RST Mozo Pro rebuild help

[ishaw]

I bought a set of these recently knowing they would need work. Once done I'm donating to a friend who I've built a bike for, and just can't let him use the boat anchor sync forks on the bike right now (though in their defence, they do work).

The Mozo Pros I have are seemingly in decent shape, previous owner had them apart to a degree and the sliders are immaculate.

I've got a new steerer on the way as my mate is tall and the threaded one was no good for the aheadset anyway, plus too short.

I knew that despite the sliders being mint, the fork would not budge through any travel at all.i assumed that the elastomers would be rock hard and likely the cause, but I removed the top caps and pulled out the elastomer stacks and both sides were still nice and supple and so not the cause. There were also springs at the bottom of the stack, a little rusty but still compressed and rebounded fine.

Even with the elastomer stacks removed, the sliders don't move at all.

I have no idea what else is within these forks that I can tear down but usually with the elastomers out of say a Judy, the sliders move up and down.

I assume that there is some form of damping going on outside of what the elastomers provide, also read that there could be air involved but at this point I'm clueless and want to get them working.

Anyone know their way around these forks and can point me in the direction of disassembly and servicing?

I'd also prefer to swap the brace over for a v version as the canti mount is redundant on the bike, so if anyone can help me with that, awesome.

The forks are dark grey with red decals. Lower legs have a few scrapes but pretty sound all round.

Cheers

 

[JRGSXR]

I had a set of these on a Zaskar ages ago. Bought the bike and the forks were solid like yours. Stripped them down but still no movement. Turns out it was the dust seals at the top of the legs where the sliders enter. On mine corrosion inside the alloy fork bottoms where the dust seals sit/locate had expanded, crushed the dust seals against the sliders and locked up the forks. I turned the forks upside down, held the bottoms and using a rubber mallet drifted the sliders out by hitting the underside of the steerer tube. Once out I cleaned the corrosion off, painted the inside where the seal sits. Applied a little grease, refitted the seals and rebuilt the forks. They worked perfectly. Not sure if that’s your issue? But worth a check.

 

[ishaw]

Thanks, I'll check that though previous owner had the sliders out and they appear to be very clean. I'm not sure of the process to remove the sliders, there are a couple of bolts, one on each leg lower that are recessed unlike Judy or modern forks I've serviced. Assume these are simply undone and can be used via bubber matter to break taper of the damper and release the uppers?

 

[mk one]

There is an RST Mozo Pro service guide in the archives.

 

[mk one]

Here..

 

[ishaw]

The 3xod3d diagram is what I was expecting. I've serviced tons of retro forks and by the looks of it these aren't much different.

Strange that I can't get any travel out of them with the internals removed, this must mean that rods are stuck.

Anyone got any thoughts on freeing them without damaging anything?

 

[ishaw]

I suspect I know what the issue is. The springs at the bottom of the elastomer stack were pretty crusty, so my theory is that this has contaminated the gap between the slider and rod, preventing them moving.

I don't want to damage anything sorting this, any ideas on what I can use to soak, penetrate and dissolve this without causing any harm to the internals?

 

[tombrown788]

Any aftermarket springs available in 2022 we could use to upgrade this fork??