for moto or loosen it up a couple for woods, but you're going to be in a normal range, unless you do something drastic with the springs or preload.

I guess you are running stock spring rates?

So, basically you like the off road habits, but not the moto? You want more bottoming resistance? How is the rest of the track?

BTW- You also need to check the rear sag when changing the valving, too. The forks can cause a shift in weight bias that can move the sag around on you.

 

[ray_ray]

I'm using 100% of the travel ... It does not feel hard at all but the entire stroke is used up ...

Yep these are stock springs ... I'll be sure to keep at least 2 clicks off from the bottom in the future and go back to the default settings tomorrow as a starter point ... I'll move the rebound back also to ~default also ..

The front sag has increased itself to ~38mm ... It was set a few months back to much lower and a mystery to me how it moved ... I probably should change the pre-load when I go back in the forks next time ...

The trails are fine with this stack ... maybe a little firmer than some would like but feels fine to me at speed ... Most of the trails here are really walking paths across the hills and valleys ... not too bad and definitely not shop-worn ... almost virgin stuff from knobbies

The tracks are like an outdoor door SX tracks ... just doubles that I have to single \ drop jump across sometimes, a few table tops, the usually bermed corners \ flat corners, a few holes and ruts ..some braking bumps... Nothing rough ... I have only seen 1 track here with whoops and they were short... I'm not too concerned with all this stuff ... The forks seem OK for all this stuff ...

I'll check the rear sag tomorrow also before I go back out ... No rain today and none tonight so far ...The track was pretty good today except for mud holes ..

More bottoming resistance is what I need ... the changes you have suggested so far are good, but we need more resistance I think ; with the top of the stroke about the same as it is now

 

[MOTORHEAD]

ray_ray, you got me here. To stop a low speed bottoming from a vertical drop like that is going to be tough, if not impossible, to do without making the action super stiff on everything else.

More oil and stiffer springs are about your only choice.

What I'm picturing here is you coming to a steep faced jump and loosing most of your forward momentum as you pretty much go straight up, then dropping straight down with with little forward speed.

Is that correct ?

What do you weigh?

 

[ray_ray]

I'm about 145lb in street clothes ... I'd like to go stiffer in a small way if possible .... I need some relief here ... The more oil is an option but it really has side effects also .... I can add 5ML or so with out side effects and help some ...that was where I started ... 10ML over the full amount ..

You have made very good improvement already I think, we just need another push in the bottoming stuff ...

What you have described would be an extreme case and is here also to a lesser degree ... In that extreme of a case, I just roll a jump if I can't fly across and land on the second jumps' downside ... many of us roll jumps here ;0 ... This separates the different classes of riders here ... One track and all levels of riders ... we all are not PROs or experts ... I might have been giving you too extreme of cases above ...

The attached pics shows me doing a small double ... Not very long in distance but the take-off ramp is very tall so we get kicked up ... You can see in the landing photo that the suspension has collapsed to almost the max ... If I over jump that landing ramp and hit on flatter ground, the forks are used at about 98% ... I'm just sitting on the MAX mark all day many times ... Any mistakes (over \ under jumping )and I can get a big 'clang' (sometimes) as the forks totally bottom ...

The third pic shows more of the track ... that is a small triple to the far right ... The double in my pics is to the left and above that is another small double ... The track is mostly like what U see at the bottom of this pic ...smooth with a few bumps mostly here and there ... They are into logging air time here ...not so much bumps or whoops on their tracks ... Sound familiar?

So I'll be glad to try any stack you can come up that might help this ... I'll deal with the stiffness after it happens ...

 

[MOTORHEAD]

Well, the stock springs should be good for your weight.

Do you have any more shims?

If not, then try pulling the 12 from under the low speed stack.

 

[ray_ray]

No more shims ... I have contact with the states now on an order with some Husky dealers ... maybe the Husky dealers have shims? What do I need? Some of the 22s?