Mountain Bike Reviews Forum banner
101 - 120 of 634 Posts

·
Registered
Joined
·
22 Posts
Shim Stack Tech

I think the article on the DVO suspension website will be helpfull to understand Shim Stack Tech clearly. (Sorry I could not attach the exact link because of my limitation.)

By the way, I need HH or MH tuned Monarch for my 2.94:1 Leverage Ratio Frame but hard to get one.
So I am planning to buy MM one but is there much difference between Monarch RT and RT3?
I think RT can do more fine external tune on Low Speed Compression but what is the pros of RT3 beside it can handle 3-step LSC on the fly?
If RT3 makes things difficult to tune, I would like to have RT one.

I am struggling to get valving shims to tune Shim Stacks, because the former link might not ship them worldwide...
 

·
Registered
Joined
·
2,310 Posts
2013 rt3

After ordering the six mm shims to change my medium 2013 rt3 to a low tune, I opened it up to find that the new ones are totally different. Notice six shims in the stack. One is an inner shim with another one around it. Anyone have any shim stack info on these new ones? I couldn't get accurate thickness measurements with my plastic caliper, but they are 9mm ID.

The stack starts at the nut, up the right column, then up the left column.
 

Attachments

·
Registered
Joined
·
22 Posts
2013 RT3 is quite different

I heard that Monarch RT3 had big modify in 2013 from Rockshox or other articles online.
And the brand-new look shims are the exact ones that makes difference, I think.

According to the spare parts list from Rockshox, the main piston options on RT3(2011-2012) are shown like below.

Main Piston, Tune Rebound-High/Compression-High3 - Monarch RT3/RT/R

But only the ones of RT3 2013 shown individually as

Tune Assembly 2013 Monarch RT3 MH F 320
(mid rebound, high compression, firm threshold)

This may reveal that only the RT3 has got "threshold" feature instead of using Platform Damping Shim Stack, like L3/M3/H3, since 2013.
I am thinking "F 320" means FIRM and it has the breaking point when the pressure is 320[PSI].
It looks like Rockshox has applied the new feature which is similar to Boost Valve settings on FOX Float.

Rockshox claims that Monarch RT3 2013 has got greatly refined the damper to provide independent tuning in the three adjustment positions.
It means that the open is more open, the lock has more lock, is desired by Europe style riding scene.

For sure the brand-new numbers of shims, orders and accurate thickness information are helpful but could not find online right now.
Will be excited if we can see the measurement results here.
 

·
Registered
Joined
·
14 Posts
I'll tell a little tuning story for you. :)

A friend of mine bought a Commencal Super 4 and a Monarch RT3 shock for it.
Well it turned out that the shock was horrible in that bike. So he bought a Fox Float RP23
and had it Pushed. It worked well and he was happy. I told him that the Monarch can not be
that bad, or at least it can be tuned to work much better than it had. He told me what he
wanted to be changed in the shock; way less compression damping and more rebound damping.
I made some changes and he tried them out. Compression damping was now better, but the
shock blew too easily through its middle stroke. Rebound damping was better but clicker had
to be too close to the minimum setting.

So, what to do with the middle stroke dive. I came with an idea that I tried with my RP23 Boostvalve shock.
Since there are shims in the compression side of things only in the LSC, which some in
my opinion falsely have said to be only check valves, it was only place to tamper with them.
I added an crossover there and it seemed to work.

So it was my plan to try that with the Monarch also. I also fine tuned the rebound.
And it worked. My friend was very pleased. He said that the Monarch was now very close
in performance to the Pushed RP23.

The compression tune was about the low tune of Rock Shox.
And the low speed compression shims were:
20 x 0,1
13 x 0,1
10 x 0,2
18 x 0,15
16 x 0,15

I also made the same changes to a Nuke Proof Megas Monarch but that has only seen
parking lot testing so far but it feels quite promising.

Oh and the original tunes were M/M on the Super 4 and M/H3 on the Mega.
 

·
Registered
Joined
·
128 Posts
Wow, the DVO site is pretty informative on this topic. I actually have a customer's RC3+ in for some tuning right now. He has a Blur LT and the shock has the MM tune. The problem he is having is the rebound speed is too slow, even in the fastest setting. The service dept. is fairly slow right now, so I told him I would happily try to improve the performance.

Even though most of you are working with the RT shock, I've found this thread to be super helpful. I actually have a small stash of shims at home, but for now I might just remove one to see how much of a difference it makes.

I have a question for you guys who are doing this on a more regular basis.....are there any good books out there that I can learn from? I know it's a lot of trial and error if you don't have an engineering degree and a dyno, but those two things aren't gonna happen for me anytime soon, so I was hoping for a "working-man's" approach to this. Years ago, in my brief moto-mechanic career I found a lot of good reading on the moto side, but nothing purely on suspension.

Thanks in advance
 

·
Registered
Joined
·
22 Posts
Second Moment of Area

Yes, DVO is the best site to understand on shim stack technology.
They don't show actual numbers on those shims right now but they will in the near future.
Wait until they sell their shocks or study a little bit on "Second Moment of Area" might help you.

If you could tell me the shim dimensions, like Inner Diameter and Outer Diameter on shims, someone could calculate the actual value of Second Moment of Area on each shims.

I hope DVO makes smaller sized shocks...
 

·
Registered
Joined
·
128 Posts
Rebound needle may be stuck...

Ok, so I just removed a shim from the rebound stack for a quick test and started to reassemble it. when bleeding the air out, the rebound is almost totally locked, and I can barely pull the shock to full extension. I saw that it was KTM520 I believe that had a rebound needle that was too long. Possibly mine is jammed now.

Has anyone removed the needle on the Monarch RC3 Plus? I saw some were doing it on the RT model, but this appears to be pretty different.
 

·
Registered
Joined
·
29 Posts
I was planning to remove a .1 shim out of my MM tune RT3 to improve small bump performance on the compression side. But then the shim stack has changed.

Any info about different shim setup for M and L compression on the 2013 RT3?

And how to improve the 2013 model?
 

·
Registered
Joined
·
1,824 Posts
I posted this on another thread but thought you would be interested as well.

Shim ReStackor, Finally software to tune a shim stack

These are the 2012 Monarch details. I don't think there was a change for '13 but don't quote me.

l tune comp: LS valve - 22x.15, 22x.10, 22x.15
m tune comp: LS valve - 22x.20 then 4 22x.10
m tune reb: 15x.10 then 14x.20

mk
 
  • Like
Reactions: Deerhill

·
Registered
Joined
·
122 Posts
I have a 2013 RT3 also and many things have changed on it compare to the 2012 one, not only the shim but even the casing.I have a 2013 RT3 also and many things have changed on it compare to the 2012 one, not only the shim but even the casing.
 

·
Registered
Joined
·
29 Posts
Anyone knows the different between a M / L compression tune on a 2013 RT3?

Or has experience with tuning the 2013 RT3 shim stack?

I am looking for better small bump performance / more plush ride. I have lowered the IFP pressure according to this great thread.
 

·
Registered
Joined
·
122 Posts
UPDATE to my problem of slow rebound and air-oil mix noise on my RC3 Plus: I FOUND THE PROBLEM !!! It's the IFP (internal floating piston) reservoir that was not presurize at the recommanded 250PSI. Go to the RockShox site to dowload the maintenance manual. You will need a schrader removal tool and a air adaptator to inflate the IFP reservoir. Now no more noise and a really faster rebound !!!
It's not the RT3 but the +RC3 but anyway has I had already complained in this thread I thought I should let you know.
On my RT3 no problem from now but there is also an IFP, not in a piggyback indeed but in the main core.
Laurent
 

·
Read Only
Joined
·
2,101 Posts
Wow, the DVO site is pretty informative on this topic. I actually have a customer's RC3+ in for some tuning right now. He has a Blur LT and the shock has the MM tune. The problem he is having is the rebound speed is too slow, even in the fastest setting. The service dept. is fairly slow right now, so I told him I would happily try to improve the performance.

Even though most of you are working with the RT shock, I've found this thread to be super helpful. I actually have a small stash of shims at home, but for now I might just remove one to see how much of a difference it makes.

I have a question for you guys who are doing this on a more regular basis.....are there any good books out there that I can learn from? I know it's a lot of trial and error if you don't have an engineering degree and a dyno, but those two things aren't gonna happen for me anytime soon, so I was hoping for a "working-man's" approach to this. Years ago, in my brief moto-mechanic career I found a lot of good reading on the moto side, but nothing purely on suspension.

Thanks in advance
This book is excellent - Suspension Bible
 

·
Handmade in Switzerland
Joined
·
296 Posts
Hi,

I have a Monarch RT3 2014 shock with M/M default tune. But I need more end progression.

Has one of you guys tuned the Monarch with a L3, M3 or H3 tune and can explain the difference to the standard L, M and H tunes?

Thanks and regards
mat
 

·
Registered
Joined
·
22 Posts
Hi,

Rockshox says that "L, M,and H are platform tunes, while L3, M3, and H3 are progressive compression tunes" in their Compression Tune Reference Chart.

So if you need platform tunes, tune your Monarch into M3 tune.
But now, you want more end progression, so tune your IFP pressure.
You can get the adaptor sold by RS then increase the pressure.

I've tuned my monarch's IFP from 110[PSI] to 200[PSI].
Now it feels good while riding, especially in doing manual.
 

·
Registered
Joined
·
122 Posts
I think it's regarding a kit with which you could reduce the air volume of the HV (High Volume) canister: less air volume, more end progression. I have bought this kit on ebay but I'm not at home so can't give you the reference. You will find it on the sram.com site in the exploded view of the RT3 2013 with parts number.
I didn't use mine for now because on my Tallboy LTC with standard M/M I won't reach the bottom out with a 30% sag. It really depends of the bike cinematic
Have a good ride in Switzerland
Laurent
 
101 - 120 of 634 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top