# Slipping deck belt for the blades



## dsmith1313 (Dec 7, 2012)

I have a Troy-Bilt Bronco 42" cut that the deck belt slips. On the raising/lowering lever when it is in 1, 2, or 3 the belt slips and the blades do not turn. When it is in position 4 it will turn after I put some water on the belt. What is causing the belt to slip. I contacted Troy-Bilt they said there is no adjustment for the deck belt. YOUR HELP WOULD BE GREATLY APPRECIATED.


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## jhngardner367 (Apr 5, 2011)

Welcome to the forum !
There are a couple of things to check.
First,if it is over 3 yrs old,the belt may be stretched,and needs replacement.
Second,check the tension spring on the deck,to make sure it hasn't broken/disconnected.
Another thing to check, is the adjustable "j" shaped deck rod,at the front of the deck. If it is out of adjustment,it can let the deck tilt at the front,and can throw off the tension .
Drop the deck all the way down,and measure the clearance at the front,and back. If the front is lower,TIGHTEN the adjustment nut. If the front is lower,LOOSEN them. Do this until they are equal.


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## dangeroustoys56 (Jul 26, 2010)

Is it built by MTD? I know on my older MTD's they had different deck settings for different sized decks ( where the allignment plate sits, tension spring) - id say if the belt is older then 5 years - then its probably due for a replacement - as Jhngardner367 mentioned, over time and use, belts wear, stretch sometimes get slick/worn spots in the belt .

I have a '92 White that had OEM belts on it- after 18 years it was due for a belt change ( wouldnt climb the hill out back).


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## dsmith1313 (Dec 7, 2012)

Yes the belt is a new OEM belt. I have adjusted the leveling of the deck on the left side of the deck with the large adjusting nut and have adjusted the front deck connection. There are two springs listed in the drawing for this mower/deck. Do these need to be replaced both or just one, I had a guy from MTD/Troy-Bilt mention the cable that goes from the selection lever for height to the deck might have stretched, I checked it, it does not appear to be loose or stretched. I guess I am at the two springs ..... what do you think???? I was out bagging up leaves today with the mower, it is doing a really poor job. If I disengage the deck in level 4, the new belt even jumps off the pulleys.


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## wjjones (May 28, 2010)

Where did you get the belt? I bought one off ebay that said it was oe but it didnt fit corectly. It sounds like you may have a bad deck housing/ mandrel if the belt is jumping off. If there is a bad one it is making it hard for the belt to do its job of turning the blades causing the belt to jump off. Take the belt off to see if the blades turn freely by hand, or are in a bind.


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## dsmith1313 (Dec 7, 2012)

I bought if off the internet from Troy-Bilt company parts. Not familiar with what you are referring to as mandrel, please explain. The blades do turn freely and have been changed several times. The belt is just sloppy loose around the pulleys. There is just too much play in the belt, but it is the one for the model/serial number of this particular riding mower.


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## dangeroustoys56 (Jul 26, 2010)

Sounds like a slightly different setup then on my tractors - mine doesnt have a cable ( i have 2 dynamarks with a cable setup) - once the deck lever is engaged/lowered , the deck automatically turns on .

Its possible the cable has stretched somewhat - is there any sort of adjustment on the cable?


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## wjjones (May 28, 2010)

Mandrel/ housing is the part the blade mounts to with the bearings inside. Do you have your belt diagram? I was just wondering if there was any chance it had came off one of the pulleys, or is not routed correctly. The only other thing I can think of is the pivot arm tension spring (1716777), or the pivot arm is froze up, and not holding the belt tight. Do the blades have a manual arm to engage the blades, or a electric pto?


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## RC Wells (Dec 26, 2008)

Hi dsmith1313,

I am speculating on the mower deck you have, but most of the 42's are nearly identical to the parts diagram found here:http://www.partstree.com/parts/?lc=troy_bilt&mn=13AV60KG011+Bronco+(2009)&dn=769043390008

Take a good look at part #31, the idler bracket. That is the usual culprit when the correct belt is used. Either one of the springs is off, or the engagement rod that connects to the blade brake is bound or disconnected.


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## Generic User (Sep 26, 2018)

After removing & reinstalling the deck to replace a bent blade, I had the same condition. Belt was fine before changing blades, then way too much slack. After much troubleshooting, here's what I found as the solution to my problem:

The PTO engagement cable/spring was re-attached in the wrong spot.
Here's the top view of my deck -








There are two locations on the tension bar, where the PTO engagement cable can be attached:
Option 1 -








Option 2 -








Both holes will allow connection of the spring which is at the end of the PTO engagement cable.
Thumbs down on hooking to Option 1.








Thumbs up on hooking to Option 2.








Both locations will actuate the tension lever, but only the second option will pull out enough slack to properly operate the blades for cutting.

Hope that helps save someone some time and frustration!


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## dad004 (Apr 16, 2013)

jhngardner367 said:


> Welcome to the forum !
> There are a couple of things to check.
> First,if it is over 3 yrs old,the belt may be stretched,and needs replacement.
> Second,check the tension spring on the deck,to make sure it hasn't broken/disconnected.
> ...


I'm having this same issue. If I set the cutting deck lower than 5, the belt comes off. I was checking the deck clearance, when I noticed that the pulley's were not all level. For example, the deck idler pulley(left) was slightly lower than the large spindle pulley. Would that cause the belt to come off? If so, I do I correct it?

Thanks


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## Longhorn294 (Oct 13, 2019)

jhngardner367 said:


> Welcome to the forum !
> There are a couple of things to check.
> First,if it is over 3 yrs old,the belt may be stretched,and needs replacement.
> Second,check the tension spring on the deck,to make sure it hasn't broken/disconnected.
> ...


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## 123GO (May 20, 2019)

Old posts, old mowers, old problems still happen till your old. lol

If belt keeps falling off be sure its belt guide part # 683-04414 (original design) didnt fall off. Its just a bar near the lower engine pulley on manual PTO mowers that tends to vibrate loose and get lost. 
The original part has one end that slides into the frame & the other end has a loop where a single bolt fits in & holds part on the mower. (See part in link). The bolt vibrates out so this guide gets lost then the belt falls off whenever PTO is stopped!
MTD later welded an extra tab on this part so two bolts are now used to hold it on better to reduce this from happening!
Its just a bar that fits over the lower engine pulley to keep its belt on if PTO is off in case yours is missing? (Sorry mowers gone so I dont have pic)
While looking to buy another guide for a friends mower I noticed a single Ebay seller sold over 90 of these guides so they must fall off often. Just thought Id post about the issue?
The upgraded 2 bolt design is part #683-04414-0637 (See link)
and something to look for if your deck belt keeps falling off. 

Belt Keeper Bracket Assembly (Powder Black) - 683-04414-0637 | MTD Parts


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