Marzocchi 55r travel issues

Moogface

Been running some Marz 55rs (2009) for about 9 months but can't get more than 140mm travel. I've looked into the spacer travel adjust issue, but it was already in the 160mm setting above the spring.

In order to get the full 160mm travel, the crown will be about 4-5mm from the fork seals, which seems extremely close compared to any other fork I've tried.

I've removed the top cap of the spring leg, leaving just the damping cartridge in place, and can still only get 140mm so the restriction is not down to any setting in the spring leg.

Faulty cartidge perhaps, or just that Marz are being a bit light on the truth about the travel of the 55s? Has anyone actually acheived 160mm with the 2009 55rs?

nicklouse

4 to 5mm between top crown and lower is about right for marz ( or a bit big a couple is normal).

so when you remove the RH top cap you sill cant get the fork to go fully compressed?

what happens if you remove the other cap as well?

Moogface

With both top caps removed I can compress to the full 160mm, but with just the cartridge leg cap in place and the spring left open, I can only get 140mm max. The cartridge performs well in use, so I don't know whether it's faulty or just made this way. It is certainly the limiting factor on my 55s though. I know travel complaints are common on the 55s, but all the variables (spacer setting, oil level, air preload) are in the coil leg, and I'm having trouble with even with this leg out of the equation (spring top cap off)

The cartridge leg only takes 30ml of oil, so I don't know whether reducing this will make any difference? I'm assuming not and that it's only there for lubrication, so I'm reluctant to reduce the volume

nicklouse

so you are compressing the air in the closed leg and that is making it hard to compress the fork.

can you get the cart to move through all it travel after you have compressed the leg (caps off) ?

Moogface

Ah! Interesting question! There is no apparent way for the air to escape once the caps are on, so maybe that's it. Off to the shed now to have a crack - will let you know shortly... (fingers crossed)

joshtp

ah! had this one before!

firstly, as nick said the caps efectively create an air spring, and when you compress the fork it comes into play usualy in the last 1/3 of travel, this often stops you getting full travel for seemingly no reason.

also, another point to note is that, for some reason beyond my grasp the "r" damper provides its own spring, it self extends when to pressure is applyed, and in the last portion of travel its actually pretty firm. so those combined create a pretty big resistance to full travel, without the spring even i place...
to conter this, whenever i put a "r" damper fork of this kind back together after a service, i compress the forks halfway before finaly sealing them off. this creates a small negative air spring in the first part of the stroke, untill the point at which it was when i reassembled it.
this also lessens the final ramp up...

all in all it makes it alot more supple and a tad more linear.

nicklouse

joshtp/mbukman
that is only any good for a fork with that does not have air as the spring or preload. so one side of the fork only..

joshtp

nicklouse wrote:

joshtp/mbukman
that is only any good for a fork with that does not have air as the spring or preload. so one side of the fork only..

yes, obviously, so on an air spring or preload fork then the neg air spring is only in place on the damper side, on a coil fork then its effective on both sides, it stillw works, and can work wonders to make a stiff fork feel smooth.

for EG, on my old air 44's i ran this sysem on assembling the damper side about 2/3 of the way into the travel, this made it really nice and supple and great on small stuff with a smooth ramp up in the mid stroke and a firm, but not overly harsh feel in the final part of the stroke, when the air neg sping stoped being neg, and started being pos.

turned an OK fork into a great fork.. it was just a shame you had to do the mod to make it any good, the Thor's im running now are just good, no fiddling needed, they are also loads stiffer, not much heavyer and that little bit of extra weight goes into making it stiffer and stronger.,and have much better damping.. but then they do cost almost twice as much....

Moogface

Hmm, has made a bit of a difference, but still got best part of 20mm travel left to go. Having been on my own as I tried it, it took some effort to get the damping cart compressed enough whilst I tighten the top cap. The cart is one hell of a spring on it's own as mentioned above...

I tightened the cap at about 75% travel (my hand still has the top cap shaped mark to prove it), so is a bit more I could do, but I feel that this last 25% won't make too much difference.

Feels like the damping cart is over pressurised? Not much I can do about that...

Moogface

Bit of an update: Things got progressively worse with the reduced travel and I was getting less than 100mm on a trip to cwmcarn last week. Having done a bit more research, I've found a mod where the damping cart is drilled to release the presure and create an open bath system. It's worked an absolute treat with full travel now available and no effect on damping.

If anyone else has suffered the problems with these dogy carts, post here and I'll run through the mod.

nicklouse

link to that mod?

Moogface

There arer a few different guides floating around on various forums, but the one that worked for me is below:

---

Tools needed:

» Drill
» 1.5mm drill bit
» Fork oil (160-180 cc of 7.5w)
» A paper clip

Step One = Drill a 1.5 mm hole 21mm from the bottom of the hexagon nut.

The cartridge will loose pressure. Dont expect a huge BANG ... It only did a quiet psssssssssss. At the end of the cartridge there is a seal. If you do here the first drill only the nitrogen will get out. This is why this step is very important... If you drill somewhere else the pressure will push the oil and the result is a huge mess.

Step Two = Make a 1.5mm hole at 35mm from the bottom of the cartridge (make the operation very slowly).

The oil will begin to leak so get something to put it.

Step Three = Make a 1.5mm hole at 12mm from the top of the tube. Depth of drilling max 4mm.

Now The oil will leak with ease and you will be able to cycle the rod trough all the travel. Make shure the respect the 4 mm (the clip with a mark will help) otherwise you can damage the rod.

Step Four = Make sure the cartridge has no oil in it and then re-assemble the cartridge in the fork. Get rid of the oil from the cartridge.

Step Five = Fill back up with 7.5w suspension oil (quantity varies from 160 cc to 180cc)

---

Some additional tips from my experience:

Worth wearing eye protection throughout, especially for that first hole as the pressure does suddenly hiss out, and with swarf around it could easily get blown wear you don't want it.

I needed to use about 185ml of 7.5wt to get consistent damping. Used 160ml at first but the top hole was occaisionally uncovered when things got rough resulting in pogo-ing as air got in, and a noisy clunk on top out. 185ml keeps things quiet and smooth.

Overall it's transformed the fork from something pretty bad to something altogether reasonable! Very smooth, and full travel is available. I'll post back if any issues arise

nicklouse

nice. I have a dead cart somewhere.

97th choice

I got my 140mm 55r converted to open bath for free by windwave, a 2009 should still be under warranty IIRC.