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Discussion Starter · #1 ·
All,

I've got a 2002 Marathon, the one with "Doppio Air" and three position lockout.
I've set up the thing as described for a 175 lb rider weight and it feels plush.

The problem is that it dives about 2-3 inches when I apply the front brakes at
any given time. This is esp. a problem when I'm going down hill, the back
brakes are sliding and I need to STOP...

I think this could be a potentially dangerous situation, so any advice would be
appreciated.

Here are the settings/levels to the best of my memory:

oil: left is 35cc, right is 110cc
air: compression left is 35#, right is #35, rebound is 110#

I'd like to keep the plush, lose the dive, any advice?

Thanks in advance
 

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ok, first i'd want to make sure that i was using the correct spring rate. Just because it doesn't bottom doesn't mean it's correct, and a good idea may be to use a little less sag than recommended, this may help a little bit if you do it right, and still give you a fairly compliant shock.

What you can do is increase the oil weight, stock is 7.5, you should try 10wt. It helps, but it's also not a huge effect. The reason your fork does this is because it is a marzocchi (newer 05 shocks are going to have different technology and features that may get around this). Marzocchis usually have very little compression damping, because they shoot for the best suspension performance. This means that when you apply the brakes, the weight shift easily lets the fork move through it's travel. When you have a fork that doesn't operate like this, it is sacrificing the suspension feel and action to do so. A little stiction, low speed compression, or a "platform" are the kinds of things that will keep forks from doing this, but in each of those cases, you will not end up with a fork that is as "plush" or "acive" as the marzocchi is. So in the end, it is a tradeoff.

Fox forks with the compression adjustment and a couple others do have adjustments that will allow you to counteract the brake dive, and the new marzocchis will have some sort of compression adjustment as well, but in the end you may find yourself not using the adjustment (just like many people have in the past) because you may find the tradeoff (decreased suspension performance) is not worth it.

It's also not an especially dangerous situation, although it may decrease your travel significantly (the most i've ever seen with a marz is around half from heavy braking), you simply have to weight your body correectly to stop, as you would in any situation. Do not lock the brakes (obviously this doesn't help you stop). Get your weight back, and use the front brake as much as you can without locking it.
 

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It's also possible that the fork is packing down a bit if there tend to be bumps coming into the turn (like braking bumps, etc.). If this is the case, you could try a bit less rebound damping to keep the fork extending quickly enough after each hit.

-Ryan
 

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bikerx40 said:
It's also possible that the fork is packing down a bit if there tend to be bumps coming into the turn (like braking bumps, etc.). If this is the case, you could try a bit less rebound damping to keep the fork extending quickly enough after each hit.

-Ryan
Hi Ryan, are you also familiar with the 2004 Marathon. What is the difference in it's internals compare to 2003 model.

I don't know if you still remember me. Anyway, I got experience a clunking problem with my 04 Marathon due to loose rebound shaft inside the damper. It was unscrewed that cause a clunking sounds if you compressed it.

Fortunately, I notice it immediately and fixed it using the information I got how to change oil on a Z150 and Z1FR.

Aside from the spring preload on the 2003 and an air preload for 2004, what are the other difference between this 2 models.

Thanks a lot.

Manny
 

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Bullit_cn said:
Hi Ryan, are you also familiar with the 2004 Marathon. What is the difference in it's internals compare to 2003 model.

I don't know if you still remember me. Anyway, I got experience a clunking problem with my 04 Marathon due to loose rebound shaft inside the damper. It was unscrewed that cause a clunking sounds if you compressed it.

Fortunately, I notice it immediately and fixed it using the information I got how to change oil on a Z150 and Z1FR.

Aside from the spring preload on the 2003 and an air preload for 2004, what are the other difference between this 2 models.

Thanks a lot.

Manny
Hi Manny,
I don't want to hijack Mtmikebr's thread here, but yes the air assist preload and different rebound / eta levers were the main differences - internals are the same. PM me if you have any other questions.

Thanks,
-Ryan
 

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Discussion Starter · #7 ·
reduce negative...

Louis said:
Try lowering your negative pressure by about 10lbs
Louis,

Ok, will try that. It's 110# now, I'll make it 100# and let the list know what happens!
Thanks!

--Michael
 

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Louis said:
Try lowering your negative pressure by about 10lbs
Got a NOS 2002 Marzocchi Marathon and btw i am very green as regards to suspension forks. Can you pls tell me how to adjust the negative pressure? Thanks.
 

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Check for oil in negative air chamber.

With the negative air chamber fully pressurized, screw the adapter in (covered with a rag to catch any oil). Oil in the negative chamber really makes the fork perform like garbage and it is a common problem with this fork.

Also, try less negative air pressure - maybe 90 psi. Trying increasing the positive pressure too (shoot for ~20% sag regardless of pressure). I weigh 165 and usually ran around 30 psi x 105 psi. The fork is quite sensitive (less initial compression damping than some other forks) and may dive more than what you are used to by design.

Edit: I just realized this was an old post that was revived with a different question.
 

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Negative chamber valve is in the center.

There is one valve for the negative chamber in the center of one fork leg. The outer valves are for the positive chamber. The positives get the same pressure (probably around 26-34 psi depending on your weight) and the negative should have around 3-4 times that depending on your preferences.
 

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mtmikebr said:
All,

I've got a 2002 Marathon, the one with "Doppio Air" and three position lockout.
I've set up the thing as described for a 175 lb rider weight and it feels plush.

The problem is that it dives about 2-3 inches when I apply the front brakes at
any given time. This is esp. a problem when I'm going down hill, the back
brakes are sliding and I need to STOP...

I think this could be a potentially dangerous situation, so any advice would be
appreciated.

Here are the settings/levels to the best of my memory:

oil: left is 35cc, right is 110cc
air: compression left is 35#, right is #35, rebound is 110#

I'd like to keep the plush, lose the dive, any advice?

Thanks in advance
Sorry for this, as it may appear a stupid question, but I am not very familiar with suspension forks, but may pls tell from where i can adjust the rebound / negative on my 2002 Marathon as the middle valve of the left leg seems to be a blank chamber. Thanks, your reply would be appreciated.
 
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