So I’ve had a set of Sid Ultimate 120mm for about 10 months. Always had a bit of stichion and I’ve not ridden bike much over winter but after reading about lack of oil/grease from factory I dropped the lower legs and took out the air spring. Not much grease or oil in either so I put it back together with the required amount of both and they were lovely and buttery smooth and needed another 10psi to get same sag setting. First ride out I noticed they started to pack down and after letting air out the fork sucked fully down. I tried the zip tie down the seal but made no difference so I stripped them thinking the pos/neg notch on the inside of the upper leg was blocked with grease and after struggling to get the air spring out ( it came out with a pop) cleaned out the notch but didn’t notice anything untoward .They were great for a couple of rides but been out today and after a ride with quite a few decent hits it’s packing down again. What am I doing wrong?. I’ve serviced loads of forks/shocks so have the tools and know how. All ideas gratefully received.
Too much grease on the air spring blocking the negative air port? Had this on some Pikes and an easy fix was to pump them up much harder. (80psi worked for me) then bounce on them a few times. If you hear a sudden hiss, that's grease moving g out of the negative air port and allowing the positive and negative chambers to balance again.
If not, a strip down with less grease in that area works.
I had this on a set of Revelations a few years ago.
Assemble with less grease and pop 1ml of oil in on the top of the air shaft should help.
I don’t know if it’s your problem - but check the instructions for grease / lube needed. On the Lyrik ultimates I’m sure it suggests a bit of lube / oil in the air spring as well as the lower legs - it’s something tiny like 2 or 3 ml I think.
Some of the Sid ultimates came with bushings that were too tight as well I think - might be worth getting them checked out whilst still under warranty.
Sounds like an air seal has gone to me.
So I started to have a look at the forks today but after reading something on mtbr I turn the bike ove, removed front wheel and replaced axle and with no air in positive side ( fork was sucked all way thru travel) I gave it a sustained pull. After 5 or 6 seconds there was a squelching and the forks came up thru the travel and sat at normal level. I’m going to put a bit more pressure in and see if that works.I was running them quite soft and wonder if that’s part of the problem.