Ducati Monster Forum

Anyone have a how to on fork oil and spring changes?

thanks to mangeldbug

http://www.squidbusters.com/sb/showthread.php?t=7816

Thanks man,  [thumbsup]

yeah, once you do it, it's pretty easy.  jsut getting thru it the first time is tricky..

It looks like it.  The how to doesn't show how to get the fork off, but I'll figure it out.  I'm thinking front wheel off, loosen the triples and they should slide out?  I'm looking at new springs at the same time so it's good to know how easy the springs are to change.

yes, BUT

you have to have a good way to re-position the fork in the triple.  here is how i do it:

1.  remove wheel.
2.  remove calipers and use some bungees to hang them from the frame, not by the hose.
3.  remove ONE fork.  don't touch the other one or loosen screws.  do your oil change.
4.  Now use a micrometer and measure where the remaining fork is in the triple.  Reposition the removed fork back into the triple at the exact height above the triple.  Tighten the upper and lower screws enough to hold it (don't need to torque it yet)
5.  R&R the other one.  Rinse, repeat.
6.  Torque the screws properly.

The big issue is having a good way to know how high up the fork is.  I just leave one in and use a digital micrometer and measure off the remaining one.

Some people measure things before hand then do the swapout, but i have too much going on in my head and too many quaaludes in my system to remember that shit.

This is getting bookmarked with my spring rate thread.  Thanks for the info ducatizzz.  BTW your clown avatar freaked out my wife lol

I agree that you need to be careful when repositioning the forks in the triple but tend to favor the more accurate, perhaps anal, method below over the one described above.

The reason I disagree is because fork tubes are hardly ever the same length so measuring from the top of the triple to the top of the fork cap can yeild entirerly different positions for the forks at the axle clamps.

I recomend measuring from a fixed point on the lower triple down to another fixed point at the bottom of the axle clamp. Then use the same fixed points and match the measurement on the other side when repositioning the forks.  Once both are done and where you think they should be slide the axle through both forks and check to see that it spins freely by hand.

Hope this helps!

Gage

Just as addition to what was said above, after I reassemble forks, I usually cycle the suspension a number of times by bounching the bars, then lift the front again, and just loosen all the pinch bolts slightly so that any stresses will sort of work their way out, then tighten it up again, and ride away.

Justin

Thanks for the help.  I probably won't be doing this for a couple weeks yet but I'll let you know how it goes.

SgtH, Are you going to the next Italian Night? Come talk to me there about your forks if you want. I can give you pointers and a copy of the Ducati manual for this job. I would also recommend making sure that your new springs have some preload on them. They need some preload to get into the working range properly. It's easy to do by adjusting the spacer at the bottom.
Just come to the next gathering, and I'll explain this stuff to you.  [thumbsup]

[laugh]

I'm planning on being there.  I start a new job that day so it might be a little sketchy but I shouldn't have a problem making it.  Thanks for the help  [beer]  (I love these new smileys)

pm me if you need to

 [beer]

I like 'em too

that works too, i should have mentioned that i do it before and after. before to make sure they match...

works for me.

lol, hey I was just about to post that up over here!  Thanks for linking me :)

thanks for the excellent howto   [beer]

+1

I've found that a pen and paper, and digicam/voice recorder when it gets really complicated, really help. [cheeky]

]


I had a hell of a time with this when I did my adjustable ones.  I don't know if that makes a difference, but I found the $120 RaceTech spring compressor to be worth it's weight in gold.
Then again, I guess a "second person" to help me, it might have been different.  :-\

Speaking of RaceTech, GoldValves might be just what you're looking for, manglebug.  Nice "mid-price" solution, easy to DIY, and well worth it.

I have a few questions on this procedure:

1. What weight oil should I use? I have a '99 M750. I weigh 250+. Needless to say, my front suspension is soft! I was hoping to get thicker oil in there to stiffen up the forks.

2. How much oil do I need to put in each tube?

3. Should I replace the fork springs while I'm in there? If so, what type/weight should I get, and where?

4. Should I replace the fork seals? My bike has 20k miles but there are no leaks. The bike is always garaged.

Thanks in advance!

You will need springs, oil will not be enough.  I would change the seals.You need a rear spring also.  Do you have Marzochis or Showas?   The Showas will say Showa on the inside of the stanchion (fork bottom).

They are Marzochis.

What weight oil and fork springs do you think I should get, or is there a chart or something I can look at that will guide me?

In regards to the rear shock, I have been on the lookout for an Ohlins du440 for some time. Used ones don't come up for sale too often and new ones are a little pricey.

Ducvet is really good at this, better than charts.  You might want to PM him.  I would put a rear spring on the old shock anyway.  The spring will be of use when you buy the Ohlins unless the previous owner had it sprung for a 250+ rider.

Good advice from all so far.. but ..
When you are setting your forks in the trees, consider what you are trying to achieve.
What you want is that the axle is positioned correctly. To do this you need to use the measurement technique as a guide.
What I do is this:
I first set one of the legs to the distance as proscribed in the manual. In my case (S4) 195.5mm from the fork top to the top of the lower tree.
Then I present the next fork and use the axle as my guide. When the axle slides through both forks without binding (as it will if its not perfectly aligned) then I'm done.

This technique is what LT Snyder uses. Get his book, it's well worth the money.  http://www.desmotimes.com/ (http://www.desmotimes.com/)

I put a piece of tape around each fork right under the lower triple then use the the pieces of tape to let me know how high each fork should be.  If you want to put your forks back to the same position they were before the disassembly then this method should be viable.


How do you know you are loosening the bolts enough to get rid of the stresses?  What if you loosen them too much?  I don't know about that.