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Discussion Starter #1
Hi

I had a leaking fork seal on my -97 blackbird, and a friend of me stripped the forks and changed both seals. New 10W Valvoline fork oil was used.

After this job was done, the front feels very hard, and picks up really small bums in the road. I have tried another bird with almost same mileage (about 20,000km) and its a lot more smoother over small bumps. The forks seems to move really easy when it's on the sidestand, on my bike I need to use a little more weight on the handlebars to get it start moving. Feels like they "stick" a bit.

I've also tried different oil levels, and today I changed to 5W oil, and flushed and checked everything. I noticed when I try to move the forks up and down without oil in it, it was a little "sticky", need some force to move up and down. Maybe the oil isn't lubricating the seals properly? Not much difference with and without oil.

But after changing oil, the bike still feels way too hard and uncomftable to ride on the bumpy roads. Feels like it need som presssure on the front to work properly, when I apply the brake just a little, I feels better and more firm over bums, and less shocks in the handlebars.

Now I planning to strip down the seals again, and change them once more. Is there a chance that something isn't put together correctly or is the seals wrong type/size?

Maybe it will settle with time, I don't know.
 

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When you say you flushed the forks have you actually pulled the forks apart (damper rods out etc)? Do you know the condition of the fork internals?
If you haven't checked the internals I would suspect 1 or more of the bushings to be worn possibly causing the fork to compress untrue .......... a complete guess, since these forks are very simple, there isn't much to go wrong but 13 years use can cause wear! How black was the oil that came out on the original emptying?
 

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Discussion Starter #5
When you say you flushed the forks have you actually pulled the forks apart (damper rods out etc)? Do you know the condition of the fork internals?
If you haven't checked the internals I would suspect 1 or more of the bushings to be worn possibly causing the fork to compress untrue .......... a complete guess, since these forks are very simple, there isn't much to go wrong but 13 years use can cause wear! How black was the oil that came out on the original emptying?
It wasn't me that did the job changing the seals so I don't know how it looked, but the guy that did the job said the oil looked fine. The bike has very little mileage, only 22k kms. I pulled out springs and damperrods, cleaned and check them. Was hoping it just was the oil that had too high viscosity, but it didn't help that much. The problem seems to be between the slider and tube, so maybe it is the bushings.

But it seems strange since the bike was good before he did the change of seals and oil.
 

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Just checking the obvious, did you measure the oil level with the forks fully compressed with the damper rods in?

You can tell if the bushings are worn by the amount of copper showing through the black/grey teflon coating and it is this coating that tends to help turn the oil black and unpleasant - hence my question on the oil colour. At 22k that does sound too low to have serious issues. 10wt is fine so it can't be that - some prefer lighter (I run a 50/50 mix of 10 and 5 for instance) but most Birds in the UK run on 10wt.

So if the oil level is correct the dampers are clean and the springs were OK before the strip it can only be the 'sliding mechanism' ..... which is mainly the bushings. Is there any possibility that one did not seat correctly?
Have you tried compressing the forks independently (i.e off the bike) to see if the problem lies in just one or both?
 

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Discussion Starter #7
Just checking the obvious, did you measure the oil level with the forks fully compressed with the damper rods in?

You can tell if the bushings are worn by the amount of copper showing through the black/grey teflon coating and it is this coating that tends to help turn the oil black and unpleasant - hence my question on the oil colour. At 22k that does sound too low to have serious issues. 10wt is fine so it can't be that - some prefer lighter (I run a 50/50 mix of 10 and 5 for instance) but most Birds in the UK run on 10wt.

So if the oil level is correct the dampers are clean and the springs were OK before the strip it can only be the 'sliding mechanism' ..... which is mainly the bushings. Is there any possibility that one did not seat correctly?
Have you tried compressing the forks independently (i.e off the bike) to see if the problem lies in just one or both?
Yes, oil was check fully compressed, damper rods in, (spacers and springs out). I've also compared level with another -97 blackbird. Tried different levels too.

The damper rods moves fine, haven't tried to move the forks independently, but I will try to do that. Most likely I want to take the sliders apart again, so I need a new set of seals before I do that.
 

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Sounds like everything has been carried out 'correctly' and you have checked what I would, so I am out of 'obvious' answers. I had to go up into my attic earlier where I happen to have a couple of spare sets of forks ...... so I tried manually compressing them just by resting the lower end on the floor and compressing, quite hard work (as expected) but you can certainly compress the forks far enough to be able to tell if both forks are working the same, I would certainly try this first since it might well show up if you have just one 'faulty' leg or you need to strip both again.
 

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Discussion Starter #9
Thanks for your effort for trying to help me, really appreciate it.

I also have a Ducati 996, this bike has a much harder setup, so normally I use the bird for long trips. But after the forkseal change on the bird, now the 996 feels most comfortable. Today I rode the same route that I used for testing the birds setup. Clearly a big difference, so something isn't right on the blackbirds front end. Specially when hitting small bumps in the curves it feels nervous and vibration coming right to the handlebars.

I was just thinking if one or both of the bushing are gone, shouldn't the forks become more loose and spongy then? Im not sure about that.
 

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996bip said:
I also have a Ducati 996
thought that to be the case your username is a bit of a give away! But the 'test' was a good idea, I sometimes wonder 'is it just me or is something not right'............ but guessing that you had a 996 told me that you would know a decent ride!

I was just thinking if one or both of the bushing are gone, shouldn't the forks become more loose and spongy then?
yes and it is usually accompanied with 'clunking' type noises. It was for this reason that I posted
Is there any possibility that one did not seat correctly?
I was wondering if one of the bushings had moved slightly not allowing it to close fully (or there was a gritty particle behind it) so expanding the busing and making the fork harder to compress.

Taking a completely different line of attack (but one of my favorites since it causes all sorts of handing issues) did you tighten the front spindle correctly i.e. bouncing the front end to seat the spindle before tightening both sets of pinch bolts at the bottom of the forks? Theoretically if the spindle is not perfectly in line as it passes through the fork legs the load distribution (sorry I'm an engineer so my mind works in strange ways!) into the forks will not give equal forces on both sides and this will change depending what part of the tyre you are riding on ............. which might explain some of the strange sensations you are having.
 

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Discussion Starter #11
Yes Duck, your right. Hehe !

Interesting about the procedure for setting the front axel:

"With the front brake applied, pump the fork up and down several times to seat the axle."

That was new to me, always tightened both side of pinch bolt at the same time. I'll try it when I mount it back in again.

Today I have stripped the forks completely, but everything looks like new inside, bushing are fine and it's nice and clean in there. So I'll have to go and get a new set of seals and oil and try again. ;)
 

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Resurrecting an old thread but I really would've liked to have found out what the answer was to the OP's problem - I just did the seals and bushes on my 2005 bird and the front is now really horrible and oversensitive to the road. It seems to be bobbing up and down on all but the smoothest of surfaced roads. I used 10wt oil which I presume is what was in it from the factory so why the sudden change in feel? Someone who's had this problem and found the answer and who could share the good news with me would be much appreciated :)
 

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Resurrecting an old thread but I really would've liked to have found out what the answer was to the OP's problem - I just did the seals and bushes on my 2005 bird and the front is now really horrible and oversensitive to the road. It seems to be bobbing up and down on all but the smoothest of surfaced roads. I used 10wt oil which I presume is what was in it from the factory so why the sudden change in feel? Someone who's had this problem and found the answer and who could share the good news with me would be much appreciated :)
Something not mentioned in any of the manuals(AFAIK) is to ensure after tightening r/h clamp bolts that the spindle is correctly aligned with the l/h fork- there is an undercut on the left end of spindle inward of the holes. This should line up with outside of fork lower. It could be possible for the fork to bind if it doesn't as the tubes will not be parallel. If its badly out, there can also be a clearance issue on front l/h caliper.
 

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bladebird
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HI all iv noticed on my vids that my front end is bouncing up and down despite the surface
in 3 years iv done 3 oil changes and seals so just bought Hyperpro font springs, honda seals ,
top and bottom bushing kit and came with with 7.5wt oil its being done on tuesday looking
forward to see the change
 

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Yes I used Honda seals and bushes. Sitting on the bike and bouncing the front up and down on the front brake ras it is shows the forks to be pretty stiff with very little 'spring' or bounce in them. I'll loosen up the front wheel again and see how I go.
 

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Something not mentioned in any of the manuals(AFAIK) is to ensure after tightening r/h clamp bolts that the spindle is correctly aligned with the l/h fork- there is an undercut on the left end of spindle inward of the holes. This should line up with outside of fork lower. It could be possible for the fork to bind if it doesn't as the tubes will not be parallel. If its badly out, there can also be a clearance issue on front l/h caliper.
Lining up with that mark can also cause stiction.

The way I have always done it is to leave the pinch bolts on the left fork ( as you sit on the bike ) loose.

Bounce the front of the bike to align the forks

Then tighten the pinch bolts.
 

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One thing I've not seen mentioned is greasing the seal and the wiper to eliminate seal stiction. I use Mobil one synth grease and make sure the seal and the space between the seal and the top bushing are filled with grease. Be Careful with the grease on the wiper as it will make you think your seals are leaking. I have 89K miles on an original seal in one leg and just replaced the other one with oem seal. I've used this method on all of the bikes I've owned for the last 20 years and unless the tube gets nicked don't have seal failure problems. I also make sure to use a full synth fork oil as it helps keep wear down.

I see a lot of people talking about leaving the axial pinch bolts loose and pushing down on the forks to compress them several times. This what I do when I've just removed the front wheel but when I've removed the forks as well I only tighten the top fork clamp bolts leaving the bottoms loose and do the fork bounce tighten the bottom triple clamp bolts then bounce it some more and finish the tightening process. Another thing I do is make sure the fork legs are exactly at the same height by using the axial as a guide. If the axial will slide easily into both fork legs with no binding what so ever I know the they're level with each other. Yes it's a lot of work but telescopic forks do not do well with any binding at all.
 
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