Without looking at diagrams etc. Are you sure that this is not an internal bump stop so as not to get harsh bottoming?
Hi
I initially also thought this foam 'doughnut' was a bump-stop but it can't be once you look at the construction. Hard to explain without a cutaway diagram but it sits over and around the casting that the main shaft screws into and the kinematics of the shock are not changed by removing it. I.e. the piston cannot go any further with it taken out as it's stopped by a rubber o-ring, a large washer (more of that in a minute) and another o-ring below this. They all stop at the point where the main shaft is threaded into the upper part of the shock. The mystery 'doughnut' goes above this so doesn't affect the mechanics of how the shock works. It's also made of a very rigid type of white expanded foam that would make an awful bump-stop. I think it's what I first suggested - a volume reducer...
Coming to the o-ring/washer/o-ring assembly that serves as the bump-stop/end of travel limiter I noticed that compared to the RockShox service manual I download of a standard RT3 shock that there's a 4mm plastic spacer put into the assembly that seems, to me, to be a travel limiter for the shock. As a standard RT3 is 51mm travel and this one is stamped (197*47) on the bottom this is probably the addition that limits the shock travel and makes the shock 'proprietary' to the Levo. In fact I'd suggest this is just a standard 190/51 shock with a 4mm plastic washer put at the top of the piston to limit it to 47mm. Which - stay with me here - also suggests that one could take it out to restore the 51mm of travel and thereby turn the rear suspension into having about 4 * 2.8 = 11mm more travel so you'd have 145 at the rear ONLY after testing the suspension could handle it and nothing collided with the frame etc.
Thinking more (I can't help it, it's how I'm made!) the presence of this 4mm spacer would also explain the volume limiter that was put in. If the shock can't go it's full travel before bottoming out then Specialized probably added the volume reducer to ramp up the shock at the end of the travel and prevent bottoming. In effect it restores the minimum volume of the shock at full compression and will make the ramp-up curve steeper throughout the travel. I guess, as I suggested earlier, that this works very well for 'mr average' (75Kg, 5'10") but not so well for us older fatties (95Kg, 6'0") who ride a bit less aggressively due to age but need a hefty amount of pressure to get the sag required. With us the volume at the end of travel will be too small and we'll get a shock which we only get 80% travel on OR we have to have too much sag and whack the pedals every 30 seconds on rocks.
So I might take out the plastic washer if I can figure out how to get the shock apart without doing a major rebuild on it, which I don't have time for right now, though it's actually not particularly difficult given a couple of cups of tea and about 2 hours and a few special tools. I've rebuilt many in the past - Fox DHX 4.0 (which was supposedly unserviceable by a home mechanic), Fox Float forks, the dreaded Fox Fit 4.0 cartridge (that was a bastard), many Fox air shocks, my daughter's downhill bike's Monarch that needed lighter weight oil in it as it had way too much damping for her weight and a Stealth Reverb dropper post (another bastard). At the end of the day shocks are not much more than glorified pogo-sticks with some damping built in and once you start taking them apart they are easy to modify by changing oil weight, shim stacks, valving heights etc. If the kinematics of the suspension will take the extra 10mm of travel I'll give it a go and see...
One last thing - why did Specialized limit the travel if it can handle it? I don't know! Maybe to prevent pedal strikes or damage to the motor casing over big terrain? Perhaps with more travel the bike wallows a lot when pedalling? Or maybe the suspension arms really do hit the frame at a full-travel 146mm. Not sure but I'll have a look and report back. If the limit washer, however, is a bugger to get off and requires an entire shock rebuild to get at it it'll have to wait a while as I have work and kids to attend to. In fact that's my missus calling time on my visit to the loo, where I'm typing this whilst perched on the crapper, so I'll have to be off.
Musing about suspension is great but not if it entails an angry missus and a cold cup of tea afterwards...
Regards, Mark
