I have an older JD STX46 mower/tractor. It has the 3 blade 46” deck. Last year I took it off in the fall to clean up. I reinstalled it this week. When I activated the mower it almost shook my teeth out. I didnt let it run long for fear of doing some damage. So I took it apart last night. The one plastic idler/tensioner is bad, the main metal idler bearings grind, while the second stationary plastic one is ok.

I pulled the middle spindle and checked the pulley. It has about 1/32 runout, but the bearing feel ok. The other 2 pulleys have a little runout, but much less. I checked the blades and the are in good shape (new last year).

What the heck could be causing such severe Shake?? Are the pulleys that far out of true??
The belt is ok too.

I looked on amazon and
Egay about replacing spindles. Part number am124511 is about $35 and up. Part am124512 with a slightly smaller pulley is about $150 and up!!! Shit go figure. Some folks said they switched pulleys and the new spindle worked fine. I’m tempted to do that but I am afraid my pulley is too far out of spec. Any opinions?

Watch some YouTube videos and it might give you a good direction on what the problem is.

My girlfriend ran over a cedar stump and warped my JD mower deck. It also bent a spindle. I replaced the spindle and spent a lot of time with a sledge hammer and wooden blocks trying to true it back up. I got the wobble out of it, but it was not fit for cutting anymore unless you were happy with the bushhog look. Never could get an even cut after that.

Hey minnow, my other tractor is cutting bad on the middle blade. Hmm. I’m sure it’s bent now that you mentioned it. I’ll look after I get this one squared away.

Performed all the u-chube suggestions on the JD. No luck. I just bought 2 new pulleys to replace the idlers with have bad bearings. Maybe that will do it. I’ll try again tomorrow. I suspect the belt tension at this point. Thanks

I have replaced spindles, it was easy to do and not expensive. I saw a YouTube video today that showed grease fittings that didn't really grease the bearings, they came with sealed bearings. Being home for the last few weeks I have been working on my riding mower just for something to do.