40mm Aluminium Marzocchi's. 2014 GG.

[Rod]

Anyone had these apart for an oil change or inspection ? From what I've read on Trials Central it's not as straight forward as I'd hoped with bleeding of the closed chamber cartridge complicating things somewhat.
Also these forks of mine have had an audible clunk in them from new when you push down on them in a static environment ( not steering head bearings), not noticeable when riding.
Someone from Australia mentioned a broken wave shim as a likely and known culprit, compression leg I'm assuming however the rebound leg also appears to have a wave shim from the diagram I have.
Do I need any specialist tools to dis-assemble the cartridges and/or bleed ?

I don't really want to send them off to a suspension specialist if I don't need to as I enjoy working on my bikes nearly as much as riding them, just that I know little about these particular forks, yet!

[Chumley]

Howdy Rod, your old mate Chris here. The other source of a clunk can be the floating brake disk moving on the bolts.

There is obviously some top-secret trick to getting these forks to work right but nobody is willing to pass on the information in full.

Some people say you need to remove the cartridge on each side to fill it properly. Some say to use a syringe to inject oil into the small holes in the cartridge. Problem is the oil just falls out the other side or falls out when you reinstall the cartridge into the empty fork. Some say to pump the rod up and down until all the air is gone but it never gets to that point and they forget to say if the adjuster shaft should be removed or not. They all say to use the level method to determine the correct amount of oil but nobody agrees as to what level. They agree the level is checked with the fork fully bottomed out but nobody has said whether the damper rod is fully down or up (it makes a difference). One person did get some info from Marzocchi but it was in broken English and glossed over the important bits.

I did make a bleeding tool as described by Jon Stoodley on TC. That is used to pump the damper rod up and down to get the oil in and the air out of the cartridge. If nothing else, it is useful to retrieve the damper rod when it slides down to the bottom (after removing the fork cap).

For your info, the thread on the top of the damper rod is M12 x 1.25 which is a metric fine thread. Go to the local bolt shop and get an M12 x 1.25 nut and weld it to a piece of ½” tube say 400mm long. Also, the lock nut under the fork cap is 19mm and the cap itself is 22mm.

In the end, I’ve tried everything to get these forks to work nice including filling the oil up to the very top and pumping the rod all day. The compression and rebound adjusters do virtually nothing and they feel like there’s damping at the top and bottom of the stroke but nothing in the middle. To make matters worse, I’ve now got a Montesa 4RT Race Replica with the Showa forks so now I've tasted what good suspension should feel like!

Be prepared to make a big mess. If you find the "secret", please let me know!

Regards,
Chris.

[The Hell Team]

No secret.
But there is no Marzochhi service manuals available , hence the fact you have to ask around for the fix.
it is air in the right hand cartridge. As the forks go to full extension as soon as the piston runs into air instead of oil - Clunk!
It is an easy (if slightly fiddly) fix.
Pull the right fork leg apart.
With the cartridge out of the fork, turn upside down - so the bottom of the cartridge is the highest point . Then remove the retaining spring clip in the bottom of the cartridge, then remove the cylindrical bung and little bottom out spring, push the rod up releasing the piston and fill with 5W oil. It will be reasonably obvious that you have to put these back together with NO air in this cartridge. As you reassemble keep every cavity full of oil (so piston rod at full extension and fill it up).
Best done over a bucket or tray because you will make a mess, but it is a really straight forward simple task, definitely no "secrets".
If you get the the air out of the cartridge and properly filled with oil, they will work a treat.

[Rod]

Thanks Chaps, It all sounds a bit tedious but I want to put fresh oil in before the weekend, the forks are out and the caps loosened with the compression leg draining in a bucket, the rest can wait until tomorrow night.

Chris, that clunk on compression could well be the floating disc, I didn't realise how much float it had until the plastic guard came off and I could see things more clearly.

Paul, I was going to use 7.5wt with an air gap of 160mm, does this sound OK ?

[Chumley]

That's good information Paul. I've not seen that before.

Do you have any hints as to the fill level and is it done with the piston rod pulled up or left down?

Chris.

[The Hell Team]

Fill the oil with the stanchion as per the drawing below.
You have to leave the cartridge at full extension when putting it back in the lower leg. Once it is full of oil and re-assembled be careful with it as you re-fit it into the stanchion.
You dont want to pump it at all and get any air into it until that lower leg is filled. Only then should you think about moving the rod.
Look carefully at the bottom of the cartridge you will notice some very fine holes. They are that small that the oil will not run out of them when the cartridge is reassembled, but if you pump the rod then it will push oil out, and hence suck air in. So once the cartridge is full of oil, get it in the leg, and get that filled so it is basically in an oil bath.

Rod. 7.5 W is OK, 5W makes them a bit faster. 160mm gap is correct

Next time I fix a set, I'll do a little video or photo essay because this seems to be a common question.

PS. If you get the "clunk" when the forks go to full extension (when you wheelie, or quickly lift the front wheel off the ground) then it is definitely the forks, not the Floating disc.
You can feel the 'float" in the front brake disc by holding the handlebars, locking on the front brake, and rocking the bike back and forth. You will notice a little freeplay. That is an allowance to centre the disc in the caliper. The disc retaining bushes can get worn with age, and this will amplify this movement, but it is quite different to the issue with air in the Marzochhi forks.

[Rod]

Whats the procedure on the left compression leg chaps, is it simply tip old oil out and fill with fresh oil or does the cartridge also require removal and some type of bleeding?

Geez, I can't wait until my old Ossa is mobile, at least I can do an oil change on it without requiring some sort of degree in science or physics.

[Rod]

I'll answer my own question, yeah just fill the leg with fresh oil ya fool. After taking the chamber out which is a completely different animal to the rebound chamber it is obvious that this cannot be filled with oil and then inserted into the fork leg without loosing all that oil. Only thing I wasn't sure on, as Chumley pointed out, is the 160mm air gap with damper rod compressed or extended. I did mine with damper rod fully extended.

Only the right rebound leg is a true closed cartridge design, the left compression leg even though a cartridge within a cartridge is really just an "open cartridge" design. I think?

[eagle]

Every fork i've done work on the oil height is with the fork leg compressed, it would be a lot of oil if you have the fork leg extended!!

[Rod]

Forks compressed, springs/spacers removed, damper rods fully extended is what I did on these Marzocchi's for an oil measurement.