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How to adjust my shim stack?

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Hi all, I have a gasgas ec300 2006 with marzocchi shiver 45 forks, I had them revalved locally, I don't really get on with how they feel, and I finally gained the balls to get them apart today, the stack reads as follows;

14x0.1
22x0.15
22x0.15
11x0.1
17x0.1
16x0.1
14x0.15
14x0.1
12x0.2
12x0.2
12x0.2

I am 95kg (210lbs) naked, and have 0.5N/mm fork springs and 5.7kg/mm rear shock spring, sag is as close to standard MX as I can get.

Anyway, the forks are too soft, I tried the 5w (24cst) oil recommended by the tuner, but this was way too soft, and now have 7.5w (33cst) which feels a lot better, but I still have the compression clicker only 6 clicks out.

What I am looking for is a little bit more low speed damping, and a little less high speed (rocks are harsh on the first hit even with the rebound all the way out... and in).

I know I only have a check plate for the mid valve for now, and will address that later on, but as I will be riding tomorrow, any advice to make this fork a little more firm on the ride and forgiving on the harsh stuff? I use the bike for enduro, but practise a lot on MX tracks, on the MX track the front is far too soft, they compress too far no matter what I do with the clickers on corners so I have little confidence, and if I hit a brick or anything in enduro the bars want to break my wrists!

Edited by moto_psycho
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I’m not familiar with these forks, but I’d consider getting rid of the 14 face shim which is likely allowing a lot of LS bleed. Try replacing it with another 22 x .15 face shim if you have one to fully cover the piston ports. If that’s still too soft, you can swap the 11 crossover for something larger like a 13 or 14.

 

For the HS, you might try removing the 14x .15.

 

If you don’t have additional shims, put your current 14 face shim as a crossover before your 11 and put your 14x.15 after your 12 clamps. That creates a larger crossover than you probably desire, but your only other option is to place the 11 as your clamp. That’s a big step down from the 14s and may be too much HS softness. Your other option (working only with the shims presently installed) would be to leave both 14s in the HS and try the 11 as your clamp to avoid over softening the HS.

 

This sounds like your first revalve attempt. Be sure to keep the total stack height the same thickness so the shims don’t float.

 

These changes will stiffen LS and soften HS. Others experienced with your forks may have additional input. Knowing this may take a few revalve attempts will aid your decision making process since you’ll get good feedback information from each attempt.

 

Good luck!

 

 

 

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Considering how well revered that tuner I used is, I can't keep the stack the same height as one of the legs has one less shim... as stated, no mid valve, only check plate, what do you think of this...

 

22x0.15
22x0.15
14x0.15
11x0.1
17x0.1
16x0.1
14x0.1
12x0.2
12x0.2
12x0.2

??

Edited by moto_psycho

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I’d swap positions of the 14s. Put the thicker one lower, in the HS. This will lessen the crossover gap.

Both forks should have the same number of shims. If one is missing a shim, that stack may be floating which will soften your LS. Check this out first. It may be the biggest contributor to your overly soft LS.

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The way the valves assemble they pinch up on the shims no matter the stack height, so I put the spare at the very top of the stack. Can't wait to see how much difference this makes...!

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The changes I proposed are going to make a big difference in LS damping. I’m not familiar with forks designed with small face shims allowing free bleed. Your forks may be designed for this, and I know it’s a tuning option sometimes used when revalving. It seems you are seeking fork action similar to what I like, so the proposed changes will certainly get you headed the right direction. The changes may be more dramatic than you prefer, so it’s your choice. A less radical change would be to leave the 14 face shim followed by the stack you proposed with some exceptions. Put the original 14x.10 back as the face shim, place the other 14x.15 on the bottom after the 12s. This renders that 14 inoperable on the non working side of the stack since it can’t flex (assuming there’s a base plate before the nut.) That’s how you keep the stack it’s original height.

 

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Do you think it would be firm enough? Other stacks I see for this fork seem to have at least an extra shim in the LSC. I've put it together, it feels pretty firm, but if I push down really hard on the bars I can move the suspension a fair amount... I supposed I'll find out tomorrow!

 

Cheers!

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22 hours ago, moto_psycho said:

The way the valves assemble they pinch up on the shims no matter the stack height, so I put the spare at the very top of the stack. Can't wait to see how much difference this makes...!

It just changes the amount of clicker range you have with the zokes.

 

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What stack did you end up installing for this test?

Good luck and let us know how things turned out.

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I went with the one I posted as I'd already had it assembled by the time you'd posted. Scared the crap out of my as I flipped the bike upside down to do it, when I pushed on the forks there was nothing... All drained out didn't it :p!

It feels nicely firm, but I can plough it through the stroke if I push hard on the forks. Does the 14x0.15 serve to make it firmer or plusher where I put it? 

 

Fingers crossed the track is open in the morning so I can test it.

Edited by moto_psycho
I can't shut up

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It will make your LS firmer for sure. It could end up also making your forks plusher if you were previously diving right through overly soft LS damping. Under that scenario you would have been activating the stiffer HS Valving earlier(which includes all the LS shims as well).

 

You’ve also slightly softened your HS and delayed the crossover into it. Only riding it now will let you know if you’re on the right track. Don’t be afraid to try big clicker changes during testing.

 

Good luck!

 

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Track is open, so the proof will be in the pudding!

I've downloaded the demo of restackor and have multiplied all my values by 0.4545r to get it to work with the limitation. It's nice to have a visual representation of whats going on even if its not necessarily correct...!

How you've explained is exactly what can be felt pushing the forks when stationary, nice and firm but with a good push can move quite quick, going from feeling I may end up tightening the HSC, but the graphs restackor has plopped out shows me that it's still significantly increased overall.

I'll either be moaning or rejoicing shortly, either way its quite exciting having another aspect of the bike to tune!

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Righty, first getting on the bike it felt amazing, plush as can be. But later in the day when the track started getting choppy they felt really harsh over acceleration / braking bumps. No amount of compression or rebound tweaking helped.

After much searching on the interwebs, it seems I have 3 options.

1 - drill out the valve to flow more oil, apparently the orifices are too small and at a silly angle that causes problems?

2 - add a mid valve and make the base valve softer

3 - race tech gold valve

Any advice?

 

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I've got them apart now, will machine them out at work tomorrow. I've noticed there is a bleed hole in the side of one of the port's, should I epoxy this?

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Was it an improvement?

I imagine Gold Valves are going to be more likely to flow better than modded stock pistons.

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I think it's fairly well accepted that the pistons are sh*t, and even drilling as much as possible (4mm?) won't help a lot. Having said that, it may be worth a shot if you have the time and maybe with a small dremmel you can clean up the entry and the inner of the exit (the leftover bit of the shim side after you drill) and get some decent gains. Just be real careful of the shim face.

Clicked was talking about using 1 leg for rebound to negate some of the restriction, I wonder if you could do that for compression too?

I wouldn't epoxy the bleed.

edit; You gonna try Terry's mod to the bushing lands?

Edited by DEATH_INC.
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I'll do the valve at work today and take some before and after pictures.

I haven't seen any pictures of "Terry's" mod yet to know how it looks. There is already a slight relief from standard so I can't figure out whether the shim is to widen the relief or make it deeper?

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Also, I'm pretty tempted to make my own valve, I work in a machine shop and they're pretty simple. I can only assume the gold valve take from the rebound return to give to the compression? 

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The way I read it is to widen the relief....he says start from the standard one and cut back @ 1deg leaving an approx 8mm flat in the middle. I'm gonna try it on mine next time I have them out.

Yes the gold valve does to an extent. You have 9 fairly even sized holes, 6 compression and 3 rebound. There isn't much metal between them. (same as the one pictured bottom)

Have a look at these, from riders edge suspension, should be fairly easy to replicate and apparently make a big difference.

riders edge valve.jpg

SMGV5003.JPG

Edited by DEATH_INC.
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Half way there, will finish them off tomorrow! &%$#@!ed the originals up a bit, have repaired them with epoxy but would rather have something special...

IMG_20171106_160546.jpg

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