Mk2 180 Front Fork Fluid Specs

Steve G.

Steve G.

Hero member
Just wanting to confirm fluid specs on Marzochi front forks. Info I have shows 240cc each, and shows 15w oil. Im
Actually thinking of using a thicker oil, much thicker, like 30w fork oil. Any thought on these figures?
 
I must have tried every computation of fork setting under the sun in that huge suspension thread, over 10,000 posts thankfully not all mine and I found a few basic things. As long as the oil level covers the damping bits, being exposed to just air is really bad and doesn't get high enough to hydro lock the fork it doesn't have a hugely obvious effect. You hear bottoming resistance but I didn't notice much of that You need to be careful to have the fork be balanced to the rear shocks, which means standing next to the bike with one foot on a peg and both ends moving similarly with downward pressure. I am pretty heavy so I ended up using 15wt, I tried 20 and that slowed the fork too much. One of the things I was trying to remove was the fork bobbing slightly up and down like an out-of-round wheel would produce. I have race tech emulators fitted and it took ages to find what I liked. My breakthrough was ending up with 4 holes in its plate, late model kits came like that, mine had 2 x 7/64th holes instead of 4. What don't you like, my goal was to use 95% of available travel on both ends and a nice plush controlled ride on rough backroads we use in a typically sporting Laverda way of riding. Using the correct spring rate is so important also the correct preload. If that's wrong you can chase your tail till the cows come home, damping changes won't fix the wrong spring rate, guess how I learned that.
 
30wt sounds like a recipe for a very rigid front end. The secret to good suspension is suppleness and control - look at modern bike setup: low stiction, full use of available travel etc. In the 70s it was all about heavy springs and heavy damping.
 
I’ve just been looking at my service records, and I used 10w in there now. Yeah, 30w I agree is way too heavy. I’d like to try 15w. I’m a big guy as well, 250+ right now. Is 240-250cc correct for a non rebuilt fork?
 
Damping is only damping, trying to keep it going up and down just once for every bump. If you want to compensate for extra weight you’re talking heavier springs, or cutting a coil or two off the ones you have.
Then there’s sag of course, but that’s where your spacers come in.
I understand the he main thing about fluid quantity is making sure you’ve got enough to cover the damping holes, plus a bit for safety. I find it easier to measure the air gap than measure quantity. I use a bit of metal tube and blow bubbles down the fork. A decent air gap is important so it doesn’t over pressurise. I’d say measure your current air gap and use that.
 
Steve G. said:
Just wanting to confirm fluid specs on Marzochi front forks. Info I have shows 240cc each, and shows 15w oil. Im
Actually thinking of using a thicker oil, much thicker, like 30w fork oil. Any thought on these figures?
Click to expand...
I hope that you have a good dentist.
You're going to need one to replace fillings with 30W.
Paul
 
Steve G. said:
I’ve just been looking at my service records, and I used 10w in there now. Yeah, 30w I agree is way too heavy. I’d like to try 15w. I’m a big guy as well, 250+ right now. Is 240-250cc correct for a non rebuilt fork?
Click to expand...
Same bike and similar weight.

I put some progressive springs in mine with about 40mm of preload and the recommended 10wt 240mm of fork oil.
The front feels really good staying in contact with the road not skipping between bumps.
YSS shocks on the back which compliment the front.

There are other more experienced blokes here but this setup works for me.

Cheers.
 
Basically I was looking for the ml amount of fluid, and viscosity thickness, as I can’t seem to find these two specs in my manual.
 
Steve G. said:
Basically I was looking for the ml amount of fluid, and viscosity thickness, as I can’t seem to find these two specs in my manual.
Click to expand...
I understand what you are looking for but thought you want to change something to improve the front. If so, it would be interesting to understand what you are trying to improve to help on that matter.
 
I only asked about spring rate because going with 30 weight oil seems extreme for our standard damper rod forks.

It's been mentioned, correctly, that not all "10wt" oils are the same. I always try to determine a fork oil's viscosity rating in centistokes (cSt). Not all oil manufacturers report this measurement. LiquiMoly does - so I have started using their fork oil.
 
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