This guide explains how to fit load control shaft seals on four cylinder John Deere tractors.
What the load control shaft does
The load control shaft runs through the rear housing of the tractor.
It links the draft and position control system to the rear linkage.
Seals around the shaft stop transmission and hydraulic oil escaping.
Why load control shaft seals matter
Worn seals let transmission oil leak from the back end.
Left alone, the tractor can lose a large volume of oil.
Low oil harms hydraulic pumps, lift arms, and internal gears.
Replacing the seals early protects the whole rear end.
Which tractors this guide covers
This job applies to four cylinder John Deere 20, 30, 40, and 50 Series tractors.
The layout and shaft design are similar across these models.
Seal sizes still depend on the shaft diameter on each tractor.
Tools and parts you need
- You need new load control shaft seals matched to your shaft size.
- You need a good pair of pliers.
- You need a 5/16 punch.
- You need a hammer.
- You need a small pick.
- You need emery cloth or similar abrasive strip.
- You need a topped up oil can.
- You need clean rags.
- You also need patience and time without rushing the job.
Safety and preparation
Park the tractor on firm level ground.
Apply the handbrake and chock the wheels.
Lower the linkage and remove any mounted implements.
Switch off the engine and remove the key.
Clean around the rear housing before you start work.
Step one: remove the linkage
Start by removing the linkage from the load control shaft area.
Remove the spring clip that retains the linkage pin.
Use pliers and keep the clip under control to stop it flying off.
Spring clips like to disappear into gravel and workshop clutter.
Knock out the retaining pin with the 5/16 punch and hammer.
If the pin is seized, expect to use controlled force to move it.
Step two: slide the bush off the shaft
Once the pin is out, slide the bush off the load control shaft.
Expect the bush to feel tight after years of use.
Work the bush off with steady pressure and a slight wiggle.
Avoid marking or scoring the shaft while you move the bush.
Step three: drain the transmission oil
Drain the transmission oil before you disturb the seals.
Place a suitable container under the drain point.
Undo the drain plug and let the oil flow out gently.
Wear gloves and avoid hot oil burns.
Use rags to contain any stray drips and splashes.
Step four: disconnect linkage from the shaft
Disconnect any remaining linkage pieces from the load control shaft.
Make a note or take photos so you refit parts in the same layout.
Clear space around the shaft ends so you can work cleanly.
Step five: inspect the load control shaft
Clean the exposed ends of the shaft with rags.
Use emery cloth to remove light rust and glaze.
Check the shaft for grooves where it runs in the seals.
Expect some wear after years of work.
Excessive grooves might justify a new shaft in future.
Step six: knock the shaft inward
Clean the end again so dirt does not pull into the housing.
Use a hammer and suitable drift to knock the shaft further into the tractor.
Use firm but controlled blows rather than wild hits.
Move the shaft enough to expose the inner seal on the outer side.
Step seven: remove the first old seal
Use a small pick to hook the exposed seal carefully.
Work the seal out of its groove without scratching the housing.
Accept that the old seal has done its time and may crack.
Discard the removed seal and clean the groove with a rag.
Step eight: fit the new seal in the outer bush
Fit the first new seal into the groove on the bush that sits in the housing.
Press the seal in square and even all the way round.
Use fingers or a blunt driver rather than a sharp tool.
Aim for a snug fit with the lip facing the oil side as required.
Step nine: push the shaft back to expose the second seal
Push the shaft back through from inside the housing.
Move it until the second seal appears at the opposite side.
Keep the shaft supported so it does not drop on internal parts.
Step ten: remove and replace the second seal
Remove the second old seal using the same small pick method.
Clean the second groove with a rag and emery cloth if needed.
Fit the second new seal into the groove on that side.
Seat the seal evenly so it matches the opposite side.
Step eleven: centre the shaft and refit linkage
Move the shaft back to its central working position.
Check equal exposure of the shaft on both sides of the housing.
Refit the bush onto the shaft.
Refit the linkage to the load control shaft.
Install the retaining pin and secure it with a spring clip.
Check that the linkage moves freely without binding.
Step twelve: change the hydraulic filter and seal
Spin off the hydraulic or transmission filter housing.
Remove the old filter element.
Clean the housing and sealing surfaces with rags.
Fit a new filter element as specified for your tractor.
Fit a fresh seal on the housing before refitting.
Tighten the housing by hand to the correct seating.
Step thirteen: refill with oil and check for leaks
Refit any drain plugs with clean seals or washers.
Refill the transmission and rear axle with the correct oil grade.
Use a topped up oil can if you need to prime any circuits.
Start the tractor and run the hydraulics.
Stop the tractor and inspect the load control shaft area.
Look for fresh oil around both new seals.
Dry castings indicate a successful repair.
Common mistakes with load control shaft seals
People skip the oil drain and end up soaked in old oil.
People drag dirt into the housing by not cleaning first.
People gouge the housing with sharp picks and drivers.
People forget to change the filter and housing seal while access is easy.
People rush the seal seating and cause new leaks.
When to ask for help from Nick Young Tractor Parts
If you find heavy grooves on the shaft, ask about replacement shafts.
If you are unsure on shaft size, ask for help matching the right seals.
If leaks persist after new seals, discuss further checks on housings and bores.
Nick Young Tractor Parts can cross reference series, shaft size, and seal kits.
Quick recap for fitting load control shaft seals
Remove linkage and the bush from the load control shaft.
Drain transmission oil and clean the shaft area.
Knock the shaft inwards to expose and remove the first seal.
Fit a new seal in the bush and push the shaft back to reveal the second seal.
Replace the second seal, centre the shaft, and refit linkage.
Change the filter and housing seal, refill with oil, and check for leaks.
With this load control shaft seal guide based on your four cylinder video, your blog can turn simple fixes into informed customers and healthier tractors.
