Speaking of mowers . . .

Tue Sep 21, 2010 3:16 pm

I've got a 3160 deck that I'm going to put new bearings and seals in. Anybody have opinions on torque setting for the nut? I'm thinking somewhere between 50-90lbs-ft, then back it off 90*. What does everyone think?



BTW . . .NAPA has/can get the seals and bearings. Seal# 12437, a little over $7.00 each. Bearings# PBR14, a little over $5.00 each.

Re: Speaking of mowers . . .

Wed Sep 22, 2010 5:07 pm

WHAT ! ! ! ! Nobody has an opinion?

Re: Speaking of mowers . . .

Wed Sep 22, 2010 5:10 pm

If you know the size and grade of the nut, there are charts (in front of most of the service manuals) that spec the torque based on that. I'm not familiar with your mower.

Bob

Re: Speaking of mowers . . .

Wed Sep 22, 2010 9:05 pm

One little wrench in the spokes . . . These are tapered roller bearings so they need "some preload" on them. Hence the torque guesstimate and then the "loosening" a bit. Kinda like an old style front wheel bearing on a car or truck.

Maybe I'm overthinking this too much . . . LOL

Re: Speaking of mowers . . .

Fri Sep 24, 2010 11:08 am

Your not over thinking it your conserned about doing it right the first time. Adjusting and preloading of the tapered bearings are very important. I see it done wrong most of the time. Being a retired class a machine builder i have to do it right the first time. Adjusting bearings for preload is very import ant to bearing life too.

First make sure your bearing races are fully pressed into the spindles. They need to be seated properly all the way down into the spindles. In some cases we freeze the bearing races and heat the housings.(250 to 300 degrees) This expands the bearing race bores and shrinks the outer races so they can be assembled with ease. After everything is room temperature you need to make sure there seated all the way down. A light tap with a bronze punch will tell you there all the way down and in place.

Do not over torque these nuts it will lead to bearing failure. I like to seat the roller bearing by over tightening them a little first, this will center the bearings and race together, then i back off and just tighten them enough so there is zero play in the shaft. Thats it. If its tight hit the end of the shaft on both ends with a soft hammer lightly, like just a tap to see if it loosens up. If not back off on the nut and repeat until it turns freely, yet there is no play in the shaft. Where talking vertical play in the shaft. With bearings things expand when they get hot. Now the next step is to assemble the spindles into the mower deck with the blades. You need to check if there is any play in the blades at the tips. If there is play you need to readjust the nut until the play is zero, gone. Then you know its right.

All the mower decks that have good bearings can be readjusted by the nut if they have any play in them. I have seen good bearings growl when the nuts are loose or not adjusted correctly. These can be readjusted and the'll be quiet again. With some grease too. I like to check the spindles every year when sharpen the blades and grease the deck. Then i can adjust the preload or replace the bearings if need be ahead of time before they fail. Just tighten it until there is zero play in the blades. If the spindles growl after you readjust the spindle nuts and grease them the bearings/seals need to be replaced.

I do the same adjustment on the 4x4 front wheel bearings(roller tapered bearings) and i see so many that aren't adjusted correctly and they fail. Even when its done by dealers and shops i never see the front wheel 4x4 bearings set right. Any play on the 4x4 bearings allows water to get in thru the seal sooner or later.