[Closed] Marzocchi fork damper/rebound help

Sorry, double post.

What seal have you replaced on the air side? (If possible could you indicate the number from the diagrams on marsocchiworkshop.blogspot site please). Have you had the fork back together since doing it? Did it hold air properly.

Hi nixie,

I'm not sure it has its own number as I guess it would be part of a seal kit. So here it is pictured.

Yes I've had it back together, ridden on it properly (not just a car park test), and yes it seems to be holding air, although I've been fiddling about with pressures and adding oil to make the forks a bit more progressive, so I may do further checks on that later on.

I'm suprised it worked, but for the quid it cost me I thought it had to be worth trying, and was on the recomendation of a local mx suspension specialist. I know they could be ditched altogether but I was gonna try and replace the main oil seals if possible, as well as the one on the damper that I'm asking about above....

theres a big thread on mtbr,

<div class="posthead ui-bar-c"><span class="postdate old"><span class="date">21-2017</span></span></div>

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<div id="post_message_13346642" class="nolinks">After some experimenting here are my tips for significantly decreasing the initial stiction in 350 CR forks......

1. Use a minimum 15wt oil in the air side lower leg.

2. Use a minimum 15wt oil in the air chamber if you're tuning spring rate . If you're like me and choose not to, still add only 1-2ml 15wt oil just to lube the air position and seals.

3. Chamfer the top and bottom corners of the Air piston head with a Utility knife (remember to remove the seals first so you don't cut them). The 350 air piston head has a very square corner on it. The chamfering will help reduce fiction between the piston head and the air tube. It will also help the oil to get to seal.

4. Roughen the whole piston head with some 240 grit sand paper.... "if a surface is too smooth there is nowhere for the oil to stick to to the surface"..

5. Pack the air piston head seal grooves with grease before reinstalling the seals. RWC super slick grease seems to work much better than molykote 55 for greasing the piston head and seals</div>
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thanks scruff, yeah I have seen that, and as I've said above changing the v ring for a quad ring has sorted the air side out, if it hadn't, I would be trying the above recommendations.

I don't remember seeing anything about the seals on the damper side though, but it's probably worth trawling through it again in case....

Do you have a size, supplier or part no for the new one you put on?

There's a place local to me called industrial component supplies ( http://www.bearingsuk.co.uk), obviously they do bearings and seals and the like. I took the original one in as it actually has the measurements on which they used to pick the equivalent replacement.

I have a stock code number from the receipt, but I'm not sure if that's any use if you have a similar shop near you, it's QR118N170.  I was hoping to be popping back in to get one for the damper, so if i do i can check if there's a proper part number.

having said that I bought 2, so if you wanted to email me your address I'll pop the spare one in the post. I assume you have the same forks so I'd be interested to see how you get on with it?

Thanks for the info. Only just serviced mine but would definitely be interested in removing some stickion. Never noticed while riding them but car park test there always seems to be loads.

What oil and grease are you using. Just greased mine with the remains of the Rsp stuff from an old tf tuned lowers kit so need some new grease.

That mtbr thread is great. Didn't know about setting the damper Allen set screw to 6mm deep. Just checked mine and it was at 5mm, might explain why the damping range didn't feel correct!

I'm using slick honey and silkolene fluids, but it didn't seem to matter how much oil or grease I was using that seal on the air spring would just be really sticky.  I was going to get some of the molykote which is mentioned a lot in that mtbr thread, but it works out even more pricey than slick honey or sram butter.

I think I've had mine apart 4 times in the last 3 weeks, i'm starting to get to know them very well.....

How many times have you ridden them?

Marz forks seem to benefit from quite a long running in period. My 350CRs seemed to get a lot smoother with less initial stiction after a good couple of months hard riding.

Mine did that as well (on my second set now, first set of CRs were warranty replaced for a set of NCRs :D). They always feel like they have stiction in the car park test though.

Do you guys also find the air pressure guide a bit off? I'm 80KG+ kit (so max 90KG) and I'm running 60 PSI (using compression damper to avoid blowing through the stroke). After the recent service I had 80PSI (mid suggested value for my weight) in them and they felt awful.

I've also got silkolene oil. Like you I was going to get some molykote till I saw the price and a read a post on the ex windwave blog mentioning slick honey.

That code seems to be a stock number, this thread is the only hit in google for it.

I'm planning to get some of the fork leg spray mentioned in that thread and give them a frequent wipe over to see if that helps.

Yeah i had heard they can take a while to break in but I've now ridden them a few times, the 1st weekend I had them I did about 40 miles at Afan, so that was a good start on them I guess.

Trouble is I hadn't really set them up properly and it was only later when I starting setting them up properly I noticed how sticky they were

Going back to your original question I wonder if the end comes off that shaft in a similar way to the air shaft end (when you adding or removing travel spacers). Step 10 on here  http://marzocchiworkshop.blogspot.com/2015/04/travel-change-for-350-ncr-cr-series.html

It's a good thought, I had a bit of a go earlier with twisting/pulling at that end and nothing seemed like it was gonna give way, and I don't want to force anything without knowing that what I'm doing is right.  I think I'll have to go an ask an expert.

I think a lot of people agree that the pressure guide is off. I'm a similar weight to you, probably 80/85kgs and would say around 55/60psi seems like a good pressure.

Nixie, I take it you do your own servicing? If so and you are confident to take the fork to bits, you could try doing what I did and test each area to see which is sticky. I took the air tube and spring out and tried it with no valve to be able to see how easily the seal slides. I also did the same with the damping side. And then as I'd removed the internals from both sides it was easy to try the movement of the lower legs on the stanchions without any pressure from the other parts. Hope that makes sense? It was by this method that I found the air spring seal to be the worst.....

I do yes. I'm intending to take the air spring side apart at some point as I currently have the forks spaced down to 150mm and I'd like to try them at the longer travel setting (think the ones I have now will go to 170mm!). Should be easy enough to do that test ont he air side while its all apart.

I have the NCR so the damper is different to the one in your CRs so testing that probably not as useful. I also don't fancy bleeding the DBC unit either (its the one thing I haven't done to them).

I've bled mine 3 times now, it was much easier than I was expecting, I followed this video but I don't know if your cartridge is bled in the same way?

So, It seems my NCR has a different air seal head configuration than the CR, with two seals instead of one seal and a foam ring. Robred kindly sent me a different seal so ive replaced the upper one and given them a lower oil / lube change. Will report back after a ride. At worst they may not even hold any air and ill have to put the old seal back on.

I put mine back together yesterday and they were still holding air pressure this morning, but I've not ridden on them yet. let us know how you get on scruffs.  I did read on that long thread on mtbr that someone was recommending ditching the foam ring and replacing it with another o ring.

going back to my original issue...nixie was correct in that the splined bit at the bottom does indeed pop off. I used a small puller and didn't have to put much effort in. To replace I gently tapped it back on again.

but replacing the seal isn't easy.  a standard o ring or quad ring size fits on the rod no problem but is too small to fit inside the plastic bit meaning it won't seal properly.

I spoke to a suspension specialist who is going to have a look at it for me as I'm not sure what to try next......

I also have checked, the seal part number is 118. this is a standard o ring size, but also relates to the quad rings too.

so in the number I posted above qr is for quad ring, 118 is the size and ni is for nitrile, which I think is the type of rubber.

I tried standard silicone spray on the stanchions and dust seals this weekend. There was a very noticeable reduction in stiction in the car park test immediately after applying. I ended up increasing the fork air pressure after a few miles to 70 psi (and backing off the compression slightly) as 60 psi was now too low (blowing through travel). Forks felt amazing over the very, very rocky Peak district trails and I've definitely been getting full travel.

Anyone, please, measurements for that new x-ring?