Hard to believe - Welded JD 730 crank

andy r

Member
I responded to an ad where a nice young man has a JD 70 diesel pony start for sale. I asked why the flywheel cover was off and he said that either the end of the crankshaft or taper lock flywheel was wearing on the cover and he was afraid it might wear a hole. He said the flywheel splines had gotten bad and he had a welding shop repair the splines. He was 100% for sure the man cut the end of the crankshaft off with the splines and then welded new shaft on and cut new splines. He said he had already hack sawed some of the crankshaft end off as it was way too long at first. First I have never ever heard of this type of repair and secondly could this actually be strong enough to support the demands of the two cylinder engine. How would you ever get it perfect? I know if you weld up and machine most combine shafts they will break in short time. He was positive that it was repaired in that manner. I believe he said it cost not much over $100 maybe 15 years ago. Would someone who actually knows John Deere two cylinders be interested in a tractor with such a repair? Nice guy and seems as honest as can be. Said the tractor had plowed for a couple hours and one shank sub-soiled with it maybe 6 hours after the repair. Just hard to believe that type of repair could be done. He can't figure out why the cover rubs. Maybe there is a wobble in the flywheel on a not so true shaft????? Decent looking tractor otherwise.
 
"a nice young man has a JD 70 diesel PONY START for sale"

Is there any other kind?

"Just hard to believe that type of repair could be done. He can't figure out why the cover rubs. Maybe there is a wobble in the flywheel on a not so true shaft?????"

NO need to worry/stress over it, sometimes you just gotta turn your back and slowly walk away from someone else's "problem child"!
 
"[b:654c4848f0][i:654c4848f0]<font color="#6699ff">Would someone who actually knows John Deere two cylinders be interested in a tractor with such a repair?[/i:654c4848f0][/b:654c4848f0]</font>"

As the fictional character <a href="https://youtu.be/EAiU0PjDyC4">Jenny Curran</a> once said "[i:654c4848f0]RUN FORREST, RUN![/i:654c4848f0]"
 
People are mistaken about facts every day,where would civil court be without people who don't understand facts? I suspect the shaft was built up and machined,not cut into and reassembled. I've had cranks spray welded and never a failure.
Did I ever tell you about the guy who welded concrete treads on steel stair stringers for me?
 
It can be welded up, machined back down to size, and re-splined. How good the job comes out depends on how good the machinist is. The $100 price for the job shows the guy who did the job wasn't very good.
 

Not familiar with the Deeres but I have read many times of crank repair work like this. It sounds like it will need to be done over though.
 
Do you know where you could get a GOOD used crank? And flywheel and main mearings as well as the sheild. To me that sounds like the only way you can have a safe to run tractor. You can buy a ready to use tractor cheaper than rebuilding that one. Run away fast. Sounds like a death trap. I had 2 JD B & 3 JD A, no 70.
 
There very well could be other issues, but on the subject of the flywheel shield rubbing - my 720 did that after I installed it's taperlok flywheel. I found threads here in the archives from other people having the same trouble after installing taperloks. The endplay was correct and all. I just put a washer behind the flywheel cover at each bolt and that fixed it.

Having said that, I would NOT buy that 70. A crankshaft of unknown quality is a deal breaker for sure with these. I've been through it all with this 720 of mine! Good used cranks are getting impossible to find. I finally found a guy with a N.O.S. crank after almost a year of looking. Then you can run into issues with mix and match main bearing housings, flywheel spacer, and thrust washers. On mine, some of those parts had been updated through the years and some had not, and it was not working! And this tractor ran good when I bought it.
 
I really doubt the crank was cutoff and new piece welded on, much more likely it was built up then re-splined, but that would probably be at least a grand of work.

Whole story seems fishy, run away.
 
It sounds a bit like the tractor may have changed hands in the 15 years since the repair was made and the current owner only knows that it was repaired, but does not know what was done?

Could you ask the owner if he could remove the flywheel cover and let you inspect the flywheel, or ask him to take some pictures for you? It might have a Taper Lock hub and the current owner does not know how to describe it. The downside would be if you confirm it has a Taper Lock, the price might go up.
 
You could maybe weld a new end on if you turned down the original and bored a new end shaft to the same or real close diameter then heated the outer shaft to expand it and slide it on. Once it was on and cooled it would be very tight and a weld at bo th ends might hold. I've seen repairs on shafts done like this but never a crank shaft.
 
If you don't buy it and the seller can't find any other interested buyers, I'll bet the selling description changes and any mention of crankshaft issues disappears. It's buyer beware these days.
 

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