Replacing Fork Oil

[jandyb]

Hi

Bike: 2006 TXT Pro 125 Racing with 40mm Marzocchi alu forks.

Yes I have read the document here http://www.trialspartsusa.com/tech.html but there it says:

1. Disassemble the superior cap of each suspension leg.

...ok no problem.

2. Remove the spring.

..ehh now it becomes difficult. I cant find a way to remove the spring.

Ok so I loosen the allen bolt at the bottom and withdraw all the "stuff" inside. Out comes -surprisingly easy - everything inside and also surprisingly it sticks together with no loose parts - spring and all. Ok so the tubes are loose and let me clean them out. Something that was very needed as "someone" had painted the springs with a kind of paint that dont withstand oil. Result is that the bottom of the tubes were full of red paint particles. Why paint the springs anyway??

Cleaned out and got it together again no problem. But how much oil to put in. The "measure level" method wont work as the springs are not out, but now I know the tubes are absolutely empty. The document says 230cc left and 130cc right, but can I trust this as the other things dont work?

-Jan

Edited July 9, 2009 by JanDyb

[laser1]

I would pop the caps off and measure it. As I remember, the Aluminum caps are two piece assembly's with the spring retaining nut threaded into them. It can look like a one piece solid assembly at 1st glance. ( the rebound side) - I would have sworn I used more fluid than whats listed, but didnt measure the volume and just rely'd on the height in the tube. I have also seen other PDF's that listed 270cc for each side on the AL Zokes. (more like what I would have guessed I put in)

[jandyb]

I would pop the caps off and measure it. As I remember, the Aluminum caps are two piece assembly's with the spring retaining nut threaded into them. It can look like a one piece solid assembly at 1st glance. ( the rebound side) - I would have sworn I used more fluid than whats listed, but didnt measure the volume and just rely'd on the height in the tube. I have also seen other PDF's that listed 270cc for each side on the AL Zokes. (more like what I would have guessed I put in)

Hmm.. Think I will need detailed info on how to get the caps off. I have tried with no luck. Dont want to destroy anything you know...

-Jan

[jandyb]

Finally got the cap off the left leg, but I really dont think this is the right way to fill oil on theese type of forks? When I got the cap off I of course could remove the spring, but then the internal rod disappeared to the bottom of the fork. Only way to get it up again was to turn the fork up side down, and then it was a heck to get the cap on again.

I think i will try to use the amounts thats stated earlier. I know now that the forks are absolutely empty so if the amounts are right it cant be wrong..

-Jan

Edited July 12, 2009 by JanDyb

[laser1]

Any update?

[jse]

Finally got the cap off the left leg, but I really dont think this is the right way to fill oil on theese type of forks? When I got the cap off I of course could remove the spring, but then the internal rod disappeared to the bottom of the fork. Only way to get it up again was to turn the fork up side down, and then it was a heck to get the cap on again.

I think i will try to use the amounts thats stated earlier. I know now that the forks are absolutely empty so if the amounts are right it cant be wrong..

-Jan

Jan,

If you are going to do much work on the Marzocchi forks, you might want to make a tool like the fork cartridge bleeders I made. They are tubing, about 36cm long, that a nut the size of the cartridge rod threads is brazed onto and have a bleed hole at each end (these I made cover four different sizes of rod ends). The tool is threaded on the end of the cartridge rod and is used to bleed the cartridge by pumping and also holds the rod end so it's easy to pull out to attach the rest of the components.

Jon

Edited July 16, 2009 by JSE

[jandyb]

What I found was that it was very easy to loosen the allen bolt in the bottom and withdraw all the internals. All internals stick together no problem, and reassembly was no problem. Then it was peace of cake to remove all old oil and to clean out both cartridges and inside the tubes. The cleaning was absolutely necesarry because of all the paint particles from the spring. Next time there will not be so much paint because now almost all the paint are off the springs...

After this when I knew the forks were completly empty it should be easy to just add the right amount of oil without having to measure the lenght from the top.

Problem is that I am still not sure that the amounts are correct (130cc right and 230cc left), but the forks seems to work OK now so it may be right.

My conclusion is that "my way" is much easyer than removing the top cap and spring.

-Jan

[jse]

Problem is that I am still not sure that the amounts are correct (130cc right and 230cc left), but the forks seems to work OK now so it may be right.

-Jan

Jan,

I think the 125 forks are the same as the larger models (guessing, not from experience, however) and the 270cc spec. seems right for the aluminum upper tubes (the "waisted" design of the upper tube means less of an air gap to start with so a little less oil is required). I know the 125 Marzocchi forks with the steel upper tubes take about 290cc's. The 130/230cc type measurement is generally for forks that use only one spring. I havent worked on the 125 aluminum forks but I'm assuming the 125 aluminum forks use two springs? Unless there is one spring or somehow the internal cartridges are radically different from the larger models, the oil volumes will usually be the same for both sides.

Jon

[jandyb]

Jan,

I think the 125 forks are the same as the larger models (guessing, not from experience, however) and the 270cc spec. seems right for the aluminum upper tubes (the "waisted" design of the upper tube means less of an air gap to start with so a little less oil is required). I know the 125 Marzocchi forks with the steel upper tubes take about 290cc's. The 130/230cc type measurement is generally for forks that use only one spring. I havent worked on the 125 aluminum forks but I'm assuming the 125 aluminum forks use two springs? Unless there is one spring or somehow the internal cartridges are radically different from the larger models, the oil volumes will usually be the same for both sides.

Jon

Jon

You mean one or two springs pr fork I hope?

Theese forks had one spring in each fork. The internal cartridges looked very similar, but one had more and bigger holes in the cartridge than the other. Also it seemed like the "nut" in the bottom for the allen bolt was loose on one fork and was set on the other. Cant rememer witch was what now.

-Jan

Edited July 18, 2009 by JanDyb

[jse]

Jon

You mean one or two springs pr fork I hope?

Theese forks had one spring in each fork. The internal cartridges looked very similar, but one had more and bigger holes in the cartridge than the other. Also it seemed like the "nut" in the bottom for the allen bolt was loose on one fork and was set on the other. Cant rememer witch was what now.

-Jan

Jan,

Yes, one spring per leg. Sounds like the forks should take equal amounts of fluid in each leg. The slightly larger holes in one cartridge is probably the compression side, which has generally a higher piston speed that would require a little more bleed area/volume (rebound speed of the cartridge piston is usually slower than the compression side, as the compression take a big, fast hit-like a big rock- and the rebound is pushed back by stored energy in the spring).

Jon