30 series seat suspension rebuild

2 years 9 months ago - 2 years 9 months ago #4634 by shea
Many have found the rubber torsion spring needs replaced because 60 years of weather has deteriorated it. Case no longer carries this part.and the aftermarket will not hold up for a year. Since I am rebuilding the tractor and repainting I needed to rebuild the seat suspension without the rubber torsion spring. Most importantly is for the rebuild to be functional, and look as original as possible. My solution was to use a coil over shock, i used one that is used on the Allis Chalmers WD45 seat. It is the correct height and gives a decent amount of support to the case seat. As far as changes to the original case suspension i drilled one hole and cut one support shorter by 1 inch, and ground down two 1/2 inch spacers, all other parts are original and untouched.

Parts you will need to purchase:
Seat spring Allis Chalmers WD45 Part number 70226042 grandpas tractor part ACS196 Approx $99
One 5/8"x3" carriage bolt
One 5/8" lock nut
One 1/2"x3" carriage bolt
One 1/2" lock nut
One 1/2"x1.5" bolt, nut and lock washer
One bronze spacer 1/2"x1"
One bronze spacer 5/8"x1"
One 5/8" x 1.25" bronze spacer

Lets get to work!
First remove the 2 5\8" pivot bolts that holds the seat to the base.
Remove the torsion spring assembly.

when removing the pin for the torsion spring assembly i had to cut the original pin on both sides. You will not be using the pin so it is okay to cut it and the spacers.

Now remove the rubber torsion spring from the assembly. I used a small angle grinder and ground off the rivets then used a chisel to separate the pieces.

Grind down the two inside spacers, grind about 3/4ths of them off. It is easier to grind them if you take the support bracket off so you have 3 Pieces.

You can either cut this support in half so it is half as long or cut out 1 inch. i cut out 1 inch.

Re-assemble the torsion assembly

Drill one 1/2" hole in the top pan of the seat suspension. i drilled it in the center and it works well there.

now you will need a bracket to hold the top of the shock. i had an old strut laying around so i cut the bracket off of it, you could make one from flat metal. drill a hole in the center so it can be bolted to the underside of the suspension top using the hole you just drilled.

Take both carriage bolts and grind the 4 square corners down so the bots are round all the way to the rounded top.
The 5/8" bolt and bronze spacer goes on right,1/2" bolt and spacer on left.

use the lock nuts on the carriage bolts and tighten them till they are tight. I used pliers to hold the round bolts and an impact to tighten the nuts.

its time to put the bottom of the shock in place.
Before we get carried away we have to change the bushing in the lower rubber mount. press out the original bushing and replace with the 5/8"x3/4"x1.25" bushing. i used a little vaseline and a small press. it goes so that the bottom pivot pin going through the base the shock will go into the space in the middle where its open.

Now put the upper pin back in that goes through the torsion bracket and the base.

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