V-belts twisting

fynney1

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My first post here; who can help?
I have an 1982 Allis Chalmers 919H (twin sister to Simplicity 7119, I think), and when I recently replaced the drive belt to the mower deck, the v-belt will often twist sideways when under a heavy load (tall or wet grass). It's never done this before. (I did NOT have access to factory replacement size - 78", I believe - and I now have a 77" one on there.)
Would a belt that does not have enough slack cause twisting?

Fynney1
 

Catherine

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Hi and welcome to the forum!

:welcome:

I'm going to move your thread over to the Allis Chalmers section to see if someone over there has had a similar issue.
 

Rivets

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I did some checking on your 919H and I came up with a model number of1691121. This unit is what I am basing my response on. The belt number I came up with is 1713515. This belt is 78.1 inches long and .5 inches wide. I see that this belt is making a 90 degree bend off the front PTO. This is one case where I would say using a nonOEM belt is causing your problem. Most nonOEM belts are made to be used in a straight line with no twists or bends. Add to this you are using a belt that is more than 1 inch shorter than the OEM. Don't know what you paid for your belt, but the price for the OEM belt is only about $27.50, which is relatively cheap for that type of belt. Just my opinion.
 

bertsmobile1

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And further to the previous post, a belt that is too tight tends to cause the tensioning pulley to to twist on its arm which makes things a lot worse.
Check the bearings on the tensioning arm and wear at the tensioning arm pivot.
 

fynney1

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And further to the previous post, a belt that is too tight tends to cause the tensioning pulley to to twist on its arm which makes things a lot worse.
Check the bearings on the tensioning arm and wear at the tensioning arm pivot.

Thanks for both insights. I discovered that my front deck bearings were bad, putting shaft at an angle, and allowing slop in the belt. Not knowing that, I went to the small belt and had the other fore-mentioned belt problems. Once I replaced front bearing assembly and put things back OEM, it runs GREAT! Good call!
 

fynney1

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I did some checking on your 919H and I came up with a model number of1691121. This unit is what I am basing my response on. The belt number I came up with is 1713515. This belt is 78.1 inches long and .5 inches wide. I see that this belt is making a 90 degree bend off the front PTO. This is one case where I would say using a nonOEM belt is causing your problem. Most nonOEM belts are made to be used in a straight line with no twists or bends. Add to this you are using a belt that is more than 1 inch shorter than the OEM. Don't know what you paid for your belt, but the price for the OEM belt is only about $27.50, which is relatively cheap for that type of belt. Just my opinion.

I discovered that my front deck bearings were bad, putting shaft at an angle, and allowing slop in the belt. Not knowing that, I went to the smaller belt and had the other fore-mentioned belt problems. Once I replaced front bearing assembly and put things back to factory spec, it runs great. I'll stop trying to scrimp on belt costs - not worth it in the long run. Thanks!
 
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