Sprocket bolts

General help and support for your Lindeman through 2010 John Deere crawler
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Pocketfarmer
MC crawler
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Joined: Sun Oct 30, 2016 8:13 am
Location: Long Island New York

Sprocket bolts

Post by Pocketfarmer » Wed Jun 28, 2017 8:54 pm

Hi , I have what seams to be a phase one 420c . I bought it about a year ago. I've been using it to grade the drive way ,let my young sons push snow, haul the odd log and handle a large leaf pile (10 -12 tons). I was crawling up the pile and heard a loud clunk and then a second. The old girl kept pushing all seamed well. A few days latter ,after pulling all the leaves off , I discovered 4 of the 6 bolts holding the port side sprocket had snapped off. So yesterday I started the fix. The heads of the bolts that were left and some of the ones on the other side are 7/8 and 13/16. The size of the threads are the same . They seam to be in sets one each. Is this normal? Or another " suprise" I have to deal with that the last restorer left? Oh yeah I just had my first vocabulary pop quiz ....the easyout snap off in the deepest bolt. Any thoughts would be great. Thanks
JD 750MFWD loader b-hoe,'37 L

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Lavoy
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Re: Sprocket bolts

Post by Lavoy » Thu Jun 29, 2017 8:57 am

All should be 9/16"NF bolts. It is likely that someone had or found a bolts or bolts in that thread with a different head size. Normally they will be 13/16".
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

Pocketfarmer
MC crawler
MC crawler
Posts: 4
Joined: Sun Oct 30, 2016 8:13 am
Location: Long Island New York

Re: Sprocket bolts

Post by Pocketfarmer » Fri Jun 30, 2017 2:03 pm

Thank you for getting back to me. Do you know what the torque setting is? Also the manual I have shows lock washers .My machine doesn't have them and the sprocket hole are concave as if for lug nuts. The washer make no sense to me.
JD 750MFWD loader b-hoe,'37 L

JimAnderson
1010 crawler
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Re: Sprocket bolts

Post by JimAnderson » Fri Jun 30, 2017 8:13 pm

Very early on Deere used a tapered bolt to hold the sprocket on.They are similar to some modern trailer hub bolts.They then upgraded to dowels
plus taper headed bolts.The final upgrade for the two cylinder machines were dowels, normal bolts and heavy washers.If the sorockets you have do not have a counter sunk hole then washered bolts work.If tapered holes are in the sprocket you can use either bolt type.
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