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32 mm FIT RLC Cartridge Service Procedures


010 32 mm FIT RLC Cartridge Assembly drawing 820-04-174

010 Upper FIT RLC Assembly drawing 820-03-132

010 RL RLC Damper Shaft Assembly drawing 820-03-134


Pictured here are the basic tools needed to complete the FIT cartridge service procedure.


"32 mm FIT RLC Cartridge Disassembly" | "Re-assemble the Topcap Assembly" | "Re-assemble the Bladder and Shim Stack" | "Disassemble the Rebound Piston and Shaft Assemblies" | "Reassemble the Rebound Piston and Shaft Assemblies" | "Reassemble the Rebound Piston Subassembly" | "Install the Assembled Damper Shaft into the Cartridge Body" | "Servicing the FIT RLC Lockout Assembly" | "Bleeding the FIT Bladder Subassembly" | "Wrapping It Up"


32 mm FIT RLC Cartridge Disassembly

The cartridge is shown below, as removed from the fork assembly, with all knobs and bottom nut removed. This is the starting point for this FIT servicing procedure.

Secure the cartridge into the vise with clamps.

Loosen the seal head assembly with a 13 mm cone wrench. Back the seal head off ~1/2 turn, so it's only hand-tight.

Loosen the cartridge connector nut with a 20 mm crow's foot or open end wrench, in the same manner.

Separate the top and bottom halves of the complete cartridge by hand, and drain the oil.

After completely draining the oil, unscrew the seal head and remove the damper shaft assembly.

Unthread and remove the lockout assembly from the topcap, and finish draining the oil.

Secure the lower internal coupler with a 6 mm hex wrench as you loosen and remove the lower external coupler with a 20 mm wrench.

Note:  During this operation, do not anchor the topcap end of the bladder assembly in any way.

Remove the lower bladder retaining ring by pushing it away from the topcap with your fingers and thumb.

Insert the topcap end into a 26 mm socket secured in a vise. With the 6 mm hex wrench, loosen and lift the shaft from the bladder assembly.

With gentle thumb pressure, peel the bladder out of the bladder cap.

Take care to keep the topcap hex side down as the bladder comes off, to avoid spilling the shim stack.

Lay out the valve shims in their stacking sequence on a clean shop towel. Do not alter the shim stack sequence; refer to diagram 820-03-132.

The shim stack has a ring shim. When you reassemble the stack, be sure the outer ring shim is centered over the inner shim.

Continue with disassembling the topcap assembly. Push through the topcap center hole with a hex key, to free the compression piston.

Carefully inspect the piston head for any wear or damage. Replace the piston o-ring at this time.

Re-assemble the Topcap Assembly

Before reassembling the topcap assembly, take note that the hole in the compression piston must be lined up with the pin in the topcap assembly, as shown in the following two pictures.

Work the compression piston into the topcap. Use the bleed hole as a visual guide, to properly align the piston as you gently steer it into place.

Re-assemble the Bladder and Shim Stack

Be sure all the parts are clean. After inspecting closely for any nicks or cuts, place grease on the inside and outside lip edges at the ends of the bladder.

Insert the coupler assembly into the bladder from the smaller end.

Install the bladder ring into the opposite bladder end.

Install the valve shims in their correct sequence, and carefully center the ring shim. Refer to the 010 Upper FIT RLC Assembly drawing.

Note:  Be sure all the shim valves fit over the step in the coupler.

Install the topcap assembly over the valve shim stack.

Use the FOX FIT bladder install tool (PN 398-00-321) to guide the bladder lip into the topcap assembly.

Set a 6 mm hex key wrench into the vise.

Set the bladder assembly onto the hex wrench, lower coupler end first.

Tighten the coupler assembly into the topcap, to 50 in-lbs torque.

Note:  As you tighten the topcap assembly into the coupler, the bladder must be nudged with the FIT bladder installation tool upwards and evenly into the topcap assembly chamfer, without twisting or buckling. If there are any twists or bulges in the bladder after tightening to torque specification, disassemble and repeat this step.

Use the FOX FIT bladder install tool (PN 398-00-321) to help guide the bladder lip into the topcap assembly, as you tighten to torque specification.

Install the upper bladder ring onto the bladder assembly.

Before installing the lower external coupler onto the assembly, replace its o-rings.

Hold the bladder ring in place squarely with the coupler and the bladder itself, as you thread the lower external coupler to finger-tight.

Holding the bladder ring squarely in place is important, or as shown below, the bladder may twist as you tighten down the coupler.

If the bladder subassembly is correctly assembled, the bladder sides are straight, with no buckling or twisting.

Tighten the external coupler with a torque wrench to ~75 in-lbs while anchoring the internal coupler with a 6 mm hex wrench.

Note:  During this operation, do not anchor the topcap end of the bladder assembly in any way.

Disassemble the Rebound Piston and Shaft Assemblies

After thoroughly disassembling and cleaning, carefully inspect the piston and damper tube for any nicks or scratches.

Secure the assembly into the vise with clamps.

With an 8 mm wrench, remove the piston bolt and assembly from the damper tube.

Note:   There is a snap ring on the piston end of the tube (from which you just removed the piston and piston bolt), as shown below. Do not attempt to install the seal head from this end. Damage to the internal seals will be the result, causing the cartridge to fail. Install the seal head assembly onto the damper tube from the adjuster end only.

With a 1/2" wrench, remove the adjuster cap assembly from the damper tube.

Remove the rebound tube from the damper tube.

Remove the rebound needle and the rebound needle spring from the damper tube.

CAUTION:  The removal of the rebound needle must be done through the adjuster end of the damper tube. Your failure to do so will damage the rebound needle o-ring.

Reassemble the Rebound Piston and Shaft Assemblies

After careful inspection of all shims and o-rings, you're ready to rebuild the piston and shaft assembly. Refer to the Damper Shaft Assembly and Main Piston Assembly diagrams.

Clamp the damper tube into the vise with the clamps. Be sure the snap ring end of the tube is on the bottom. Inspect the seals inside of the seal head for cuts, nicks, or excessive wear. If necessary, replace the seal head assembly.

Use a greased FOX bullet tool (PN 398-00-320) to install the seal head.

Apply grease to the rebound needle o-ring and inner diameter of the damper tube. Insert the damping adjuster rebound needle into the damper tube.

Note:  The fluted end of the rebound needle is first inserted into the damper tube.

Insert the rebound tube into the damper tube, using it to chase the rebound needle. Insert to just below the top edge of the damper tube.

Thread the adjuster assembly into the damper tube.

Tighten the adjuster assembly to 55 in-lb torque.

Invert the damper tube in the vise clamps. Drop in the rebound needle spring.

Install the compression check limiter collar over the retaining snap ring. Be sure its flange or larger OD rests against the snap ring on the damper tube.

Set the rebound check spring over the compression check limiter collar.

Reassemble the Rebound Piston Subassembly

Place the shim stack onto the piston bolt. Refer to the Main Piston Assembly diagram, to ensure the correct sequence of the shim stack.

Follow with the rebound piston.

Note:  Be sure the correct face of the piston is facing into the shims.

Finally, follow the piston bolt with the rebound check shim.

As you tighten the piston bolt into the damper tube, push down on the rebound check shim to keep it from binding.

Tighten the rebound piston assembly into the damper tube to 55 in-lb torque.

After tightening the piston bolt to torque specification, check the free play of the rebound check shim with a pick tool.

Note:  If the rebound check shim does not freely separate from the piston, disassemble and re-assemble the rebound piston subassembly. Before proceeding, you must achieve free play here.

Install the Assembled Damper Shaft into the Cartridge Body

As you compress the pink glide ring between your thumb and forefinger, insert the damper shaft into the cartridge body.

Thread the seal head into the cartridge body. Tighten to ~75 in-lb torque.

Fill the cartridge body with oil, carefully working the damper shaft assembly up and down a few times to help free up any trapped air. Be sure the rebound adjuster assembly is fully open, to better ensure the evacuation of trapped air.

Top off the cartridge body with oil as shown, and set it aside for now.

Servicing the FIT RLC Lockout Assembly

Note:  If you are not having any negative issues with lockout, then consider servicing the lockout assembly an optional procedure. For the sake of completeness, we offer it here. Be advised that any parts constituting this kit are not sold individually. Ordering a new lockout assembly (PN# 820-03-153-KIT) would most likely be more cost-effective.

Disassembly

Refer to the FIT RLC lockout assembly drawing as you proceed.

Using a pick tool, carefully leverage out the retaining lock ring, to free the lockout threshold adjuster.

Find the slot down the inside of the lockout screw, which will allow you to insert your pick behind the retaining lock ring.

Twist the adjuster to line up the detent ball with the internal groove in the sleeve, as you pull straight up to remove it. Take care not to lose the detent ball and spring, as the adjuster comes out.

After setting the detent ball and spring aside, use the adjuster to unscrew and remove the threshold adjuster screw. When the threshold adjuster screw is removed, this will permit removal of the blowoff spring and piston.

Clean and inspect all parts and o-rings for wear and tear. Apply grease to the o-rings before re-assembly, which is simply the reversal of the disassembly procedure. Refer to the FIT RLC lockout assembly diagram.

Once the lockout piston assembly is completely re-assembled, it is ready to be inserted back into the bladder topcap assembly.

Screw the lockout assembly in only about 1-2 turns. Be sure to engage the threads of the lockout assembly, to ensure a fully seated lockout assembly o-ring that seals the topcap. This o-ring should not be visible, as shown below.

You are now ready to bleed the assembled bladder assembly with the lockout piston.

Bleeding the FIT Bladder Subassembly

Set the topcap end of the bladder assembly into a 26 mm socket mounted in the vise. Fill the oil syringe with ~25 cc of oil.

Press the rubber gasket point of the syringe down into the hex opening of the coupler.

Note:  Do not rush this part. You will risk agitating the oil, mixing air into it as a negative result. Take your time!

Apply steady and even pressure to the syringe, to slowly push oil down into and through the coupler assembly, and through the stacked valve shims and flutes in the topcap assembly. As the oil is pushed through, it will force out the air that is trapped inside the bladder assembly. Oil fills the bladder section completely, pushing to displace the check shim off its seat, to completely purge all the trapped air.

When the bladder assembly is completely filled, the oil will just peek beyond the hex opening in the coupler.

Drain any excess oil from the syringe, and remove the syringe plunger. Lay the syringe body to the side, staging it for a later step in this procedure.

Top off the bladder assembly with 10 wt. oil.

Top off the rebound shaft and body assembly with 10 wt. oil.

Tip the topped-off bladder and the rebound shaft and body assemblies into each other. With one swift movement, screw them together.

Clamp the complete assembly into the vise, and tighten the bladder assembly connecting nut onto the cartridge body to ~75 in-lb torque.

Bleeding the Complete Cartridge Assembly

Your next step is to purge any trapped air within the entire assembly. First, remove the lockout lever assembly, and press the syringe body into its threaded opening in the topcap assembly.

Fill the syringe reservoir with 10-15 cc of 10 wt. oil.

Gently squeeze the bladder, progressively rolling the squeeze from your pinkie to your index finger. Sustain your squeezing, and watch for air bubbles rising up from the cartridge into the syringe reservoir. Allow enough time for the air bubbles to rise to the oil surface and escape, before you release finger pressure.

Release your grip on the bladder, to allow it to return to its smooth-sided cylindrical shape.

Repeat this process; gently squeeze the bladder, progressively rolling the squeeze from your pinkie to your index finger. Keep squeezing, allowing enough time for any trapped air to bubble up through the oil reservoir in the syringe. Keep watching for air bubbles; repeat this operation as often as necessary, until no more air bubbles can be seen.

While maintaining your squeezing of the bladder, with your other hand slowly push the end of the shaft up all the way, to further purge any air still trapped internally in the piston and coupler assemblies. Slowly return the shaft end downwards to full extension and release your grip on the bladder, which will draw oil back in from the syringe reservoir.

Take a break and let everything sit for perhaps 30 minutes, to allow a chance for more air to bubble out. If air bubbles are still present, repeat the bleeding process once again. Repeat this process until you see no air bubbles appearing when you squeeze the bladder.

The total time it takes to complete the bleeding process can vary, depending on:

Wrapping It Up

Draw the cartridge shaft all the way back down, which will draw most of the oil in the syringe body into the cartridge. The bladder must be back to its natural, cylindrical shape; no dents or dimples. Lift the syringe out while capping the point with your finger, and return the excess oil back into its container.

What you should now have is a cartridge completely filled with 10 wt oil, evidenced by the oil slightly overflowing into the topcap.

Insert the lockout assembly, and screw it into place finger-tight for now. Again, be sure to engage the threads of the lockout assembly, to ensure that the o-ring fully seats and seals the topcap. The lockout assembly o-ring should not be visible.

Note:  Some oil will be displaced into the topcap well when you do this, which is normal and should not re-introduce any air into the cartridge.

Remove the cartridge from the vise clamps and dump the overflow oil in the topcap into a drain pan.

When the lockout is completely closed, a successfully rebuilt FIT cartridge will not compress, or have any air gaps when you compress it. The final step is to test this before installing the rebuilt cartridge back into the fork assembly.



use proper tools, supplies & kits · read all warnings · know oil volumes and inspection guidelines · know disc brake specifics for all Fox forks · know air shaft travel specifics for FLOAT and F-Series forks · use correct fork torque specifications