Replacing the Deere Secondary Belt Tensioner Spring   

  Gordon Speer, 3304 Woodlawn Road, Sterling, IL 61081-4144  
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My 3 tractors are all 1972 vintage, so occasionally there are repairs to do. Usually the service manual provides all the help needed, but in this case I had to ask the experts at the Deere dealership for advice.

While sweeping leaves a few weeks ago I noticed a sudden loss of pedal pressure and found that the secondary belt tensioner spring had broken. The service manual didn't provide any help, but now that I have replaced the spring I thought I should write up the procedure.

The Model 110 tractors (and probably most of the larger ones of the same type) have two main drive belts. The primary drive belt goes from the engine to the variator (continuously variable transmission). The secondary drive belt goes from the variator to the transaxle. The tension on these two belts is provided by a spring from the secondary idler to the tractor frame. In the Model 110 Serial# 250,001- this spring is part number M41946, and it retails for $4.95. You can see the black spring in the photo just to the right of the gearshift handle, and the idler pulley is just to the right of the spring. When you replace this spring, remember to put a little grease on both ends, and on the little hook that holds the rear of it. The whole procedure follows:


  1. Unscrew the four black knobs (mower height, PTO, brake lock, gearshift). If they need to be painted, now is a good time - use bolts to support them and spray them with glossy black enamel.
  2. Remove the gearshift escutcheon (2 screws). Unplug the neutral safety interlock connector.
  3. Remove the four acorn nuts that hold the deck to the rubber support bushings (1/2" hex wrench). If your seat has an electrical interlock for safety you'll need to unplug it. The seat can stay attached to the deck.
  4. Raise the front left corner of the deck about an inch with a block of wood.
  5. Remove the cotter pin that keeps the pedal in line and loosen its clamping bolt with an offset 9/16 wrench.
  6. Gently slide the pedal off its shaft. If it requires some tapping, take some time to clean up the pedal and shaft until you can assemble them easily by hand. Lubricate both of them with oil.
  7. With a helper, lift the deck & seat off the tractor and set it aside. You have a perfect opportunity now to change the transmission lubricant while you are replacing the broken spring. I have a half-gallon plastic milk bottle with a "Sharpie" line drawn at the 3-1/2 pint level (halfway up the handle) that I keep in a dust-free ziplock bag just for this purpose. I keep a little funnel in the same bag. Note that the top threaded plug has a breather to let air in and out of the transaxle, and the bottom (drain) plug has a magnet to hold iron particles. Clean both of them carefully, and DONT MIX THEM UP.
  8. If you are lucky the little hook that holds the rear of the tensioner spring will still be in the metal plate that the idler pulley is attached to. If it is missing, or badly worn, buy another one from your dealer. Mine was still there and in good condition. Grease it.
  9. You will need to fashion a long hook to stretch the spring as you install it. I made one from the wire bail of a 5 gallon plastic bucket.
  10. Reach under, about where the instrument panel is, and find the hole in the frame where the spring attaches. I was lucky enough to have part of the old spring still hanging there. It was farther forward than I expected, but easy enough to reach. Hook one end of the spring there.
  11. With your helper holding the little hook the rear of the spring attaches to, stretch the spring back and hook it on. This was not as easy as I expected it to be, but we got it done.
  12. Do any necessary touch-up painting and lubricating while you have the chance, and reassemble everything.

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