So, could this be done?…..or, more specifically, has anyone had a go?

My forks (Marzocchi 44s) are shafted and, as I currently have access to a vast workshop of fancy machines and equipment, thought it might be fun to have a go at building a new damping cartridge.

However, there are some issues:

-I don’t really know what I’m doing
-I don’t really know what I want
-I don’t know where to start
-I don’t even know if it’s possible, and actually possible to achieve a good result

I know I could just buy a replacement, or an Avy cart, or something, but where’s the fun in that. I thought that, if nothing else, it might be an interesting learning exercise.

So, thoughts?

Buy a pair of high end forks, take them apart delicately, copy the damper, and then send them back unused?

Are they old? I had the last PAR assembly from the parts bin at Windwave about a year ago.. so if you can sort it out then let us know!

I’d be interested in a closed cartridge for my 66s, then I could put some of the properly slippy stuff in the lower leg.

i have the knackered damping cart of some 44rc3tis you could have to play with if you like

I currently have access to a vast workshop of fancy machines and equipment, thought it might be fun to have a go at building a new damping cartridge.

Never mind that, what have you got in your cutlery drawer?

Its just oil flowing through an hole how hard can be? … 😉

I think Rock Shock’s basic motion control damper is a pretty simple design. Maybe have a read up on that and see if you can make something similar.

I think Rock Shock’s basic motion control damper is a pretty simple design. Maybe have a read up on that and see if you can make something similar.

Simple to manufacture on a large scale, probably not in a machine shop. It’s a big stiff spring/poston that lets almost no oil flow untill the forks moved a few mm to displace the piston, then there’s a shim stack inside for the actual compression damping.

If you want simple, get a hold of some really old marzocchi forks like the Z1’s or MX comps, there must be loads out there and the dampers are simple shim stacks and often adjusted internaly so no dials/rods to deal with.

I thought the Moco body acting as a very stiff spring was only used as the floodgate when high levels of compression damping are used or when locked out?

So when fully open or only using mid amount of compression damping the Moco body is rarely, if ever compressed?

I may be wrong so please correct me if I am.

COuld you knock me up a moon buggy while you’re there?

(it’d be possible but it’d take hours and hours of faffing to get it right)

I think if you wind the threshold off it uncovers the hole all the time, but for most of the range of adjustment it’s covered and takes varying ammounts of movement before it opens. As there’s nowhere for the oil to flow without it opening it acts as a 2nd spring untill the fork compresses enough to open it. The plastic MOCO bit you can see isn’t itself the damper, it just locks the fork out untill it gets an impact, then opens.

It’s an elegantly simple solution to the problem of adding a threshold adjustment to the fork, but I’m not sure it would be the easiest thing to make from scratch, you’d have to get the spring rate of the plastic right. Compared to a simple compression shim stack and one way valve which could be mouned directly onto whats left of the old damper (assuming the rebound is still fine, or do that to the rebound and leave the compression alone if that’s what’s broken).

Elastomers will be the next big thing. 😉

I guess it might be a little more complex than I originally thought. I was sort of hoping that someone might have done it themselves, out of interest.

I’m not entirely sure what characteristics are in fact desirable in suspension, let alone how to achieve that. I think if I were to have a go at making one, I’d have to start at the bottom, simple shim stack, and then develop it from there. This is probably a bit more than I can chew at the moment (studying for a PGCE) so might have to sit on the back burner.

Kimbers – incidentally, what was it that went pop in your RC3Ti damper? Mine seems to be permanently set to pogo mode at the moment.

look out for an old Rissee cartridge use one of them on a modified 44 shaft(amazingly Rissee still sell the Gem cartridges for Judy’s!)

I could probably make something basic from scratch- a damper rod and cartridge emulator setup or something. I’ve modified stock parts enough to understand what’s going on with those, though not to say what settings/apertures etc would be right or wrong. If it worked well, it’d be pure luck though.

But if you’ve got the existing parts, can you replicate that?

I guess I could have a go at rebuilding/creating a new RC3Ti cart, if nothing else then it would give me an idea of what’s going on inside. I could leave out the air preload as well, which would be good as that seems to cause me the trouble and I never fiddle with it anyway.

possibly interesting reading? http://www.shimrestackor.com/index.htm

I would make some high flow pistons and try to find low friction seals and then experiment with shims on an existing unit.

studying for a PGCE

Those who can do… and so on 😉

Do you know what’s broken on the fork already? have you taken them apart yet? identifying the problem/damaged or broken parts, that would have to be the first step, then look at whether you replicate whatever is already there, and/or try producing a modified version to allow some different adjustment to stock…

The Older 7″ Boxxers were great for this sort of thing, lots of people used to make their own base valves from delrin or aluminium, bore out the ports on the pumping rods or piss about with the high speed compression assembly, it was an ideal fiddlers fork.

No idea what’s in current Boxxers or 44s for that matter, but I doubt its exactly on a par Brain surgery…

Those who can do… and so on

Very true in this case, though I’m enjoying it more and more, despite the endless bureaucracy and doing things “because that’s how we do it”.

That shim stack website is great! That said, not very accessible, I’m reading each sentence about 4 or 5 times to picture the effects on a fork.

cookeaa – Member

No idea what’s in current Boxxers

This:

Actually pretty lovely, I spent ages playing with mine a while back and quite a lot of that was just turning the dials and looking at it. Decided against messing with it, not hard to figure out what does what on a basic level but I didn’t have any more than that- just did the repair and ran away. Three cheers for any company that colour-coordinates the inside of their forks, though 😆

People say, why are pushbikes as expensive as motorbikes- here’s what was inside my motorbike forks:

And half a pint of what seemed to be fish guts.