How to adjust tension on belt of John Deere Ride On D140

John Deere 42in Deck: There are 2- 10mm adjusting bolts on the bracket that secures the cable & spring to the tensioner pulley arm. .As the belt wears it will stretch . with the engine off, tension the belt with pto on then check belt tension,it should feel firm but not loose. loosen the 2-10mm bracket bolts on the cable bracket & move away from center of deck then tighten.This will increase spring tension for the tensioner pulley.

I bought a new belt and tightened this pull and my belt still jumps off within 5 minutes of cutting. Also it only has 14 hours on it.

How to adjusted Cutting Deck Belt Tension

You do not say which size cutting deck you have. I will be writing about the 48", 3 blade cutting deck

The belt on this deck is self tensioned. The tension is provided by a spring attached to a moveable pulley on the deck. When the belt is in place you can manually force this pulley forward/backward and it will release the tension.

If the belt is off track, place the belt back around all the pulleys in the correct path, lastly force this spring loaded pulley forward/backward (depending on your deck, the direction is not important, the tension is) to get the belt around the pulley. If the belt is placed correctly, when you release the spring loaded pulley it will properly tension the belt.

Typically, these belts should not be jumping off. If yours is coming off frequently the belt may be worn. When they wear they get quite a bit longer, then the tension pulley cannot apply the correct tension. Rarely does the tension spring have to be replaced.

The other problem that causes belt jumping is worn spindles and stationary pulleys. The spindles are the most likely to need replacement. You can buy excellent replacements for JD spindles on Amazon for very reasonable prices. The following spindles are super replacement spindles for the 48" deck. They may very well be the same for smaller and larger decks; I have not researched that. Just search Amazon for Silver Streak # 285851.

Silver Streak # 285851 Spindle Assembly for JOHN DEERE GY21098, JOHN DEERE GY20962,

Product description:
Spindle Assembly / John Deere GY21098 Pack Size:1 JOHN DEERE GY21098, JOHN DEERE GY20962, JOHN DEERE GY20867, JOHN DEERE GY20454 OREGON 82-359, ROTARY 12910, ROTARY 11964 JOHN DEERE D100, D110, D130, D140,D150,D160, LA100, LA105, LA110, LA115, LA120, LA125, LA130,LA135, LA140, LA145, LA155, LA165, X110, X120, X140 Includes grease Zerk, pulley lock nut, blade lock nut, and washer , Height: 7 ", OD: 5 "

You can also find replacements for the flat pulleys on Amazon. If you cannot find what you need there, go to http://www.greenpartstore.com//