Slipping in 3rd Gear

steve0701

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Feb 17, 2011
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My 1990 walk-behind started slipping in 3rd gear recently. All the transmission gears look perfect and I changed the grease, but the problem is still there. I can feel the gears intermittently trying to catch. The belt is fine and so are 1st and 2nd. Has anyone experienced this problem? Is there some way to adjust the shifter cable? I am thinking that the transmission lever may not be moving far enough for 3rd gear to engage. Could this be related to the automatic clutch? I don't know where it is located but it's supposed to prevent the drive wheels from reversing, unless you let it coast forward for a few inches first.
 

scorpwrench

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Apr 24, 2011
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That auto clutch you're talking about is the "rocking key " pawl mechanism they use in the pinions for the rear wheel drives. The idea was when the mower was put into drive the keys in the drive pinions would tilt in one direction engaging the pinions and driving the wheels. When you stopped or pulled the mower backwards the keys would tilt the other direction allowing the pinions to disengage and let you pull the mower back easy. Sometimes they would hang up & you had to push the mower forwards a few inches to get them to let go.
If they hang up a lot, just take the wheels off exposing the pinons, take them apart and give them a good cleaning and some light oil. That should get them working again.
 

steve0701

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Thank you for the reply. Yes, those troublesome little clutches are not acting right- they actually turn the gears backwards when I back up, but my primary problem was a worn bushing where the output shaft enters the gearbox, probably made worse by having too much tension on the drive cable. Once the bushing enlarged too much the gears had room to move apart and disengage. Check out the before and after photograph, it clearly shows the damage. BTW, this part cost me $17, but it did exactly what it was supposed to do- sacrificing itself to prevent the shaft from wearing out.
bushings.jpg
 

scorpwrench

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I have one of those 3-sp mowers too with a Duro-force engine on it. Thanks for telling us about that bushing, I'll watch out for it on mine. I also have one with the "personal pace" system. I like the 3-speed better. That sliding handle is hard to get used to.
 
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