Mower deck vibration problem

[KREP 15]

Hey folks, I’m here most of the time to read and learn, but today I have an issue. My 48” deck on my 416 is vibrating badly. The machine runs great, but when you engage the pto to get the blades moving it shakes like crazy. I spun the blades by hand, and the left blade is not off, but the pulley dips a little on one side. So little you have to really look hard to see it the other 2 blades and spindles and pulleys seem to be ok. What am I missing. Thank you in advance. 

Edited November 11, 2020 by KREP
Rephrase

[oldlineman 1,495]

possibly bad bearings in one or all spindles, there will be more help coming. Pictures would help a great deal. 

[KREP 15]

If you grab the blades and pull them side ways, there is no play in them. Or up and down slop. 
 

it’s just a good old red deck, with 3 blades. 

[oldlineman 1,495]

Possibly blades themselves are out of balance  

[pfrederi 18,360]

Pull the deck and flip it over.  Check to see if the blades meet at the same level end to end. Areas of the deck the spindles mount in could be warped (though with the brace on 48" decks that is not frequent issue...but if you are convinced the spindles themselves are OK...worth a look.

 

Also see if the idler pulley is in good shape and the sliding bar it is mounted on moves freely..

[oldlineman 1,495]

Just a thought are the belts in good shape?

[KREP 15]

.

Edited November 11, 2020 by KREP

[KREP 15]

Only about 2 hours. OEM From dealer 

[KREP 15]

The blade tips are ok, I checked them first to see if blades were bent. 

[KREP 15]

I will pull the blades and see if they’re off balance?  They don’t look like they’ve been hit or chipped.  Maybe I’ll do that this week.  Like I said. The onan runs real smooth, but when you pull the pto lever it shakes like a wet dog. 
 

I took the belt off and spun the blades while looking at the top of the spindle, and no off center movement. Then I did the same looking at the bolt holding the blade in place. All 3 were ok. The blades were seated nice and flat on the spindles and no wobble when rotating. All I can think of is something I can’t see.  And the only thing I can’t see is the bearings, but they rotate smoothly and not noisy. I put a 45 degree zerk fitting on the middle spindle a long time ago, so all 3 are easy to lube, and get grease frequently.  Hmmm 

 

I got a while to figure this out because I don’t think I’ll need to mow again til spring. 

Edited November 11, 2020 by KREP

[peter lena 9,097]

krep, sounds like you should be able to find this issue fairly easy, did you hit anything ?  or did this just start to  go crazy? I  would think its an impact or bearing failure , never had the wet dog shake issue. drop the deck and give it a thorough inspection , might be hiding in plane sight , let us know , pete

[tom2p 2,394]

1 hour ago, oldlineman said:

Just a thought are the belts in good shape?

and mower / rotary belt properly tensioned ?

 

 

 

[Lee1977 7,046]

A small piece out of either the deck belts will cause it to shake. You can't always tell if a bearing  is bad by turning it by hand.

[Ed Kennell 40,604]

Inspect all the Vee pulleys for something lodged deep in the vee.    I have found pieces of belts and chips of wood.       Check the PTO, the mule drive and all the deck pulleys.

[Bill D 2,103]

Check your mule drive pulleys.  My Dad had the bearings fail completely on one of his.  It made the whole tractor shake.  Check for debris stuck in the vee pulleys.  I have also had a pulley break the hub out at the weld.  Also, is it just the deck that shakes, or the whole tractor?  If it's the whole tractor check the compression in both cylinders.  It is possible you could have a broken connecting rod.  Remote but possible.  A broken rod would make the whole machine shake under load.  Bill

[KREP 15]

I got to thinking back. I bought the new belt because the deck started shaking, and it didn’t help. I mowed that way a couple of times, but was afraid I’d cause damage that way so I quit and started using my Ford 640 with Woods 60” again. 
I checked out the deck and finally got on this site for help.
 

Last year I had electric trouble and the folks here helped me out. I was just out and I noticed the tensioner seems loose. I’ll look at that tomorrow and see if it’s broke.  I don’t know if reduced tension will cause this condition, but I will see tomorrow. I am thinking of taking the blades off tomorrow and comparing them to see if there is any thing obvious or out of balance. 
 

thank you for the suggestions and your expertise. 

[Bill D 2,103]

Are you talking about the mule drive tensioner for the engine to deck tension, or the spring loaded tensioner for the deck belt?  A loose mule tensioner may indicate failed bearings in the mule drive pulleys.

[KREP 15]

I’m thinking the tensioner on the deck. Spring loaded to tension belt on pulleys. 

too much going on today, can’t look at deck today. thank you 

[KREP 15]

Probly won’t get a chance to look until next week. Got a full schedule for a few days. 
 

I'm suspecting the deck belt  tensioner is not working correctly.  Will look at it as soon as I can. 

[KREP 15]

Blades off and Check ok. Belts fine. Looks like I’ll be ordering 3 new spindles tonight. Are 8ten  brand ok? No brand on most on EBay. 

[Bill D 2,103]

Any pictures of your spindles?  Loose blades can cause vibration by wearing the shaft and causing the blades to no longer be centered.  From everything you have posted I don't think you need new spindles.  I think it's a tensioner issue.  Fix the tensioner before you buy new spindles.  Bill

[johnnymag3 2,559]

You dont need spindles...............................

 

Something is way out of whack, other than spindles

 

PICTURES PLEASE...

 

 

 

[KREP 15]

Well, the belt is nice and firm, not loose as it revokes. Blades flat with no damage. The spindles all revolve with widely varying resistance. One easy, one with lots of resistance, one in between. So I’m guessing that’s it. A hundred bucks for a set of 3.  Nothing else is visible. Blades don’t wobble.  Belt not damaged, pulleys all clear. The spindles are original from 1989. It won’t hurt to change them. 

Edited November 17, 2020 by KREP

[953 nut 58,102]

10 hours ago, KREP said:

One easy, one with lots of resistance,

That would do it, the belt tension on the deck would be bouncing from the variance of resistance. 

[Bill D 2,103]

You can get 12 6203 bearings for less $30.  Spindles can be rebuilt in deck if you want.  Very easy to do and they are better quality than anything new that isn't OEM.  If the spindle housings aren't rotted, rebuild them.  Save them for parts if you do replace them, or sell them.  Bill