repairing 503 Deere rotary cutter + oops!

mndel · Nov 9, 2016

My first post here.
Just acquired a beat up 5' brush mower (503), good price, the gear box seems ok, but it needs a new bottom seal and stump jumper. I got as far in disassembly as the holder bar, and of course it was frozen in place. My baby puller did nothing, so added 2 bolt/nuts to push from backside.
I know it would put compressing stress on the shaft, but the bar was bent back 1/4" already so I cranked the 2 bolts until it straightened out. Heard a loud satisfying pop as the frozen in spine let go....well not quite, it was the 1" x 4" iron bar that snapped in two. I'm dumfounded, what did they make these out of anyway??
Best price I see on a replacement bar is well over $200, but it's still stuck in place. I am open to any ideas!

JRobyn · Nov 9, 2016

Wow, that sux! I assume it's a mild steel (maybe forged?) bar, so should be a routine project for a qualified welder. That's a potentially highly enough stressed (and potentially dangerous) item that I personally would have a good shop do it. And all assuming that you can get it off! Try heat?

DieselBound · Nov 9, 2016

The stories of dealing with all this can be quite epic.

Get lots of penetrating fluid working. Figure a way to shock that connection (as you discovered, a slow, even force can go sideways on you). Don't know if this is keyed or not, but if not then perhaps (once soaking time has elapsed) holding the PTO side of the shaft and then smacking on that bar will help break its bond with the shaft. I'm really not versed in all of this, so others who have more battle scars than I can give better guidance.

I was fortunate in getting the blades off a recent acquisition: had to buy a 1200 ft-lb air impact to get the job done. Had that not worked I was hauling the cutter off to a shop!

LD1 · Nov 9, 2016

Get a better puller. Put on the same way as yours. After applying a good bit of pressure, continue to try to tighten the puller with one hand, while smacking the jackscrew of the puller (where the wrench goes) with the other hand.

Once off, you can measure the diameter and spline count and start shopping aftermarket. I am betting you can find something under $100.

I would consider myself a component and qualified welder. And there is no way I would weld that. Just ain't worth the risk of breaking and sending a 20# sharpened blade out at 200mph

mndel · Nov 13, 2016

Success!
If I can load more pics you will see my 'better puller' - hydraulics to the rescue. Even with it it took full crank of the handle, 5 minutes with the rosebud, (while cooling the shaft with poured water) and...banging on the holder bar with a 4 lb hammer.
Now I can see that it is not only splined - it is a tapered spline, no wonder it was so awful tight. But now i see the weak spot in the bar - that the turned spline holder rally cuts into the strength of the bar, I see no way even a certified welder has enough bar there to weld safely.
Does anyone know of a JD mower junkyard?
(cant tell if pics attached, fingers crossed....)