It's ages since I've made a frankenfork and I'm out of practice! I know there's some fellow suspension perverts on here that like this sort of thing so if anyone has any thoughts I'd love to hear them.
I picked up one of those cheap Merlin Foxes, which turned out to be a 2022 chassis. My old, very battered and nonboost 2015 has a Vorsprung Smashpot in it and a modified RC2 damper with an Andreani piston in it, it all works really well. So I'm attempting to fit all these nice, newly serviced old bits into a new home and I'm just thinking about detail stuff and especially oil.
As far as I can tell, everything physically fits, the threads seem the same and the bottom-of-leg sizing seems identical. I'll not know 100% til I actually get to it but all my reading suggests a chain of compatibility down all the models and that matches with my observations so far too.
Back in 2015, Fox said put 30cc of 20wt gold in the damper leg, but I'm not sure if I still want to do that. What triggered this is that Vorpsrung normally also recommend 20wt gold as an option but say that Fox Gold gets "extremely thick below 5c" and I do a bunch of riding at or below that. So on the coil side I'm going to follow their recommendation and switch to either the Fox 5wt ptfe I have spare from a Grip damper, or Rockshox 0W30. It should be better some of the time and fine all the rest of the time.
But I'm thinking, is that a good swap for the damper side? There's no RC2 dampers any more, Fox still recommend 20wt for the Fit4 bath but 5wt teflon for the Grip and Grip2. It's a fully sealed damper so I don't need to worry about bath oil and damper oil mixing. Anyone got any ideas?
Similiarly, I've half-serviced the damper but not oiled it up yet... and with the Andreani piston in it works so much better than the standard RC2 did, but I'm light (10 stone) and after a couple of bad crashes I have a plate in one arm and a gimped thumb in the other hand, and well, I get shaken up more easily than I did! Even with the hsc rolled all the way off it's still a little blunt, and I've tons of room to spare in the rebound and LSC... So I was also tempted to drop down to maybe 7.5wt.
(this gets a bit apocryphal, Fox recommend the 10wt Red for this damper, but allegedly they actually came with 7wt Orange from the factory. Now I have no recollection of what they rode like 10 years ago 😉 And the damper isn't standard anyway. But it's not too difficult to swap oil in an RC2 and I don't think there's any risk of a compatibility thing.)
I doubt any of this is outright a bad idea and, tbh, I doubt anyone else out there is riding on a 2022 fork made out of random parts from across a decade. But 2 opinions are better than 1!
5wt teflon for the Grip/Grip2 is no longer used. Now 4wt, and Motorex 4wt is the same stuff.
I'd like to know why the 2019-2021 air spring won't fit the 2022-on 36s. Only reason (ish) I just got a 38 PE to replace my 36 FE was I'd have to spend another 90 on a new airshaft to take out to 170mm.
I guess that's got to be a wall thickness thing?
Just bolted this thing back together, so far so good, it all seemed to go together as Fox intended. There's bits I can't really totally confirm a perfect fit, like the bottom of the fork legs, but I'm like 99% confident in it. Went with the 5W for the bath (purely because I have a bottle of it and I have nothing else to do with it) and stuck with 10wt in the damper, easy enough to change out if I want.
Been out to the garage to check … bottle of 7.5wt there that I used in one old fork for same reasons as you (cold riding and dodgy arm). Can’t say it made any real difference. Air spring though.
As for cross compatibility… dampers can be moved between all three 36 platforms*, air springs can’t. I don’t know about Smashpot, but the Marzocchi coil kit only fits one platform.
*older 36, current 36, Rhythm/Z1
That was the original plan. Merlin paint defect 36 and chuck my old grip2 damper on there, but as i need 170mm it would've needed the new style airshaft.
Made sense to go 38 PE in my head after that.
Good choice. The overlap in a 36 isn’t ideal at 170 anyway (I have one set up like that with a coil, and while it works and is nice and smooth, it’s not got that solid chassis feeling the 38 has).