350 sprockets for 420

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my fathers son
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350 sprockets for 420

Post by my fathers son » Fri Jan 11, 2019 12:21 pm

I’ve found someone to weld my 420 centers into new 350 sprockets. Two questions. My 420 sprockets are offset approx. 2 1/2. Is there a specific year or model 350 to specify in purchasing new sprockets. And I assume the cut and the weld are at the circular edge of the flat surface which mates to the drive flange. Thanks

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Lu47Dan
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Re: 350 sprockets for 420

Post by Lu47Dan » Mon Jan 14, 2019 7:01 am

Lets get some terms correct, first.
Sprocket, whole part to include, mounting flange, disc and rim.
Rim, toothed part of the sprocket. The teeth drive the rail.
Mounting flange, the flat part that mounts to the axles flange via bolts.
Disc, the spoked part of the sprocket on a 420 , between the mounting flange and rim.
Now that is out of the way...
No, the rim is cut away or off the disc, NOT the mounting flange.
If you cut it at the mounting flange there is not a 350 sprocket that can be used to replace the offset part.
A 350 rim is basically just a circle or hoop of steel with the teeth on it.
The 420 sprocket has the rim cut off, to match the new 350 rims inside diameter, weld prep done and the new rim welded on.
I discussed this with a retired welder, before he passed. He had done several of them. Takes a lot of cutting and grinding and the correct rod but he thought I could handle the job myself.
I am not a amateur welder, I have welded professionally as a pipefitter.
Hope this helps.
Dan.
1956 420C with GSC blade
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Jim B
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Re: 350 sprockets for 420

Post by Jim B » Mon Jan 14, 2019 4:34 pm

Attached is a photo from the web of a weld-on sprocket rim. Along with Dan's post, this should give you a visual idea of where the cut and weld would be. As Dan described a 350 sprocket would get cut up to get the rim to a similar shape as this, to weld to your 420 sprocket disc. Check with Lavoy, he has had some weld-on rims in the past, I read in some old posts when I was thinking of putting a bottom on a 430 I had.

Image

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my fathers son
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Re: 350 sprockets for 420

Post by my fathers son » Tue Jan 15, 2019 9:48 pm

Appreciate you taking the time to clear this up. Thanks, Jim

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