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All,

Had loaned a 21" Craftsman mower (917.378641) to my brother-in-law some time back, he finally returned it to me this week. Mower has fairly low hours and 7.0 B&S engine, so although not collectible, I'd like to put it up for sale to recoup $50 or so on it. Unfortunately, when it was returned to me, the front drive was not working.

I traced the problem to the transmission, and not the drive wheels.

I've removed the transmission and disassembled and noted that the worm shaft is not contacting the gear within, suggesting wear. The wear looks to be at the helical gear as the teeth are squared off and there is a significant curvature on each tooth.

Anyone have experience repairing these? Although experienced with small engines on most brands, models, and sizes, transmissions is not an area where I've got experience. I could pick up a replacement transmission at $60 which makes the mower not worth re-selling, or I can pick up some of the components within the transmission at a few dollars each. I just don't know if I'll need more than just the gear to make it work again (worm shaft too? bearings?).

Thanks in advance!

#11, doesn't look normal to me:


#13, doesn't look too bad:

Consider looking at a new piece. Or best bet at a junk yard and getting a new tranny without the labor and extra cost.

that mower is worth more than $50 from what your saying.....more like $120....if you can get that tranny for $60 new...get it.....otherwise get a new helical/worm gear/4 new #4 bearings and needle bearing and some grease to rebuild...total= $45 plus shipping?

reddragon said:

that mower is worth more than $50 from what your saying.....more like $120....if you can get that tranny for $60 new...get it.....otherwise get a new helical/worm gear/4 new #4 bearings and needle bearing and some grease to rebuild...total= $45 plus shipping?

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Thanks, I probably did underestimate the value of the mower, I will definitely ask more.

Still, after looking at the trans innards some more, and finding a post on another forum by someone with a similar problem, I think the helical gear is the only problem. For $9, I think I'm going to start there.

Thanks!

Hello there. Does anyone knows where i can buy the helical gear and the worm. I bought a new transmission and of course when I installed, the wheels started to spin backwards :thumbsup:, so i will have to replace the gears for the right ones.

Thanks in advance.

check to see what mower parts are local.....if somethings wrong...you have a real person to talk to... http://www.searspartsdirect.com

reddragon said:

check to see what mower parts are local.....if somethings wrong...you have a real person to talk to... http://www.searspartsdirect.com/partsdirect

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Well, first of all thanks for the quick response. I tried that, and they sears wants to sells me a new transmission again, and all i need is the helical gear. Any other suggestions?/

Best Regards

go ahead and give us your model/serial numbers and gearbox numbers too....thanks

reddragon said:

go ahead and give us your model/serial numbers and gearbox numbers too....thanks

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Red dragon, just found them in the lawn more store by the corner, bought the worm and the helical, and lawnmower working like a new one. All i hope it last another 15 years perhaps??:biggrin:

Thanks again for all your suggestions

Best Regards

good deal!:biggrin:

rfernand1970 said:

Hello there. Does anyone knows where i can buy the helical gear and the worm. I bought a new transmission and of course when I installed, the wheels started to spin backwards :thumbsup:, so i will have to replace the gears for the right ones.

Thanks in advance.

Click to expand...

Got mine online: jackssmallengines.com. To my door in two days.

Ended up replacing just the helical gear and it's working great again!