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Red Plaid is Timeless
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Discussion Starter · #1 ·
With a lack of snow and antsy to work in the shop, I made up a suspension seat for the 400. The stock spring loops have their limitations and when I extended those back to add some clearance between my shirt buttons and the steering wheel the spring function was overwhelmed and I found the seat back bouncing off the gas cap.

Then I had to resolve the bottoming issue with the doggie dish air booster system. Got to be too much so started looking at suspension systems. They are spendy and I needed to stay as low as practical. I also wanted to provide some rebound dampening by using a pair of gas props.

I ended up with about 2" of travel and it moves forward on compression to keep me away from the future back window on a cab. McMaster was the source of springs and props. These are 80 lb. gas props and about 50 lb. per inch travel springs. As luck would have it, that combo works out for my 220 pounds. With very little pre-load on the springs, the seat drops about 1/2" when I sit on it and that first bit of movement is absorbed by the gas props. Progressively, the springs take over from there until it bottoms on a pair of soft rubber pads. There are no bushings, but there are a bunch of grease zerks to keep things from sqweaking.

Yep, that was me out in the shop bouncing up and down on the seat that the neighbors saw through the window. The suspension doesn't have a huge range of adjustment but I am the main operator. My son is in the same weight range as me. Someday the grandkids may complain about the hard seat. Jay
 

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Red Plaid is Timeless
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Discussion Starter · #2 ·
A few more completed pics. It's hard to see under the seat.
 

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Jay, another fantastic job.. by chance could you post the materials list.. id like to give one of these a shot.. was just looking at suspension seats on ebay last nite !

Thanks,

Joe
 

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Kish JD 318/420/430
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GandPaJay I second that request, I spent hours looking at ebay, A&I, michiganSeat, Northern Tool, TSC. Plus I looked for just coil springs to add to the spring loops ugh!
 

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That's got to be about the most highly evolved 400 on earth!!:thThumbsU
 

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Absolutely a fantastic job! Here is a quick question, do you think it would be a possibility to add gas shocks like yours to a factory JD suspension seat? I have often thought the seat suspension would be much smoother with something to dampen the springs a bit. You could manufacture and sell those bases and bet you would have a lot of interest.
 

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Red Plaid is Timeless
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Discussion Starter · #8 ·
Thank you all!

Here is kind of a material list:

6' of 1" x 1/8" angle iron-frame
2' of 3/4" x 1/8" angle iron-parallel arms
4' of heavy wall tubing about 3/8" i.d.-pivots
4' of 3/8" c.r. rod.-pivots

Gas spring (2)-McMaster Carr-9416K14 (80 pound) $13.50 plus ends and ball pivots.
Extension springs (2)-McMaster-9654K274 $6.54 (I'm 75% sure this is the spring)

The parallel arms are 4" o.c. on the pivot tubes and positioned 3" o.c. on the frame. The gas spring is the up stop and keeps some preload in the parallel arms (so they aren't standing straight up at rest)

I took note of where I had the seat positioned in relation to the fender pan holes from a previous modification of the loop spring. For me, the front seat hole is now 1" behind the rear most pan hole. This is in the range of 3" farther back than a stock rear most setting. This setup is also about 1" higher than stock. I didn't want to get much higher and lose knee/lap room under the steering wheel. But I needed to be a bit higher to get a little more travel. For reference, I'm 5'-11" and 220 pounds. If my doctor is reading this-yeah, I know-I told you it was for ballast. Jay
 
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Red Plaid is Timeless
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Discussion Starter · #10 ·
Absolutely a fantastic job! Here is a quick question, do you think it would be a possibility to add gas shocks like yours to a factory JD suspension seat? I have often thought the seat suspension would be much smoother with something to dampen the springs a bit. You could manufacture and sell those bases and bet you would have a lot of interest.
Thank you! I don't really know how the JD seat works. A challenge with using the gas spring is that it really needs some travel to be effective. I spent some time trying to figure out how to build in the most travel. It's still only 2". There might be a way to use a shock dampener more effectively if you don't need any compression force.

As it were, I'm a prototyper and not a manufacturer. Thanks for the thought, though! Jay
 

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Three of my friends
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Jay that's a nice project,I have kicked around building one similar to a Cessna Landing nose wheel.
 

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Thank you all!

Here is kind of a material list:

6' of 1" x 1/8" angle iron-frame
2' of 3/4" x 1/8" angle iron-parallel arms
4' of heavy wall tubing about 3/8" i.d.-pivots
4' of 3/8" c.r. rod.-pivots

Gas spring (2)-McMaster Carr-9416K14 (80 pound) $13.50 plus ends and ball pivots.
Extension springs (2)-McMaster-9654K274 $6.54 (I'm 75% sure this is the spring)

The parallel arms are 4" o.c. on the pivot tubes and positioned 3" o.c. on the frame. The gas spring is the up stop and keeps some preload in the parallel arms (so they aren't standing straight up at rest)

I took note of where I had the seat positioned in relation to the fender pan holes from a previous modification of the loop spring. For me, the front seat hole is now 1" behind the rear most pan hole. This is in the range of 3" farther back than a stock rear most setting. This setup is also about 1" higher than stock. I didn't want to get much higher and lose knee/lap room under the steering wheel. But I needed to be a bit higher to get a little more travel. For reference, I'm 5'-11" and 220 pounds. If my doctor is reading this-yeah, I know-I told you it was for ballast. Jay
Thank you Jay !!!
:thThumbsU
 

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Thanks Jay.
Gonna have to bookmark this one and give it a try.
:thThumbsU
 

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This is pretty nifty, the gas struts probably help dampen the otherwise horrific spring slam, I might have to look into something like this.

What would really be neat is an adjustable gas charged strut that could act as both the spring and the damper.
 

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Wow Jay that's really nice. Makes me feel guilty as my 400 sits with the engine on the bench. :hide: no wonder my 400 keeps muttering something about wishing it went to live with Jay instead of the lazy a&& it got :sidelaugh
 

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Beautiful workmanship! Truely brilliant!:thThumbsU
 

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Red Plaid is Timeless
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Discussion Starter · #20 ·
Think mountain bike rear suspension - oil-damped air shock. :)
Andreas
Andreas-I did see those and there is nifty bike seat suspension springs/shocks, too. Oil dampening would be much better than gas dampening. They were just too spendy for experimental use.

Today, I installed the tip up seat mod for the suspension seat. Not sure why I didn't do it from the start but it was an easy evening project. Jay
 

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