Fork experts...your help is required!

[Harryburgundy]

Following on from this thread regarding my FAT Mr Dirt forks (inverted or up-side-down)

http://www.retrobike.co.uk/forum/viewtopic.php?t=130683

whilst I havn't a scooby about forks, I do like to fix stuff myself....so whadya think.....

Pic 1 shows the forks as if sitting on bike...the left leg seems fine but the right isn't doing much.

Pic 2 Shows the top cap removed...that looks like an oil seal type thing?

Pic 3 Shows the internals at rest

Pic 4 Shows the internals at compression

In my 'I-don't-know-anything-about-forks' mind, I'm starting to think the lhs is coil and the rhs oil compression....and as there is no oil..that's the 'problem'

Do you think I might heading in the right direction?

Cheers
Carl

 

[Tallpaul]

I don't know anything about these forks, but I'd agree with your assessment based on the information you've presented.

The LH leg contains the spring and the RH leg takes care of the damping with oil. I guess the dial on the top of the LH leg adjusts the pre-load on the spring. Is there anything on the RH that may adjust the rebound? It's possibly that the only way of tuning the damping is by the amount/weight of oil used.

When they are fitted to a bike did there appear to be any damping? If not they probably just need a top-up (assuming they are missing oil and that the loss of oil isn't due to a failed seal). The problem is knowing how much oil, what weight and where to put it.

 

[Harryburgundy]

Thanks Paul...can't see any other obvious adjustments so I guess you are right regarding the type and amount of oil to adjust the damping.
The forks felt okay when fitted, but a friend with more suspension knowledge thought they didn't feel quite right...the rhs certainly isn't doing anything now.
More chin rubbing.
Thanks for your input.
Carl

 

[big.eck]

i'd agree with above , but the left leg should have an air cartarage , should'nt it :? so there should be a valve under the top cap , if there is you should see if it's holding air

 

[Harryburgundy]

i'd agree with above , but the left leg should have an air cartarage , should'nt it :? so there should be a valve under the top cap , if there is you should see if it's holding air

Nope...just a spring and stuff..I'll getting pretty sure these are just oil and coil

 

[Harryburgundy]

Some help from the guys on MTBR

I have the Quad Bypass (just the number of ports on the bypass...should be the same as the Triple).
They're unbelievably simple to work on. These forks also don't loose oil so if it worked before, and now it doesn't, I suspect the nut that retains the piston/shim stack has worked itself loose and fallen off. If no damage, some loctite should fix things right up. If the shims are damaged, just get some new ones from the moto shop. I believe the shim stack is used for compression, while the dial that adjusts the bypass ports is intended for the rebound.
Just open it up and take a look. They're unbelievably simple to work on, and yet work so well.
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