DUCATI TT and F1 FORUM
 
It is currently Thu Dec 14, 2017 5:58 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 98 posts ]  Go to page 1, 2, 3, 4, 5 ... 10  Next
Author Message
 Post subject: forcella italia fork rebuild
PostPosted: Mon Dec 26, 2011 6:07 pm 
Offline

Joined: Sat Oct 29, 2011 3:38 pm
Posts: 423
Doing the forks on my 86 f1 what do I need to know as far as oil weight, level/air gap.Are there any tricks to make them work better?
Bike is track/race only.
Thanks Paul


Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Wed Dec 28, 2011 11:08 am 
Offline

Joined: Fri Oct 15, 2010 12:20 pm
Posts: 1214
Location: Vermont, USA
Hi Paul,

Recently finished completely rebuilding two sets of these excellent forks, and have been meaning to write this up. You have given me the push needed to sit down a start typing. Basically, these forks need no tuning tricks, just good springs and set up for your preferences. Back when I first got my F1B, I sent the forks off to Traxxion Dynamics for rebuild, springs and possible Gold Valves. They told me after running them on their dyno, that they worked just fine without Gold Valves and not to waste my money on them. They installed .9 rated springs, based on my weight and riding, and I have found them (and an Ohlins shock) to be just right for me. I have been told that this spring rate is probably a little too stiff for a street bike, but I really like the way the suspension works on the F1. For comparison, the same forks on my track TT we used .85 rated springs, which also work very well. Obviously, they have different sprung and un-sprung weights. On both bikes with these forks, the rebound adjuster on the bottom of the sliders was a source of oil leaks, so special attention was paid to them. Part number references are from a Ducati parts manual for the 750 F1B / Montjuich, page TAV.20.

Dis-assembly is straight forward. I used a long common screwdriver to hold the inside, and a small impact zippy wrench to loosen the lower bolt #46. Remove the (3) #31 screws and old sealing washers, being careful not to loose the ball and spring under the l/h angled screw. Un-screw the two halves of the #28 rebound adjustment barrel. It has normal r/h threads, and will unscrew itself with a quick push on the allen wrenches. The slider and parts is probably all that needs to be washed in hot water and Dawn dish soap. Replacement parts for #’s 29 o-ring (Ducati new # 938232056) and #30 (Ducati # 025070050, now in an aluminum crush washer form) are available from Ducati. #45 o-ring is not still available, but substituted McMaster-Carr # 9262K247, and it works. Lubricated the o-rings with petroleum jelly, threads with anti-seize, and used Permatex thread sealant on the #31 screw threads for no-leak insurance.

I used Motorex racing fork oil in both sets. 15W for the track TT, and 10W for the street F1, both at 135mm down from the top of the tube, spring out and fully compressed.. The length of the pre-load spacer depends on the length of your springs and sag set-up.

The worst thing about these are the fork seals (Ducati # 067037225), which are now un-obtainable. The ones on the TT weren’t leaking, so they stayed in and are still oil tight. I have one pair of o.e.m. seals that are staying in the TT spares box. The ones on the F1 were leaking, so I’m trying an experiment with those. The only seals I could find, that had an o.d. that reasonably fit the #24 screw on holder, are the Leak Proof “Classic” #7234 or Leak Proof “Pro-Moly” #5234 seals. These don’t have the wiper that sticks up thru the holder, so I ground and sanded down the old seals until about .050" was left of the bottom part (see photo). These are sitting on top of the new seals, so when they are assembled they still do some wiping and look original. I finished the F1 rebuild too late in the season for a test ride to see if the Leak Proof seals leak. I did test them as much as I could on my kitchen fork dyno by working each stanchion by hand, w/o springs inside and my foot on the axle thru the bottom. Didn’t leak, so they’re on the bike, waiting for spring. I really hope this works, as pulling fork stanchions off a F1 is not my favorite job.

Hope this helps,
Bill


Attachments:
File comment: F1B Parts Book TAV.20
F1_TAV20_001.jpg
F1_TAV20_001.jpg [ 889.16 KiB | Viewed 2675 times ]
File comment: New stack up.
F1_fork_seals 015.jpg
F1_fork_seals 015.jpg [ 60.71 KiB | Viewed 3375 times ]


Last edited by pantah_good on Mon Mar 26, 2012 6:30 pm, edited 2 times in total.
Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Wed Dec 28, 2011 4:46 pm 
Offline

Joined: Sat Oct 29, 2011 3:38 pm
Posts: 423
Thanks Bill, I will see what I can find in the way of seals.
Paul


Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Thu Dec 29, 2011 10:07 am 
Offline

Joined: Thu Apr 21, 2011 4:29 am
Posts: 275
Images: 1
Bill,
do you know of a source for the nylon guide rings that fit inside the stanchions for these forks?

Clinton


Top
 Profile Personal album  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Thu Dec 29, 2011 4:13 pm 
Offline

Joined: Fri Oct 15, 2010 12:20 pm
Posts: 1214
Location: Vermont, USA
Clinton,
Ducati says the nylon guide ring (Ducati # 067037230) is no longer available. I didn't go any further with those, figuring/hoping they were a slow wearing item.
Bill


Last edited by pantah_good on Wed Jan 04, 2012 3:21 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Fri Dec 30, 2011 12:10 pm 
Offline

Joined: Thu Oct 14, 2010 11:23 am
Posts: 1129
That was a really great write up, Bill. The kind I have printed out for future reference, and save as a doc. Very clever use of the old wiper/seal, especially for those who want to restore an F1. I do wonder if a racer would need that, since some do not use dust wipers on the forks on the track. MikeV


Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Fri Dec 30, 2011 3:25 pm 
Offline

Joined: Fri Oct 15, 2010 12:20 pm
Posts: 1214
Location: Vermont, USA
Thanks Mike. I was worried about water getting trapped inside the screw on seal holders if that wiper part wasn't sticking up thru the gap, either street or race.
Bill


Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Wed Jan 04, 2012 1:52 pm 
Offline

Joined: Sun Aug 21, 2011 10:14 pm
Posts: 59
I see a lot of fork seals on eBay, are they not the correct items? My fork seals are shot from shipment from the US to Australia, they fully emptied all over the discs, rims and tyres. I bought a set on ebay but sounds like they wont be the ones? There are so many advertised, so I am now worried given you mentioned they are unobtainable. IM not worried about what I have purchased, more so that they may not fit and I 100% have to get a set.
I note you mention part numbers, are they Ducati part numbers?

Many Thanks for this very informative write up.


Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Wed Jan 04, 2012 3:48 pm 
Offline

Joined: Fri Oct 15, 2010 12:20 pm
Posts: 1214
Location: Vermont, USA
Hi Ozzy,
I went back and edited my posts to clarify which numbers are Ducati numbers. After the Ducati # 067037225 fork seals became unavailable, I have bought over the years 4 or 5 pairs of aftermarket fork seals that were supposedly for these forks, including the Pyramid ones off eBay. The problems with them all is that the o.d. is too small to properly fit the i.d. of the black screw on holder and they do not have the wiper part that sticks out the top of the black holder. That is why I'm trying the Leak Proof ones, because I think they may fit "good enough". I know Mike Weber is trying fork seals from the Monster model that had 40mm fork tubes, and maybe he could chime in on how he's coming with those.
Bill


Top
 Profile  
 
 Post subject: Re: forcella italia fork rebuild
PostPosted: Wed Jan 04, 2012 4:13 pm 
Offline

Joined: Thu Oct 14, 2010 11:23 am
Posts: 1129
None of the people selling fork seals on eBay have the correct seal for the Forcella Italia 40mm forks (or any other size of that style); the attitude is, "if it doesn't work you can send it back". Even ORSP will send you a generic version by Ariete. They are as scarce as the proverbial "hen's teeth" MikeV


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 98 posts ]  Go to page 1, 2, 3, 4, 5 ... 10  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Template made by DEVPPL