Did you work with the new Marzocchi CC forks? The ones that GG uses on the Race models. What is your general opinion about the forks ? Do they require a tight maintenance plan ? Have any literature you could spare ?
Thank you.
Yes, I got some good info on the Marzocchi CC 48's from my overseas trip. The thing that's going to confuse a lot of people is the PFP (Progressive Floating Piston) adjustment. The PFP is simply a preload adjuster for the cartridge pressure spring (its the 24mm star adjuster in the center of the fork cartridge cap) The PFP, when set right, will allow for a rider to run an enduro shim setting with either offroad or MX, with only a few click and PFP change to adjust for either form of riding.
I'll have to give a quick overview of my GG experience thus far, so bear with me...
I've been riding and racing my '11 250XC Race for a month or so now (400+ miles of dual sports & trail rides & (1) ECEA sand Enduro [A-250]). The first thing I do with any new bike is simply ride the shit out of it bone stock to see how it is out the box. Plus, as the bike is our shop demo bike, I didn't want to tune the bike to the point where its so far from stock that a demo rider gets in inaccurate feel from a "bone stock Gas Gas". (I must admit, I did swap to Dunlop MX31's F&R right away, I just wasn't feeling the FIM's)
On the first NJ sand test, the bike had way too much weight on the front tire. (I'm 195#, 6'3") As a roadrace guy also, I'm OK with a lot of weight on the front, but it was too much for the sand. A quick -2T of rear preload and the bike was money. No more twitchy feeling, but turned on rails.
In regards to the fork, I usually give the suspension 5-8 hrs to really break in to get a good feel. Even still, I was not that impressed with the fork action out of the box in heavy sand whoops or corner entry chop. The forks had a really pronounced "clunk" on fast extension (rebound) during fast whoop sections. Not un-rideable, but did give a sensation like a loose steering stem (not the case) when I was on the hammer. I did not like the 48T sprocket or "rain" ign mode either, gave a rich slow feeling to the bike.
Anyhow, went back to the shop. Overnight, I swapped to the 50T rear, "sun" ign map. (Yes, the wheelbase got a bit shorter with the 50T, but I'm OK with that for Enduro style trail) I checked over the clickers and PFP setting. I found my PFP setting was backed all the way out (Zero turns) Standard PFP setting is 2 turns in (from all the way out) for '11 & '12 forks. Not out of the ordinary for suspension settings to be off from standard out of the box.
Fast forward to my Italian trip... I soon learned that though the Marzocchi CC fork mimics the KYB is many ways (same seals & bushings, similar cartridge dimensions), it differs in how the cartridge oil height/volume effects the PFP preload, thus effecting your external setting (relative to actual PFP spring preload) After I re-tested the bike on day 2, not only did the motor/gearing rip, the fork was much better in rough chop. The fork rebound clunk was still there, but much less. I've ridden the bike at this setting for the past 300 miles, which brings me to my EICMA/Italy trip where I was brought up to speed with the Marzocchi CC fork details/tuning theory.
In summary, what I came to find, was that my '11 XC250 cartridge was under-filled at the factory, thus setting the PFP at a lower position. My first sensation when I felt the rebound clunk, was that the setting was way too fast or the top out spring was too stiff, not the case as I found. Less oil sets the PFP piston at a lower height & gives the spring press preload due to the lower piston height. What I felt was the floating piston actually contacting the compression base valve at fast full extension (rebound though whoops/chop) (NOT good) Overall, the Marzocchi CC fork has to have the cartridge oil height/volume set correctly to make the overall package work properly. An under filled cartridge can lead to lower cartridge pressure because of less spring preload (cavitation) and incorrect relative external PFP adjuster setting (having to add PFP preload just to get back to normal setting) There was some debate withe factory Marzocchi tech as to exactly why adding PFP preload helped eliminate the "rebound clunk", but I gathered that it had to do with specific cartridge pressure settings & cavitation. Though I cant say if I have an "outlier" fork, I'ld rather know the small short comings so I can correct the forks for my future customers before they take deliver of their new bike.
So adding PFP preload in my case was just a temporary band aide. Next step is to fully service the fork, set the correct cartridge volume and retest. On a side note, I'm aware the the springs are too soft for me (.42Nm), but I'm actually glad I didn't just swap the springs first and overlook the cartridge settings. I'd rather retest the fork set properly, regardless of the spring rate. I've just stocked up on all the Marzocchi & Ohlins springs for the new forks/shock for some personal and customer testing on all weight ranges. (More posts on that later)
Here are some additional notes on the new Marzocchi 48mm CC forks:
The black and red rube model forks (standard and race) have the same cartridge and dimensions, as per the factory tech I spoke with. The red tube forks have slightly better coatings for reduced friction. The newer forks are supposted to have the spring seat preload grooves moved higher on the cartridge to allow for primary spring per-load changes without disassembling the fork. (similar to WP SXS forks)
- I did see some Gas Gas race bikes fitted with KYB's at the EICMA show, however the Marzocchi tech told me Cervantes runs the same "Red/DLC" tube fork that the upgrade model comes with.
- There are optional cartridge springs available. Standard is 20Nm. Optional PFP springs come in 15Nm and 25Nm. The optional springs are different lengths, so cartridge oil volume varies with what spring you are running.
- All PFP settings are measured from full out position (unlike std clickers set from full in). Actual PFP spring preload is 7mm when set correctly @ external adjuster set at (ZERO) Turns. 1 Turn on PFP = 1mm preload change on PFP spring
- Min/Max main oil volume is 280-400cc. Standard is 330cc
- Standard setting; C20, R20, PFP +2 Turns in, 4.2Nm spring @ 5mm preload
- The cartridge spring seat does not have a bushing, don't be alarmed its not there if you pull your fork apart (other forks do, so it looks like there's something missing upon first look)
- There are many other notes, but some cards I'm holding for myself and my customers
In summary, I don't even think I got an accurate test from the CC forks. I have been overall very very impressed with them (aside from the rebound issue), to answer your question. Do I think the service interval is less than others? No, not at all. When set correctly, they will be just like any other CC fork for service intervals. I am very exited to get mine set properly and re-test. No sense changing variables until I understood the theory behind the forks in detail.
I'm in the process of importing all the spare parts for the 48mm CC direct from Italy. Spare PFP springs, cartridge seals, special shims, pistons, DLC upgrade tubes, ect. I'll post info as I receive it along with the new results from the next round of fork testing.
As a long time KTM/WP tech, I came away very impressed with the Marzocchi forks (the 50mm bladder forks are ridiculous as well), I have no reservations they will work as good or better than any other fork out there. You just have to know how they work to get the most out of them.
