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After my previous bit of work on the asgard, changing the oil, I'd ended up with a bit too much oil in there, so the forks weren't giving up full travel. I've just rebuilt them again because of another issue arising from my previous rebuild (something was loose), and with a bit of thought over how the damping system is built, I realised how to set the level just right.
First off, magura's recommendation on oil volume seems to have changed significantly over the years, without a change in the fork's design. Measuing the exact volume you're putting into the fork is a tad tricky too, so here's how to get it right easily. A syringe and tubing can be handy for taking oil out of the fork too.
With the fork empty of oil and the air caps from both legs removed, put the forks upside down, and push the lowers down to the crown. Through the hole on the damping leg you'll be able to see the bottom of the damping mechanism, into which the hollow bolt screws. Lift the lowers about 1/2 inch (12-15mm), and put in about 30ml of oil (less if it starts to overflow of course). Put your thumb over the hole and pump the forks a good number of times (5-10). Be careful when removing your thumb over the position of the lowers, as it may result in some pressure release which can be accompanied by flying oil. Repeat for another 30ml of oil. And another. Now you've got 90ml of oil in the fork, and you're getting close to the target amount.
When you pump the forks, make sure you get the lowers right down to the crown. Add oil more slowly between pumpings now, just a little at a time. You'll see that the hole which the hollow bolt screws into is filled with oil also. Pick the fork up, tilt it so that oil pours out into the lowers, and turn it back up again, so it flows down around the damping mech. That oil in the hole is what can later leak out of the rebound knob.
When do you stop adding oil? With the pumping, you pump down to the crown. Add oil until with your thumb over the hole you can not push the fork down to the crown - the oil is stopping you. Lift the lowers and release your thumb, and as you push the fork down to the crown again, some oil will overflow. Let that out, and with the fork pressed to the crown, pick it up and let the hole for the hollow bolt drain out also (the o-ring will stop the damping oil coming out). Now put the hollow bolt back in, and once it gets harder to turn, start to imitate an impact wrench to tighten it a bit more (or if you have an impact wrench, use that...) - the object it's screwing into can turn freely within the fork leg.
Now you have exactly the right volume of oil in the fork... you've set it to allow maximum travel, but you should have filled out all of the space inside the damping mechanism. If you want a "soft" bottom-out protection, you can add a little more oil, but it really does not take much at all to lose 10mm of travel.
I did this with the other leg empty, filling that once I'd done the damping leg. Oil volume in the non-damping leg is non-critical.
First off, magura's recommendation on oil volume seems to have changed significantly over the years, without a change in the fork's design. Measuing the exact volume you're putting into the fork is a tad tricky too, so here's how to get it right easily. A syringe and tubing can be handy for taking oil out of the fork too.
With the fork empty of oil and the air caps from both legs removed, put the forks upside down, and push the lowers down to the crown. Through the hole on the damping leg you'll be able to see the bottom of the damping mechanism, into which the hollow bolt screws. Lift the lowers about 1/2 inch (12-15mm), and put in about 30ml of oil (less if it starts to overflow of course). Put your thumb over the hole and pump the forks a good number of times (5-10). Be careful when removing your thumb over the position of the lowers, as it may result in some pressure release which can be accompanied by flying oil. Repeat for another 30ml of oil. And another. Now you've got 90ml of oil in the fork, and you're getting close to the target amount.
When you pump the forks, make sure you get the lowers right down to the crown. Add oil more slowly between pumpings now, just a little at a time. You'll see that the hole which the hollow bolt screws into is filled with oil also. Pick the fork up, tilt it so that oil pours out into the lowers, and turn it back up again, so it flows down around the damping mech. That oil in the hole is what can later leak out of the rebound knob.
When do you stop adding oil? With the pumping, you pump down to the crown. Add oil until with your thumb over the hole you can not push the fork down to the crown - the oil is stopping you. Lift the lowers and release your thumb, and as you push the fork down to the crown again, some oil will overflow. Let that out, and with the fork pressed to the crown, pick it up and let the hole for the hollow bolt drain out also (the o-ring will stop the damping oil coming out). Now put the hollow bolt back in, and once it gets harder to turn, start to imitate an impact wrench to tighten it a bit more (or if you have an impact wrench, use that...) - the object it's screwing into can turn freely within the fork leg.
Now you have exactly the right volume of oil in the fork... you've set it to allow maximum travel, but you should have filled out all of the space inside the damping mechanism. If you want a "soft" bottom-out protection, you can add a little more oil, but it really does not take much at all to lose 10mm of travel.
I did this with the other leg empty, filling that once I'd done the damping leg. Oil volume in the non-damping leg is non-critical.
