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450 rototiller broken chain drive

1550 Views 6 Replies 5 Participants Last post by  Superglidesport
So I picked up a 450 tiller this spring. Looked to be in great shape. Tines still had oem paint on them. Bought a slip clutch so I wouldn't break anything. Well so much for that. Was tilling a friends horse arena to chop up the weeds and smooth out the sides. Tiller stopped all of a sudden and the slip clutch slipped. Didn't hit anything so I was puzzled. Pulled the side plate off. Drive chain is snapped!

It is 16b British Standard Chain (metric #80). Stamped REX Germany. JD parts no longer available. OK so google it. Rexnord Germany. Only comes in 10 foot lengths $770 plush shipping....other brands are cheaper. Can find some Chineseium chain or short lengths of quality chain on eBay for $100ish shipped. Ok so that's figured out.

Next issue. The sprockets are worn. Not terribly worn but enough that the chain is close to bottoming out on the small sprocket. Bottom one not so bad. JD parts no longer available and when they were they were $700 ish for both sprockets. They are odd ball metric sprocket with 6 spline 1-3/8" bore (bore is same as type 1 PTO). Must have been a custom specified sprocket from JD as no one makes them. Weasler who makes PTO parts sells a 1-3/8 6 tooth spline hub and separate sprockets you can weld on and make your own custom sprocket. Only problem is they don't do metric chain sprockets. Martin roller chain company makes metric sprockets. Figured I can machine one of their sprockets to fit the Weasler hub and weld it on. BUT Martin only goes down to 11 tooth. OEM small sprocket is a 9 tooth!!! The large sprocket is 14 tooth and available from Martin. Going to call Martin and see if they will do a 9 tooth custom. May as well ask if they will cut a 1-3/8 6 tooth bore as well. I guess I could go up 2 teeth on the top sprocket and down 2 teeth on the bottom to keep the tine speed correct. But the needed rotation force of the PTO would increase, I think!!! This is a good idea in that smaller circumference sprockets wear faster. Going up in size alleviates that problem. But then I may run in to issues with the tensioning device.

The other option is say to hell with metric and convert everything to #80 ANSI chain specs. I can even go to #80H (heavy duty) with thicker side straps for increased strength.

I think the failure could have been caused by incorrect chain tension? The tiller seemed to be oscillating. I think the tensioner was not tight enough creating a shock load on the chain. OR since this came with no slip clutch a previous owner may have hit something and partially fractured the pin and it finally gave out when I was using it. Or it was a manufacturing flaw and since this tiller doesn't look used much it finally reared its ugly head and failed the first serious use. No way to tell for sure.

Anyway hope this post is helpful for anyone looking to repair their 450 tiller. I think going #80 ANSI chain is the easiest. You can probably find cheap parts on eBay as this is commonly available stuff.

Adding some more pics soon....

weasler 6 tooth 1-3/8 splined hub (same size as a type 1 PTO) you weld your sprocket of choice to this.
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Change the system to ANSI spec and never worry about this problem again. The site/company linked below will have everything you need at very reasonable prices.

Accessories – Weasler Engineering, Inc.
Ok update for you guys. Weaser does not make a 9 tooth sprocket in 16B or #80 so im SOL. Unless I want to start fooling with different gear ratios.

Luckily I scored some Tsubaki Japanese 16b chain on eBay. Got a few extra master links as well.

Looks like the main shaft got bent somehow??? The bottom sprocket is welded to the main shaft and oscillates up and down quite a bit. I straightened the main shaft as best I could with a porta power. This in turn made the bottom sprocket run true sorta. New chain gets pretty tight but not over tentioned. Ill probably disassemble and take to a machine shop in the off season so they can “heat it and beat it” straight. Gear wear is present but I think it is not too excessive.

So far the “fix” is working. Ran 2hrs no problems last weekend.


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Wow, I wish I would've seen this before I wasted a bunch of time looking up the chain type. I ended up replacing my chain with a 16B or #80 chain. My bottom sprocket was wore so I replaced it with a 14 tooth 1-3/8" shaft sprocket used a keyway and welded it on.
John deere wanted $280 for the chain- I got one new for $50. They wanted $480 for the sprocket! Found one for $35 on Carnell Sales. Also replaced bearings- made the one greasable. And sealed chaincase and filled with gear oil.
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This rototiller was made for JD by one of the Italian implement companies. I can’t think of the vendor off hand but someone might. It’s possible you could source parts from the OE manufacturer.
The 450 tiller was made in Germany by Howard.
The 450 tiller was made in Germany by Howard.
Yup. Howard. You jogged my memory. (y):)

At least I was on the right continent and the company is headquartered in Denmark.
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