Ducati Monster Forum

Leaking fork seal! UGH..

Anyways, Since the previous owner had the frame powder coated, the actual frame number stamp isn't very clear, and I can't seem to decode the year from the title.

My 900 is carbed, and has a 3 wire stator, which definitely makes it a 98 or 99? It also has adjustable front forks. Are all 900 fork seals the same? Some searching on the ebay for allballs seals shows different listings for 93-98 m900's and 99-00 m900's, but allballs lists the same seal for 93-99.

Is there any difference, all 900 monsters had adjustable front forks, right? Therefore all 900 seals from 93-99 will fit?

You have adjustable Showa forks...43mm I think. Not all Monsters had adjustables. There were a few Monsters that had Marzocchi forks which were 41mm.

All Showa forks should use the same seal.

Is that the inside diameter or the outside? Weren't the Marzocchis for the lesser displacement monsters? I'm assuming that the allballs ones for the carbed 900 will fit then?

Thanks!

Inside...or tube diameter.

Ducati threw whatever they had on the Monsters at times.

https://www.allballsracing.com/index.php/55-119.html (https://www.allballsracing.com/index.php/55-119.html)

So these should fit, being as they mention it fits all m900's 93-00 apparently.

Some cross reference with the AB part number yields this measurement: FORK SEALS PAIR 41x54x11 55-119

Yeah they should.

I just checked my owners manual and the fork is listed as a GD-041 41mm Showa.

Make sure you don't have pits in the chrome or the new ones will leak too.

Good lord I hope not. Is there any remedy for pitted tubes? I'll give them a close look over when I remove the front end.

If the pits are shallow you can clean them up with 1000 grit wet-or-dry paper. The important part is no rough edges.

Make absolutely certain you don't sand through the chrome.

they went to 43mm forks in 98 or 99, so that's the variation in seals.  possibly at the same time they went to the 65mm caliper bolt spacing and the big 25mm hollow axle.

early 900 had 41mm non adj showas, then 96 or so they ran the 40mm adj marzocchi (blue knob on top) then went to non adj 43mm forks, possibly from both showa and marzocchi and adj showa on the s models.  showa have a 17mm hex on top of the non adj forks, marzocchi is usually 30mm or so.

of course this is all for euro spec models, usa models may have varied. 

To the OP...

did you measure your tube diameter?

negative, I would be measuring the chrome tube, right? I spoke with AllBalls and they're sending me the set they have on file for the 98-99 M900.

Edit: The front axle is indeed the 25mm, but the front calipers are teh 40mm goldlines. I dont have a caliper to measure the fork diameter though.

Yes...the chrome tube.

You can pick up a set of calipers cheap on fleabay. I wouldn't do aerospace work with them, but they'd be a great addition to your tool box.

I just took a tape measure and did some math and end up with 40.7mm for the diameter. I will give it a second and third measure to make sure.

Took measurements at top, middle, and bottom of exposed tube, and ended up with a 41.06 on both fork legs.

The part of axle inside wheel is 25, really?

sorry, I just measured the part on the right fork leg. A quick ebay search for the fron axle shows that it hasthe actual part that is inside the wheel is smaller than the otherside? Never took the front wheel off before, but it seems to be kind of like that one engine mount bolt that threads into the frame? One part has the hex end and the other end threads into the left fork leg?

You probably have a 20mm front axle.

There is an insert in the left fork leg. The threaded part of the axle is approximately the same dia. as the actual axle and is the number referenced when measuring axles.

So the part in the right fork leg is infact, larger?

Thanks for the help again guys! Never underestimate the DMF!

Yes, it is.