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Aluminum Marzocchi forks/No damping after oil change

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After dumping the fork oil and pouring in new oil I'm unable to bleed the cartridges. Forks worked before (could tell difference in the adjusters, rebound and compression) oil change so it must be something I have done. I did not completely tear the forks down, just removed caps, pre-load spacers, springs, inner cartridge adjuster rods. Over filled the oil capacity and worked the outer fork leg then the cartridge for quite a while without ever feeling much resistance. Let them sit for about ten minutes but never saw any air bubbles come up. Went ahead and set oil height at 160mm and put them back together.

Now the forks are very springy feeling, must have air trapped inside the cartridges, they also top out very badly. Have compression set all the way out and rebound all the way in and tell any difference. Any and all help would greatly be appreciated.

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I had the same issues while working on my 50mm Zokes. I had to fill the shock all the way up over the top of the cartridge and work the cartridge back and forth with the top of the cartridge never going above the oil level. I ended up letting the shocks sit over night with the oil level over cartridges to get the remaining air out.. I then pulled the oil level down to the correct level. Good luck to you on bleeding the air out. I couldn't find anyone else with any experience so I hope this helps.

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Thanks Lincolnlock for the reply, I did find some information on Trials Central. A guy had the same problem and said to remove the cartridges and fill with 80cc oil and re-install into fork. Then add oil to desired height, but this does not make sense to me. Why would you have to go thru this much work and how and where to fill cartridge before re-installing them?

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Thanks Lincolnlock for the reply, I did find some information on Trials Central. A guy had the same problem and said to remove the cartridges and fill with 80cc oil and re-install into fork. Then add oil to desired height, but this does not make sense to me. Why would you have to go thru this much work and how and where to fill cartridge before re-installing them?

Exactly what I was thinking when I was servicing my forks the first time. Here is a video. Hope this helps.

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Sometimes when you lift the tube all the way up it will suck more air into the system. Stroke from all the way down to about 75% up.

Also I have found that if you put your hand over the top of the tube, and then compress it while holding in all of the pressure, then quickly remove your hand, it will draw up the bubbles pretty well. You'll see some fog in the tube when you're doing it right.

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Exactly what I was thinking when I was servicing my forks the first time. Here is a video. Hope this helps.

Good video, but wasn't that for upside down Showa forks? I believe he is talking about the same aluminum tube Marzocchi forks I have on my 07 Gas Gas Raga. Correct me if I'm wrong.

There were good videos on the Gas Gas Forks but the ones I used were for the older forks made by Gas Gas up to I think the 04 Gas Gas Pro. However, my wife's 05 200 Pro uses the Gas Gas branded forks.

Now that I think about it, I'm not sure I have ever taken my 07 Raga forks apart so I'll be needing any new video about them too. :bonk:

Edited by 2PLY

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Also I have found that if you put your hand over the top of the tube, and then compress it while holding in all of the pressure, then quickly remove your hand, it will draw up the bubbles pretty well. You'll see some fog in the tube when you're doing it right.

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Ya I've been doing that trick for many years and its always worked on open chambered forks but no dice on these marzocchi's. I guess further tear down of the forks (remove cartridge's and try to figure out how to charge them with oil is in order.

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You really shouldnt have to do anything but pump the cartridge with it covered with oil. Its best to use something threaded to rod, so you can really grab it and push/pull it with gusto. A Stupid question - but what oil did you use? If you say changed to a 5wt oil - it pretty springy and the high speed adjusters will do hardly anything just pushing on the ft end. Brands of oil can have much different viscosities as well and marked the same weight.

Was the old oil real dirty?

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Ya the oil was pretty dirty, flushed it out twice with atf. Refilled with a 50/50 mix of Honda cartridge 5w and Honda ss10 cartridge fork oil. I'm assuming it came out to be a 7.5w mix. Tried calling Marzocchi tech support in southern Ca. earlier today but will not be back till January 3rd.

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Sounds like you did everything right - call to tech a good call. You will probably need to take a look inside the cartridges. Another stupid question - Did you measure the 160mm with springs out? You could try over filling by 3mm-4mm (157mm) and see if problem goes away after working in real good on the bike? (while you wait for tech?)

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Finally got a hold of tech support in SoCal but the person I talked to did not have any experience with the trials fork and referred me to marzocchi Spain. This is his reply:

Ciao Mark, it's a plesaure help you with your fork.

I'm racing Dep. For Marzocchi and I support Supermoto, Motocross, Freestyle, Enduro, Trial ...........

Your Trial Fork, it's a 40mm. Marzocchi and You will use inside 7,5wt oil.

Oil level : 140 mm.

For do the right vaccum in the right side (rebound) You will do .........

1st) put the cartridge up side down and put the oil inside and start make a manual vaccum (push the shaf up and down and release the air inside)

2nd) put oil level to the small hole (up to the tube) and put inside the flooting piston (put grease in the teflon ring) without the screw (take easy because the oil can coming outside ........ In your face!!!!)

3rd) push the flooting piston to 60mm. (From the top of cartridge ..... With out the small screw) and make 2/3 time up and down with shaft (if you have a air .... Use torche for take out)

4th) push the flooting piston to 70mm. (10mm. More) and close the hole with a small screw)

5th) put spring and cap.

6th) push the shaft wide inside and you will see the extra oil coming out side from the small hole in the cartridge

Put all togheter and make oil level .... In both legs at 140mm.

Note : I do a special kit for that fork ...... And if I will coming (I think soon) in USA (Marzocchi USA at Valencia) I will bring one special kit.

Ciao and be good

I'm sorry for the e-mail ..... Because I'm driving my truck to Spain and write down for You!!!!!

Pietro "Pedro" Palladino

Recing Dep. "Marzocchi Corse"

Tenneco - Marzocchi

Don't exactly know what he is trying to explain, sounds like the cartridge has to be removed first. Anyone read in between the lines on this one?

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:smirk::lol: Driving while writing that TOO??? :bonk:

I'd be careful about those flooting pistons.. They can floot across the room in the blink of an eye if you're not careful. :lol:

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Im very leery of the 140mm. Ive done several Al 40mm Zoke oil replacements and have always used a 160mm air gap (per the GG USA spec sheet) and never had to disassemble the fork to get the air out. I DID have to work the cartridge for a few minutes on most. Always smooth as silk after some "on the bike" time. My worry is that he's more of a supermoto guy than trials or something is lost in translation here. (and blowing out the fork seals from over filling)

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Tore the forks down completely today, seemed normal until I pulled the stantion tubes out from their lower fork legs. Bushing stayed on stantion tube but seal did not come with it. Seal, spacer,other bushing remain in fork leggs. Now the hassle of trying to remove the seal without damaging the fork. Gonna work on that tomorrow again as I did not have much luck with it today. Tried priming the rebound cartridge in the upside down position without any success as well. About ready to take these dam things to a professional and be done with it.

Sure wish I could find a video of these forks being serviced, Gas Gas USA has a couple but they are not for the 40mm forks.

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Finaly made some progress, forks feel like they have damping now but still cant tell any difference when turning the clickers. Measured out fork oil for reach side and poured directly all of it through the extended cartridge rod. Had to slowly compress cartridge rod and extend to get all the oil in. I did not try to quickly bleed the rod or cup the stantion tube to get the air out. After filling the cartridge rod I put the adjuster rods back in and over filled the stantion tube with oil, then siphoned off the 160mm air gap. Forks are rideable now, feel much better. If the damping adjusters worked I would really be happy.

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