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Discussion Starter #1 (Edited)
This thread will teach end users how to shim tune a Manitou Mcleod rear shock.

Lets start with the basic information

McLeod shock bleed video: https://www.youtube.com/watch?v=6vmNyZC8qTo

McLeod Full service videos: https://www.youtube.com/watch?v=6vmNyZC8qTo

Stock oil is Maxima 5wt which is [email protected] Stick in the 14-16cst range if you use other oils.

You can buy shims here: Revalving Shims

You can buy the IFP tool here:


[https://hayesbicycle.com/collections/manitou/products/rear-shock-3-in-1-ifp-service-tool

I'm not going to spend anytime on the rebuild process, the videos are clear on what to do. Only the bleed video is needed to change shim stacks, but the full rebuild videos give excellent insight into how the shock works and are worth the long watch.

Now on to the good stuff. There are 2 separate compression shim stacks in the McLeod and no low speed needle circuit. You read that correctly, the McLeod compression damper has no orifice/needle circuit. Its all shims. There is a 10mm ID shim stack and a 8mm ID shim stack. Generally speaking, you will only tune the 8mm shim stack and leave the 10mm stack alone, but we will dig into both.

10mm stack:


The the 10mm stack is the stack you can see when you pull the damper out of the shock body, like in this pic

Piston as.jpg

This is what your IPA lever adjusts. When you run the compression damping full open, the shims rest on the pistons lip with no preload or possible a very small amount of float. How much preload or float you have in the open position is based on the eyelet/damper shaft adjustment. You can see how to adjust this in the above videos, but it mostly should be left alone unless you are doing a full service.

The stock 10mm stacks differ depending on the year of the shock, but the overall damping characteristics have not changed much over the years. Still a pretty firm lock out in when fully closed and a very active feel when fully open. So why change this stack? In reality, there is very little reason to, its pretty dialed and is not really addressed in the upcoming guide. Changing it changes the range of the adjuster, but not the main damping characteristics which are controlled by the 8mm stack. If you dont want a firm lock out, or want to make the difference between the 4 clicks of adjustment closer for fine tuning, then you would lighten the 10mm stack to change the range that the adjuster gives you.

The most current 10mm stack is the following
Damper shaft
10x14x.1 (2 shims)
10x 20x.2 (3 shims)

The best way to adjust this stack is to replace shims with different diameters. For example, If you want a smaller adjustment range, take a 20x.2 out and add (2) 14x.1's at the top of the stack. This guarantees you keep the correct spacing and relative stack thickness which is VERY important. There is no reason to use diameters other than 14mm and 20mm, only number of shims( and thickness of the 20mm shims) matter in this case. 20mm shims for to change damping, 14mm for spacers/clamp shims.

8mm compression stack:

The 8mm compression stack is where the main damping happens. The newest stock stack is as follows:

8x11x.1 (functions as a clamp shim)
8x16x.1 (velocity shim)
8x14x.1 (gap shim)

First thing to note is that the overall stack stiffness is .3mm thick. You want to keep this to a max of .4mm thick or the IPA adjuster may have a hard time reaching its 4th click.

Lets start with the gap shim. Unlike most shim stacks where you change shim thickness to change damping characteristics, in this case, you change shim diameter. We are essentially controlling a small amount of free bleed by not fully covering the compression ports with the face shim. A 16mm diameter shim fully covers the the ports, a 12mm doesnt cover them at all.

This Dyno graph shows how increasing the gap shim diameter changes the damping curve:

Gap shim.png

On the trail, gap shim size mostly relates to low and mid speed damping (though it affects the whole curve). If you want more low speed control from your stack, you would increase the gap shim diameter. If you want less low speed damping, you would decrease diameter to allow more bleed.

Next we have the velocity shim. This shim tends to control the mid to high speed characteristics. You can change the diameter from a 16 down to a 15 which allows for more free bleed at the lowest shaft speeds. Most riders tend to like the 16mm for more support though. If you add thickness to the stack, this is where you would do it. Adding a second .1mm shim adds mid to high speed damping if desired.

Last is the 8mm stack clamp shim. (its not really a clamp shim as the 10mm stack sits directly on top of it, but if functions similarly as well as creating a gap for the 8mm stack to work independently of the 10mm stack). Clamp shims change the slope of the damping curve by changing the stacks pivot point. You do this by changing the diameter of the shim which mostly changes mid to high speed characteristics in relationship to the low speed characteristics. Buying shims online can limit what you can do here as only 10 and 11mm diameters are available.

Pistons:

There are two pistons available. A red piston (stock in most cases) and a yellow piston that has a small free bleed that allows a very small amount of oil to pass on both the rebound and compression stroke. This allows for a better response when transitioning between the compression and rebound strokes.

Bleed Pis.png


Rebound Stack

The rebound stack tuning is like a normal shim stack for tuning. Depending on the year of your shock, you may have a 16x.2 paired with a 11mm clamp shim, or the most current stack of

8x15x.15 (2 shims)
8x12x.15 (2 shims)
8x10x.2

This stack is very good on most frames and is a great place to start if you have a older stack you are not happy with.

If you open up you shock and find its using a 16mm diameter rebound shim, switch it to a 15mm shim as the 16mm shims slightly cover the compression ports. This was by design originally, but we have since found that the 15mm rebound shims not covering the ports works better.

Lastly, you have the rebound check valve. Leave this stack alone, its only purpose is prevent back flow through the rebound orifice on the compression stroke.

As Op View.jpg

LSR Check.jpg

I will update this thread with more information in the upcoming weeks with some different stack combinations and the dyno info for them, as well as some more detailed pictures of the damper. I dont have it readily available currently.

A few other things to note. Manitou has clamp shims of 10.3, 10.5, 10.7 and 11.3mm in diameter. You can not get these elsewhere to my knowledge. If you ask them nicely, they may be willing to send some out if you find you need them. They are used to change the rebound damping slope, not for use on the 8mm compression stack. If you ask really nice, they may be willing to send you a yellow bleed piston as well (make sure you have a red piston before you ask).
[email protected]
 

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For almost the last two years I was running 6x 8x15x0.1mm rebound shims. My notes say I could go even softer but I don't think I ever did and I don't recall if I ran the numbers on it. I've been riding a coil for the last 6 months or so.

I found a big improvement in high speed response with 15mm instead of 16mm. I also found a higher VI oil and higher IFP pressure was needed for harder use.

Because these shocks only have a small oil volume they heat and cool rapidly. Which can be felt with the rebound speed changing as the oil thins out with heat and thickens again on cooling.
I've been running a 405 VI oil which fixed that for my riding.

I also have in my notes a 15mm dual stage rebound stack. Did you persist with that?
 

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Discussion Starter #5
For almost the last two years I was running 6x 8x15x0.1mm rebound shims. My notes say I could go even softer but I don't think I ever did and I don't recall if I ran the numbers on it. I've been riding a coil for the last 6 months or so.

I found a big improvement in high speed response with 15mm instead of 16mm. I also found a higher VI oil and higher IFP pressure was needed for harder use.

Because these shocks only have a small oil volume they heat and cool rapidly. Which can be felt with the rebound speed changing as the oil thins out with heat and thickens again on cooling.
I've been running a 405 VI oil which fixed that for my riding.

I also have in my notes a 15mm dual stage rebound stack. Did you persist with that?
Locally, we have a lot of chatter and some medium sized chunk. The bigger chunk is there, but its in small spurts spread out. I dont think I get the peak temps that others do. I do have a few higher VI oils , but havent tried them in the McLeod yet. I will have to test that in the future.

We did do a lot of testing with 2 stage rebound stacks. A few people really liked them. Most seemed to find they lacked mid speed damping (inferred from reports). We then switched back to single stage.

I actually have some dyno info for one of the dual stage stacks shown with what is now the current production stack(labeled Mullen stack because it was before it went into production shocks)

0.png

We did testing on softer stacks as well. They tend to pair well with the king cans. Clamp shim seems to be the best changes we could make when fine tuning shim stacks. Thats why we have such small changes in clamp shim diameters.
 

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Thank you for using dyno graphs in Newtons! Are the compression graphs a bit fuzzy or is it just my phone?

So does the velocity shim not fully seal to the piston either? And does the gap shim flex at all? Not that there seems much room to change thickness there

I like the gap shim concept, seems like the ideal way to gain control of the slope in dished pistons!
 

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Discussion Starter #8
Thank you for using dyno graphs in Newtons! Are the compression graphs a bit fuzzy or is it just my phone?

So does the velocity shim not fully seal to the piston either? And does the gap shim flex at all? Not that there seems much room to change thickness there

I like the gap shim concept, seems like the ideal way to gain control of the slope in dished pistons!
Those are a bit fuzzy, that will be fixed when I up update in the next day or two. They have switched formats a few times so the quality is not the best.

Both the gap shim and the velocity shims will flex. A 16mm velocity shim pretty much seals. The the main sealing of the compression stack comes from the 10mm compression shim stack though, that's what allows for the use of gap shims without alloing oil to backflowon the rebound stroke
 

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Discussion Starter #9
Finally have a update:

Shim Info.jpg

This page talks about the gap shim, Oil flow paths, and yellow bleed piston. Posted earlier, but this is the complete page and should have better quality

Piston.jpg

Hopefully updated pic of gap shim changes

Gap shim change.jpg

Compression stack suggestions and Dyno info for them. Notice that the 10mm stack stays the same in every configuration, yet the curve changes significantly by only changing the 8mm stack:

Comp stack 1.jpg

Comp stack 2.jpg

Comp stack 3.jpg

Comp stack 4.jpg

Comp stack 5.jpg

Comp stack 6.jpg

Comp stack 7.jpg

Comp stack 8.jpg

High Speed.jpg

Yellow bleed piston against Red piston:

Red vs yellow.jpg

Yel comp 1.jpg

Rebound Stack suggestions and Dyno info:

Reb 1.jpg

Reb 2.jpg

Reb 3.jpg

Reb compare.jpg



Clicking on the pictures, they appear clear on my computer. I hope this Info is helpful to people and get used.
 

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Nice, that’s a goldmine of information right there! Shame other brands don’t make that kind of info public, but I guess that would just expose how woeful the big 2’s stock tunes are. Fox give us a least 9 rebound tunes of varying use while compression tends to come in soft, really soft, harsh but soft or really harsh but soft!

Interesting comparing the rebound graphs between the red piston and blue piston, the red looks softer even with no bleed and more shims just because of the 0.5mm change in clamp! - I wouldn’t have picked that
 

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Discussion Starter #14
Nice, that’s a goldmine of information right there! Shame other brands don’t make that kind of info public, but I guess that would just expose how woeful the big 2’s stock tunes are. Fox give us a least 9 rebound tunes of varying use while compression tends to come in soft, really soft, harsh but soft or really harsh but soft!

Interesting comparing the rebound graphs between the red piston and blue piston, the red looks softer even with no bleed and more shims just because of the 0.5mm change in clamp! - I wouldn’t have picked that
I need to rework that bottom rebound pic, a little bit if information is missing off to the side. I will try to fix it tonight.

Both stacks use the red piston, it just compares two stacks that are similar on low speed rebound, but separate as rebound speeds are higher. While the clamp shim makes a significant difference, the added 12x.15 makes the top stock have more high speed rebound in comparison
 

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Great! Too bad for someone like me new to suspension tinkering it's all hieroglyphics :D

Any suggestions for a 140 lb rider, before gear (I do put water in my pak) should do? I'm on a Bronson v1, so terrible small bump/initial stroke, looking for something softer. When I set the Mcleod to have a softer initial stroke, I sit really low (pedal strikes, go through travel a bit) and when I have it a little firmer, still harsh on high speed chunder and then don't blow through travel at all.

I have the 2018 tune right now, but the first one not the revised one (per another post you replied to). I'm also thinking I need to try the king can.

I'm not aggressive anymore (but maybe that's because I've lost confidence in my suspension), so I don't mind giving up a little on top end so it's more comfortable.

I'm also wondering if it's my stiff carbon frame and my carbon enve wheels that is causing me this feeling of harshness.
 

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I don’t know if there’s room for or if people advocate it for the McLeod but in the past on shocks with a sealed neg spring, I’ve added an extra top out bumper or oring to reduce the neg spring volume and give a higher negative spring force/softer initial rate for better sensitivity
 

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I don’t know if there’s room for or if people advocate it for the McLeod but in the past on shocks with a sealed neg spring, I’ve added an extra top out bumper or oring to reduce the neg spring volume and give a higher negative spring force/softer initial rate for better sensitivity
That gives a lower negative compression ratio, less negative force and higher positive preload.

The opposite of your intent. Because the chamber volume increases in size more than the volume of the bumper/oring used.
 

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That gives a lower negative compression ratio, less negative force and higher positive preload.

The opposite of your intent. Because the chamber volume increases in size more than the volume of the bumper/oring used.
I’m talking about in the air can to reduce the negative chamber volume

I guess I should have clarified this more, like I say I’ve not had one of these open to know what space is available.

The way to do it is so that the new o ring nests inside or outside any that may already present so you aren’t reducing the extended length in any way, or extending the length of the neg chamber
 

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Just saw the service manual, I see the top out bumper does cover the whole width. Do these shocks have a hard top out against the bumper instead of a pneumatic stop or hydraulic top out in the damper?

I assumed there wasn’t a physical top out in the air spring so adding a spacer wouldn’t affect the size of the chamber
 
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