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Bear with me on this, it's a bit complicated so yes just ride the damn bike etc etc, I know 🙂
The above mentioned forks have an air spring cartridge with two chambers separated by a floating piston that's tethered to one end by about 100mm of string. The idea is that you fill the smaller chamber with higher pressure and it starts to move when travel gets towards the end of the stroke.
Now the problem is, the fork works quite nicely like that but you lose loads of travel. If you put the same pressure in both for a more linear feel, you still can't get full travel ever. I'm considering removing the piston altogether, effectively increasing the chamber volume by the amount that the piston takes up. At the top of the stroke this could make big difference and improve linearity.
Anyone done anything similar?
what if you just shortened the string - bigger main chamber but still some bottom-out protection ?
(is string just there to tether the piston ?)
Hmm, not a bad idea.. it takes up a fair bit of volume though that's the thing.
The travel of the main piston goes almost all the way up to the end of the cartridge, see.
Bottom out protection can be had easily enough by putting air over the oil in the damper leg - or adding more oil.
Hmm.. googled this and one of the main results was me, on here, two years ago telling you all how well sorted my fork now was. Balls.
I removed the piston from mine. They were still shit. Sold them and got some U-turn coil lyrics. Sorted.
They were still shit.
I think that sums up marzocchi's air forks. The coil 66's I had were really nice though.
They aren't ideal (although can be good) but what's the alternative? A replacement would cost £700, continuing to faff with these will cost £0.
Shit in what way? What effect did the removal have?
I have the same fork - prob posted on yr other thread too molgrips - I quite like it, though don't ride it much except when I go to the alps
I use about double the pressure in bottom as top for nice & soft on small bumps but firms up lower down. I seem to remember not getting full travel when wound out to full length, but getting it when wound down (which I don't understand at all - but then I don't really know what ATA does to the internals)
It ws doing well, then it wasn't so plush, then it almost siezed up at Cwmcarn - lack of servicing.
Oiled it up now but I think the seals need replacing. It's been what, 4 years now without a proper service 🙂
news for molgrips:
ust re-read those mtbr threads and had a go at dismantling the ATA side cartridge. before I did, I wound ATA out to "180", depressurised all chambers and still couldn't achieve the last 30mm or so of travel - was like a solid block/lock
Now on a lot of those posts people say that internal pressure cartridge volume is low and that makes full travel hard to achieve.
when I took the cart apart, WAY more than 25-30 ml was in there (that's what I scooped into a beaker), and a bit mucky too. cleaned it out and put in 10ml or so (it's only to lubricate). Another 15 or so in the body of the leg, for fun and pumped it up.
whether it was the dismantling, cleaning or the reduced oil vol, I can now get more travel than I've had before (not 175 but over 165 I reckon, even just in the garage without impacts)
I used to have a pair of these forks
As scaredypants says, take em apart, more oil in the chamber than stated as standard... Yes, I was only getting about 155-160mm out of mine too.
Anyway, took em apart, cleaned em all out etc, rebuilt with recommended amounts of oil, and I started getting about 170-175mm travel. Not quite the stated 180mm, but certainly better than from the factory.
But as davidtaylforth says, compared to the coil versions of the same, they were shit to be fair!