Installing and Adjusting the Jab MTB Clutch

Safety

• Safety glasses
• Recommended: Nitrile gloves

Tools

• Small precision tweezers with stiff/strong tips
• Metric hex keys (individual, not from a multi-tool)
• T25 Torx driver
• Pick
• Needle nose pliers
• Small flat blade screwdriver
• Utility knife

Torque and Threadlocker

All fasteners require threadlocker and proper torque.

Torque and threadlocker specs are on this page.

Parts

• MTB clutch parts kit

Supplies

• Threadlocker (such as blue Loctite 242)
• Marine grease
• Citrus degreaser
• Rags
• Small brush

Remove Derailleur

Make sure you have the tools and supplies above before beginning. It makes the work a lot easier.

Remove the Jab derailleur from the bike.

No need to break the chain. Remove the upper chain pulley and lower cage spacer, and the chain will come out of the derailleur.

Clean all dirt off the clutch cover and surrounding area.

Don't let dirt get inside the clutch housing, or the clutch won't operate smoothly.

Remove Clutch Cover

Remove the M3 flat head screw.

Insert a knife under the clutch cover where the M3 screw was.

Pry the clutch cover up and remove it. Wipe off dirt.

Remove Clutch Parts

Remove the M5 screw using a T25 Torx driver.

Remove the 2 M3 screws and any parts held in place by them.

Depending on the clutch already installed, the parts may look different from these photos.

Remove the washers, shims, and conical disc springs from the spindle.

The photos below show removal of the Gravel clutch, but the removal of each clutch is similar.

All parts should be removed from the housing, leaving just the spindle and its bearing exposed.

Tip: If some parts are hard to remove, first try tweezers or a pick. If they're still hard to remove, try needle nose pliers as shown. Take care not to damage the surface of any parts.

Clean Housing

When all parts are removed, you should see the black bearing shield.

Clean out all dirt and grease.

Lay Out Parts

Arrange the MTB clutch parts for the next steps.

Install Shim, Washers & Ratchet Ring

Install the 0.5mm thick ring shim (not a 0.2mm thick shim). Then apply grease to it.

Install a washer with the large outside diameter and the square hole. Then press it down and apply grease to it.

Install a washer with the small outside diameter and the square hole.

Install the circular ratchet ring. Make sure the tips of the teeth point counterclockwise, as shown. Then press it down and apply grease to it.

Install a washer with the large outside diameter and the square hole. Then press it down and apply grease to it.

Install Conical Disc Springs

Important:

Locate the 2 M8 conical disc springs. The orientation of the springs is critical for proper function.

When installed, they should face each other as shown, creating a void between them, like two crash cymbals.

Install the first M8 conical disc spring. Then press it down and apply grease.

Install the second M8 conical disc spring. Then press it down and apply grease.

Place Pawls

Apply a small amount of grease to the 2 small pockets shown here.

Using a magnetic tool, like a hex key with a flat end, install the 2 ratchet pawls as shown.

If you don't have magnetic tools, tweezers will work too.

Prepare Screws & Springs

Apply a very small amount of threadlocker to the 2 M3 x 6mm socket head screws. Wipe off any excess.

Slide the small torsion springs over the 2 M3 x 6mm screws.

Start Screws

Important:

The next steps are easier if you follow these techniques. Follow the text and photos carefully for the best outcome. We've done our best to describe the easiest techniques.

Using a 2.5mm hex key with a flat end, place the M3 screw (with spring installed) on the end of the hex key. The parts should stay on the tool by friction.

While holding the parts on the tip of the tool, move the screw to the threaded hole at the angle shown.

Once the tip of the screw is at the hole, line up the screw and tool with the hole so you can begin threading it in.

The spring should not be caught on the higher edge of the aluminum. It should look as shown.

Thread the screw in a couple of turns, but don't tighten it. It only needs enough thread engagement to stay in.

Repeat the steps above for the other screw and spring.

Set Springs On Pawls

Move the pawls so they contact the ratchet ring.

Using tweezers, carefully grip the end of the spring and place it in the groove on the back of the pawl.

Tips:

Don't bend or over-stress the spring. This can damage the spring and cause the ratchet to work improperly.

Start by wedging the tweezers under the end of the spring to get a good grip. Hold the tweezers at an angle, not vertical. This helps grip the spring.

Move slowly and grip tightly.

Release the spring when you are certain it is on the back of the pawl.

Use the tweezers to seat the leg of the spring in the groove on the back of the pawl.

Tighten Screws

Now tighten the M3 screws with very light torque. The clutch cover will also hold the screws in place later.

Tightening the screw might also push the spring down a little more.

Important: After tightening, check that the pawls and springs still move properly.

Check Springs

Use the tweezers to verify that the legs of the springs are seated in the grooves on the pawls.

Tips:

Grip the leg of the spring and wiggle it up and down. You should see the pawl move up and down with it.

Gently push the pawl and both ends of the spring down with the tweezers.

Install Shims

Start by installing 5 or 6 adjustment shims on the spindle. The shims are 0.2mm thick.

This is not a firm rule. What matters is the friction after the clutch is shimmed properly.

You will probably add or remove shims in a few steps. This number is just a starting point.

Install the 1.5mm thick shim after the adjustment shims.

Install M5 Screw

Install the M5 screw with 2 washers.

First place the serrated lock washer on the M5 screw.

Then place the standard flat washer on the M5 screw.

Tighten the M5 screw. It will be removed during adjustment, so there is no need for threadlocker yet.

Adjustment Tips

The MTB clutch uses 0.2mm thick shims.

The purpose of the clutch is to reduce chain vibration. This reduces the chance of dropping the chain from the chainring, and reduces chain slap noise on the frame.

The MTB clutch applies friction in one direction when the cage is moving.

To make the clutch have more friction: Add 1 shim at a time, reassemble the washers and screw, then check the friction.

You can adjust the MTB clutch to apply a lot of friction if desired, but be careful not to make it too hard for the cage to move. The conical disc springs can bottom out, which will damage the derailleur and probably other parts of your bike too.

To make the clutch have less friction: Remove 1 shim at a time, reassemble the washers and screw, then check the friction.

You can even set the clutch to have no friction if desired. This gives the cage maximum freedom to move. But depending on how rough the terrain is, it may move too freely.

Threadlock M5 Screw

After you get the friction you want, remove the M5 screw with a T25 driver.

Make sure the male and female threads are free of grease.

Apply removable threadlocker to the threads, and reinstall the screw.

Torque specifications are here.

Pack With Grease

Apply more grease to completely pack the pawls and springs.

Make sure all parts are coated with grease. This prevents contamination and corrosion.

Make sure the walls of the housing are coated with grease. This helps the o-ring seal on the cover keep water and grit out of the clutch.

Make sure the o-ring is clean and seated in the clutch housing grooves as shown.

The o-ring may stretch across 1 or 2 corners. That is OK.

Install Cover

Locate the D-shaped slot in the clutch housing.

Locate the D-shaped protrusion on the clutch cover.

First, insert the cover's D-shaped protrusion into the D-shaped slot.

Then rotate the cover down, taking care not to pinch or tear the o-ring. Snap the cover all the way down.

Install M3 Screw

Apply removable threadlocker to the M3 flat head screw and install it. Take care not to over-tighten the screw.

Torque specifications are here.

Reinstall Derailleur

Clean all excess grease off the derailleur, then reinstall it.

Installation and adjustment instructions are here.

Done!