Author Topic: larger pulley sizes, trans alignment questions  (Read 2624 times)

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Offline MOWtaku

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larger pulley sizes, trans alignment questions
« on: February 17, 2015, 01:13:44 pm »
I've done some research on here for a while (been a lurker for probably a couple of years before I finally joined) and it sounds like a good basis for pulleys on a prepared class with a 700 is with  6" to 4" or 8" to 5". I was pondering why not go larger diameter, yet maintain the overdrive ratio? Like 9" to 5" or 6", or 10" to 6"? The one reason I thought of this would be more area for the belt to grip, but I take it that with the sizes already ran, that going larger might cause clearance issues under the frame, and if I had belt slippage, that's going to be more of a tension issue?

 The second thing I was pondering was side-to-side location of the 700. If the motor and trans are straight back from each other(sans clutch and idler(s)) the belt basically sits in a teardrop shape, and in terms of degrees of rotation, the motor side would be over 180 and the trans would be under. I figure after accounting for the clutch, it will bring the belt in closer towards the trans pulley on that sside. So I was thinking would it help if the 700 was offset to the side of the chassis opposite the clutch, to try and increase the amount of belt contact on the pulley.  Once again, this might just be more of a tension issue.

 I'm pretty sure I'm over thinking this, but they say the only dumb question is the one not asked.
If my second question is hard to visualize, I will try to get a picture up later today to help with what I am asking.
Zach Jensen
Irene, SD

Offline redline

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Re: larger pulley sizes, trans alignment questions
« Reply #1 on: February 17, 2015, 01:38:03 pm »
With decent quality pulley's and proper tension, there is not a slip issue on anything 4" and above in my experience.
I ran a 3.75" on the top of the jackshaft on my old mod-x before with no issue.
That being said, there is no reason to have the extra weight and mass of a larger pulley slinging around under there. Plus, the longer belt required.
Unless you have an oddball setup, you have close to 180 degrees of contact on both. Can't ask for much more than that.
Ed King

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Offline cycloneracer

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Re: larger pulley sizes, trans alignment questions
« Reply #2 on: February 17, 2015, 01:42:50 pm »
and if you run odd size pulleys it is harder to find replacements.

I've loaned out pulleys at the track before..............


On the 700, mount it so you can change gears.   Also make it so you can take the top of the case off in the mower.  This will aid in repairs at the track if you only break shift keys.   Also make it so it comes out easily.
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Offline MOWtaku

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Re: larger pulley sizes, trans alignment questions
« Reply #3 on: February 18, 2015, 06:33:28 pm »
Thanks for the info guys. I will keep this stuff in mind. Won't try to reinvent the wheel on this when I get started on mine.
Zach Jensen
Irene, SD