Oil change, Zan? 750 Formula front forks

Ventodue

Ventodue

Hero member
Location
France
Hi Zanistis,

(With, as always, apologies if you've already seen this on Yahoo!)

Time to change the fork oil in my 750 Formula. And, given that neither the Laverda workshop manual nor the Paioli manual covers the Formula's forks accurately, a couple of questions, please:

1. Is it really necessary to remove the top nut, pre-load adjuster and fork spring simply to change the oil? Or does the oil (or near enuf of it) come out by just inverting the fork leg?

2. If it is necessary to remove all that stuff, how do I get to the attachment nut? I.e. how do I get enuf downwards force on the spring so that the pre-load spacer - the long white tube in the photo - will clear the nut so that I can get a spanner on it?

DSCF5022.jpg


3. When it comes to re-filling, is 150mm down from the top correct?

TIA

Craig
 
Craig,

These things are a pita!

It's a good idea to dismantle the fork legs completely, you'll be surprised at the amount of crap that you will find in there.  It will not be removed by inverting the fork leg, you need to rinse the parts copiously.

You will require brute force and stamina to further depress the pre-load spacer and remove the top nut.  Very difficult to do by yourself, really need another pair of hands!  IIrc, you will need a 14 and 17mm spanner.  It all falls to bits once that's off....  Dont lose the tiny ends of the adjuster pushrods in the damper rod!

150mm is correct, no spring and fork leg fully compressed.

Cheers.
piet

 
Cheers, Piet - thanks.  I had a horrible feeling that was gonna to be the answer.

It's less the getting the thing apart, more the re-assembly that I fear.  Trying to thread the nut back on while someone else is straining to depress the spring does not sound amusing.  I need to give this some further thought ...

Rats!  Paioli must have had a special tool for this ...

Ciao

Craig
 
Hi Craig,
  The pre load spacer (white plastic distance piece above spring) ,hasn't that got to holes opposite each other?
The Honda forks I've got have these two holes.A tool bigger version then something looking like a 'die holder' fits over the top of the forks,and the handles skrew in wards ,the ends of which engage into the holes.Thus allowing you to push down the pre load spacer,and then allowing a flat plate to be placed uder the bottom face of the locking nut,but above the pre load.I still reckon you're need a second pair of hands to place the flate plate,while compressing spring.

Hopefully helps with thought process!
Andy
 
Ah, a nice thought, Andy  ;).  But regretably Paioli were not so kind to the innocent owner ...  :(

But I've made progress, nevertheless  :).  A bit of imaginative use of some basic tools and I have a spring compressor ...

Forks1.jpg


And here's what we find:

Forks6.jpg


Which is as far as I can go without (yet another) Paioli special tool to get the cartridge out.  Which tool comes/came as part of the seals overhaul kit.  And replacing the seals is something I don't intend doing, despite Paioli's recommendation that the seals are renewed every 10,000km (WTF!).

Still can't believe I'm having to do all this just to change the wretched fork oil ...  :o

Ciao

Craig
 
Craig,

IIrc, you needn't remove the damper for seal replacement.

Carefully remove the dust lip and the wire circlip locating the oil seal.  With the fork leg lower in a vise, tug the slider upwards firmly and the seal will be pulled from the slider.  This will also remove the slider bushes if they are not too worn.  If they are, they will slip over one another.  Once they are worn thus, it's not much use replacing the seals only, the play between the stanchion and slider will allow oil to escape almost immediately the fork is in use again.  This is a fault inherant to USD forks, conventional forks are far more forgiving.

Oil seals have the nasty habit of failing within 2 weeks of replacing the oil..... :D

Good luck,
piet
 
Thanks Piet - noted.

I have a query about the amount of oil, tho' ...

The little Formula-specific supplement from Laverda clearly says 300cc.
Formulaoil.jpg


And that's pretty much what came out, too.

However, when I put this much in, the level is waaaay down.  About 210mm from the top of the leg.  Now the Paioli book for the S model specifies 340cc (for the 1997 model), and notes that this amount should bring the level up to 150mm from the top of the leg.

Which just makes me wonder: which is actually right, 300cc or 340cc?

Any idea?

Ta.

Craig

* And Paioli and Laverda don't even agree on that: the Laverda workshop manual says 320cc and 170mm; the Paioli book, 340cc and 150mm.  Grrrr....

Differentamounts.jpg
 
Craig,

At OCT they are always filled to 150mm, irrespective of build year.  Actually the same forks, guess the higher oil volume is just an update measure.

Only thing you can really be sure of is that they will soon be leaking again..... :D

Cheers,
piet
 
Great stuff, Piet - thanks.  (You do realise you're in danger of becoming the Zan? specialist here?  :P  :P) 

Right, 150mm it is, then.  I think that 300cc bit from the Formula supplement is tosh, btw.  'cos, guess what?  It's also what the standard S model handbook says, too ...  Tsk!

I'll e-mail Roger about a seal kit.

Once again - grazie mille.  Be good to get this bike off the bench and on the road.  Track day season approaching ...  :D

Ciao

Craig
 
Repeat after me....
                     
                            OMMMMMMMMMMM, OMMMMMMMMMMMMM......... 8)

piet
 
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