fork rebuilding

Ducati Forum

Help Support Ducati Forum:

Poseursan I'm sorry everything is too technically hard for you. I suggest you contemplate how you would figure the oil height by calculating the amount of air spring contribution you want. Ain't that hard bud.
 
My Ohlins fork model is FG9250. I'll try to find the Kyle racing number and give them a call--
 
Last edited:
BTW SFV4 I was actually telling you how I changed the bushings such that if you wanted to change the head angle on your own bike (I'm assuming you have a SF) that you could do it without taking the front frame off the bike. It was driving me crazy that the bike wouldn't turn in like it should so I'm thrilled there's a ready (and cheap) solution and I was attempting to be helpful to you. I seem to remember also that you kept telling me that I was wrong about the head bushings until overwhelming evidence shut you up.
 
greggiacona said:
My Ohlins fork model is FG9250. I'll try to find thew Kyle racing number and give them a call--
Click to expand...

Dan would always electronically forward the documentation I needed so maybe I never recognized there's not enough documentation on line. The non OEM documentation is readily available so this is a Ducati OEM thing. Be careful when you reinsert the lower into the seal. Ohlins runs light seal loading to lower stiction which is part of the reason they leak so readily. Pump the cartridge to fill it. Use the ohlins recommended fluid. I always measure oil height with regular dial calipers. I can't overstate to keep the tubes clean (and no poorly landed wheelies) and you should be able to get 20-25K street miles on the seals. 6K miles what a PITA.
 
airjawed said:
Same forks ( FG9250 )as my 1199s tricolore. Email from one of the guys at kyle racing (Mike Wheeler) as follows:

Oil level is 220mm with no preload tube or spring
Click to expand...

I would just confirm this with your other fork leg (not bc I don’t believe the value, but more for reassurance that everything is matching up right).

And just to be clear, you don’t just put in 220 mm of oil and call it a day. You put in the oil, cycle it to bleed the cartridge, and then re-measure and top up to the correct height.
 
Thanks guys--yes, I have the Motion Pro Fork Oil Level Tool--I'll be removing excess fluid after I settle all the fluid and continue to measure. I'll measure the right fork as soon as I get that fork off--(fork off!!???). LOL!
 
baggerman said:
Poseursan I'm sorry everything is too technically hard for you. I suggest you contemplate how you would figure the oil height by calculating the amount of air spring contribution you want. Ain't that hard bud.
Click to expand...
I’m not the one have difficulty with it. Again showing a lack of comprehension.
baggerman said:
BTW SFV4 I was actually telling you how I changed the bushings such that if you wanted to change the head angle on your own bike (I'm assuming you have a SF) that you could do it without taking the front frame off the bike. It was driving me crazy that the bike wouldn't turn in like it should so I'm thrilled there's a ready (and cheap) solution and I was attempting to be helpful to you. I seem to remember also that you kept telling me that I was wrong about the head bushings until overwhelming evidence shut you up.
Click to expand...
I never told you that you were wrong about steering head bushings…I have no idea where you got that from. Please link the post in your pending reply.

You are the last person on this form I’d ever take advice from. Time and time again you are just flat out wrong or just making stuff up.
 
Guys- let’s not let this get personal. You are both helping me and i appreciate you both!

I’m about to button up the left fork. I’ve got the new seal/cap in, lower fork into upper, fully closed on the vise and fluid in. 220mm gap. That took about 400ml fluid by the way, for the record. Had to suck out a little bit-

I’m waiting to drop in the spacer/spring- I’ve ordered a couple M12 x 1.00 bolts from Amazon, to facilitate holding the rod if needed while I screw down the upper spring nut. I may not need those to tighten down--the upper cap should assist me. And yes I’ve learned to NOT screw that bolt all the way down to the upper spring perch. The nut needs to rest UP against the cap.

I could probably raise the rod -drop the spacer/spring and catch the rod before it drops! It moves nice and slow now with new fluid in. Another method would be to attach a little safety wire to the rod so I could retrieve it in case I drops too far below the spring-??

Nuts arrive today from Amazon. Home Depot/Lowes does not carry the fine-thread M12 x 1.00 nut! The right side fork should go ALOT easier now that I know what I’m doing—sort of!
Greg
 
greggiacona said:
It moves nice and slow now with new fluid in.
Click to expand...

If you’re not using the Ohlins oil, this isn’t necessarily a good thing. From what I’ve seen is that damping rod should move pretty fast since the valves are fully open.

I wouldn’t button up this fork until you’ve confirmed with the non leaking leg the air gap. It’ll save you from having to redo things.
 
I hear ya, but it's not THAT slow---it drops from top to bottom in about 7 or 8 seconds. It's super cold in my garage so that will slow things down. I'll have to be quick--that's why I'll probably tie a bit of safety wire around the top of the rod.

I've checked for leaks, all good--believe me--that's my main concern. I'm using a good fork grease on the seal, Slickoleum Light Grease, designed for fork seals, o-rings, bearings, etc. This job is simple once the spring can be removed. That's the tricky part.

I can probably get the right side done in under an hour as long as I can get that top nut off without a hassle.

Greg
 
Last edited:
SuperDomestique said:
If you’re not using the Ohlins oil, this isn’t necessarily a good thing. From what I’ve seen is that damping rod should move pretty fast since the valves are fully open.

I wouldn’t button up this fork until you’ve confirmed with the non leaking leg the air gap. It’ll save you from having to redo things.
Click to expand...
Dan Kyle one time on the phone explained to me the nuances of the shim stack order and the surface prep and orientation of the shims themselves and their interaction with the fluid with respect to both flow and surface tension effects. Use the ohlins fluid. There's a reason these guys are the best in the world. The oil characteristics are part of their design.
 
I've already added the Liquid Moly fluid. If it causes problems, I'll drain it and replace with Ohlins oil. At this time, I'm not that worried about it. I'm a heavy rider at 250lbs with gear so I want a heavier oil.

Greg
 
So look at it this way. On the compression stroke the speed is initially controlled by springs and modulated by the damping. Increasing the viscosity of fork fluid will only make the fork harsher relative to small bumps and such. The springs are already putting the compression damping in the right range. So no gain and the fork becomes less compliant. On the rebound side if your were to put in way heavier springs then maybe you'd need some changes to the rebound side. Have you had a problem with the fork pogoing or something where it feels it needs more rebound? What do you have for springs,11's? The rebound damping should be in range. You have to ignore the oil weight rating and look at centipoise at 40 to compare the fork oils. Ohlins is using a 19 centipoise fluid in that fork as delivered. Anyway you can use Ohlins fluid the next time you change seals and see if you can detect the difference. Good luck.
 
greggiacona said:
Guys- let’s not let this get personal. You are both helping me and i appreciate you both!

I’m about to button up the left fork. I’ve got the new seal/cap in, lower fork into upper, fully closed on the vise and fluid in. 220mm gap. That took about 400ml fluid by the way, for the record. Had to suck out a little bit-

I’m waiting to drop in the spacer/spring- I’ve ordered a couple M12 x 1.00 bolts from Amazon, to facilitate holding the rod if needed while I screw down the upper spring nut. I may not need those to tighten down--the upper cap should assist me. And yes I’ve learned to NOT screw that bolt all the way down to the upper spring perch. The nut needs to rest UP against the cap.

I could probably raise the rod -drop the spacer/spring and catch the rod before it drops! It moves nice and slow now with new fluid in. Another method would be to attach a little safety wire to the rod so I could retrieve it in case I drops too far below the spring-??

Nuts arrive today from Amazon. Home Depot/Lowes does not carry the fine-thread M12 x 1.00 nut! The right side fork should go ALOT easier now that I know what I’m doing—sort of!
Greg
Click to expand...
Sounds similar to my observations when changing my fork springs. I took 350 ml but probably put 400 back and my air gap was set at 220 as well. I used a non-Ohlins 5wt oil but after reading this thread, I’m going to put the Ohlins stuff in it and change my fork seals while I’m there. The Ohlins stuff is SAE 7.5wt, but they call it “No.5” on the bottle. I’ll probably set the air gap at OEM, since I went with heavier springs and in retrospect I likely don’t have to worry about bottoming the forks. I don’t think any of this is super critical though. Run the oil you want, if you don’t like it change it. Run the air gap you want, if you don’t like it change it.

I recall having to pull up the damper rod with a pair of needle nose pliers.

It sounds like you’re on track for a successful project though. Once you get it back together set the suspension to manual mode and go between max and min on compression and rebound to verify everything is moving and adjusting like it should.
 
Recognize that as you decrease the airgap the end pressure in the fork is higher so you're even more likely to blow a seal out landing a wheelie poorly. The air gap spring contribution is only meaningful near end of stroke. Messing with it is pretty subtle relative to what you feel. But you can use it to run a slightly lighter spring and it will help to stop bottoming out the fork as SFV4 comments. Put in the right springs for your weight and set the height to whatever they suggest. The high speed valving is a collection of decreasing OD bevel washers (sorta of little thin cone shaped guys with different surface prep on either side) and springs (for return) essentially controlling a piston which moves to bleed off pressure. Since the piston moves based on the rate of pressure rise in the cartridge changing the fluid will not change the relative piston motion versus pressure but a viscosity increase will cause the fluid to bleed off more slowly so the average pressure in the cartridge rises. Makes the fork harsher. Lots of subtle engineering has gone into these.
 

Similar threads

F
2018 Panigale V4S bits of gold in oil, some questions on next steps
Replies
19
Views
457
shade
shade
T
2013 Panigale 1199
Replies
0
Views
61
Theking225
T
R
Ohlins electronic connector
2
Replies
22
Views
578
BP PanigaleV4S
BP PanigaleV4S
D
Crankshaft Bearings Destroyed
Replies
12
Views
1K
Raidoctober
R
M
A little shoutout to Ducati Omaha Parts Department
Replies
12
Views
537
SBK-SP
SBK-SP

Register CTA

Register on Ducati Forum! This sidebar will go away, and you will see fewer ads.

Recent Discussions

Back
Top