MTD deck Issue

[Freddie21]

Hello All, I have a 2007 MTD\Troy-Bilt that the deck is causing me nightmares. The deck will vibrate heavily when the blades are first turned on or when under heavy load. When the manual PTO is engaged, it vibrates then smooths out. I have replaced blades, belt and spindle shafts. Blades are in alignment with each other and same distance off ground forward and side-to-side. Cuts evenly.
If it were a cracked spindle housing, I think it would not smooth out. Pulleys are level and even with each other. Brakes are releasing. The only thing I'm not sure of is the spring to the idler bracket. If it has lost tension, would it cause this problem? Thanks in advanced,

 

[ILENGINE]

Could be the case where the belts is trying to engage before the spindle brakes release. Could also be related to wear and slop in the deck hangars which allows more movement than would be normal. A 15 year old mower would have wear that could cause issue.

 

[Freddie21]

Thanks for the info. I did replace both hanger bars as the holes had egg shaped. I also replace the right brake spring as it was missing. The replacement belt is two inches longer than what was on the deck, but it is the correct OEM spec'd length. I will watch and make sure the brakes release before the belt tightens.
I did try another set of blades that were off a 38" deck and the vibration was much less. That's why I replaced the blades. I'm thinking the loner blades have more mass which amplifies the issue.

 

[StarTech]

Can be a bearing issue too.

 

[Freddie21]

All bearings are smooth and quiet. Thanks

 

[Hammermechanicman]

Get some zip ties and use a couple to compress a few coils if the belt tension spring to add some more tension and see if it helps.

 

[Freddie21]

That was a thought and I'm glad that someone else agrees with my thought process. I'm checking the brakes now.

 

[Freddie21]

Brakes are loose, tightening return spring did not affect. Last thing, I can think of, would be to replace spindles.