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Discussion Starter #1 (Edited)
Hi guys, I have a gt235 tractor that is giving me some grief. A history of the tractor goes like this, purchased new in summer of 1999, sometime in 2005 I was cleaning the deck and noticed a small chunk of the drive belt missing so I called the local JD dealer (who shortly after this went out of business) to come out and pick it up and replace the drive belt, everything was fine for 2 weeks or so. Then one day while I was mowing it started to make an unusual noise, I immediately stopped and checked the tractor over and noticed the PTO had fell down about 1/4 inch and the bolt that holds it was loose. I tightened the bolt and finished mowing, from then on I was paranoid about the bolt loosening again and began checking it before every use.
Since then I have purchased new bolts approximately 2 times a year since because they keep coming loose. Now approximately 1 year ago the PTO failed and I had to remove it and replace it and noticed that the keyway in the engine shaft was in poor condition but I put on PTO anyway and kept checking the bolt tightness before every use.
Now about 2 weeks ago the PTO shorted to ground, again I removed PTO and the crankshaft needs to be replaced before I will put on a new PTO.
While it was apart I did some measuring of the parts and noticed that only about 1 3/8" of the PTO is actually on the engine shaft and of that only 1" of the PTO key is on the engine shaft, then the bottom of the PTO is supported by the bolt and a key spacer from the bottom. In between the bottom of the engine shaft and the top of the spacer is nearly 7/8" of no support at all.
Surely this must induce some twist and stress to the PTO and PTO bolt that caused all these problems? I don't feel comfortable just putting on new parts and then 5 years or what ever and have to do this all over again.
JD says there has been no redesign and the only parts available are the original parts. So my questions to the experts here are:
1. Has anyone had a similar problem, what did you do?
2. Should I find a local machinist to make up a longer spacer to close the gap between the bottom of the engine shaft and the bottom of the PTO to help reduce the twist?
3. Can I replace the crankshaft myself or does it require special tools?
4. Also as a side question the the anti-rotate pin that keeps the PTO from spinning is beat up, does it need to near perfect condition?

When this tractor works it does its job very well and I would like to keep it. It just seems that stress on the PTO should not then also ruin the crankshaft.

Thanks for taking the time to read this and help me if you can. Feel free to ask me more questions as I will check this thread frequently.
:thanku:
Sorry I almost, forgot the engine I have is B&S 18HP V-Twin. The tractor itself doesn't have an hourmeter and runs great, I would guess total hrs. on it would be around 400.
:thanku:
 

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All the mating surfaces and the crank stub got buggered up when the improperly tightened bolt came loose the first time. When you replace the crank also replace the top pulley so all the surfaces are true. You should be fine. Having only a small part of the crank stub into the pto is pretty normal. Not ideal by any means, but typical nonetheless.
 

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Did you replace the key in the key way with a new key. I would get some lock tite and apply it to the threads prior to replace the bolt the next time.

Dick
 

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Discussion Starter #4
Thanks guys for you replies. Not having owned another JD tractor I don't know what's normal for other PTOs. I thought that mine was poor design? The engine shaft is only 3 5/32" long and the traction drive pulley takes up 1 3/4" which leaves only 1 13/32" to support the PTO which 3 5/32" long, so that leaves 1 3/4" of the PTO unsupported by the engine shaft, the other support from the bottom up only comes up 7/8" into the PTO. And the accessory drive belt is on the bottom of the PTO which of course puts a side load onto the PTO and the bolt and the spacer is supposed to handle this side load, still seems like poor design to me. And yes loctite was used on the bolt every single time, the key isn't taking any wear at all just the engine shaft.
Guys please feel free to leave more comments I appreciate them all.
Another BIG THANKS to those who replied.
 
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