violent shaking

rscott99

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I have a Husqvarna rider with Briggs and Stratton Intek V twin 24HP, 724cc engine. Was mowing along when the engine began to shake violently. I shut it off and inspected underneath. The belt to turn the blades had fallen off and the shaft coming from the bottom of the mower that this belt rides on is angled(bent?) I started it back up with the blades NOT engaged and the shaking remained. I am guessing that shaft has bent or come loose?

Thanks for any help!
 

Boobala

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If this is a "tractor-style" rider, and the shaft you mention heads down from the engine, it's what is called a "stack-pulley" which normally drives the mower and also the cutting deck, if that's so, then it sounds like the assembly has slid off the engine crankshaft, there should be a bolt going through the center of the bottom pulley up into the crankshaft which locks it into place, in any case, DON'T run the engine until you can verify if that's the case, the vibration could do some serious damage and even damage the crankshaft assembly and stack pulley further.
 

rscott99

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Thanks for the input. I checked the part you mentioned and that looks to be correct. I also checked out an illustrated parts breakdown and it looks like there is an electrical clutch on that shaft which has come loose. There is an odd shaped gold rod the IPB calls "keeper belt engine" which is loose as well. It is dark now......I will look more tomorrow........looks like everything just came loose off of that shaft.
 

rscott99

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If this is a "tractor-style" rider, and the shaft you mention heads down from the engine, it's what is called a "stack-pulley" which normally drives the mower and also the cutting deck, if that's so, then it sounds like the assembly has slid off the engine crankshaft, there should be a bolt going through the center of the bottom pulley up into the crankshaft which locks it into place, in any case, DON'T run the engine until you can verify if that's the case, the vibration could do some serious damage and even damage the crankshaft assembly and stack pulley further.


I was able to remove the bolt attaching the clutch and stack pulley. IMG_0676.JPG Obviously bent and stripped a bit at the end. Is it worth trying a new bolt or do you think the receiving threads are shot based on the condition of this bolt?
 

NorthBama

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i would use a thread tap and re-tap the threads before using the new bolt
 

Boobala

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I was able to remove the bolt attaching the clutch and stack pulley. View attachment 34876 Obviously bent and stripped a bit at the end. Is it worth trying a new bolt or do you think the receiving threads are shot based on the condition of this bolt?

After seeing your pic, ( wow lucky you didn't really tear up more than you did !! ) what I would do, is buy a couple of those bolts, ( dependant on price $$$ ) just in case you "booger" one up, then with the PTO ( clutch) and pulley still off the crankshaft VERY GINGERLY,... try with fingers ONLY, try to thread bolt into the crank, if too much resistance , I would run a "tap" into the crank threads ( being PERFECTLY CENTERED ) might take bolt with you to the mower shop, ( don't think I would buy at a hardware store or "Big-Box" store either ) and have the threads checked for correct diameter and pitch, in case you need to tap those threads, I would use a great deal of PATIENCE doing this, you don't even want to think of replacing or pulling the engine to repair the crank, and after re-assembly of clutch and pulley be sure to torque the new bolt to specs. it looks like it may only be the first few threads may be damaged, That's MY opinion, other members may suggest other ways, Please keep us updated, and hopefully you luck-out on this issue !
 

ILENGINE

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typically that pulley mounting bolt is 7/16 fine thread grade 8.
 

bertsmobile1

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and please resist the urge to loctite the bolt as you have to pull the pulley off in order to change the drive belt and when loctited into position the bolts tend to break off.
I had a mower come in with a bent con rod because the owner had put red loctite on the bolt so he could not hold the shaft tight enough to stop it slipping, so he pulled a plug , stuffed rope in one cylinder ( standard practice ) and hit the bolt with a massive impact wrench, breaking off the bolt head and bending the con rod.
AS previously mentioned you should be able to run an intermediate tap up the hole then a plug tap to make sure the threads are clean all the way to the bottom.
If you do not have the very thick washer that goes under the bolt, get a new one and also a new spring washer.
The washer has sharp ends which aid it's retention and once rounded they do not work properly.
On some set ups the thick washer is cupped to add some tension to the bolt and these must be fitted so the cup is being compressed.
 

rscott99

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thanks for all of the help! I was able to tap the threads and can hand tighten with no problem. Everything went together seemingly fine, i tightened the bolt up and nothing seems loose.. The only remaining issue is more noticeable vibration than usual when running the throttle medium-high. It does look like the clutch area may be the source as I can see it vibrating. I noticed that when I spin the clutch with the mower off the part above the pulley rubs or grinds on the frame of the clutch. The frame has a rod to stop it from spinning that engages with this frame. I believe everything is tight....someone mentioned "correct torque"? I just made sure it was very tight with no loctight. Any suggestions on the vibration?
 
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