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Discussion Starter #1 (Edited)
If there is an online resourse to this information, please advise. I would like to better understand compatibility between different Ducati forks.

Specifically, overall length and diameter through the triples.

748
749
998
999
ST2

ST3
50mm top tube dia, 54mm bottom triple tube dia
centerline of axle hole to top of fork is 725mm
centerline of axle hole to buttom of upper tube is 240mm
upper tube length is 485mm

ST4
ST4S

Thanks for any information
 

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Ducati23 said:
If there is an online resourse to this information, please advise. I would like to better understand compatibility between different Ducati forks.

Specifically, overall length and diameter through the triples.....
I took off my ST4s forks last night and I will measure them tonight and post my findings.
 

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dharhay said:
I took off my ST4s forks last night and I will measure them tonight and post my findings.
Be sure to post the year of the bike (the pre-2004 length will be different than the 2004/2005 model years).
 

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Ah, work is over!!! Back to reality.
Here are my dimensions for the 2002-2003 ST4s forks:

50mm dia at the top of fork tube, 54mm dia of the fork tube where the bottom triple tube is

Centerline of axle to top of fork tube cap shoulder where said shoulder meets the top of the fork tube, 697mm ( I measured a hard number that wont move with differing preloads, etc)

Centerline of axle hole to bottom of fork tube, 244mm (measuring to the tube not the seal)

Upper tube length, 450mm ( tube proper, no seal or cap)


BTW, Jocie and I crudely measured the fork spring rate and got a range of .77 to .79 kg/mm. Most of what I have seen mentioned for stock rate is around .84 - .86 kg/mm.

I hope that fills in your table of values.



Dave Harhay
 

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Discussion Starter #5
Perfect! This exercise will become a very good asset to the forum knowledge base.

Summary so far:

748
749
998
999
ST2

ST3 - year 2004-2005
50mm top tube dia, 54mm bottom triple tube dia
centerline of axle hole to top of fork is 725mm
centerline of axle hole to buttom of upper tube is 240mm
upper tube length is 485mm

ST4

ST4S - year 2002-2003
50mm top tube dia, 54mm bottom triple tube dia
axle centerline to top of fork is 697mm
axle centerline to bottom of upper tube is 244mm
upper tube length is 450mm

ST4s - 2004-2005


Let's keep adding to this fork database.
 

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Anyone see any issues with replacing stock 04 ST3 forks with a set of 03 ST4s forks? In addition, I'll use the upper triple off of the ST4s as well as clip-ons off of it as well. That should should nullify any length issues... yes?
 

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mcd said:
Anyone see any issues with replacing stock 04 ST3 forks with a set of 03 ST4s forks? In addition, I'll use the upper triple off of the ST4s as well as clip-ons off of it as well. That should should nullify any length issues... yes?
It should nullify the issues...

I'm pretty confident that the dimensions of all forks and clip-ons are identical pre-2004 for all models*. You will likely have a slightly different rider position with the older upper triples/clip-on combo, though.

*This could easily be determined largely by cross-referencing part numbers for the various years. I know for fact that a lot of part numbers carried over through years and models.
 

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Discussion Starter #8
It would be very useful to understand any dimensional length differences between the 748/998 forks and the 749/999 forks if anyone has access to this information.
 

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Ducati23 said:
It would be very useful to understand any dimensional length differences between the 748/998 forks and the 749/999 forks if anyone has access to this information.
Have you cross posted in the superbike forum?
 

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Discussion Starter #10
updated with new info on sbk forks.

Please contribute to this fork database if you have additional information.

748 year 2000-2001
53mm top tube dia, 53mm bottom triple tube dia
centerline of axle hole to top of fork is 717mm
centerline of axle hole to bottom of upper tube is 244mm
upper tube length is 473mm

749
53mm top tube dia, 53mm bottom triple tube dia

998

999
53mm top tube dia, 53mm bottom triple tube dia

ST2

ST3 - year 2004-2005
50mm top tube dia, 54mm bottom triple tube dia
centerline of axle hole to top of fork is 725mm
centerline of axle hole to buttom of upper tube is 240mm
upper tube length is 485mm

ST4

ST4S - year 2002-2003
50mm top tube dia, 54mm bottom triple tube dia
axle centerline to top of fork is 697mm
axle centerline to bottom of upper tube is 244mm
upper tube length is 450mm

ST4s - 2004-2005
 

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ST2:

50mm top tube dia, 54mm bottom triple tube dia
centerline of axle hole to top of fork is 700mm to the top of the cap (not the hex or the adjuster)
centerline of axle hole to buttom of upper tube is 240mm (to the dust wiper lip)
upper tube length is 460mm from top of cap (not the hex or the adjuster to the dust wiper lip)
 

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(Bump) I'm looking for the length of 998 and 999 forks from center of axle to top of fork tube if anyone has one available to measure.
 

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Discussion Starter #13
998 forks are 717mm in length from centerline of axle hole to top of fork tube.

I'm not exactly sure on 999 forks, and keep in mind that the fendor mounting point and method is completely differnet on the 749/999 series.
 

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Advice request on ST3 handlebar compat. with 748/996 top tube

748 year 2000-2001
53mm top tube dia

- snip -

ST3 - year 2004-2005
50mm top tube dia, 54mm bottom triple tube dia
I have an auction bid in for some 748/996 forks and have read the fitting options for these on the STs. My question is will the ST3 handlebar fitting (which I presume is for the 50mm top tube dia.) be a feasible fit to the 53mm top tube of the superbike forks?

http://www.ducati.ms/gallery/files/3/0/4/8/4/d_sir_e_remove_b4_flight_img_2371_dukems.jpg

What have owners done with their fork swap like this?

many thanks,

Dave (Newbie)
 

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What you'll need to do is mate the top cap, upper tube and upper bushing from the ST with the internals and lower slider of the 748. The resulting forks are then a perfect fit. I had mine done by a local suspension guru and he said everything fit together perfectly without any drama. The forks turned out about 1/2" shorter than the stock ST forks so I mounted them almost flush with the top of the triple tree. That results in a slightly lower front end that quickens turn in but still maintains perfect straight line stability.
 

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Thanks

Thanks for your reply.

Your solution is obviously a different approach than the other one in which the top clamp is bored out to 53mm and the lower shimmed by 1mm. It sounds a more elegant option if, as we have, both 748/996 and original ST3 forks are available for use.

I was predicting quicker steering from the slightly shorter fork length of the 748 fork. In any case I have also obtained an adjustable ride height rod through auction, so will need to experiment carefully to avoid making steering too rapid.

Have already obtained great replies from NCRick and Stryder through this Forum.

Thanks,

Dave
 

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ST2, ST4, early ST4s all use dimensionally identical forks. The only difference is the nitride coating on the 4s sliders.

(All also use identically dimensioned swingarm, shock & linkage)

Mark.
 

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Bath...

Thanks Mark,

Say hi to Bath for me - I went to Uni there in the mid-late 70s = a lifetime ago.

I remember Brassknocker Hill very well :))

cheers,

Dave
 
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