[dilzy]

Ocean engineering eh? Built any sweet oceans lately?

There are also situations where compression damping can increase force transmissibility (extremely high speed movements at low displacement, like hitting a fist-sized rock at 70km/h) as compared to having only a spring of higher stiffness. However, to put in perspective how fast this needs to be over say a 3" high hit, for a stock valved rear shock (DHX5) to do that with mid-range compression settings, a 450lbs/in spring and a 3:1 leverage ratio, you'd need to manage to move the wheel at approximately 6m/s. This is about the upper limit for possible vertical wheel speeds on a bike, the actual land speed you'd need for that is phenomenally high if the suspension is only moving 3" vertically.

Obviously if you run more compression damping though, the speed at which that can occur is lower...

Mate The Atlantic...thats right, mine.

When I used to ride dirt bikes, I used to do a lot of high speed desert stuff and used to run a single stage stack with a lot more base shims and much smaller clamp shims to build cartridge pressure quickly before letting go for the really high speed stuff.

It would be nice to work with a back pressure balanced damper with high speed spools. I have some models done up for a cartridge with a mid-valve back fill check valve and proper high and low speed adjustment with an air backed IFP, but it requires a twin tube design ala CK, so is a bit of work to make.

Maybe when I get time in Tafe.

 

[Steve M]

That stack setup sounds a lot like what mine is at the moment. I considered trying a two-stage stack but all that's going to do is increase the HSC without having any effect on the LSC at all, which is the opposite of what I really want.

As it stands now though, I think my stack is probably a bit too stiff - with the LSC cranked, it's REALLY stiff, almost like the moco lockout, which makes me think it's probably got more HSC than it needs, so I'll probably take one or two backing shims out. Another ride test tomorrow...

Don't quite get what you're on about with the damper design though - mid valve back-fill check valve? Feel like elaborating on that?

 

[dilzy]

I need to re-install Auto cad to view the files, but heres a drawing I found in my sketch book.

You can see at the base of the cartridge the back-fill valve that allows the oil to flow through on compression, but forces it through the mid-valve rebound stack on rebound.

It's I suppose a less complicated version of a CK DB. IE there is no high speed rebound adjustment, but most of the oil does flow through the adjustable compression assembly.

The back-fill port sizes need to have quite a high total area, so that they can accommodate (without the a greater pressure drop than over the compression stack) the flow of the system.

This flow would be at low to mid-high shaft (point at which mid-valve comp stack opens up) speeds up to 100% of the volumetric displacement of the mid-valve (minus the shaft displacement of course, which is accommodated by the IFP)

You'll have to save this image and then blow it up, because RM is a bloody stooge with its JPEG limit and when you click on it, it doesn't come up at 100%..wait I just hosted it in PB to fix that.

 

[Steve M]

Ah yeah, that's pretty cool, quasi-positive displacement damper like the TTX40/CCDB (well TTX40 is positive displacement, CCDB isn't quite). I think Avalanche use a recirculatory system that's pretty similar to that in their forks too (though no IFP I don't think). Would be pretty sick to see that kind of thing up and running! Any plans to build it?

 

[djivotno]

Hummh... so i've got a new Kingpin, but i plan on having 2 working forks at the end of this build, so i'm going to run the boxxer's rebound on the Kingpin, moving the Air assist top cap to the other side, and.. i'll have something close to a cheap Domain in terms of damping (i'll work from there on to make a decent fork out of it)

It's pretty streight forward with the rebound, but i'm planning to get a spare rebound shaft out of a Pike, and run it with my spare MoCo's top cap or drill a spring side cap.

I was interested in how much shims are you (Udi) running on your modified C-damper? I have the set of shims from the Boxxers ShimStack and those from the Compression Assy on the Kingpin, and... i don't think it'll be enough (i'm running the MoCo half way Comp. with a full on Gate and 2 shims on the internal stack)

I guess i'll post the result once it's done. For now i have the rebound in but with no frame i can't realy give it a go

 

[Cabdoctor]

Maybe I missed it somewhere in the thread, but what year boxxers will this work with?

 

[djivotno]

Maybe I missed it somewhere in the thread, but what year boxxers will this work with?

06 to 09 (The Motion Control Boxxers)

You can do it with an earlier model, but you'll need a new rebound assy, and a new (single) spring.

 

[Cabdoctor]

I have a friend with an old 2004 boxxer. I'm a manitou man but, I was thinking about pulling this thing apart and seeing what I could do with it. Any advice, or any threads I could turn to? Thanks!