Monday, 20 April 2015

Travel change for the 350 NCR (CR) series.

Travel change for the 350 NCR (CR) series.

We categorize procedure as advanced, only undertake this if you are a competent mechanic with access to the correct tools and working environment. If you are in any doubt please ask a professional to perform this process for you.

1/ Remove air-valve dust cap and let the air out of the fork.
2/ Using a 27mm socket, un-screw the air plug and then completely remove the plug and air tube from the station.
3/ Using a 1.5mm hex key, remove the rebound adjuster
4/ Using a 5mm hex key, remove the RH foot nut
5/ Using a 12mm socket, remove the LH foot nut
6/ Separate the upper assembly from the lowers
7/ Remove the dust seal external springs and remove the dust seals. NOTE: Removing the dust seals makes refitting the upper assembly easier.
8/ Once the dust seals have been remove re-fit the external springs (removing the springs prevents damage to the seal).
9/ Using cir-clip pliers remove the cir-clip from the base of the air leg and remove rod assembly.
10/ Remove the disc from the base of the leg, this is a tight fit and may require tapping off with a small hammer.
11/ Remove negative spring.
12/ Install travel spacer and push until you hear an audible click.
13/ Re-install the negative spring and push until you hear an audible click.
14/ Re-install the disc to the bottom of the rod, again this may need tapping down with a small hammer.
15/ Re-install the rod in to the base of the stanchion and re-install the cir-clip. NOTE: Check the cir-clip seating and make sure it’s fully in its groove.
16/ Install the dust seals on to the stanchion and re-fit the upper assembly. BE CAREFUL! Make sure the stanchions do not tear the oil seals as the stanchions pass through them.
17/ Re-fit both foot nuts and torque to 10NM + or – 1NM.
18/ Re-fit the rebound adjuster and secure using the 1.5mm hex key.
19/ Press the dust seals back in to the lower legs.
20/ Invert the air tube and place 25ml of 7.5w oil inside.
21/ Invert the fork and re-install the air tube. NOTE: You will need to tap the air tube in with your hand to get it past the piston head on the rod assembly, as the tube goes in the pressure inside it will increase so make sure you expel the air to make installing easier.
22/ Using the 27mm socket re-fit the air plug and torque to 20NM + or – 1NM
23/ Re-inflate to your desired pressure
24/ Check travel.

Part numbers for travel change spacers:

536181 = 20mm spacer
536216 = 10mm spacer

CR model: the procedure is pretty much the same except that the air tube in the CR is not removable.

350R internal for reference only

Wednesday, 15 April 2015

Understanding the 380 C2R2

Set up: Understanding the Marzocchi 380 C2R2 Ti 2014 & 2015 380 C2R2 Ti and steel spring.

The 380 has a lot of adjustments, here is a guide to what everything does. Every adjustment is relative to the spring rate, so get the spring correct and work from here.

Spring options

Soft k=4.4 " 5141956
Medium k=5,5" 5141918 (standard spring in 2014 forks)
Hard k=6.5" 5141957 (standard spring in 2015 forks)
X Hard k=7.7" 5141958/P

Soft k=4.4 " 5141959
Medium k=5,4" 5141923
Hard k=6.5" 5141960 (standard spring in 2015 forks)
X hard k=7.7" 5141961

Note: The stock spring changed between 2014 and 2015 due to the fork feeling too soft as the fork generates far less fiction compared to the 888 model. These springs are also used in the 888.

Pre-load adjuster
Spring Pre-load
Spring pre-load can be done with the external RH adjuster on top of the fork. Pre-loading the spring will compress them slightly and increase the initial force needed to compress the spring. Marzocchi forks can use the maximum amount of pre-load from the adjuster and the fork will still get full travel. Spring pre-load is used to fine-tune the spring rate to adjust for the proper sag measurement. Minimal spring pre-load is recommended for better performance and longer working life of the springs, so it is better to change to a stiffer spring rate than to add significant pre-load (10+ turns.)
Sag refers to how much the fork compresses when the rider is in the normal riding position. Marzocchi recommends 20-30% of DH travel in sag to provide the best overall ride. The easiest way to measure sag is to put a zip tie around the stanchion and then measure how much the fork compresses when the rider is in the normal riding position. Keep in mind that the normal riding position on a DH bike may not be correct on level ground.

Low speed rebound (RED) + High speed rebound (SLIVER)

Rebound Damping
Rebound damping controls the rate in which the fork is able to extend. All Marzocchi forks have adjustable rebound damping. Rebound damping should be set fairly fast, but without causing a sudden, harsh force back to the rider. This will allow the fork to comfortably extend to full travel as soon as possible after impact.
The 380's damping adjuster's are located at the base of the right hand leg, with low speed adjustment in RED and high speed adjustment in SILVER.

Low speed adjustment is for low velocity movements with high speed for high velocity movements. Turning the adjuster's clockwise will slow the rebound speed and therefore turning the adjuster's counter-clockwise will speed up rebound.

It is a good idea to get a feel for how the different rebound adjustments affect the fork. Try turning the adjuster all the way counter-clockwise to the fastest rebound setting and then quickly compress and release the suspension several times. Next test the fork with the adjuster turned all the way clockwise and then somewhere in between. This will demonstrate the differences between damping settings.

Low speed compression (GOLD) + High speed compression (ORANGE)
Compression Damping
Compression damping is the oil flow resistance felt when compressing the fork. Compression damping is categorized in two ways: low speed compression and high-speed compression. Low speed compression refers to when the fork is compressed slowly and gradually, for example during rolling impacts and rounded bumps. High-speed compression refers to the resistance felt during multiple, hard impacts and square-edged bumps.Too much compression damping creates a harsh ride because the suspension cannot compress rapidly enough to absorb large impacts. Compression damping is not a substitute for proper spring rate and should not be adjusted until the fork has the proper spring set-up for the rider.
The 380 features a 3 stage compression circuit (all shims) with adjustable high and low speed damping with the 3rd stage (MID) controlled and adjustable via a shim change (never needed). The MID stage is specifically set for smoothing the transition between high and low stages.

The compression adjuster's on the 380 is located at the top of the RH leg, with low speed adjustment in GOLD and high speed adjustment in ORANGE. Low speed adjustment is for low velocity movements and is useful to dial our brake dive with high speed for high velocity movements and useful for making the fork more progressive. Turning the adjuster's clockwise will slow the compression speed (firmer) and therefore turning the adjuster's counter-clockwise will speed up compression (softer).

DBC Damping
The semi-open bath cartridge combines the damping feeling and the reliability of the open bath cartridge with the lightweight of a closed cartridge.
A compensation port releases any excess oil out of the damper into the lower leg keeping the bushings and wipers lubricated. As soon as the oil level in the cartridge decreases, oil volume is instantly restored by bringing the previously expelled oil back inside. The DBC cartridge use less oil than the full open bath design, thus saving weight and because the cartridge is also open it can’t fail like a closed damper.
A unique feature of the 380's DBC cartridge is that the complete compression module can be removed from the damper (and fork) without dismantling the fork front he bike.

Torque Settings (NM)
Bottom crown fixing screws 6±1
Fork leg top caps 20±1
Pumping element locking bottom nuts 10±1
Pumping element/cartridge bottom nuts 10±1
Rebound adjustment knob fixing screws 2±0.5
Top crown fixing screws 6±1
Wheel axle Allen screws 6±1
Wheel axle screws 15±1

8501682/P: 20mm Taperwall axle
8507017/P: Axle pinch bolt screws (titanium) (11pcs)
7051315FB/P: Lower crown with tapered steerer, flat black
7051316FB/P: Lower crown with 1" 1/8 steerer, flat black
501641FB/P: Upper crown, flat black
8501760/P: 38mm SKF Seal Kit
507963GD/P: 38mm Espresso Stanchion (pair) 

NOTE: This page will be updated