midvalve

[Papakeith]

Could someone walk me through the purpose for and the actual mechanics of the midvalve? What variations are there? What do different configurations do to the suspension?

 

[marcusgunby]

Papakeith i want to help you but its alot of writing-a search will show loads of good info.

 

[Papakeith]

Thanks marcus. I was searching on "mid valve" and hadn't gotten what I was looking for. I searched for "midvalve", and viola! 7 pages of excellent information.
After reading through almost all of the dissertations, I can see why you were hessitant to type it all over again.

First, I've found that I had some of the terminology used in suspension talk all backwards. This might go a bit off topic from my original post, but it might be helpful. Please correct any and all of this if I am way off. Be picky, I want to get this correct in my head.
This is all regarding the fork:
Active valving= rebound piston
passive valve= compression piston
midvalve float = distance the shim stack is allowed to lift off of the piston face before shim stack deflection comes into play
check plate = in leau of an actual shim stack there is a single shim held in place by the cupped washer and spring

Does the (as I call it) rebound piston have a proper name?

I do have a question regarding alot of the Gold Valve questions though. When they say they are removing the midvalve, are they simply removing all of the shims on the compression side of the rebound valve?

Hopefully I've made the question not quite as broad as it was originally. :)

 

[swaldrop]

Your definitions all sound good to me. Not sure about the Gold valve though. All I know about it is what I have heard, and none of it was good.

 

[James]

Papa,

I have a Goldvalve fork kit and it includes check plates (spring, cup, washer) to replace the midvalve.

I'm not an expert by any means, but holding the stock piston and gold valve side by side, I can't see where one would be leaps and bounds beyond the other. One of them is more shiny.

 

[Papakeith]

I don't really give a hoot about the gold valves. I was just using them as an example. From what I gathered in the posts I read they suggest removing the shims.

 

[swaldrop]

James, you pretty much summed it all up with that last post. Not a whole lot of difference. It is pretty though isn't it? Dont remove the stack on the compression side of the active valve. It has to be there for a reason or the really smart guys who do suspension would not have put them there, right? Like I said, I don't know a whole lot about suspension. What I do know is that the active and passive valving work together to form some kind happiness and screwing with that would be bad.

 

[Jeff Howe]

PapaKeith,

Midvalve removal is actually "midvalve replacement" with the check plate system. This is just a thicker single shim used in place of the midvalve stack. The midvalve is also referred to as "bending checkplate" by some. The midvalve stack can be tuned for different feel. You don't have that option in a checkplate.

A fork can work with the checkplate system, as you will no doubt find lots of happy RT customers, but the Gold Valve system will also work with a midvalve, and I think it works better with it myself.

 

[JTT]

Sounds like you got it pretty much down Keith, but just to clarify the rebound piston and the midvalve are in effect, "opposite sides of the same coin". This is the piston that is attached to the damper rod and moves through the fluid in the cartridge, in the rebound direction, it controls rebound. In the compression direction, the "midvalve" side comes into operation (or checkplate in the case of RT), but it is only one actual piston (active).

You may already know this, but it just kind of seemed a little unsure in your definitions ;)

 

[Papakeith]

I know it now thanks to some archival research. I was very confused about the whole thing. But I now have some sort of picture as to what is going on in there and why.
Moving on to the basevalve. Does anyone ever use anything besides a checkplate on the "rebound side" ?

 

[James]

Originally posted by Shocknut
Midvalve removal is actually "midvalve replacement" with the check plate system. This is just a thicker single shim used in place of the midvalve stack.

I should have clarified this part to my response to Papa, RaceTech suggests you "convert" the midvalve and supplies the necessary parts (not simply taking the midvalve off).

My comment about the comparison of the Gold Valve was in response to the comment that they are crappy. To clarify, I think it is more in the setup than the actual "Gold valve" itself. I left the midvalve in with my GoldValve but adjusted the recommended settings to compensate. I think I am going to pull that stuff back out and replace it with a modified stock shim stack next oil change.

 

[JTT]

I've got a few pics of a Showa Twin Chamber internal if you are interested in seeing one opened up.

 

[Papakeith]

I'm always interested in seeing the guts of suspension components. Bring it on! :)

 

[JTT]

Here's the base valve.....

 

[JTT]

...and the midvalve...

 

[marcusgunby]

LOL joe -what a example to use-a base valve that sits at the top of the fork:)
keith the check plate on the base valve is just for refilling the cartidge on rebound.

 

[marcusgunby]

Heres a base vlave from a early showa-alot like a KYB/wp/ohlins base valve.

 

[marcusgunby]

And heres a nice pic of jers lovely new base valve pistons(good to compare to a gold valve to see the difference in theory)

 

 

[JTT]

mmmm....pretty.....me likes gold.... :D

 

[Papakeith]

here's a picture of the stock passive valve on my 98 cr500 kyb fork.

 

[Papakeith]

here's another one showing the active and passive valve for the same bike

 

[bclapham]

great thread guys, it is really hard to get any ideas on suspension until youve had it apart!

Marcus, if you get chance, can you maybe upload those photos i sent that show the float meaurements and maybe those drilled peens in that other thread just for completion sake? Thanks, i would but they are on my comp. at home!

Papa, on the basevalve is that a stock piston or a red andonised aftermarket?

 

[Papakeith]

the latter :)

 

[Jeff Howe]

Originally posted by James


I should have clarified this part to my response to Papa, RaceTech suggests you "convert" the midvalve and supplies the necessary parts (not simply taking the midvalve off).

My comment about the comparison of the Gold Valve was in response to the comment that they are crappy. To clarify, I think it is more in the setup than the actual "Gold valve" itself. I left the midvalve in with my GoldValve but adjusted the recommended settings to compensate. I think I am going to pull that stuff back out and replace it with a modified stock shim stack next oil change.

Certainly won't hurt James. But the Type 1 Gold Valve and 23mm Showa are pretty similar. You may as well work with your GV as long you have the money invested. But, if you are the very experimental type, assuming you have T1 pistons, send them back and ask for exchange to T2. Your stock pistons are very close to a T1 in design and with the T2 you have another option in smaller ports. I personally prefer the T2 design most of the RT products. They will ask for a CC # until they recieve your T1 pistons, but they will exchange them... even up swap. Thats a very nice customer service option they offer.

 

[flynbryan]

This is great stuff guys.......your actually inspiring me to work on my suspension. I'm having a local suspension specialist to work on my showa twin chambers.(47mm I believe) He is converting my midvalve to a checkvalve system. I wanted to eleviate some mid stroke spike and I've been told this approach will help. Outside opinions? I thought this was a good thread on something I'll one day try my hand in.
Kudos Papa Keith!! :thumb: