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Lawn Boy Insight, no self-propel, rear wheels lock up.

Discussion in 'Mechanic and Repair' started by jim d., Dec 23, 2006.

  1. jim d.

    jim d. LawnSite Member
    Messages: 61

    So today I'm happily munching leaves with my Lawn Boy Insight series self-propelled mower when suddenly the self-propel mechanism stops working and the rear wheels lock up when I try to pull the mower backward. I tried removing the rear wheels to see if leaf debris of some sort was responsible and found nothing. Any ideas?
  2. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,247

    Several general things to check:

    1. Remove rear wheels and check for anything lodged between the pinion gear and gear on inside of wheel. Make sure gear on inside of wheel is still solidly attached to the wheel.

    2. With the wheels now off, on a flat concrete surface, start unit up and engage drive system. Does the axle turn? It it does, your problem likely is in the frictionwasher, clutch washer, thrust washer, engagement key and pinion assembly on either or both sides of the drive shaft. If the rear pivot arms have not been greased on a regular basis, the plastic clutch washer gets hot and becomes ineffective in engaging the drive key inside the pinion.

    3. If the axle does not turn in (2), check for something lodged in the drive belt/transmission pulley. With the unit off, try turning the transmission pulley by hand. If it will not turn, you have issues inside the transmission or the axle could be frozen in the pivot arm. LB started haveing some real problems with excessive wear in the input pinion and bevel gear. I would guess that I replaced at least 30 such sets between 99 and 02(my last year in the shop). If the pulley does turn and the axle does not react, this is likely your problem.

    4. If you cannot pull the unit backwards, you most likely have a lock up situation somewhere.

    5. For a parts breakdown go here http://www.lawn-boy.com/productinfo/mowers/Insight/flash/feature.html
    Choose your model number and you're good to go.

    6. I believe Lawn Boy still has a 2 year warranty so is your unit is less than within the time frame take it back to your dealer. On the other hand, if you have not regularly greased the rear pivot arms, any damage there will be on you.

  3. Roger

    Roger LawnSite Fanatic
    Messages: 5,929

    Dutch, you must have worked on these mowers recently. I have older LB and have worked extensively on the drive systems in the rear wheels.

    I looked at the parts diagrams for the Insight mowers. It looks like the mechanism is similar to the older models, but not quite. I see the retainer washers, the step washer, pinion gear, etc. And, I see a key on the outboard shaft. But, it is not a "rocking key" and is not shown as a right hand and left hand part. This would lead me to believe the mechanism is not the same.

    Are the newer mechanisms better or worse than the former ones?

    I am very interested in the impending Platnium model, with the Honda X engine (I am told available by June/July 2007). Based upon past history of LB products, I would think the rear drive wheel assemblies will be the same as the Insight Gold as questioned in the top post.

    What do you think (presuming you have some experience in repairing the existing models)?

  4. Roger

    Roger LawnSite Fanatic
    Messages: 5,929

    Dutch, one more question ... How does the Sens-a-Matic (or whatever the marketing term) work for variable ground speed contol. I look at the part diagrams and I see some parts on the upper part of the handle, including springs. But, I don't see how any movement in the upper part of the handle translates down to the drive assembly and transmission.

    I thought a variable width sheave was used on the engine-to-transmission transfer. But the parts diagrams only show two pulley halves, bolted to the pinion shaft (down to the beveled gears in the final drive). Therefore, that sheave is not opening and closing allowing for different drive rates.

    Any insight (bad pun) on this variable ground speed control? Is it a sound system, or one that is prone to failure with heavy commercial use? Maybe I need to spend more time trying to figure out the parts diagrams. Obviously, I have not taken one apart.
  5. jim d.

    jim d. LawnSite Member
    Messages: 61

    Thank you very much for the detailed information, Dutch. I'll check it out today.
  6. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,247


    It depends on the age of the LB. For the most part, from the time Toro bought out Lawn Boy, possibly a dozen years ago or more, the drive systems have been pretty much the same on the two brands, very much like the Insight series.If you post the model and serial number of your LB I'll check it out. I hope you're not going as far back as the old LB's that used the serrated roller to drive the rear wheels.

    What Toro refers to as the Personal Pace is identical to the LB Sensi drive system. There is no variable speed pulley and the system depends solely upon belt tightness/slippage against the friction of moving in grass. When you push down on the upper handle, the cable attached to the handle activates the arm on the transmission, tilting it back a little, thus tightening the belt.

  7. Roger

    Roger LawnSite Fanatic
    Messages: 5,929

    Dutch, thanks for the information. Two things come to mind, ...

    First, thanks for the offer regardfing the parts information. I do have parts manuals for the machines I own, one is a Dura-Force, the other a pre Dura-Force model. The wheel assemblies are the same in both, and I have repaired and replaced them many times. I think you answered my question: the Insight series uses a similar mechanism, even though the diagrams aren't the same as my machines.

    Second, I am amazed at the speed control being a slipping belt. I guess such an idea goes against everything I've ever understood about proper belt tension. I would think the belt life would be short to run the machine much of the time with a slipping belt. Presumably, the only time when it would be running tight, with no slippage, would be at maximum ground speed (specs say 4mph, a bit too fast for my walking).

    The diagram shows a ground drive cable running from the handle assembly (the movable portion), but the destination of that cable isn't apparent. Anyway, thanks for that information.
  8. AndyTblc

    AndyTblc LawnSite Fanatic
    Messages: 5,480

    Samething happend to me 2 years ago, I will never own a lawn boy ever again. Not dependable at all.
  9. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 13,835

    I didn't understand the explanations but what I found is the mechanisms that actuate the variable speed devices wasn't returning. I lubed everything I could find, like cables return springs lever pivots etc. and the problem stopped.
  10. Roger

    Roger LawnSite Fanatic
    Messages: 5,929

    I don't think the Insight models were on the market two years ago. What was not dependable on your LB? A consumer model, or a commercial model? Please elaborate. Thanks.

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