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Air preload

gmac

Monkey
Apr 6, 2002
471
0
Is it a mistake to try to run a Marzocchi fork which is designed to use air preload at 0psi ?

I dumped my air preload (4psi). I did this because I didn;t care for the forks feeling w/ air in it. And after dumping the air I was so pumped w/ the way the fork felt. Ultra ultra smooth, quick... But I didn't care for the metal clunk on big drops. Ouch !

So, I added 5ml oil to each leg. The fork hasn't bottomed yet. But it definetly stiffened the fork ride. I plan to let 2ml from each leg before my next ride and see if I can feel it. Seems crazy 5ml in each leg would make such a big difference.

So, my question is regarding air preload. Is this a going to work (messing w/ oil heights) Or should I accept the fork was built to use air preload.

PS: w/o air it appears I'm at proper sag.

PS2: Why can't all Marzocchis feel like my 03 Shiver SC ? Super smooth never bottomed on anything. And I never even opened the thing. It just worked. (I've owned six 97-04 Bombers this was the best damped fork)
 
Apr 9, 2004
516
8
Mount Carmel,PA
The air is just that, pre load. if you do not need any you do not have to add any. I actually compress the fork and take air out. it gives a smoother small bump ride. you are correct in changing the oil levels to adjust your ride. you are on the right track. it is all about spring weight, oil weight, and oil height. the air is to adjust the sag and fine tune things.
 

Bati

Monkey
May 8, 2003
354
0
Santiago - Chile
Not just preload....

If the system is pressurized you lessen the appearance of foaming and cavitation. You enhace the dampening consistency.

PS1: That's the only reason (cavitation) why shocks are pressurized. Shaft (then oil) speed is too much for atmospheric pressure.

PS2: Add a schrader valve to the right leg on a Psylo and add about 10psi. Goodbye spiking and have a not-so-soft stock spring.

PS3: Shake a bottle of Coke when its unopened and see how low is the foam.... let it rest then open the bottle (despressurize it) and shake it again, Voilá!!.
 
Apr 9, 2004
516
8
Mount Carmel,PA
Good point, but the valves on the fork are for air preload period. as soon as you sit on the bike and you settle into the sag you are pressurizing the fork( in a sense). Modern day suspension oils do not foam., at least the good ones don't. you have stated all valid theorys, but I thinks you are putting way too much into it. forks and shocks, although performing similar functions are not the same. the miniscule air bubbles you may find in highly agitated fork fluid causes no real concern in the way a fork, especially a marzocchi dampens, but it would really kill the ride of a shock, whos shims and valving orifices are much smaller and the oil moves much quicker due to the short stroke of a rear shock.
 

Bati

Monkey
May 8, 2003
354
0
Santiago - Chile
teamkranzelbike said:
Good point, but the valves on the fork are for air preload period. as soon as you sit on the bike and you settle into the sag you are pressurizing the fork( in a sense).
Of course, but sometimes is not enough pressure to avoid spiking.

teamkranzelbike said:
forks and shocks, although performing similar functions are not the same. the miniscule air bubbles you may find in highly agitated fork fluid causes no real concern in the way a fork, especially a marzocchi dampens, but it would really kill the ride of a shock, whos shims and valving orifices are much smaller and the oil moves much quicker due to the short stroke of a rear shock.
I'm not talkin about foam inside the shock, I'm talking about cavitation (steam pressure), which is the SAME reason for spiking in forks. It's true than in a marzocchi cartrige foam isn't important, but it can be noticiable in others like RS and can get an inconsistent damping mainly with high viscosity oils.
 

gmac

Monkey
Apr 6, 2002
471
0
Well I added 5ml to each leg

Then I drained the air (while slightly compressing the fork)

Still I bottomed on a 3-4' to flat landing.

What the F ? I'm going to add 5ml more oil I guess.
 
Apr 9, 2004
516
8
Mount Carmel,PA
If you are running a negitive air pressure you will need to add extra oil .You must get yourself a good understanding of basic hydraulics. Basicly all a fork is, is a hydraulic cylinder. In fact Marzocchi has been making hydraulic pumps much longer then they have suspension forks. the oil compresses less under pressure than air. the more air volume the softer the fork , the faster it goers through it's travel. by adding more oil you take out air cushion. by in essence making the air chamber a negitive it is even softer. oil weights have little to do with the compression factor. that is for the dampeing qualitys. I am sorry to say .but dont you have a friend who is savy on suspension? it is much easier once you have an understanding or a good teacher.
 

gmac

Monkey
Apr 6, 2002
471
0
Well that is an interesting reply. Honestly it is kind of frustrating. But, that is how you learn.

Still, I love the fork. It feels great right until I bottom. I guess up untill now I've been spoiled w/ forks that just worked well out of the box. I just set rebound and went riding.

Here is what I'm going to do.

1)I'm going to dump the whole fork and fill the thing w/ factory weight oil to the manufacturers specs(175ml) + 5ml in each leg.
2) I will then dump the air by opening the schrader w/ the fork uncompressed.
3) I'll post w/ results.

PS: What is the overall feeling on airpreload ? Doesn't seem to work any better than the old system. Plus, you need to buy a pump ?
 
Apr 9, 2004
516
8
Mount Carmel,PA
I personally, prefer the old method . I really do not think precise adjustment can be felt by the average rider.I have found most people using excessive air as a fix for too soft of a spring. they end up blowing out seals and then blaming in on the fork. I have never been able to ride a fork straight from the box. I am too big of a guy and always require a spring change .and most of the time an oil change as well. I learned years ago as a Motorcycle Mechanic, when suspension first became a factor back in the mid 70's. It really isnt that difficult. a Marzocchi is the easiest to figure out. I think a manitou is the toughest. always remember, your fork should bottom every now and again or you are not using up all the intended travel. But it shouldnt bottom excessivley or make a lot of noise when it does.
 

maxyedor

<b>TOOL PRO</b>
Oct 20, 2005
3,653
863
In the bathroom, fighting a battle
you all forgot the other question, why does nothing compare to a shiver, well the monster is believe it or not more plush, and the 888 is about the same, because of the motorcycle cartiges in them they tend to have a better ride quality, but you gotta throw down the cash to get it hence the price difference between a 888 and the new travis triple form manitou, or any of the boxxers except the wc
 

RhinofromWA

Brevity R Us
Aug 16, 2001
4,625
0
Lynnwood, WA
Speakign of air assist/preload on Marz forks. Anyone know the max level of air to put in the fork? I just picked up a 05 DJ3 and have been commuting on it. Never checked the air....other than a breef moment when I pressed the vavle open with my finger to see if it had air. :D You would think I was 4yo or something. I figure I will check the preasure this weekend and play around with the settings. I did not get a manual so anyone off the top of their head know the range suggested for thier air preload/assist perasure?

Once again 2005 DJIII 100mm....I beleive it was OEM overstock.