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Discussion Starter #1
So I've noticed a trend among 110, 112, 120, 140, 300, 312, 314, 316k, and 317 seats. It's mainly among the smooth seats, but also can occur in even new seats and fender pans, such as the fenders for the 316, 318, 322, 330, and 332.
It's an issue on all tractors, but so much worse on 120 and 140 because of the longer seat springs.

The issue is that some genius designer over at deere decided it would be a good idea to essentially mount the seat on 2 stilts with 8 toothpicks, with the springs being the stilts and the bolts being the toothpicks, and the glass being the fenders when they crack and break the mounting bolts off.
Below I have analyzed it, and I think I've got down what causes the issue.
Front view, with no forces applied. Everything is fine. No cracking occurs.
seat issues 1.jpg
The issue arises when you apply a sideways load to the seat, such as sitting on it, or mowing on a hill. This causes huge stresses which, because of deere's genius design, lead to cracking.
seat issues 2.jpg
When you apply a load to the side of the seat (one spring only), the forces are similar, leading to slightly less stresses, but still a lot. cracking occurs, but slower.
seat issues 3.jpg

From the side isn't much better.
Side seat 1 (1).jpg
When you apply a load to the back, it provides some... Subpar results. You'd think it'd be fine, but no.
Side seat 2.jpg
Applying a front load is a tiny bit better, but it's still an issue.
Side seat 3.jpg

There's a couple fixes.
1. Widen the springs. Pretty difficult, probably not the best option.
2. Weld 2 bars between the springs. This essentially makes the springs one assembly, and also spreads out the load and keeps them from twisting as much. This mainly helps because the springs twist not because they're too thin, it's because the materials they mount to is too thin.
3.Add seat suspension. Even making your own is better than the stock springs because of how skinny they are and how tall they are.

I'll also add a reply comparing seat suspension.
 

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Just do away with the springs and install rubber bushings like some of the compact tractors use. Gives a softer ride also.

Steve, Samsung On5 using Tapatalk
 

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Discussion Starter #3
Just do away with the springs and install rubber bushings like some of the compact tractors use. Gives a softer ride also.

Steve, Samsung On5 using Tapatalk
On a 140 that wouldn't work because the seat would be on top of the dipstick and too low.
 

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Just weld washers on the bottom.

I don’t consider the design defective, after 50 years most are still usable even if cracks have appeared. The only complete failures are rust caused, not cracks.
 
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Discussion Starter #5
Just weld washers on the bottom.

I don’t consider the design defective, after 50 years most are still usable even if cracks have appeared. The only complete failures are rust caused, not cracks.
I have a set of fenders off my 317 that ripped the bolts out from the fenders. Like, clean out. There was no rust at all. It just cracked so bad it ripped the bolts out.
 

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I have a set of fenders off my 317 that ripped the bolts out from the fenders. Like, clean out. There was no rust at all. It just cracked so bad it ripped the bolts out.
Either way a washer fixes it.
 

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I agree with welding on the washers...

The fender pan and the seat pan will crack at these points over time...many of these tractors are over 40 years old. I have had several 140 tractors come through my herd with improperly tightened seat springs (probably after adjusting the fore and aft distance...) which would exacerbate this cracking, as would improper assembly of the seat spring hardware as was the case in some of these tractors. Most folks take off the seat before removing the fender pan from the frame and conversely put the seat assembly back on last -- where stacking the washers, straps, etc. is difficult to get exactly right while reaching under there.

There have been several threads on the WFM site about reinforcing the bolt hole area in this area once cracks are evident. There is even a good thread about fixing a seat pan with cracks with excellent photos -- Don was replacing the U springs with a full suspension mechanism.

https://www.wfmachines.com/forums/sh...der+holes+seat


A one time repair in 30 to 40 years of use does not really point to a systemic design flaw, particularly when this is not the case on all tractors of that vintage...here is a thread on proper technique of using "stop holes" on such cracks in the fender pan itself when adding these reinforcements and welding the cracks.

https://www.wfmachines.com/forums/sh...rce+holes+seat

Chuck
 

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Trying to see if this link works:

Suspension Seat Installation on 1974 JD 112 +112

Chuck


The second link was pre-crash of the WFM site back from 2009, so it took a different approach to get it readable here. I was able to capture the contents of the second thread into a PDF file...hopefully that should open for everyone.

PDF of WFM 314 fender deck repair thread from 2009.pdf
 

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Just weld washers on the bottom.

I don’t consider the design defective, after 50 years most are still usable even if cracks have appeared. The only complete failures are rust caused, not cracks.
I agree, I am guessing JD didn't think their Garden Tractors would still be running after 50 years. I am also thinking that based on the design budget and technology at the time, this was as good as it got. Now, it's unfortunate stress cracks are appearing but it happens. I am thinking all the NVH issues with the tractors are also a factor in the cracking. I consider JD's designs of the early generations pretty robust but not excessively comfortable! :laugh:
 
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