Marzocchi 350cr basic service issue. Stuck nut

[Zac Hinton]

Hi All

Just attempting to drop the lowers on these forks to replace fluid etc. I have done this before on these forks but this time is a bit harder. I can't get the rebound side lower Allen bolt out of the fork leg. It turns about one full turn and is then notchy, consistently. The fluid has drained, so it's definitely loose but won't pull out. It can even tighten up again fine, so not stripped.

Theres no info online about rebuilding these forks unfortunately. Probably extremely similar to 55cr forks. I have tried extending and compressing forks and that doesn't help.

For anyone else doing the same, you will need 15mls of 90 weight gear box oil for the air preload chamber (remove valve core to drain/replace) and 20-25mls of 7.5 weight for the lower legs ( mix 5 and 10 weight, bought from motorbike shop). Don't squirt any oil into the rebound cartridge, it will slowly drain out over time (out of the rebound adjuster). Fluid weights and volumes confirmed by Marzocchi USA tech dept via email.

Using an impact driver seems to be recommended, but I wanted to see if anyone else has dealt with this issue before I damage anything.

 

[SummitFever]

I'm not familiar with those forks either, but the turning bolt is a common fork related disassembly PITA.

If you don't have a impact wrench, then you need to put some pressure on the rebound rod to stop it turning. If the fork has a lockout, put that on and compress the fork while you try to unscrew the bolt. Otherwise, put the axle in and use a tie down looped around the crown and axle to compress the fork. The more you compress it, the better the chance of getting it undone. Removing the spring may assist as well.

 

[Zac Hinton]

I have a Makita battery powered impact driver so will try that in the morning. Might pump up the preload to extend forks, or try ultimate compression option. Will post results

 

[EMF]

No dice

Did the lower service with ease
Legs had no oil
30cc in each leg
Plus a good amount of suspension grease in the groove under the leg seals
Now my 350s equal the Pike car Park challenge test protocol

Sounds like a rattle gun job

Hi All

Just attempting to drop the lowers on these forks to replace fluid etc. I have done this before on these forks but this time is a bit harder. I can't get the rebound side lower Allen bolt out of the fork leg. It turns about one full turn and is then notchy, consistently. The fluid has drained, so it's definitely loose but won't pull out. It can even tighten up again fine, so not stripped.

Theres no info online about rebuilding these forks unfortunately. Probably extremely similar to 55cr forks. I have tried extending and compressing forks and that doesn't help.

For anyone else doing the same, you will need 15mls of 90 weight gear box oil for the air preload chamber (remove valve core to drain/replace) and 20-25mls of 7.5 weight for the lower legs ( mix 5 and 10 weight, bought from motorbike shop). Don't squirt any oil into the rebound cartridge, it will slowly drain out over time (out of the rebound adjuster). Fluid weights and volumes confirmed by Marzocchi USA tech dept via email.

Using an impact driver seems to be recommended, but I wanted to see if anyone else has dealt with this issue before I damage anything.

 

[Zac Hinton]

Did the lower service with ease
Legs had no oil
30cc in each leg
Plus a good amount of suspension grease in the groove under the leg seals
Now my 350s equal the Pike car Park challenge test protocol

Sounds like a rattle gun job

Why 30cc of oil? Recommended volumes are 20 for the 2014 model (that I have) and 25 for 2015. Is there no disadvantage with a little bit more?

 

[pink poodle]

There is a weight penalty Zac.

I have often found that my forks oil is underweight, especially with the rebound (mainly fox and RS). A little extra may help with heat dislersion and thus longer lasting rebound consistency. Otherwise a slightly heavier weight solves the problem.

 

[Zac Hinton]

Interesting, I put in 25mls this time but will try 30 next time. Not too fussed about 20grams of weight (he says as he drinks a beer).

Pic shows fork leg of the rebound side with the cap off (note the splined end of the cartridge visible, this locks into a spline on the lower leg. If anyone else has this issue hopefully the below helps. Fully compress forks and either use a clamp or ratchet strap to keep them compressed. This bit made all the difference...turn compression cap to all the way off...this puts more pressure on the cartridge pushing the two splines together. Make sure lower Allen bolt is tight. Use impact driver to loosen. If you feel any notchiness stop, this is the splines slipping. Go gentle and unwind the rest with a 5mm Allen Key. Pat yourself on the back and rejoice that you haven't stripped threads etc.

I used a 50/50 mix of 5 weight and 10 weight fork oil (25mls in total for each leg). For the rebound side, I put a tube over the thread so that oil didn't go into the rebound cartridge. Last time I didn't do this and it slowly weeped out for ages whilst I thought I had a blown o ring. Forks feel good now! Yet to give them a good test but very smooth so far.

 

[bell.cameron]

"Quagmire here."

"Oh god. Wheres it stuck this time?"

"My forks."