Fork oil change

[Ian]

Folks, I’m part way through a fork oil change on my 2004 V11 sport. It’s the marzocchi large diameter fork.

 

The manual say to refil with 435ml of 10wt oil but what I really want to know is what the air gap should be. I think this is a better way of getting the correct oil level because you can never be 100% certain of getting 100% of the old oil out unless you do a full strip down, which I’m not doing in this case.

 

Does anyone know what the air gap should be for this fork?

 

BTW I’ve gone through all the old threads I can find on this topic but not been able to find the answer so far

 

Any assistance would be greatly appreciated as I want to get the forks back on the bike tonight

[nobleswood]

Chuck found it;

 

http://www.v11lemans.com/forums/index.php?showtopic=7960&hl=%20ohlins%20%20fork%20%20rebuild

[Ian]

Thanks mate, but the post is for the early marzocchi fork not the larger diameter one that I have. The internals are different. I suspect 100mm air gap is in the right ball park, but I want to try and find the exact measurement for my fork.

[Ian]

No joy with researching the figure for the air gap so I’m going to try 105mm which is the figure for the ohlins fork and see how it feels

[nobleswood]

Bugger ! Sorry I missed that when I looked it over.

 

I'd forgotten how much 'Guest rachethack' used to wind people up.

 

Post how you get on, I'm always interested to learn from others as I don't seem to have as much time as I'd like try different settings.

[Ian]

Just back from the garage on a tea break. Not refilled the forks yet. Wanted to grease and adjust the steering head bearings before putting the forks back in. What a complete PITA that was. My bike has the headlight and clocks mounted on the triple clamps and it all has to come off before you can take the top clamp off and get to the upper and lower bearings. Not difficult, just really time consuming for a straightforward maintenance job.

Good news is that the bearings were in perfect condition even though they hadn’t seen daylight since 2004 and the guy who assembled them only wiped them with an oily rag rather than pack them with grease.

Looks like my new to me bike has had a really easy life in a very dry climate. Everything I’ve inspected has been in A1 condition and it’s obvious the bike has never been apart before.

Time for a cookie now before tackling the forks

[Chuck]

Some days, "you" get the bear.. 

[Ian]

Well that didnt work! Setting the air gap at 105mm took 475ml of oil which is 40ml more than the book says is needed for this fork, therefore my conclusion is that the standard air gap must be more than 105mm.

 

I only attempted this on one fork tonight so tomorrow I’m going to fill the other leg with exactly 435ml per the book then I’ll measure the air gap and take oil out of the other leg until it gets to the same measurement.

 

All good fun and pretty easy to do. I don’t understand why most folks skip doing the forks (and changing the brake/clutch fluid) at servicing time because it’s no more difficult than changing the engine oil.

 

Wait for tomorrow night for the next instalment

[Chuck]

 

 

 I don’t understand why most folks skip doing the forks (and changing the brake/clutch fluid) at servicing time because it’s no more difficult than changing the engine oil.

 

I've only worked on two forks on the Spineys, the WP on the Centauro and Olhins on the Mighty Scura. Both required removal from the bike and  disassembly to service. About a 2 hour job. The WP in particular took patience to get all the oil out then to get the air out when refilling.. certainly more work than changing engine oil. 

[GuzziMoto]

Not to sound stupid, but I would recommend measuring the fork oil level before you drain the forks first, even if you only want to know where you started.

I would also measure how much oil comes out in addition to the air gap / oil level.

Usually the air gap / oil level is not really affected by the diameter of the forks too much. Forks that are larger in diameter might hold more oil, but the distance from the top of the oil level to the top of the forks is usually fairly consistent.

It is also something you can tune by feel. If you start on the high side, you will probably find the forks are too harsh. From there, keep reducing the oil in the forks until you get the forks to feel good.

[LowRyter]

why not take the contents of oil drained from the forks and measure that?   That would be good yardstick on how much to refill?

[Gio]

Further to GuzziMotos suggestion - I checked my notes at last fork oil change - I have the smaller(?) Marzocchi fork - spec vol for which is 400ml / leg. After first overnight drain I recorded approx. 380ml from each leg and since I had to wait for other parts at the time, a further 10 ml from L (comp) and 30ml from R (rebound) over the next couple of days for totals of 390 and 410ml respectively ... close enough to spec volumes - with which I refilled. Didn't measure air gaps but forks work to my satisfaction. Hope this helps?

[Chuck]

why not take the contents of oil drained from the forks and measure that?   That would be good yardstick on how much to refill?

When you do that, you are assuming the last guy in there knew what he was doing. You are also assuming there has never been a fork seal leaking. That's more assuming than I am comfortable with.   

[LowRyter]

let me ask, does more fluid make it stiffer?   Wait, more sex talk. 

 

nevermind.

[Chuck]

Uhh, if there is too much fluid, it can get stiff enough to lock up.