Fox 40/Marzocchi Bomber 58
Open Bath Cartridge and Adaptor Kit





The best performance modification you will ever do to your fork!

Complete replacement of the damper with our open bath cartridge!

This will make your fork feel like a completely different fork, because it is!

Low speed damping that’s firm but still blows-off to be plush on small bumps,
Reduced fork dive that eases the fork through the travel without harshness,
No more high speed compression spikes and no more bottoming with the optional ABS system.

Low speed compression and rebound adjusters help fine tune the valving as to
how it transitions from low tomid and when the high speed kicks in.
Much more effective than the other dampers attempt to add high speed adjustment without the proper shim stack.

Open Bath Cartridge system for better lubrication, smoother action and virtually maintenance free.

External low speed compression and low speed rebound adjusters

Internal revalvable custom high speed compression and rebound valving.

Internal Anti-dive MidValving.

Optional ABS when using coil kits and when air progression is not enough to prevent bottoming

Optional FvAT/HSB System

Includes the 20 mm Cartridge Damper Kit Insert and fork cap adaptor.

Self install kit, user serviceable and revalvable.

All cartridges are optimized for current travel.
If you plan on changing the travel in the future, please let us know so the proper cartridge tube can be installed.


For details on Cartridge click here:

To order tools, revalving kits, and replacement adaptors click here:

Weight grams 300 grams plus oil.
(Fox Fit RC2 Cartridge -approx.300 grams filled with oil).




• Replacement open bath maintenance free speed sensitive damper assembly, "set it and forget it"
• 20 mm ID damper tube with shimmed 4 port MX style compression and rebound valving pistons
• Upper fork cap adjuster screw with 22 clicks of activated low speed rebound
• Base valve adjuster screw with 22 clicks of activated low speed compression adjustment
• Optional Hydraulic Anti-Bottoming System (ABS) for end of stroke bottoming resistance
• Speed sensitive multi-stage shimmed compression, midvalves and rebound valving
• Custom valved and set-up for each rider with printed set-up charts
• Fork spring and air pressure recommendations help us tune to to your weight riding style
Midvalve kit included with standard cartridge to prevent fork dive, adds low speed compression without
harshness, optional midvalve revalving shim kit and set-up charts available
• Designed to be self-installed or send it to us for installation if you need us to do the install

• Weight approx. 300 grams

Need us to install it for you, just send your fork to us and we will install it for $100 including Spectro 85/150 oil.

*Self install kit assumes good working knowledge of internals and service procedures.

• Optional FvAT/HSB
Floating Valving Assisted Threshold High Speed Blow-off System

click here to add it to your cartridge

For the firmer feel without harshness, have that big hit set-up that still feels plush on square edged bumps!

Available for those who want to fiddle with their set-up:
Optional revalving kit for compression and rebound pistons, with revalving set-up charts



Fox 40 Open Bath Cartridge

Fox 40 Fork cap adaptor (preproduction)

2019 Fox 40 with optional ABS and optional FvAT/HSB installed



Cartridge Cut-away View


Compression, Rebound and Midvalve shown above.



Purchase Here

Fox 40/Bomber 58 Open Bath Cartridge Kit including fork Cap Adaptor
and Midvalves installed, $449


Custom valved and set-up to rider weight, ability and riding style

Need to have us install it for you? Ship your fork to us and we can install it for $100 plus shipping, includes Spectro 85/150 oil.


Choose the type of riding that you will be doing so we can custom valve it to your specific needs.

Click here for a description of our definitions

Type of Riding

Choose your fork year that the cartridge will be installed in.

Fork Year

Choose your fork model that the cartridge will be installed in.

Fork Model

Choose your fork travel (mm) that the cartridge will be installed in.
For Talas forks choose the travel you want the set-up optimized for.

Fork Travel

Choose your fork wheel size that the cartridge will be installed in.

Fork Wheel size

Choose rider weight.
Rider weight is without gear, we add 5-7 lbs for DH gear, 7-10 lbs for All-Mtn/Freeride.

Rider Weight

Choose the spring rate/air pressure you will be using which gives you 22% sag.
We need this number to help set-up your fork rebound damping correctly.

Click here for sag setting Tips


Air Pressure
or Spring Rate

Choose your rider ability for us to set-up the cartridge.

Rider Ability







ABS Option

Click here for more details

We prefer to control bottoming with the use of our optional ABS on the damper side.
This will create a more linear spring system without any mid to end stroke ramp-up and will improve deep square edged hits and better control on jump faces.

Add option here

Price $89.95

Price $89.95, during initial build.

Price $89.95, plus labor($89) to retro fit, send your cartridge to us for installation.






Have us install your cartridge for you

Ship us your fork, we will install your new cartridge,
service and rebuild your air spring with our improved air transfer sealing system, 2015-2017 Models
replace seals and relube.
includes Spectro 85/150 Oil

Add option here, does not include shipping back to you, we will adjust your shipping total depending on where you live in the world and send you a Paypal invoice for the difference. Iit assumes your fork is in good working condition with no physical damage or scratches on the stanchions.

Add each item required to the cart. Price $100


Installation and Service

Price $100, plus shipping difference






The Avalanche Advantage over the the Fit RC2 cartridge:


A larger (20mm vs 15.5mm) 4 port rebound valve that has more low to midspeed transition control and optional high speed shim configurations for different spring rates and rider conditions.

A midvalve with user tunable shims/valving that provides anti-dive feature while still blowing off without low speed harshness on small bumps.

The same DHF proven design (20 mm) 4 port compression valve with optional revalving charts and shims available to fine tune your fork for your individual riding conditions and ability.

User serviceable, all parts are available here at Avalanche to service or modify the internal set-up.

Revalving kits can be purchased from Avalanche or any suspension tuning shop that carries standard 6 mm shims.

High speed adjustment is at best a compromise of the original shim stack, depending on the high speed spring preload adjuster rate and where the pressure is applied

on the shim stacks you can get less than desirable results in damping feel, i.e. preloading the outside rim of the shim may make the high speed stiffer,

but also creates mid and low speed harshness in the damper.

The original RC/RC2 large compression adjuster protrusion at the bottom of the fork is eliminated and cleanly redesigned.