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Discussion Starter · #1 ·
Hi.

I bought a used bicycle and have used it 4-5 times in light mountain terrain. Now I got a strange sound coming from my front suspension fork.

Look at my youtube link to hear the sound. The sound only comes when I 'release' the bike fast from the ground after pressing it hard down. Under heavier load and more smooth 'bumps' I don't hear the sound.

I have a Marzocchi 44 RC3 Ti 150mm (Newly shoptuned). The sound is also more noticeable when I set it to heavy and fast.

http://www.youtube.com/v/AGxoQwsOmjY
 

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Sounds like spring deflection.
The spring is scraping/rubbing against the inside of the stanchion tube.
Remove the spring and see if it still has the heat shrink cover on it or if it just bare spring.
Also, make sure the spring is perfectly centered in the top cap.
 

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Thats just the sound of oil going through the rebound piston. No problem at all. If you speed the rebound up it will go away, if you slow it down it will get worse because the oil flow is more restricted.

Dont worry about make the sound go away, Make the rebound speed correct and live with the noise.
 

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Discussion Starter · #4 ·
Ok. After some reading I also thought it could be the shrink 'wrap'. I'm not sure about opening it up taking a look myself... Is it harmful for the spring or tube if it is missing wrap?

And double ok :p Are you 100% sure about that Mullen119? Because the fork didn't make that noise before. You are correct about the sound being less when its sett on soft and slow. On the Video its set to max hard and fast to demonstrate the sound.
 

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Watching the video, the sound appears to only happen on the rebound stroke. That would not be the case if it was the spring rubbing on the stanchion. It also would sound the same no matter what the rebound setting is if it was the spring. Most forks make the noise when rebounding. Depending on the design, some are louder then others. You probably didnt notice it before. When the fork is loaded with your weight, it wont rebound as fast most the time, so the noise will be less.
 

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See if the sound goes away or changes if you adjust the preload/spring compression.
I have two RC3 TI Marz forks and the sound you describe has always come from spring deflection.
Less rebound damping and you'll hear it quicker and louder because the fork is returning to full height faster.
More rebound damping and it diminishes because the fork is extending much slower.
You can run the fork with or without a wrapped spring, it won't do any harm either way.
If you aren't running any spring preload, their can be excessive "slop" that allows the spring to deflect more than if you have a few turns of preload and the spring perfectly centered under the top cap.
Go ahead and open it up if you want after messing with the spring preload. You won't hurt anything by checking to make sure the spring is centered.
 

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Discussion Starter · #7 ·
Thanks. Your probably right I hope :) Feeling pretty awkward trying to learn the bunnyhop with the fork making that sound every time after getting the wheel in the air.

Thanks alot for taking time to answer!
 

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Less rebound damping and you'll hear it quicker and louder because the fork is returning to full height faster.
More rebound damping and it diminishes because the fork is extending much slower.
.
Thats the opposite of what the OP said is happening. The OP said more rebound damping and it gets louder, less rebound damping and it gets quieter.
 

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Discussion Starter · #9 ·
See if the sound goes away or changes if you adjust the preload/spring compression.
I have two RC3 TI Marz forks and the sound you describe has always come from spring deflection.
Less rebound damping and you'll hear it quicker and louder because the fork is returning to full height faster.
More rebound damping and it diminishes because the fork is extending much slower.
You can run the fork with or without a wrapped spring, it won't do any harm either way.
If you aren't running any spring preload, their can be excessive "slop" that allows the spring to deflect more than if you have a few turns of preload and the spring perfectly centered under the top cap.
Go ahead and open it up if you want after messing with the spring preload. You won't hurt anything by checking to make sure the spring is centered.
Must admit that I don't understand exactly what you mean. "Slop"?

To check the spring I open up from the top of both sides on the fork with an umbraco key?
 

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Thats the opposite of what the OP said is happening. The OP said more rebound damping and it gets louder, less rebound damping and it gets quieter.
He's saying it's louder when set "fast". Fast should mean less rebound damping.
If the spring isn't centered and unwrapped, he'll hear it more with fast rebound.
 

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Discussion Starter · #11 ·
Thats the opposite of what the OP said is happening. The OP said more rebound damping and it gets louder, less rebound damping and it gets quieter.
The the video I have turned it on max Hard (under) & Fast (top), because thats when it makes the most noise. A little less on the opposite.
 

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Must admit that I don't understand exactly what you mean. "Slop"?

To check the spring I open up from the top of both sides on the fork with an umbraco key?
Slop=the spring isn't properly aligned and compressed. You'll see where it should sit under the top cap. Sometimes it takes a few turns of preload to engage the spring.
Spring is in the right leg( rider's right)
All you need to do to inspect it is use a 2.5mm allen key to remove the adjuster knob and a crescent or box wrench for the top cap. Be careful not to lose the detent ball when you remove the adjuster.
Just compress the fork a little after the top cap is removed and the spring will rise up and you can remove it.
There is oil in the spring side of the fork, so keep the fork upright.

In your pics above, rebound is at the top of the left leg of the fork. Compression is at the bottom of the left leg of the fork.

The spring is on the right and should have a preload adjustment on the spring top cap.
 

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Lets put it this way. My 888 I had for a while had both spring noise and rebound noise. Check both. If it is happening on only the rebound stroke(which is what it sounds like to me from the video, but its hard to tell) then is it likely rebound noise. If it is happening on the compression and rebound stroke, then it may be the spring.

My 888 had the spring tube actually fall apart in the fork(into about 100 pieces, what a pain), so either way, its probably worth pulling the spring out and looking at it.

In either scenario(other then the tube falling apart in the fork like mine) the noise is not a big deal other than being annoying.
 

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Discussion Starter · #15 ·
I opened up the fork and there was oil spill. I was prepared for it and had small containers ready.

First I opened up the top left side (standing on the bike) as that's where the spring is ( https://ep1.pinkbike.org/p4pb6703612/p4pb6703612.jpg ). There is no adjusternob or anything on top, just a flat surface with aligned holes ( https://www.marzocchi.com/System/58151/M_2011_Fork_Details_074_l.jpg )

Unscrewed the top and pressed the fork down to get the spring out and it looked ok. Plastic was nicely wrapped around the spring.

Then I did something that I shouldn't have done. I screwed the left cap back on, turned the bike upside down and undid the low-speed compression on the bottom of the right slider. Found box wrench and starting to unscrew the bolt underneath of it. What happened next resulted in alot of mess. The gold adjustment nob inside of the bolt was after alot of turning of the box wrench on the bottom of the slider.... I then realised that this was not a good idea.

I then had to level the fork and put an container in each end of the fork to hold the oil that was probably coming very soon. I unscrewed the topcap of the spring again so that I could easily bottomout the fork so that I could get hold of the gold adjuster'nob' with the locknut again. After some turning while pressing the fork down I finally got it into the locknut!

I wiped the fork down for oil putted the wheel back on and turned the bike on its wheels again. Now I noticed after a few minutes that the goldcrown nob was dripping tiiiny drops of oil. With the bike upside down again I found out that the locknut wasn't completely fastened on the fork. Look at my youtube video for an explanation.
VIDEO0062 - YouTube

Right now I'm seriously considering handing the fork over to experienced technicians....
 

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You need to tighten that down a lot more. You can try compressing the lowers so that there is some friction holding that rod in place while you tighten the nut. I am sure I'll be yelled at for suggesting this, but I used my cordless impact to tighten that nut down. Just a blip to get it snug.
 

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