TE610 Fork Valving and Shim Stack Tuning

[Kyle Tarry]

Sparked had a really good thread about some DIY shim stack tuning on the shocks for the smaller bikes, so I wanted to start a similar thread for some discussion with the 610/630 guys.

I've seen a couple different valve stacks for the Marzocchi Shiver 45s that are on my bike, but when I popped my base valve off, this is what mine had:

(all shims 0.15mm thk)
3X 23
14
23
21
20
19
17
15
13
The compression side of the midvalve is disabled, instead there is a spring-loaded check plate in there. I bet at very high damper speeds you get some damping out of the midvalve anyway, but at low/mid speeds it's not going to be a player.
This is a pretty stiff base valve stack, in my opinion, even for the bike's weight. I suspect that a big part of this is due to the bike having no midvalve; if the base valve was soft, it would just bottom all the time. So, one option would be to retrofit an active midvalve. I took my fork apart and it wouldn't be too hard to swap out the stock sleeve spring and plate for a normal shim stack, you'd just need to track down the right parts (which I am going to work on). In the meantime, I wanted to try some changes to the base valve to see how the bike reacted. To start, I pull one of the face shims, and the first 23 in the high speed stack, so the new stack looks like:
2X 23
14
21
20
19
17
15
13
In theory, this should be about 5-10 clicks softer than the stock stack. So, where I used to run the bike 15-20 clicks out on compression, I should be be closer to 10 clicks out now.
For guys who have had their bikes revalved, have you pull the fork apart to see what they out in it? Did they put in an active midvalve? I wonder if any of the suspension guys (LTR, Zip-Ty, etc) would be willing to comment on whether they add a midvalve stack if you asked them about it...

 

[Kyle Tarry]

Some additional information:

I ran the TE610 shim stack in the ReStackor shim calculation program (www.shimrestackor.com) to try to get a sense for how stiff the stack was, and how it compared to some other bikes that I was familiar with. I plotted it against my '12 WR300 and a stock DRZ400 (I own one of those too). Here are the force curves:

(Stock TE610 at 15 clicks out, where I was running it)

Here are the damping coefficient curves:

Same deal with the colors...

So, you can see how stiff the stock TE shim stack is, which I believe is a function of not having a midvalve (thus requiring a stiff stack for bottoming resistance). The other interesting tidbit is the low amount of low-speed damping, which is a result of my measurement of the adjustment screw bleed; I measured the bleed at almost 3mm diameter, which is pretty big. I will confirm this number the next time I have the valve apart.

You can also see the curves here from post-revalve. At the same 15 clicks out, the new stack is roughly 15% softer. With the bleeds (clickers) closed up some, the new stack should be about the same stiffness.

I don't know what the "bump" in the curve for the revalve at 10 clicks is; seems like a software problem to me.

I have read some notes online about these forks often having bleed shims (mine did not) and about there being additional bleed passages on the compression damping circuit on the base valve (mine appeared to not have these either). Looking around, I have seen some pretty crazy shim stacks for these, on other Husky models and on Beta and GasGas stuff. It seems like a pretty common theme to have a lot of bleed and no midvalve.

I have ridden on my new shim stack, but only on the road, as my bike is set up in supermoto trim right now, and probably will be for several months. I think that the new stack will be good for rock riding, but I have some concern that it will not have enough bottoming resistance (although I never bottomed the stock setup, or even got that close, so it might be ok). In any case, I believe that the correct "long-term" solution is the addition of an active midvalve and slight further softening of the base valve compression stack. This should dramatically increase the bottoming resistance while allowing for more plush initial travel.

As a side note, these charts make you ask "what the hell was Suzuki thinking?" with regard to stock DRZ valving. I've had two DRZs, and my current one lives out west in CO and is ridden all over the Rockies and down in Baja. Both of them had/have miserably soft compression damping; with 0.48 springs, my current one bottoms constantly at a moderate pace in whoops. Using my 610 as a reference point, I've come up with a modified shim stack for the DRZ that splits the difference between the two, which should still be pretty mild but should be a huge improvement. The DRZ, like the TE, lacks midvalve damping.

Note that the WR has OC KYBs with an active midvalve, and so there is much more bottoming resistance in these forks than the plots above show; the plots above show the WR's damping force contribution from the midvalve only.

 

[Kyle Tarry]

I've moved future 610 shim discussion to the general revalve thread, might as well keep it all there. Here is the link:

http://www.cafehusky.com/threads/diy-tuning-the-sachs-shock.23893/page-5#post-326713

Mods, can you lock this one up? It was stupid of my to start it in the first place...

 

[Coffee]

Locking as requested...

/thread