2006 Marzocchi Z1 Light RC2 Service

How To

The 2006 Marzocchi Z1 Light is an acclaimed 150 mm fork made for one year only. In the US, it featured the successor to the HSCV damper in the form of the RC2 damper, which had compression, as well as rebound adjust. On the other side, it offered the well regarded ETA rebound lockdown, and finally, the TAS travel adjust system knob below. The latter offered travel change from 150 to 130mm. The EU models did not feature TAS. The 2007 Z1 RC2 offered the same specs at the 2006 EU Z1 Light, but now with a bolt on crown to stanchion interface and Bomber Orange color scheme.

The chassis featured 20mm thru-axle dropouts, IS standard brake mounts (spaced for 160mm, and a 5mm lateral offset for the tabs, requiring those thick, 5mm washers Zoke ships with the forks).

In addition to the excellent adjustability, one of the most attractive features of the Z1 Light is the reliability. There are few parts to worry about, a coil on one side, low air pressure on the other, and a large bath of oil. This also makes it very easy to service, and simple oil changes can be done in 10-15 minutes, while a full teardown and cleaning can be done in 30-45 minutes.

Below is the detailed teardown. As always, observe safety precautions, wear eye and skin protection, and if in doubt, stop, try again, or take it to someone who can finish the job.

The fork:

2007′s Z1 RC2 and the 2006 EU Z1 Light are similar.

**Make life easy for yourself and thoroughly clean and degrease the exterior. Pay particular attention to the space between the crown and stanchion.**

Step 1: Insert either the adapter into the air port, or depress the valve to release the air! Don’t point at your face, as a mist of oil can come out.

Step 2: Remove all the adjuster knobs. Only two sizes of hex keys are needed for all four: 2mm and 2.5mm. Another good idea is to have two open end wrenches available, one 14, one 18mm.

-the ETA knob and the Compression knob on the other leg use the 2.5mm hex bolts. There is an o-ring underneath the ETA knob. Keep and clean.

-the rebound knob and the TAS knob on the other side use the smaller 2mm hex bolts

* turn the TAS and Compression knobs inward a couple clicks if they are close to the stops to prevent damage while turning the bolt. You must immobilize the knobs and they can be a bit sticky, so use the open end of the 18mm wrench to hold the compression knob in place, and use the 14 to hold the TAS in place.

3. Removal of the footnuts is fairly straightforward, but it must be noted the 12mm socket needed must be ground with a taper on the end to clear the dropout ribs that are on either side of the pass through hole. Here is also where you need to be creative, as the bolts will tend to spin the end of the carts, loosening nothing.

-For the ETA cart, I’ve had luck by compressing the fork slightly and using short, fast, successive blows with the ratchet. This immobilizes the cart enough, coupled with the blows being greater than the inertia of the cart, allowing you to remove the bolt.

-For the RC2 cart, I pull the uppers from the lowers, as it’s a cart with a stroke barely longer than the stroke of the fork. That usually immobilizes the cart while I apply the same procedure to the footnut there.

There are o-rings there that could make the footnuts stick to the lower, and be difficult to remove, but they will come out.

4. Withdraw the upper assembly slightly, turn fork right side up, then drain oil from the holes in the lowers. Cycling the uppers in the lowers a few times helps remove more oil and reduces mess.

5. Slightly loosen the top caps. The ETA side comes out using a 13/16 socket, and it’s shallow, so be careful. I tried the metric and it wouldn’t fit right. The RC2 side is a bit tougher to get a socket to fit because of how the top cap is countersunk below the surface of the crown. I used a small, low profile Knipex plier. This model has a stop that won’t allow me to add much pressure to the soft caps. Only enough to hold it and turn.

6. Pull the lowers and uppers apart. The carts will come out with the uppers. More oil will drain.

7. Set the upper assembly aside carefully, then clean the interior of the lower assembly with some degreaser. Dry, then set aside. In this step, inspect the seals, and replace, if necessary (excellent visuals available enduroforkseals.com)

8. The upper assembly is now ready to disassemble. First start by cycling the damper rod, as it will release some oil from the pass through holes in the cart body.

9. Turn the top cap for the damper side and remove it with the damper cart still attached from the top. Set aside.

10. Remove the ETA/TAS side the same way, and withdraw from the top. Set aside.
11. Thoroughly degrease and clean the crown/steerer/stanchion assembly, inside and out. Dry, then set aside. I use long paper towels with a knot in the middle to wipe the inside dry.

12. I like to remove as much oil as possible from the carts. If the oil is regularly changed, flushing is not required. If the oil was not changed in a long time, it’s advisable to insert the cart into a container of oil that goes above the depth of the supply holes, and flush the carts by cycling the rods. If it’s been years, then draw new oil in and let it sit for some hours to help dissolve the sludge. Alternately, you can also simply do an “express oil change” a few rides after the main service.

13. The RC2 cart is straight forward. Simply cycle the rod to purge the oil. The ETA cart requires the spring to be removed. Use a 12mm open end wrench around the 4 sided locknut under the topcap. Use the socket on the top of the cap to break it free. You can turn it by hand once it breaks free, but resistance will be encountered again, but this is due to an o-ring part way up the shaft. Turn past it. The spring, washer, and topcap will now come off the ETA cart, and it can now be purged of old oil. Cycle with and without the ETA on (the stub of the adjuster shaft can be turned by hand).

The o-ring that creates resistance after breaking the topcap free:

Exploded view, including the tools needed for the job. Missing is the 12mm open end wrench.

Reassembly:

14. Thouroughly grease the top of the bushing (just below the seals) with Prep M or similar. Coat the seals with grease on the sliding faces as well. Insert the upper assembly into the lower. Cycle a couple times to allow the grease to migrate down a bit.

15. Install both carts back into the compressed lower and upper assembly. Push the bolts back into their holes. They will “snap” into place. Again, you might need to compress or expand the fork and use short, successive blows to reinstall the footnuts.

16. Replacing the oil. Zoke’s recommendations go by cc (ml), and are in the 165cc range for both legs. Factory fill is Spectro 7.5, though I blend mine down a bit lighter, perhaps down to about 5wt. I don’t know the exact amount I use, as I actually purge my carts in the fork and then when I can feel I’m not pumping through air or drawing the rods up through air, it’s done. I then add about 10cc’s more at that point. Keep cycling the rods. pay particular attention to the RC2 damper rod at the top of the travel. It’s still got air in it if you lose resistance. Keep adding oil, but slowly, and know the range you’re in. I use a measuring cup, available from motorcycle shops:

17. Install the spring back onto the ETA cart, then the washer, then the topcap. Tighten in the reverse procedure of disassembly. Make sure the o-ring on the top of the cart is cleaned and oiled. When tightening, all that is needed is to seat the cap on the locknut, then a tad more. Nothing else. Go too far and you’re running the risk of damage.

18. Replace the topcaps, threading on by hand, then tighten. Replace the knobs in the same manner reversed as they were removed, add a drop of oil to the o-ring under the ETA knob, and on the o-rings at the TAS and Compression shafts. Loctite all the bolts for the adjusters and tighten lightly, but snug.

19. Clean the oil and grease from the exterior, check for adjuster operation, and then ride.

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