2003 Marz MX Pro Coil & 2006 Coil Conversion

TuckerUK

OK, here’s the deal.

I have an MX Pro fork I want to convert to coil. I know the MX Comps can be converted so, but the Pros have a different rebound damping rod, the head (where the spring would rest) of which is a different design. Now I know the MX Pro was available with coils in 2003, but the rebound damping rod in my fork is part no 8031196/C (Marzocchi 2004 MX Pro damper rod 100/120) as used right up to 2007. Anyone have a part no for the 2003 MX Pro coil, or a photo of the damper rod, or a link to the exploded diagram?

nicklouse

yes but not here. will mail you it later.

TuckerUK

You're a true gent, thank you muchly.

TuckerUK

Nicklouse, from reading Marzocchi's website, it looks like the 2004 MX Pro ETA was coil spring on the rebound leg side. So, if you have an exploded diagram for this fork too that would be brilliant.

Finally, did Marzocchi ever publish (and do you have) recommend rider weights for the various coil springs available (soft-yellow, medium-white, hard-red, extra hard-green)?

Many thanks.

nicklouse

they have and I have some info.

but start here while I see what I can find

http://www.windwave.co.uk/documents/tec ... hinfo.html

nicklouse

Ok info I have. all forks with ETA had coil springs. and the other leg was air and also had the damping.

so MX Pro ETA left leg ETA coil and right leg air and adjustable damping.

MX Pro Coil had the Damping and coil spring in the left leg looks like air But there is no top cap listed.

TBH Your best bet will be to call Windwave or Mail them they are good.

If I get time I will see what is hanging around in the shop as I am sure there are some 03 forks in the "hole"

TuckerUK

I did e-mail Windwave twice but have had no reply, and unfortunately it's not practical for me to get to a phone during working hours. I'll fire of another e-mail.

Can't believe I didn't see the spring rates chart on their site before! Thanks!

TuckerUK

P.S. Top cap not an issue on the rebound side, exactly the same cap was used on the MX Comp coil.

TuckerUK

Okey dokey, still no reply from Windwave. Another e-mail sent.

I feel a bit like Andy from the Shawshank Redemption. Maybe I should write two letters a week?

TuckerUK

Obviously Windwave have gone out of business...not entirely surprising judging by their e-mail responses (or lack therefore)! :evil: :shock: :roll:

OK, so I’ve done a bit of research and here's the scoop (for anyone else considering converting any 2003-2007 Marzocchi MX fork to coil):

Firstly, can my 2006 MX Pro TAS/ETA have the rebound leg converted to coil?
Yes, the exact same rebound piston rod and top cap are used on the 2005 MX Pro Coil, so no issues there.

What length springs do I need?
For 85mm travel MX forks, you need 165mm springs
For 100/105mm travel MX forks, you need 185mm springs
For 120mm travel MX forks, you need 213mm springs
For the ETA leg on a 100/105mm travel MX you need a 165mm spring
For the ETA leg on a 120mm travel MX you need a 185mm spring
All the springs are a nominal 24mm external diameter.

Wow, that’s simple, what spring rates do I need?
OK, for an 85mm travel MX, Marzocchi recommend:
For riders of between 120-155lbs a total spring rate of 10-12.4 kg/cm
For riders of between 145-180lbs a total spring rate of 12-13.4 kg/cm
For riders of between 180-240lbs a total spring rate of 13-16.6 kg/cm

For a 100/105mm travel MX, Marzocchi recommend:
For riders of between 120-155lbs a total spring rate of 7 kg/cm
For riders of between 145-180lbs a total spring rate of 8 kg/cm
For riders of between 170-205lbs a total spring rate of 9.4 kg/cm
For riders of between 195-240lbs a total spring rate of 10 kg/cm

For a 120mm travel MX, Marzocchi recommend:
For riders of between 120-155lbs a total spring rate of 5.8 kg/cm
For riders of between 145-180lbs a total spring rate of 6.6 kg/cm
For riders of between 170-205lbs a total spring rate of 7.8 kg/cm
For riders of between 195-240lbs a total spring rate of 8 kg/cm

In all cases, where the rider is about mid way between (for example) a pair of hard springs and a pair of medium springs, they might like to go with one medium and one hard spring.

What spring rates are available?
165mm: Medium Dual-Rate (5 kg/cm & 6.2kg/cm), Hard Dual-Rate (6 kg/cm & 6.7 kg/cm), Extra-Hard Dual Rate (6.5 kg/cm & 8.3 kg/cm)
185mm: Soft (3.5 kg/cm), Medium (4 kg/cm), Hard (4.7 kg/cm), & Extra-Hard (5 kg/cm)
213mm: Soft (2.9 kg/cm), Medium (3.3 kg/cm) Hard (3.9 kg/cm) & Extra-Hard (4 kg/cm)

Where can I get the springs?
CRC sell them new, but sadly only in pairs (a pain for ETA fork owners who need two different length/rate springs)

Useful resources:
Do a search online for the old (year 2000?) Marzocchi Bomber Technical Details and Tuning Manual (pdf format). Lots of the information contained therein is still applicable to MX forks up to 2007.
Marzocchi springs come in a packet on the back of which is a useful spring rate chart. It’s not a complete resource, but used in conjunction with the sparse info found on the spring rate chart on Windwave’s website it’s OK.

With regards to suspension fluid and oil weights, I used the excellent information available at http://www.pvdwiki.com/index.php?title=Suspension_Fluid, and now use Castrol Synthetic Fork Oil 5w in place of standard oil (both rated at 28 cSt@40C viscosity), and where a 10w oil is specified (like with my heavy springs) I mix 75ml of Castrol Synthetic Fork Oil 5w with 60ml of Castrol Synthetic Fork Oil 10w per leg to achieve a 33 cSt@40C viscosity oil. I buy the 5w off Amazon, and the 10w from Halfords.

Well, that took a while to type; hope that helps someone one day.

TuckerUK

Just to add that on my 2006 MX Pro TAS/ETA fork I've gone with a 180mm 4/kg/cm coil in the ETA leg, with a 213mm 4 kg/cm coil in the rebound leg for a total of 8 kg/cm. I weigh about 218lb, and I'm thinking of upping the ETA leg coil to the hard 180mm 4.7 kg/cm coil.

I'm running '5w' (28 cSt@40C) in the ETA leg at from stanchion top level, and '10w' (33 cSt@40C) in the rebound leg again at 55mm from stanchion top level. I have the external rebound damping control about two turns out from slowest rebound (i.e. max damping - fully closed).

These aren't finalised figures, still some testing and fiddling to do.