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JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1102
Experience:  Owner/Service Technician at S & J Small Engines
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Only the right side rear wheel turns when the SP is engaged

Customer Question

only the right side rear wheel turns when the SP is engaged
Submitted: 1 year ago.
Category: Small Engine
Expert:  JohnF2015 replied 1 year ago.

Hi, my name is***** will be assisting you.

Did this problem just occur on its own or right after you had work done on it?

Expert:  JohnF2015 replied 1 year ago.

Be sure to look at the gear inside the rear drive wheel to make sure that the teeth on it aren't worn out. The key needs to float freely in the end of the axle and make sure that the spring under the key is not broken. The only other thing that might cause a problem is if the pinion gear is directional you may have it on the wrong way. Take a close look at the pinion gear and see if it has an L and R on it, if it does you will want to be sure that when it is installed the L is out toward you when installed on the axle.

Expert:  JohnF2015 replied 1 year ago.
Do you still need assistance with this problem?
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Customer: replied 1 year ago.
sorry, I am back in town now and can work on this mower again. This happened on it's own. The wheel teeth are good. Not sure what you mean by "key"
Expert:  JohnF2015 replied 1 year ago.

There is a small key that sits in a groove or slot in the axle which has a spring under it, the spring is there to push the key up into the center of the pinion gear which makes it drive or operate. If you remove the pinion gear there should be a key in the axle.

Customer: replied 1 year ago.
how far from the wheel is this key?
Expert:  JohnF2015 replied 1 year ago.

Within about 1/2" - 3/4" of the end of the drive axle.

Customer: replied 1 year ago.
ok I found the key. can i just shoot some wd40 on it to see if that will loosen it?
Expert:  JohnF2015 replied 1 year ago.

Yes, you can try that. It needs to move up and down freely in the shaft. There is a spring under the key so make sure that you don't loose it if you remove the key. You can also use a screwdriver to help free the key if it is stuck in the axle.

Customer: replied 1 year ago.
got the key out and shot some wd40 into the slot where the spring is. now the key moves up and down. I noticed the pinion gear is uneven on the inside (not completely round). Is there a trick to put the pinion back on the shaft? I don't want to get it back together only to find out the pinion gear can only slide on the shaft in a specific place
Expert:  JohnF2015 replied 1 year ago.

You want to make sure that it is installed properly otherwise it will not work. If you look at the pinion gear do you see an L on one side of it?

Customer: replied 1 year ago.
I don't see an L on it but maybe the rust is hiding it. As far a which end of the pinion gear go's on first, that is not a problem. There is a steel O ring that goes on the outside where the pinion has a O slot for the ring to fit into.
Expert:  JohnF2015 replied 1 year ago.

Okay, just keep in mind that if you get the machine back together and the left side isn't pulling that it could be a matter of the pinion gear being installed backwards. The pinion gears are both the same part number on this machine, however the gear is normally marked with an L on one side and an R on the other side, the letters would be facing outward on their respective sides of the mower. As long as the key is working freely in the axle and the pinion gear is installed correctly then the machine should operate correctly.

Customer: replied 1 year ago.
Ok are you suggesting that I take the pinion gear on the right side off also? It has never been off so there should be no way I have the 2 mixed up. The right side is pulling fine so I did not see a reason to mess with it. Once I get the left side back together, if both wheels are driving (pulling), I won't mess with the right side of the mower.
Expert:  JohnF2015 replied 1 year ago.

No, I would not take the right side off, it is not currently causing you any problems therefore I don't believe that I would do anything with it.

Customer: replied 1 year ago.
ok both sides are pulling now. thanks for your help. i also have a lawn boy that has a pull cord problem. when I took the top off, a small spring and a small steel flap came out. any suggestions?
Expert:  JohnF2015 replied 1 year ago.

The spring and flap are part of the engaging mechanism that makes the pull start work. The flap is actually called a starter pawl and it flips out into the starter cup that is on top of the flywheel when you pull the rope. The spring is only to help retract the starter pawl when the rope is released to rewind. You should have a second spring and pawl in the opposite side of the starter pulley right under the top plate that holds the pulley into the housing.