Fox 36 float r: Can you increase compression by changing the damper oil?

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  • Fox 36 float r: Can you increase compression by changing the damper oil?
  • Bagstard
    Member

    Just got a 2009 float r on a recent bike purchase and I’m currently running reduced sag to mimimise brake dive. Is it an option to change the damper oil to increase compression damping? The fork does need a lower lube service which should help smooth it out, so while it’s in bits…

    LoCo
    Member

    Yes, but will affect the rebound damping too as well as the lower leg lubrication as the damping and lubrication duties are both done by the oil in an open bath system.

    chillidave
    Member

    Sorry I can’t help, I have a similar problem with my 2009 36 Talas R forks, I have been looking for an RC2 cartridge to fix it but if changing damper oil could help that would be great. Bump.

    Bagstard
    Member

    Thanks LoCo, but will this be a bad thing? Are there any tuning options for the 2010 float r?

    You can try it – unless it results in silly amounts of compression damping (which you would feel anyway) then it won’t harm anything.

    The rebound is, at least partly, adjustable so although thicker oil will slow down the rebound, you should be able to speed it up again with the adjuster. N.B. This is only part of the story – the rebound characteristics are only partly governed by the (low speed rebound) dial.

    I tried this in my revelation forks (admittedly a completely different damper) and I didn’t like it. Fork felt ‘dead’ in a way I couldn’t really describe. YMMV.

    chillidave
    Member

    Very interesting, my problem is running 25% sag the fork dives through the mid stroke, I’m also running very little rebound samping so I’d be reluctant to use oil to fix compression if that slows the rebound further. Are there any other possible fixes?

    messiah
    Member

    I’ve got an RC2 cartridge sitting in my parts box after fitting an Avalanche cartridge to my 2009 36 Float RC2.

    I found the RC2 did the brake dive thing hence partly the change to Avalanche. If I used the HSC/LSC to try and limit brake dive there were consequences elsewhere on how the fork felt. I could never get a setting where I felt I had the sag I wanted without suffering excessive brake dive and/or the fork “choking” on repetative hits… when running these forks I just learned to live with 20% sag and a slightly stiffer sprung fork than I wanted.

    The Avalanche cartridge was/is better and I could/did run lower pressures but it still suffers a bit from the same feeling… perhaps this is just something you get with the Float air spring? The Marzocchi 55 RC3 Ti fork I replaced the Float with is much plusher feeling and the Avalanche cartridge in here is amazing and controls the brake dive brilliantly.

    I’m now running the Float at 130mm travel on my hardtail and it feels awesome… perhaps the smaller air volume with it running shorter helps… or maybe with the back end of the bike being solid I just can’t feel the forks shortcomings so easily 😉

    lornholio
    Member

    I’ve just changed the oil in my 2011 Float R for the exact same reason. I had 7.5 wt Rock Oil in them previously, which turned out to be way lighter than Fox’s recommended 10 wt green. Now with 15wt Motorex the compression is just little slower but not a whole lot, and I only had to dial back the rebound a couple of clicks. So it’s still a case of either running them too firm to minimise dive but not use full travel, or running them soft for correct sag and good use of available travel but lots of dive. I’m currently running them soft and just dealing with it, but will likely switch to the new Pikes next spring.

    See these two links for oil viscosities:

    http://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid
    http://www.transmoto.com.au/fmx/products/7799233/

    I’m also considering shortening the air piston rod to increase the volume in the air chamber (there’s a big MTBR thread about this), with a hope that would allow increased use of the available travel at higher psi, but not sure how that might affect the diving issue so I’m holding off for now.

    chillidave
    Member

    Messiah would you be willing to part with the RC2 cartridge? I appreciate it’s not perfect but should be an improvement over the R.

    LoCo
    Member

    With the float, you can compensate for dive by adding a little float fluid 5ml to the air chamber to get the air spring to ramp up a bit more mid and end of stroke, heavier oil is ok if you go to 10wt (we use Motul factoryline) 15wt would probably make them feel a bit rubbish 😉
    The old damping oil maybe a little worked and may have gone off a bit too so will be less effective too.

    It’s also worth noting that the older FIT 36 dampers (with the bladder at the bottom are now almost obsolete, with only Mojo holding a stock of the last few bladder for them, so we send the dampers to them for service while doing all other work on the chassis as they won’t supply the bladders anymore.

    Bagstard
    Member

    I may have a go with 15wt then, I can always switch back if I don’t like it. messiah, is the RC2 cartridge for sale? I may be interested.

    Bagstard
    Member

    Thanks LoCo, I will stick with 10wt then, pretty sure it is a long while since the last service and will try the 5ml of float fluid while I’m at it.

    lornholio
    Member

    Loco: With the float, you can compensate for dive by adding a little float fluid 5ml to the air chamber to get the air spring to ramp up a bit more mid and end of stroke

    This makes sense to cut down on brake dive at the top of the stroke, but surely with the whole stroke ramped up the overall travel will be limited. I was thinking of trying the exact opposite by increasing the air chamber volume (shortening the air rod myself) for less overall ramping-up but running higher pressure which might give the same characteristics at the top of the stroke but allow more use of the mid-bottom stroke. Am I thinking about this totally wrong?

    tinsy
    Member

    I dont think they are listening LoCo!!

    lornholio
    Member

    Bagstard: Thanks LoCo, I will stick with 10wt then

    See the two links above regarding oil viscocities before buying. Fox 10wt is more like most (but not all) companies’ 15wt; it’s not a standardised scale.

    tinsy
    Member

    I see, I think bagstard must have been typing the 10wt post same time as I was… 🙂

    LoCo
    Member

    Depends on how large an air gap/air chamber you have, if you cut the spring leg down 5mm and then add 5mm of float fluid, it’d be the same air gap (fluids being incompressible)

    Increasing the air gap/chamber size will make the fork more linear i.e less ‘ramp up’ but gives you more scope for tuning with addition of float fluid.

    We don’t recommend cutting the spring legs down as it can increase the chance of failure if not done properly.

    and yes fluid viscosities do vary from brand to brand hence the refernce to the Motul 10wt, it also depends on who has actually done the tests along with tempatures, kit etc.

    messiah
    Member

    Bagstard and chillidave – I’d be happy enough to sell the RC2 cartridge as when I removed it there were no problems with it. But that was a six months ago (it’s been sitting protected in a box since)… but if I was you guys I’d try faffing with the oil weight first as it might get you nearer what you want. My cartridge will probably want a service as it’s been over a year since it last had one… and Loco says above spares are getting thin on the ground.

    One of the reasons I went to the Avalanche cartridge was user sericeability – the RC2 is not something I want to try and open myself… at least with the R version you can mess with the oil weight!

    Bagstard
    Member

    Thanks messiah, I will see how I go with the standard cartridge for now, far less to go wrong!

    chillidave
    Member

    I don’t think Locos float fluid fix will work with my Talas cartridge (though I’m happy to be corrected on that one), if Bagstard isn’t interested I wouldn’t midn giving the RC2 a try, I have heard it can make a difference to the Talas model.

    LoCo
    Member

    Yep you’re right float fluid does work in Talas, it’s oil or damper mods. that are needed.

    Premier Icon molgrips
    Subscriber

    Hijack – LoCo was it you or a collegue I spoke to about my 66 SLs yesterday?

    LoCo
    Member

    That was me.

    Premier Icon molgrips
    Subscriber

    I thought you’d sound like a valleys boy, you sound more West Country!

    LoCo
    Member

    Yep Wiltshire

    Premier Icon Flaperon
    Subscriber

    Yep you’re right float fluid does work in Talas, it’s oil or damper mods. that are needed.

    If you try this with a TALAS cartridge you actually force the oil into the TALAS circuit, which ends in tears / strange performance / hydraulic lockout etc.

    LoCo
    Member

    agh! ‘does not’, Typo!! sorry

    chillidave
    Member

    Not to worry, I think in the wording it came across and I’m not going to go fiddling with the Talas cartridge in a hurry!

    What would a damper mod involve? Though perhaps experimenting with oil and seaking out an RC2 damper is my level for suspension tweaking.

    messiah
    Member

    chillidave ygm about the RC2 cart.

    I’d have a word with Loco about if its worth doing though 😐

Viewing 29 posts - 1 through 29 (of 29 total)

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