Some viewers had some observations and suggestions: 1. There is an easier way to get to the shim stack: Set the HSC to the lowest setting. Lift the green HSC preload collar with your hands as far as possible and you will see a 10mm wrench flat machined into the shaft. Hold that with a wrench and release the main piston nut. 2. You may notice the bladder is a bit "Sucked in". This isn't ideal but its easy to fix. Remove the two C-clips (careful they don't go flying on you!), move the green collars away from the bladder, then lift up the end of the bladder to allow it to suck air in. It only needs to be filled to ambient pressure. Ronnie has also suggested putting some heavy grease on the ends of the bladder.
I've had many forks and this is still my favorite by far. In terms of ease of service at home, spare parts availabilty, no special tooling, and how easy it was to mod the shimstack etc, and overall feel.
Let's get some more of these Diamond service videos next time you're putting some work in on it if possible. This one's a gem. I wish there existed one with the full service walkthrough. Cheers.
I was wondering if you had any insight, I bled my damper but for some reason, the LSC doesn't really have an effect? Before the service, the fork would get really stiff when I turned up the LSC dial, but now there's almost no change at all. I can compress the fork fully when no air is in the Air-spring side, so I don't think there's a seal problem on the damper side. I figured you might have some tips based off this teardown. I followed the service guide step by step several times over. Thanks
The preload shim (the ring shim) are a low speed preload, it'll also affect mid and high speed compression though....not sure it's the most "elegant" solution to the problem. Certainly not the "flip the piston" as it affects the oil-return orifice which needs to be free-flowing. Why not run a slightly lighter fluid with a bit more rebound and low speed compression and then remove just the smallest shim?
I like the way my fox 36 ramps up with volume spacers, I like the stiffness that you get. Are travel reduction spacers the same as volume spacers for a Dvo beryl boost fork?
No. Travel reduction spaces simply reduce the travel by 10mm increments. They are plastic spacers that snap onto the air shaft, limiting extension. If you wanto to make your Beryl more progressive you can use volume spacers. I think they newer forks have threads on the underside of the air cap. At least the Sapphire does. If not you can always add oil to the air cartridge, that will do the same thing. Call DVO for more specifics, they are great to talk to and ask questions.
Do you notice more stiction and sooner after a lower leg service with your DVO? Mine feels great right after, but it isn't long before it becomes 'notchy'..... My lower end Yari was bullet proof and felt stiction free no matter how long I went between lower services.
No, I can't say I've noticed that. What oil are you using? I use the Fox stuff. It is definitely thick and sticky which helps it coat the inner parts. If you use a lighter oil it may settle in the legs and not coat like it needs to. Try turning the bike over for a few minutes, then see if the stiction/notchiness goes away. I've ridden and felt a few DVO forks and never noticed one with much stiction, so I have to think you can figure this out and get it smooth like others'.
Still nice vid with an excellent guide how to do it. I just did it on my boost sapphire wich got the same shims. The ports of the piston are different compared to the diamond. Will see if t works.
@mtbdeli, So does this only affect the high speed compression, or does it affect both high and low? I'm not familiar with the damper design, and with what the adjusters on the fork do internally.
Essentially just HSC. It does have a small effect on LSC but nothing I ever noticed. But the engineers would correct me if I said it was only HSC. The LSC adjuster opens/closes a pin valve to restrict oil flow through the port. The HSC adjuster adds preload to the shim stack.
@@mtbdeli9018 so, (not to get too deep), but does the low speed compression not have a way of blowing off or bypassing / is it always active / fixed orifice? I suppose maybe HSC oil can bypass the low speed orifice?
@@sham8723 LCS is always active. The ports cannot be closed and will always allow SOME flow. The pin valve that lets oil get to the low speed holes on the piston can be adjusted so more or less oil can travel in the LSC circuit. However with LCS/orifice damping you can only get so much oil through there. As pressure builds it eventually is high enough to open the HCS circuit. At that point oil goes through both. As much as is able through the LSC, and the rest through the HSC. As you modify the shim stack that affects how much oil can pass through the HSC circuit under different conditions. If you really stiffen it, more has to go through the LSC making it harsher on big hits, but not changing how it feels when climbing or other LSC events (bermed turns). If you really soften it, it has a much lower pressure needed to allow flow and it can start behaving like an orifiace valve if its very soft. Shim stacks are like suspension black magic. You can do amazing things with them. Soften it initially then have it get much stiffer. Look up the Manitou Mattoc tuning guide. They have shim stack setups with dyno charts to show the different tunes. AMAZING resource, I wish DVO did that. But they have Ronnie...I asked if they had such charts, rather than send me a chart he asked me about my bike, my weight, riding, trails and gave me this tune. I hope somewhere in that is the answer you need! if not, let me know. (this might help too) tech.dvosuspension.com/piston-technology/
Hello, Hope u can help me. My fork is brand new but when I turn the HSC knob it doesn't make any clicking noise, in fact, I cannot even feel any clicks. DVO told me it's because it's new and greased, but it will start making clicks eventually. Is that the way it is? Is it normal? Because I'm thinking of return it and ask for another one. Thank you for your help and thanks for the video, it's really useful :)
Sorry for the late reply...notifications were not on. That is normal. Sometimes people refer to DVO settings as how much "Mushes". There isn't the snappy clicky feel of RS or Fox. Its more of a mushy soft click. Its a small ball bearing/spring that snaps into a detent. They pack them with grease and that really reduces the feel. You can take of the top cap and clean out some of the grease if its still mushy.
In newer DVO forks the LSC/HSC unit comes off in one piece and never needs to be separated (nice!). The HSC knob doesn't have steel balls anymore, just small plastic bumps. Almost no clicking to the HSC, which is fine-- it's pretty stiff at first, but loosens up to adjust pretty easily once it wears in a bit.
83kg body and another few with bike gear. It has more to do with the speed and terrain. A lighter rider going faster can generate higher force in the damper. I’m on the heavier side but ride with finesse and caution...so don’t generate the same forces that other riders do.
Hello Man. I bought a second hand bike with dvo Diamond... I noticed this forks are making a clunk when i pump quick like knock, on the rebound action, even in mid travel. This clunk is very noise. And i feel that on my grips. Do you know If this is normal or if not, what kind of problem is It!?
@@mtbdeli9018 i did the damper service. And searching for that issue, i found something in MTBR forum. I sanded the shim stack that stuck below the rebound piston... in compression damper i found a shim broken, so i remove it. Now, my Diamond works fine, without any clunk (i bleed the damper with Putoline GRP 6 2.5w shock oil, because its a less thicker than other 2.5w fork and shock oils)... Its very, very supple and plush... love mine. thanks
hey there did you change the blader? my mechanic find cracked shim out of shima stack...in middle with blader! do you have any idea how this happen? thanks a lot men! I could uplad photo if you have any mail thanks a lot!
Darksoul channel there is an extra bent shim in the stack. It was added to fix a noise. The noise was actually a different issue but the build spec still had it included so that’s what they built. You can toss it. It doesn’t do anything and can break free like yours did.
@@mtbdeli9018 I think understand what you are telling me! This shim i found its outside from the stack and in the middle with the blader your video in 3.47 in your right hand there is 2 shims there! My fork now works like before and smoothly without any different sounds! I upload the shim here check it for the record! I have to replaced this shim or its nothing? we.tl/t-BpihEYhaO8
Have you ever seen a video on how to rebuild the bladder? I bought a bladder kit because they recommended it when I reached out about doing a full rebuild after a year or more of riding, but I can't find any help on how to disassemble the only part you didn't touch in this video🤦🏽♂️
Its been a while, but I think this should help. I think there is a nut that holds it all together. You can briefly see that at 3:48. Take that off, then the assembly will slip apart. BE CAREFUL TO NOTE WHAT GOES WHERE!! This is the rebound damper so you can really mess things up if you lose track of what went where. When in doubt, call DVO and they can sort you out.
@@mtbdeli9018 thanks! Yeah I'm not sure if I broke it trying to get that nut off🤦🏽♂️... Of course the whole assembly is out of stock so... 😮💨😣 When I get home in a couple days I'm gonna call them and try to sort it all out. (Since I have an Angel Fire trip coming up though, I went ahead and snagged a 2023 180mm ZEB Ultimate) 🤫
Is there any proven recommendation for removing less then 3 shims? Will I notice any significant difference removing only one or two shim? If so, wich one's do you suggest to remove?
The clicks come from the balls/springs in the dial. As you turn the dial they can make noise but mine don’t make a sound either. I just feel the detents with each “click”. Its probably from the grease I use to hold them in place. No big deal since the click is just to know what potion the dial is in.
Hey mate! I ride in pretty Rocky, agressive and technical terrain, I felt a lot of hand pain today. Do you think this mod could help me for this issue? I weight around 76kg
How much travel do you use? How much sag? Another possibility is the fork is undersprung and riding deep in its travel. This leads to spiking and harshness. If you are in the 20-25% sag range and using 80-90% travel max then sounds like this mod is right for you.
I would pull it apart again and check for anything not assembled correctly or binding. Call DVO when its apart and they can help you figure out what is wrong.
Thank you. My Shockwiz keeps telling me I need softer high speed compression and its adjusted all the way soft. Weird though because I’m 230lbs geared up.
I've heard mixed reviews of the Shockwiz and how good it is for tuning. I have not used one, but tuners say they are good to get it close. It won't replace trial and error to dial it in the final bit. Even at 230, you may need less HSC. It depends on how fast you ride and what kind of terrain. Now that I'm in the Northeast, the riding is slower and more small rocks and roots. I may open it up and flip the piston to get more HSC range.
Where in the Northeast are you? I’m in Connecticut. Yeah. Kind of slower picky sections. Even at 230 I must be kind of light on the bike. I always need less compression and air than recommended to get my sag right and not rattle fillings out.
@@Jaredcouture12676 I am now in NY, outside Albany. I used to live in CT (Trumbull...miss those trails). Don't pay much attention to sag. You don't want to be way off, otherwise it can affect geometry. Its more or less a very rough starting point for tuning. It gets you close enough that for most its good enough for them. However once you dial in the suspension in other ways you can almost ignore sag. What I do is get the basic "feel" right. Not too wallowy and not springy. Rebound and compression should be wide open. You can do this in a parking lot. Then I find a section of trail that is what I want to tune for, it helps to have a faster corner. Ride it a few times with rebound and compression wide open. If you can't hold your line in rough stuff, rebound is too fast. Keep riding and adjusting rebound until the bike feels harsh. Then back it off a bit. Adjust compression as needed: bottom out...add more. Not using close to full travel, add less. Using full travel is also over rated. I NEVER bottom out, but get 130mm of very controlled travel out of my 140mm setup. Anyway, thats what I doo and it works great. Check out Shockworx website (New Zealand tuners) for more detail and explanation.
Claudio Bosticco I am about 190 with gear and water. When I talk to DVO they are surprised I want less damping. Most of them run similar air pressure and weigh less. However they are riding much harder than I and on trails with some big hits and drops. My riding is aggressive trail at most and I keep the wheels on the ground most of the time. A few 1-2 foot drops.
Your riding sounds similar to mine. But I'm 143 fully loaded, so I think I definitely need less damping. Actually I wonder if mine is a case which may benefit also from the piston flip. Thanks for your video guide!
Your bladder is sucked in it shouldn’t be like it should be round there are clips top and bottom to get the air back In the bladder that will fix the hsc instead of playing with the shim stack
Derek Lawrence , yes it was sucked in. I did fix that off camera. While that will help the fork work a bit better it won’t be enough for the change I was looking for. The shim stack mod makes a big difference and I what DVO recommends for a lighter tune.
Some viewers had some observations and suggestions:
1. There is an easier way to get to the shim stack: Set the HSC to the lowest setting. Lift the green HSC preload collar with your hands as far as possible and you will see a 10mm wrench flat machined into the shaft. Hold that with a wrench and release the main piston nut.
2. You may notice the bladder is a bit "Sucked in". This isn't ideal but its easy to fix. Remove the two C-clips (careful they don't go flying on you!), move the green collars away from the bladder, then lift up the end of the bladder to allow it to suck air in. It only needs to be filled to ambient pressure. Ronnie has also suggested putting some heavy grease on the ends of the bladder.
Love to DVO for that support. To actually be able to get hold of someone who can help with this kind of stuff is incredible.
I've had many forks and this is still my favorite by far. In terms of ease of service at home, spare parts availabilty, no special tooling, and how easy it was to mod the shimstack etc, and overall feel.
Let's get some more of these Diamond service videos next time you're putting some work in on it if possible. This one's a gem. I wish there existed one with the full service walkthrough. Cheers.
Maybe the Sapphire. I sold this one.
Crikey, respect... i just pay a specialist... this is next level DIY fork adjustment
I also tuned my rear shock's shim stack. I like to dig into things like this. Saves a ton of money too!
Thanks for this flick man... really helped a lot.
I was wondering if you had any insight, I bled my damper but for some reason, the LSC doesn't really have an effect? Before the service, the fork would get really stiff when I turned up the LSC dial, but now there's almost no change at all. I can compress the fork fully when no air is in the Air-spring side, so I don't think there's a seal problem on the damper side. I figured you might have some tips based off this teardown. I followed the service guide step by step several times over. Thanks
Any updates on that problem?
The preload shim (the ring shim) are a low speed preload, it'll also affect mid and high speed compression though....not sure it's the most "elegant" solution to the problem. Certainly not the "flip the piston" as it affects the oil-return orifice which needs to be free-flowing.
Why not run a slightly lighter fluid with a bit more rebound and low speed compression and then remove just the smallest shim?
I like the way my fox 36 ramps up with volume spacers, I like the stiffness that you get. Are travel reduction spacers the same as volume spacers for a Dvo beryl boost fork?
No. Travel reduction spaces simply reduce the travel by 10mm increments. They are plastic spacers that snap onto the air shaft, limiting extension. If you wanto to make your Beryl more progressive you can use volume spacers. I think they newer forks have threads on the underside of the air cap. At least the Sapphire does. If not you can always add oil to the air cartridge, that will do the same thing. Call DVO for more specifics, they are great to talk to and ask questions.
Do you notice more stiction and sooner after a lower leg service with your DVO? Mine feels great right after, but it isn't long before it becomes 'notchy'..... My lower end Yari was bullet proof and felt stiction free no matter how long I went between lower services.
No, I can't say I've noticed that. What oil are you using? I use the Fox stuff. It is definitely thick and sticky which helps it coat the inner parts. If you use a lighter oil it may settle in the legs and not coat like it needs to. Try turning the bike over for a few minutes, then see if the stiction/notchiness goes away. I've ridden and felt a few DVO forks and never noticed one with much stiction, so I have to think you can figure this out and get it smooth like others'.
is there any reason why the bladder got squeezed like that?
I wonder which damper performs best. Fox, rs, öhlins, dvo, ext or cane creek.
Ty for the great vid.
Where did you buy the 2.5 oil?
Motorsport.com, they also sell Red Line fluids for my rear shock (Topaz). Motorex 2.5wt fork oil.
Still nice vid with an excellent guide how to do it. I just did it on my boost sapphire wich got the same shims. The ports of the piston are different compared to the diamond.
Will see if t works.
Rad video! Super helpful
@mtbdeli,
So does this only affect the high speed compression, or does it affect both high and low? I'm not familiar with the damper design, and with what the adjusters on the fork do internally.
Essentially just HSC. It does have a small effect on LSC but nothing I ever noticed. But the engineers would correct me if I said it was only HSC.
The LSC adjuster opens/closes a pin valve to restrict oil flow through the port. The HSC adjuster adds preload to the shim stack.
@@mtbdeli9018 so, (not to get too deep), but does the low speed compression not have a way of blowing off or bypassing / is it always active / fixed orifice?
I suppose maybe HSC oil can bypass the low speed orifice?
@@sham8723 LCS is always active. The ports cannot be closed and will always allow SOME flow. The pin valve that lets oil get to the low speed holes on the piston can be adjusted so more or less oil can travel in the LSC circuit. However with LCS/orifice damping you can only get so much oil through there. As pressure builds it eventually is high enough to open the HCS circuit.
At that point oil goes through both. As much as is able through the LSC, and the rest through the HSC.
As you modify the shim stack that affects how much oil can pass through the HSC circuit under different conditions. If you really stiffen it, more has to go through the LSC making it harsher on big hits, but not changing how it feels when climbing or other LSC events (bermed turns). If you really soften it, it has a much lower pressure needed to allow flow and it can start behaving like an orifiace valve if its very soft.
Shim stacks are like suspension black magic. You can do amazing things with them. Soften it initially then have it get much stiffer. Look up the Manitou Mattoc tuning guide. They have shim stack setups with dyno charts to show the different tunes. AMAZING resource, I wish DVO did that. But they have Ronnie...I asked if they had such charts, rather than send me a chart he asked me about my bike, my weight, riding, trails and gave me this tune.
I hope somewhere in that is the answer you need! if not, let me know.
(this might help too)
tech.dvosuspension.com/piston-technology/
Hello,
Hope u can help me. My fork is brand new but when I turn the HSC knob it doesn't make any clicking noise, in fact, I cannot even feel any clicks. DVO told me it's because it's new and greased, but it will start making clicks eventually. Is that the way it is? Is it normal? Because I'm thinking of return it and ask for another one.
Thank you for your help and thanks for the video, it's really useful :)
Sorry for the late reply...notifications were not on. That is normal. Sometimes people refer to DVO settings as how much "Mushes". There isn't the snappy clicky feel of RS or Fox. Its more of a mushy soft click. Its a small ball bearing/spring that snaps into a detent. They pack them with grease and that really reduces the feel. You can take of the top cap and clean out some of the grease if its still mushy.
@@mtbdeli9018 Thank you very much :)
In newer DVO forks the LSC/HSC unit comes off in one piece and never needs to be separated (nice!). The HSC knob doesn't have steel balls anymore, just small plastic bumps. Almost no clicking to the HSC, which is fine-- it's pretty stiff at first, but loosens up to adjust pretty easily once it wears in a bit.
@ mtb deli: would you mind to tell me your weight. i guess i have the same issue. but my weight isn`t that low: 74kgs.Thanx in advance
83kg body and another few with bike gear. It has more to do with the speed and terrain. A lighter rider going faster can generate higher force in the damper. I’m on the heavier side but ride with finesse and caution...so don’t generate the same forces that other riders do.
Hello Man. I bought a second hand bike with dvo Diamond... I noticed this forks are making a clunk when i pump quick like knock, on the rebound action, even in mid travel. This clunk is very noise. And i feel that on my grips. Do you know If this is normal or if not, what kind of problem is It!?
Sounds like an issue with the OTT spring knocking. Call DVO and they can tell you want to do. I don't recall the steps.
@@mtbdeli9018 i did the damper service. And searching for that issue, i found something in MTBR forum. I sanded the shim stack that stuck below the rebound piston... in compression damper i found a shim broken, so i remove it.
Now, my Diamond works fine, without any clunk (i bleed the damper with Putoline GRP 6 2.5w shock oil, because its a less thicker than other 2.5w fork and shock oils)... Its very, very supple and plush... love mine. thanks
hey there did you change the blader?
my mechanic find cracked shim out of shima stack...in middle with blader!
do you have any idea how this happen?
thanks a lot men!
I could uplad photo if you have any mail thanks a lot!
Darksoul channel there is an extra bent shim in the stack. It was added to fix a noise. The noise was actually a different issue but the build spec still had it included so that’s what they built. You can toss it. It doesn’t do anything and can break free like yours did.
@@mtbdeli9018 I think understand what you are telling me!
This shim i found its outside from the stack and in the middle with the blader
your video in 3.47 in your right hand there is 2 shims there!
My fork now works like before and smoothly without any different sounds!
I upload the shim here check it for the record!
I have to replaced this shim or its nothing?
we.tl/t-BpihEYhaO8
Thanks a lot!!
Have you ever seen a video on how to rebuild the bladder?
I bought a bladder kit because they recommended it when I reached out about doing a full rebuild after a year or more of riding, but I can't find any help on how to disassemble the only part you didn't touch in this video🤦🏽♂️
Its been a while, but I think this should help. I think there is a nut that holds it all together. You can briefly see that at 3:48. Take that off, then the assembly will slip apart. BE CAREFUL TO NOTE WHAT GOES WHERE!! This is the rebound damper so you can really mess things up if you lose track of what went where. When in doubt, call DVO and they can sort you out.
@@mtbdeli9018 thanks! Yeah I'm not sure if I broke it trying to get that nut off🤦🏽♂️... Of course the whole assembly is out of stock so... 😮💨😣 When I get home in a couple days I'm gonna call them and try to sort it all out. (Since I have an Angel Fire trip coming up though, I went ahead and snagged a 2023 180mm ZEB Ultimate) 🤫
Is there any proven recommendation for removing less then 3 shims?
Will I notice any significant difference removing only one or two shim? If so, wich one's do you suggest to remove?
That’s a good question for DVO. Ronnie gave me this specific tune to make it more linear and softer.
I’m not hearing any clicks on my high speed knob. Any idea what might be causing this?
The clicks come from the balls/springs in the dial. As you turn the dial they can make noise but mine don’t make a sound either.
I just feel the detents with each “click”. Its probably from the grease I use to hold them in place. No big deal since the click is just to know what potion the dial is in.
Question. Are you a team rider? Make more videos.
Hey mate! I ride in pretty Rocky, agressive and technical terrain, I felt a lot of hand pain today. Do you think this mod could help me for this issue? I weight around 76kg
How much travel do you use? How much sag? Another possibility is the fork is undersprung and riding deep in its travel. This leads to spiking and harshness. If you are in the 20-25% sag range and using 80-90% travel max then sounds like this mod is right for you.
@@mtbdeli9018 I'm using 90% of the travel at 110 PSI, I wouldn't say it's undersprung at that pressure.
Hey man I had a question? Can u make a video on servicing the fork and bleeding the damper.
Sorry, I sold the fork a few weeks back. I did do a full service before that and it wasn't much different than what you can find on DVO's video.
Hello
Just saw you vid. Did this mod put back together and now my HSC dial doesn’t turn. Any thoughts??
Thx
I would pull it apart again and check for anything not assembled correctly or binding. Call DVO when its apart and they can help you figure out what is wrong.
Ty
Thank you. My Shockwiz keeps telling me I need softer high speed compression and its adjusted all the way soft. Weird though because I’m 230lbs geared up.
I've heard mixed reviews of the Shockwiz and how good it is for tuning. I have not used one, but tuners say they are good to get it close. It won't replace trial and error to dial it in the final bit. Even at 230, you may need less HSC. It depends on how fast you ride and what kind of terrain. Now that I'm in the Northeast, the riding is slower and more small rocks and roots. I may open it up and flip the piston to get more HSC range.
Where in the Northeast are you? I’m in Connecticut. Yeah. Kind of slower picky sections. Even at 230 I must be kind of light on the bike. I always need less compression and air than recommended to get my sag right and not rattle fillings out.
@@Jaredcouture12676 I am now in NY, outside Albany. I used to live in CT (Trumbull...miss those trails). Don't pay much attention to sag. You don't want to be way off, otherwise it can affect geometry. Its more or less a very rough starting point for tuning. It gets you close enough that for most its good enough for them. However once you dial in the suspension in other ways you can almost ignore sag.
What I do is get the basic "feel" right. Not too wallowy and not springy. Rebound and compression should be wide open. You can do this in a parking lot. Then I find a section of trail that is what I want to tune for, it helps to have a faster corner. Ride it a few times with rebound and compression wide open. If you can't hold your line in rough stuff, rebound is too fast. Keep riding and adjusting rebound until the bike feels harsh. Then back it off a bit.
Adjust compression as needed: bottom out...add more. Not using close to full travel, add less. Using full travel is also over rated. I NEVER bottom out, but get 130mm of very controlled travel out of my 140mm setup.
Anyway, thats what I doo and it works great. Check out Shockworx website (New Zealand tuners) for more detail and explanation.
how much do you weight?
Claudio Bosticco I am about 190 with gear and water. When I talk to DVO they are surprised I want less damping. Most of them run similar air pressure and weigh less. However they are riding much harder than I and on trails with some big hits and drops. My riding is aggressive trail at most and I keep the wheels on the ground most of the time. A few 1-2 foot drops.
Your riding sounds similar to mine. But I'm 143 fully loaded, so I think I definitely need less damping. Actually I wonder if mine is a case which may benefit also from the piston flip. Thanks for your video guide!
For now I've done the piston flip only. One ride only, but the first impression is good.
What is the ID of the sims and are the .10 or .15
They are 8mm, and I think they are 0.15mm, but not sure. I can check later when I dig out my shim kit.
Your bladder is sucked in it shouldn’t be like it should be round there are clips top and bottom to get the air back
In the bladder that will fix the hsc instead of playing with the shim stack
Derek Lawrence , yes it was sucked in. I did fix that off camera. While that will help the fork work a bit better it won’t be enough for the change I was looking for. The shim stack mod makes a big difference and I what DVO recommends for a lighter tune.