Timemaster blade drive V belt insanity

[BoxendBozo]

Just overhauled the deck with new spindles after the main one (one that takes drive directly from V belt) failed. Took a knotted wire wheel to the underside and recoated with Eastwood rust paint and man does this thing throw clipping now. Went to clean deck after mowing and there wasn't anything in there. Happy about that. However, the blade V belt idler when blades engaged dances around like it doesn't even want to be in there. Makes some squeaking noises to. The idler lever assembly seems to be ok, . There is conveniently no mention of this assembly or adjustment in the manual. I did try moving the blade engagement cable housing to and fro a bit, and while you can feel a change in tension on the lever, it make no change to the violently shaking idler or power loss. The condition also seem to be causing the loss of hundreds of watts of power into the blade drive system, making the input V pully on top of the first spindle so hot you can't touch it. I am fairly certain this heat mainly contirubuted to the spindle failure. The unit is 5 years old. The V belt is new and the blades run smooth as butter. Timing and timing belt adjusted properly, etc. I really don't get it. The belt does seem to have a bump on the back side that might be irritating the idler but I see in many pictures for sales of this part the same "growth" in one spot. The only thing I didn't inspect is the pulley on the engine shaft, but it's been raining so much I'd have to take a boat out to the barn for the next couple days. Has anyone ever seen something like this?

 

[Rivets]

Sounds like the idler pulley, on the tensioner arm, bearings a shot. Remove the pulley and spin it in your hand. Any roughness means replace. Part #26 on page 6 of the manual. https://www.toro.com/getpub/124397

 

[BoxendBozo]

I wish that were it. I just re-checked the idler assembly and amazingly everything seems to be smooth and tight. No out of round on the roller or anything unusual about it. The tensioner arm makes limit to limit excursion, about and inch or so, when blades engaged. Something is clearly wrong, and I'd think it would be rather obvious, but I'm baffled so far.

 

[Rivets]

From your description I would be looking at the idler pulley or the belt. What was the part number of the new belt you installed? You did use a Toro belt, right? Did you remove the pulley and test it? More than once I’ve found pulleys seem good, but when I remove and test them in hand I can tell they are bad. Please post your model and serial numbers.

 

[BoxendBozo]

I orderd the Toro belt number 121-5765 from ereplacementparts. I'm pretty sure it had the Toro number stamped on it, though it's already worn mostly off. I know what you mean about bearings seeming okay until you can get your fingers on them. At this point it almost has to be something funny with the belt. I kinda wish I had kept the old one for a spell so I had something to swap out. It was worn but not severely.

I know these "greenish" belts are a special class but it seems like it ought to have a little more tensioner load in the blade engage state than it ever gets with any adjustment of the control cable, but maybe it's normal.:confused2:

 

[BoxendBozo]

Timemaster blade drive V belt insanity (solved)

Alright. When I got around to checking out the idler assembly part numbers I found that they had funny names like "Washer-Rebound" and "Washer-Friction,Composite". The idler arm mount is supposed to have damping. Mind didn't. I tore it down, cleaned what's left of the Teflon film glued to the rubber washers, and took 25-30 thousandths cut off the length of the spacer to compensate for loss of compression in the stack due to wear. It worked. I don't think it's as tight as original design but now the idler wheel deflection is under 1/4" at idle with blades engaged. It'll be interesting to see if efficiency is improved. It certainly sounds better.

 

[bertsmobile1]

Good result.
Buy yourself a new washer & keep it handy because your fix will probably only be good for a season or two.
During the off season pop the new one in.
If you had included your full model number you would have gotten more informed replies as we could have looked up the IPL for your mower & deck.
People who do this stuff for a living can usually recognise wear / problem points from an IPL.
Otherwise all you will get is general causes of your synptoms which are worn bushes , collapsed bearings

 

[BoxendBozo]

I'm only hoping my "repair" lasts one mowing. Replacement parts are on the way. Thanks for the heads up on the part numbers.

 

[slinger2]

I'm only hoping my "repair" lasts one mowing. Replacement parts are on the way. Thanks for the heads up on the part numbers.

I had a similar issue. On my 2012 I noticed the belt tensioner arm vibrating like crazy. I removed the tension idler arm and noticed that the spacer (p/n 138-3244) which is the shoulder bolt type piece that the idler arm and friction washers mount on had a big groove worn in it from the belt tensioner arm rubbing on it. It was even worn at an angle so that the entire arm and idler pulley was not parallel to the other pulleys and belt. This was causing extreme heat build up in the belt and pulleys. I have ordered new parts (spacer, tension arm, friction washers and Idler pulley). This should fix it but doesn't explain why it happened in the first place.