How to Replace a Cub Cadet RZT 50 Drive Belt

Terry Clayton

Feb 16

3 min read

Updated: Sep 20

If your Cub Cadet RZT suddenly stops moving, struggles to climb, or won’t engage drive properly, there’s a good chance the main drive belt has failed. In my case, the mower stopped moving entirely while I was cutting the back lawn. Once I got underneath, the problem was obvious: the belt was cracked, loose, and barely holding together. It had slipped off its pulleys because it was in such poor condition.

Replacement Drive Belt Used for This Repair

Cub Cadet RZT Transmission / Drive Belt

DRIVE BELT LINK

This is the belt that drives the mower, not the mower-deck/blade belt. Verify the belt part number against your exact Cub Cadet model number before ordering, since RZT models use different belts.

Watch my complete drive-belt replacement video below for belt routing and installation.

This guide walks through exactly how I replaced the main drive belt on my Cub Cadet RZT 50, including what tools you need, what to watch out for, and lessons learned along the way.

https://youtu.be/HPvLEiKC1Sk?si=RKwcO436sZPSKi9x

SYMPTOMS OF A FAILING DRIVE BELT

• Mower won’t move forward or backward

• Loss of power to the wheels

• Belt visibly cracked, stretched, or slipping

• Sudden failure while mowing

Cub Cadet RZT 50 Drive Belt Diagram and Routing

Cub Cadet RZT 50 drive belt routing diagram showing transmission belt and pulleys

Using the routing diagram above, install the new belt around both transmission pulleys and route it back toward the engine pulley. Insert a 3/8-inch ratchet into the square opening in the idler bracket and rotate the tensioner far enough to give yourself the slack needed to get the belt fully onto the pulleys. Slowly release the tensioner, then inspect the entire belt path to make sure the belt is centered in each pulley and properly tensioned.

TOOLS & SUPPLIES NEEDED

•Drive Belt:

• Heavy-duty work gloves

• Socket set (10 mm, 16 mm, 17 mm)

• T30 Torx bit

• Breaker bar

• impact driver

• Thread locker (blue)

• Jack

STEP 1: DISENGAGE THE HYDROSTATIC TRANSMISSION

Under the seat are release levers near each rear wheel. Pull the wire clip up and out to disengage the hydrostatic drive on both sides. This allows the mower to be pushed or towed safely. DO NOT MOVE THE MOWER MANUALLY WITH DISENGAGING THE HYDROSTATIC DRIVE ON BOTH SIDES.

STEP 2: REMOVE THE BAGGER MOUNT

If equipped, remove the rear bagger mounting bracket by pulling the pins on each side. This provides access to the drive system tension spring.

STEP 3: SAFELY LIFT THE REAR OF THE MOWER

Support the mower securely using wide, stable supports. Avoid relying on thin frame metal alone.

STEP 4: IDENTIFY THE PROBLEM

Once underneath, the main drive belt is usually easy to identify. In my case, it was cracked badly and no longer usable.

STEP 5: REMOVE THE OLD DRIVE BELT

Cut and remove the damaged belt. The deck belt must also be removed before installing the new main drive belt.

STEP 6: DROP THE ELECTRIC PTO CLUTCH

Disconnect the clutch wiring harness. Remove engine housing bolts and use a T30 Torx bit to access the clutch bolt. Hold the top nut while loosening the lower bolt, then carefully lower the clutch. Keep track of washers. On some models you may be able to install belt without dropping the PTO clutch. I was not so lucky.

STEP 7: INSTALL THE NEW DRIVE BELT

Route the belt around both rear wheel pulleys, the main drive pulley, and the tension pulley. Heavy gloves are recommended.

STEP 8: REINSTALL THE CLUTCH

Clean the clutch, apply blue thread locker to the bolt, reinstall washers, align the groove correctly, and tighten securely.

STEP 9: REINSTALL THE DECK BELT

Carefully work the deck belt back onto the clutch pulley. Release deck tension if needed.

STEP 10: REASSEMBLE ENGINE HOUSING

Reinstall all components in reverse order. Use thread locker on fasteners exposed to vibration.

STEP 11: RE-ENGAGE THE HYDROSTATIC DRIVE

Push both hydrostatic release levers back into the engaged position.

FINAL TEST

Start the mower and confirm smooth operation and restored drive power.

FINAL THOUGHTS

This repair is more involved than expected but completely doable with patience and basic tools. If your Cub Cadet RZT stops moving, the drive belt should be the first thing you check.