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timflury

Mower deck spindle torque, bearing preload setting

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timflury
It seems I didn't torque the large nut on my deck spindles correctly the last time I rebuilt them. The preload is gone and there is even a little play side to side. When I was putting them together, I torqued the large nut until the spindle wad hard to turn, but not stuck. I slowly backed off the nut until there was a little resistance, but not too loose. I got two seasons of mowing out of these and they now make lots of racket when I start the blades. The pulleys fit nice and tight on the spindle. The old ones I pulled off had the keyed hole all wore out. What's the CORRECT procedure for rebuilding these??

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PhanDad
From the A/C B Series Repair Manual, Attachments Section: New locknut 70 ft-lbs; used locknut 45 ft-lbs, from pg C7 #4 below. Some might call this the "correct procedure", I've never seen any other specific repair instructions:




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MysTiK
Not sure what deck, or what spindle type, or if that matters in a general sense. Exploded view diagrams I have seen often have a torque range on the diagram, usually expressed as a range of torque. I think they are to be torqued to that range spec - full stop period. I might be wrong; but this reminds of guitar tuning. Beginner guitar players use the tuning pegs to dial in the correct "pitch" or note. Then they complain that their guitar won't stay in tune. I tell them, when tuning, to tune below the desired note, and then "tune up" to the exact pitch - and this ensures there is no "slack" left in the string. Slack, while playing, disappears due to vibration, or maybe stretch, and when that happens, the string has less tension, and when plucked, or played, it will sound low, or "flat". I would not back off at all when torquing - with a new assembly, new grease, etc., there is going to be some undetectable slack in the assembly of stacked parts. The torque deals with that slack. Torque figures might be specific to your deck; but probly range is like 40-60 ish ft lbs. or similar. Basically tighten and leave it alone. Just like a guitar, it seems to me. Note that your deck might have a pleasant ring to it also. 8D I tune be ear; and I torque by feel. There might be a better answer to your question.

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MysTiK
more guitar lessons :D In Phandad's diagram - "new and used" - it's same with "new" guitar strings. Going onstage w new strings is near suicide. New strings get tuned, and then they stretch and settle in with the other parts of the git, like bridge, pegs, nut, tuning machine heads, etc. It can require tuning tuning tuning like ten times, often, before it all settles and stretches and fits. Or tune it maybe twice, then walk away for an hour, and retune, and then good to go. works for me. But the settling in can take hours. The "new and used" idea is about the used metal being pre-squished - or like that. terminology. 8) I was told that deck spindles are not precision instruments. Best advise I ever heard.

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Willy
I just crank them down there not a tapered bearing,so you shouldn't need a preload. Just MHO I have never had any problems,I burp them down with my impact wrench,be careful and don't go crazy. Work:Ds for me.

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toomanytractors
Do NOT use the old nuts over!!!That's the best way I've found to lose a shaft or pulley. Self locking nuts are not made to be used over. Been there, done that and it ended up costing far more than the new nuts would have.

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timflury
Bearing preload in this case is already set in the bearing when they are new. You will notice a little resistance when rotating the bearing in your hand. In a case where you have a tapered roller bearing like on a trailer, you tighten down the bearing to seat it, then back off the nut and rotate the hub and tighten the nut until resistance is felt (this is setting preload), then put on the retainer and cotter pin.
quote:
Originally posted by toomanytractors
Do NOT use the old nuts over!!!That's the best way I've found to lose a shaft or pulley. Self locking nuts are not made to be used over. Been there, done that and it ended up costing far more than the new nuts would have.
I think this best explains my issues.:I:I

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timflury
Well, I installed a spare set of spindles and started to mow my lawn. I got about 3/4 the way done and the engine crapped out. It wouldn't run under a load, but it would idle just fine. Now I have another project.

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