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Hinomoto C174 alternator bolt snapping

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JimK67
Join Date: Nov 2007
Posts: 2 Kentucky
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2007-11-10          148074


I am having a problem with a Hinomoto C174 that I haven’t seen on this forum. The bolt on the lower part of the alternator broke in to two pieces and naturally the upper bolt loosened until I lost both bolts that hold the alternator in place.
The portion of the broken lower bolt was in the threaded female section of the alternator and was out enough that I could thread it on out through the front case of the alternator. I was able to match the thread (metric) at the local auto store. The spacer on the top part of the alternator was lost, but four thin washers seemed to be the right spacing to let the belt run straight and true at idle speed. I have tried different combinations of washers each time I replaced the bolt from two, to three, to four washers, with no luck on the repair.
I have replaced three lower bolts in the past four days, they always break cleanly like they were cut with a bolt cutter, 1/4 to 1/8 inches inside the female threads when the tractor comes up to PTO RPM. The threads aren’t battered anywhere as would be expected with this happening.
I haven’t noticed any unusual pressure or twist on the alternator at either speed, but there must be some type pressure coming from somewhere in the set up.
I wonder if the bolts I am getting at the auto supply store are too hard or if this tractor takes a special bolt to hold on the alternator, the back end of the bolt was lost the first time, so I have no way of knowing what it originally looked like.
Anyone have any suggestions as to what is happening here, I am at a loss as to what is causing this problem




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Hinomoto C174 alternator bolt snapping

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earthwrks
Join Date: Dec 2003
Posts: 3853 Home Office in Flat Rock, Michigan
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2007-11-10          148082


Could be one or a combination of the following that I've happen on other equipment:

bolt is too soft--use the metric equivalent to a grade 5 or 8 and see what happens;

don't use an autoparts or hardware store bolt--if you have to go to a car dealer which relies on good parts or a good fastener dealer such as Fasten-All a national chain;

threaded portion of the block(?) has rusted threads or something causing too much friction and you think you're tightening correctly but instead you're twisting the bolt off;

washers may be crushing just enough to casue the bolt to shear--get the right spacer or have a machine shop make one, or find a suitable replacement at a foreign car auto repair shop or other--ID, OD, and length may be critical;

if this keeps happening maybe drill out hole clear through and use larger but Standard bolt, lock washer or lock nut;
check the alignment of the pulleys involved for correct alignment with a straightedge--don't just "eyeball";

use a dial indicator used for mechaincal and machining work to see if pulleys involved are out of round, deformed, bent or loose---this will set up a harmonic vibration that damages at certain RPM's;

might want to suspect the alternator itself for having bearing issues that are causing a vibration or contributing to it--check for shaft end play when the belt is off;

the belt itself may suspect--it's likely a 10-$15 part but I'd start there after the bolt fix and see what happens.

Feel free to post any ongoing concerns and if you're lucky---your solution! :)
....


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Hinomoto C174 alternator bolt snapping

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JimK67
Join Date: Nov 2007
Posts: 2 Kentucky
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2007-11-10          148092


earthwrks,
I think I may have figured out the problem. After I made the post I went back and got the broken bolts and the top of the heads show no hardness marks. I am beginning to believe they gave me a bolt similar to a shear bolt like in combines or mower shafts. So I feel your first answer is the same one I came up with, soft bolts.
My neighbor here tells me one of the local tractor dealers has a good selection of metric bolts in several grades of hardness.
The lower bolt on this tractor doesn’t require a nut and lock washer, it goes through a threaded section of the lower housing of the alternator; the bolt threads completely through the housing and then tightens down; the end can be removed through the front plate with just finger pressure after the bolt is broken. The belt was measured with a straight edge before starting and is straight and when watched for any change in tracking while idling, no changes noted; the belt seems to running straight and true.
There doesn’t seem to be any problem with the bearing within the alternator while turning, everything seems to be smooth.
I am beginning to think the bolts I had were just too soft to hold up under any pressure at all.
....


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