Changed fork seals and I have a problem

[docc]

Thanks for confirming that "air gap" is the "proper way." 

We must just be certain to "prime" the cartridges full of oil before using the air gap method.

[Lucky Phil]

23 hours ago, activpop said:

When I took the fork tubes off the bike and drained the oil, I drained each tube into a separate graduated vessel to see if both quantities were equal. It turns out they were...600ml in each tube. Perfect I thought, both equal. I never knew how much fluid leaked for the previous owner but the telltale signs were there on the bottom of one fork tube. I used a Sealmate on it when I got it home and that pretty much stopped it, but still wanted to change the seals and dust caps because they were over ten years old, and Stelvios have a history of leaky seals. So going by volume, I guess not too much was lost. After replacing seals I filled up the forks with 600 ml of new oil.  Where it wound up as far as level down from the cap I have no clue. 

The guys at the shop said that was wrong. For a Stelvio the oil level needs to be 120mm down from the top of the tube with the spring out, fork bled and bottomed out. You can't go by volume. That proper air gap is an essential part of the suspension working properly.

So when I get the bleed tool I will uncap the forks, remove springs, spill some oil out and proceed to bleed air, then measure and fill as necessary. 

As I said before, this is my first time doing this, so I learned some new stuff in the last day or two. 

 

 

Of course they did because they have the tools to remove the caps and compress the springs again if needed and are charging by the hour to do it. All things being equal the qty of oil by volume will equate to the desired air gap give or take an amount that's moot for most road riders. Is measured level a better way to go? Yes but for most of us mere mortals it's not a huge deal.

Setting the levels with the forks out of the bike and the springs removed and the fork bled and fully compressed is the ultimate way to do it but who wants to do that every time you are fine tuning the forks oil level? Support the front of the bike and remove the caps and springs, collapse the forks measure the oil level, adjust level up or down as required and reassemble and ride. Decide on more or less oil height depending on the test results and repeat. I mean seriously who has the time for that? Oil height level tuning is in the domain of the race track prep with the tooling and the mechanics to play with it. For the average road rider it's fill by recommended volume. The level doesn't affect the damping performance only the overall spring rate and only then biased to the second half of the fork travel. What's the other alternative? Fill to volume and ride the bike. If you think you need to go one way or the other then park the bike remove each cap individually one at a time and either add 10ml by volume or suck 10ml by volume and ride it again. Don't get bogged down in the minutia of exact measured levels because even having a small level difference between legs wont matter. Are the springs guaranteed to be precisely the same rate on both sides? No, and they won't be so getting too anal about precise levels is a waste of time.

Phil 

[activpop]

Well...since the tubes are already off the bike for the seal change, I have the opportunity to do it by the book. Plus I can bleed them properly this time with the bleed tool. Once they are back in the bike, I suspect they will be good for a long time...and I learned something.

[Lucky Phil]

On 6/5/2024 at 10:55 AM, activpop said:

Well...since the tubes are already off the bike for the seal change, I have the opportunity to do it by the book. Plus I can bleed them properly this time with the bleed tool. Once they are back in the bike, I suspect they will be good for a long time...and I learned something.

All true.

 

Phil

[activpop]

After bleeding properly I checked the fluid levels by measuring distance down from top of tube.  Both sides were only about 8mm low. So I guess the 600 ml I poured out when first opening them were close to spot on, because that's what I initially filled them with after putting in the new seals. I did add a dash to bring them up to spec, and forks are on the bike now. Next is to put on lift to remove swingarm and grease bearings. Then just a few more little things to do before John Day. 

[gstallons]

Are you talking about greasing the u-joints and everything else with the axle shaft ?

[activpop]

2 hours ago, gstallons said:

Are you talking about greasing the u-joints and everything else with the axle shaft ?

Specifically the swing arm bearings.  Carc bikes did not receive proper lube from factory. It's a Stelvio, but all Carc bikes need it...per Mr. Roper. 

[gstallons]

If these are sealed roller (ball) , you can remove the dust cover and pack the bearing cavity w/grease and reinstall the dust cover . 

[activpop]

10 hours ago, gstallons said:

If these are sealed roller (ball) , you can remove the dust cover and pack the bearing cavity w/grease and reinstall the dust cover . 

I wish it was that easy. 

[gstallons]

I've never worked on a CARC rear end so IDK how difficult it is ?

[activpop]

5 hours ago, gstallons said:

I've never worked on a CARC rear end so IDK how difficult it is ?

I never have either, but now I have two of them. After I do the Stelvio, the Griso will be a piece of cake.