scottproonly
Retro Guru
Hi.i have just rebuilt a 2006 all mountain and it occurs to me that it would be easy to remove the spring from the right leg and run it as an air fork.does anyone have experience of this?
Kes
Kes
marzocchi air fork conversion
- Thread starter scottproonly
- Start date
Re:
If it already has an air valve on the spring side then, yes, you can certainly try it. If not, any Marzocchi top cap the right size with an air valve would do.
You'll need to play about with oil levels to get a usable air spring proggresion as the level that's used with the spring will just allow the fork to blow right through its travel. I'd suggest starting with an oil level around 50mm below the top of the stanchion (with the forks fully compressed) as a starting point and then add enough pressure to set your static sag at around 25%. Then test ride - if they don't ever give you anyway near full travel then take out 10ml of oil, set sag again and test again. You might have to do this several times, of course.
If, on the other hand, with correct sag set they blow through too easily then add oil 10ml at a time and test ride.
Once you get it the best it can be make a note of the actual oil level so you can repeat the setting if you have to drain the oil for servicing.
The actual viscosity of the oil doesn't matter, as all your damping is the other side. Just use 7.5W or whatever you normally use.
They'll never feel as plush as coil forks though, especially over small trail chatter, due to increased seal stiction and too high a rate at the very start of their travel. I experimented a lot converting trials forks to air forks back in my trials riding days and although the weight saving was considerable, the trade-off was always a loss of small bump compliance.
And small bump compliance is what coil 'Zokes do well......
Edit* Do these have ETA and TST? If so, the air valve is on the TST side, which is also the damping side, which makes things a bit more complex as you can't easily just whip the top cap off to add/subtract oil.
Also, if you remove the spring from the LH side you'll give up ETA surely?
If this is the case I'd just keep the coil spring.
If it already has an air valve on the spring side then, yes, you can certainly try it. If not, any Marzocchi top cap the right size with an air valve would do.
You'll need to play about with oil levels to get a usable air spring proggresion as the level that's used with the spring will just allow the fork to blow right through its travel. I'd suggest starting with an oil level around 50mm below the top of the stanchion (with the forks fully compressed) as a starting point and then add enough pressure to set your static sag at around 25%. Then test ride - if they don't ever give you anyway near full travel then take out 10ml of oil, set sag again and test again. You might have to do this several times, of course.
If, on the other hand, with correct sag set they blow through too easily then add oil 10ml at a time and test ride.
Once you get it the best it can be make a note of the actual oil level so you can repeat the setting if you have to drain the oil for servicing.
The actual viscosity of the oil doesn't matter, as all your damping is the other side. Just use 7.5W or whatever you normally use.
They'll never feel as plush as coil forks though, especially over small trail chatter, due to increased seal stiction and too high a rate at the very start of their travel. I experimented a lot converting trials forks to air forks back in my trials riding days and although the weight saving was considerable, the trade-off was always a loss of small bump compliance.
And small bump compliance is what coil 'Zokes do well......
Edit* Do these have ETA and TST? If so, the air valve is on the TST side, which is also the damping side, which makes things a bit more complex as you can't easily just whip the top cap off to add/subtract oil.
Also, if you remove the spring from the LH side you'll give up ETA surely?
If this is the case I'd just keep the coil spring.
scottproonly
Retro Guru
Re:
Hi
Thanks for the info. The forks are the basic model with just air valves at the top of both legs.the spring is on the same side as the rebound knob.
The reason I ask is because I want to lower the forks by adding spacers to the rods.unfortunately this means the spring is too long.I bought the fork in excellent condition off ebay.when I opened it there was 175ml on the rebound/coil spring side and 125ml on the other side.this is different to what I could find on the web.
Are you sure only one side provides the damping? I am also confused as to which side,or both to use as the spring
Hope you can clear things up!
Kes
Hi
Thanks for the info. The forks are the basic model with just air valves at the top of both legs.the spring is on the same side as the rebound knob.
The reason I ask is because I want to lower the forks by adding spacers to the rods.unfortunately this means the spring is too long.I bought the fork in excellent condition off ebay.when I opened it there was 175ml on the rebound/coil spring side and 125ml on the other side.this is different to what I could find on the web.
Are you sure only one side provides the damping? I am also confused as to which side,or both to use as the spring
Hope you can clear things up!
Kes
