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Pto centering
#1
Is it recommended to have the pto centered over the drive axle?
 I’m fabricating and engine mount and was just curious. I really don’t think it’s a big concern but thought I would ask before I start welding.
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#2
In short words, Brad, no. The crank in front of the axle gives you more latitude in chain adjustment. This does not apply to mounts that adjust the chain by moving the engine upwards to tighten the chain, but only to mounts that move the engine fore and aft. I'm not crazy about the crank behind the axle, but the Fox karts have the engine behind the axle, and they seem to do fine. TJ
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#3
(05-26-2020, 11:50 AM)Brad Rose Wrote: Is it recommended to have the pto centered over the drive axle?
 I’m fabricating and engine mount and was just curious. I really don’t think it’s a big concern but thought I would ask before I start welding.

If your mount adjusts up and down doesnt matter so much. 

If adjusts forward or back you need to move the crank c/l in front of axle.

One minute behind you Ted.
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#4
Believe me/ some of the old Go Kart brand machines were horrible with centered adjustment slots. Pop and I milled the swing mount slots in the 1200's longer, but you still sometimes needed a shim under the engine. The question brought back evil remembrances of HALF LINKS in our chains! This was in the days before riveting chains.  Even some of the side plate mounts we usually get have too short a slot for vertical adjustment. Rick Violet makes some very nice side plates, and I asked for longer slots. He is making them longer now. Kudos to Rick!TJ
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#5
Good thing I posted this! I wasn’t even thinking of chain adjustments. 

Thanks for the info!
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#6
Brad, as far as handling or any other considerations, engine directly above axle doesn't hurt. The Photon mount centers the engine above the axle, but I now use the side plate mount with the long slots. I got tired of having to add or subtract a link when I changed axle gears. Sure 'nuff makes life easier! Handling-wise, the Photon handles as well as any rear engine kart I've ever driven, so the centered engine isn't any big deal. Centering the engine left-to-right helps make the kart balanced, but sure can make reaching the carb needles a PITA! Ted
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#7
Brad, will your mount be anchored to the axle (i.e., swing mount)?
I'm a big fan of swing mounts, primarily because as the axle flexes, the motor moves with it.

Compare that with a "worst case" setup having the motor positioned midway between the axle bearings, hard-mounted to the frame.  Picture somebody other than Steve Miller in the seat... hit a bump, the axle flexes like a "smile" and the chain tension momentarily goes to infinity, just before the crank checks out...

Back to your question.  As long as the mount is anchored to the axle, other than the possibility of running out of chain adjustment range if you only have fore-aft slots, I don't think it matters where the PTO is relative to the axle.
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#8
Here is a picture of what I am working on. Feel free to make recommendations.

 As you can see the boxed section is not welded yet to the bottom slotted plate. That is what I’m working on is trying to find the best location for that to be mounted. From old pictures of this setup it’s pretty close.


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#9
i am at the same point with my project i am using a swing mount and i need to know
the source for the rubber mounting cushion to the frame something from Mc master Carr
or just parts from automotive shock absorber ? the pto will be centered over the sprocket
using a GEM mount the one with 2 part chain guard that has up/down adjustment so no concern there
Richard Stamile
Oceanside NY.
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#10
(05-27-2020, 07:02 AM)Richard Stamile Wrote: i am at the same point with my project i am using a swing mount and i need to know
the source for the rubber mounting cushion to the frame something from Mc master Carr
or just parts from automotive shock absorber ?   the pto will be centered over the sprocket
using a GEM mount the one with 2 part chain guard that has up/down adjustment so no concern there

Hi Richard.  Rubber cushions from automotive shock absorbers work well.  I recall that Azusa sells them too.  Above & below, with large washers, locknuts & cotter pins, etc.

However, if your swing mount can straddle the frame rail, the approach that I like the BEST is an automotive sway bar bushing that circles the frame rail.  Attach the swing mount with a U-bolt around the bushing.  NO need to drill through the frame rail (gag).  Best to use a rubber bushing, not hard urethane.  JMO
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