Fox vanilla rlc twang on compression solved, but lockout no longer works -solved

[ishaw]

I've been putting together a bike for my youngest today, giving him pic of parts to throw at it. The forks best suited for the build are done fox vanilla rlc 130mm forks. They have been sat a while but seems to be in decent shape bar some paint scuffs here and there which I'll touch up a bit.

All the dials work, rebound, compression, lockout and Lockout threshold, the only thing that concerns me is a slight twang on compression.

I'm keen to know what this may be as I don't want the fork to fail or lunch itself as it's decent and the only one I have that suits the build.

Anyone know their way around these forks that can help diagnose the sound?

Pic of the build so far and the forks in question.

Yes, my shed is a mess.

 

[clubby]

Have you pulled the spring out to check it? Is there much preload on it? If not, could be it’s just not seated properly on the top cap until it starts to compress.

 

[ishaw]

So I've removed the spring side. What was in there was not what I expected. Yes there was a spring, but there was also what seems to be an air shaft travel reducer sitting on top of the spring. Any ideas what this is about?

Anyhow, with the spring removed, I still get the clicking sound from the damper side, so I can at least confirm it's not the spring, so what else can it be? If something was broken inside I'd not expect all the dials to be working and doing their respective jobs, which they are.

Any further ideas?

 

[clubby]

That black piece is just the travel adjust spacer, looks like I’d expect.
Unfortunately there’s no way of knowing what’s going on damper side without dismantling it.

Manual, if you don’t have one.

https://www.montagnadilombardia.com/05_32mm_en.pdf

They may look in good shape, but you have to remember that they are 20 year old forks now and probably have never been serviced. Could just be lack of lubrication or any number of small parts or shafts could be worn out.

 

[ishaw]

Thanks, I'll give them a tear down at the weekend and see what's what. If I can stop the clicking the bike is actually good to go. One build off the 2025 list hopefully, then on to one for a mates son. That one will free up some much needed space.

 

[ishaw]

Update 12/01/25.

Had some time today to take the forks apart to try and locate the source of the twangy noise.

Stripping the fork didn't take much time, albeit a little messy.

All the internals were in very good shape and no source of noise when operating them outside their captive upper leg. Hmmm

One thing I noticed when compressing the damper side I'd that the spring was bulging in the middle under compression and the crappy plastic sleeve was all the way at the top.

Surely moving the sleeve down is the answer. Bingo.

So the noise was the spring hitting the inside of the stanchions.

So with that solved, a good clean and service before putting back together and some fresh fluid.

However, I didn't have any 7.5wt oil as the manual prescribed. Rider is 12 and light so used some 5wt instead.

Put it all back together, filled with the volume of oil the manual stated - 155ml in damper side, 30ml in spring side (why I'm not sure) and after completing the assembly gave the fork a test.

Rebound and compression disks work to a degree, less effective than before. I'm putting this down to the lighter weight oil, right?

However, lockout does not work at all, and it did before.

While I've used a lighter weight oil, I've put the right amount in. What could be the problem here?

Is the oil weight the cause? Solution then is to get some 7.5wt and simply remove 5wt and replace.

But is it? While I know I put the recommended volume of oil in, does it need a drop more?

Another thing I think I've noticed is the forks seem slightly noisier when in action. With no rebound they are silent, but once this gets turned on a few clicks, it sounds a bit hissy. Maybe I'm imagining it being different to how it was before, but maybe not. Iy difference in theory is the fork oil weight.

Any help with getting these forks back and fully operational greatly received.

Before and after pics for info.

 

[ishaw]

Yay, all solved. Was a simple fix too.

Did some reading and it turns out that the lockout damper position was way off. I'd just fitted the adjusters back on as they sat after rebuilding,didn't think much of it.

Basically during removal and refitting, the lockout damper must have unwound a lot. I took the dials off and used them to turn the lockout damper clockwise until it hit it's limit. Tested the forks, still no lockout, but that was down to the bump stop threshold adjuster being fully open. With that wound up fully, boom, lockout. It was then just a case of fitting the damping adjuster's back on so that the lockout one could hit it's stop clockwise, and allows it to be turned anti-clockwise to open the damper and allow travel.

Even better, the hissing noise has also gone. This must have been the oil being forced through a very open lockout circuit.

Happy days.

The bike is now almost complete, need to re-fettle the hope brakes as after bleeding, the pads are a little close to the rotor, guess I needed a larger blanking block to keep the pistons further in. A job for another day.