MTD Self Propelling - Model # 12A-559K401

Right side front has excellent drive - good and strong

Left side at first had no drive at all, so replaced the left wheel (teeth were worn), the gear and dowel. Left side now drives (the dowel had been missing), but drive power is very weak. As soon as you put pressure on the wheel it has no real pull power, but does turn ok if you tilt it in the air.

So ...strong right side + very weak left = me pushing, which is not a good thing in thick south Florida floritam grass at 95 degrees.

You've probably seen this many times, right? Looking forward to your suggestions.

 

The weak power is now at both wheels, right? If so, the engagement cable may need adjusting (if this one is adjustable) to put more tension on the belt, or the belt may need replacing.

 

It would make no sense that your left side would still be weak and not the right since you have replaced every part necessary related to the left side drive. If, indeed, the left side only is still weak then you may have a broken axle - left of the transmission. If, on the other hand, both sides are weak then you should find a thumbwheel up on the handlebar control that you can turn to increase tension on the belt. And, if needed, you can replace the belt with an MTD replacement, part number 954-04032B.

 

I did replace the belt same time as the wheel and gear. Also the adjustment for the belt is right on (thumbwheel type).

You might be on to something, regarding the axle, but the output shaft appears to be one solid piece, so at least from the schematic it doesn't make sense unless I'm missing something.

Agreed....doesn't make sense.

Guess I'll have to open this mower up further.

If any other thoughts cross your mind please post.

Thanks.

 

Ok guys here we go again........

Took wheel off left side. My nice new plastic tooth wheel has 80% of the teeth nicely smoothed down to nothing by the steel gear. Look like it probably jumped teeth while mowing and started grinding away.

Ok - that explains why after replacing these parts on the left side it seemed a whole lot better and then quickly deteriated back to its "weak left side" for pull power. This problem is repeating itself.

So, I think a steel teeth wheel would be the answer - do they exist for this mower??

Thanks.

 

A self propelled walk behind mower is designed to only pull itself and not the opperater.While you may not be trying to ride on it (like...beleive it or not I have seen with my own two eyes).The engine turns the tranny,which in turn the wheels,so fast that if you can't keep up with it,that is exactly what happens.
I get out of reading about the problem that on turns (especailly left turns) when more stress is on the left side of the mower...you walk slower causing the left wheel to drag on the ground.All the while the steel gear behind the wheel is spinning faster than the wheel.It's going to eat up a plastic gear.No getting out of it unless you stop the self propelled works to make a turn.


Just my thoughts on the matter.

 

Repair_guy - sounds funny, but maybe you have something there. Maybe I should take mower driver's ed on left turns again - just kidding.

One thing is for sure - I've never had a problem with the right side....hmmm and the mower is about 8 yrs old I think.

Just out of habit I guess I do keep the drive engaged most of the time. Guess I thought it was tougher than that.

Thanks. I'll order another wheel (have to anyway) and change driving habits.

 

When I use a self-propelled walk-behind (rarely), I pick up the front of the mower to make the turn if it's a 180 degree turn. I come back later along the ends of the cutting path to cut the edges where it missed from being picked up.

 

I'd say you either have a wheel mount stud that is well worn or the bearing plate where the axle comes through is well worn. In other words, either the wheel is quite sloppy where it mounts or the axle has too much play at the point is comes through the bearing plate and is causing the premature wear with the plastic gear in the wheel. For reference, MTD part numbers for those items are: 682-0509, pivot (wheel stud); and, 782-0511A-0637, bearing plate.