[scotian]

Hi everyone, I finally got my basket case running on the weekend, and plowed my garden. It's a 1975 JD400. It sat, in the elements, for 3 years with the previous owner due to a worn out charge pump. When he moved, he called a local garage to haul it away for scrap. I heard this, and offered to take it off his hands. He gave it to me, along with the 60" deck, thrower, and blade. It already had a Magnum 20 repower. Over the last 2 years, I've rebuilt the carb and got the motor running, picked up a complete transmission off ebay and installed it, freed the brakes, all linkages were seized, installed a ruegg hitch, built a new driveshaft, and diagnosed and fixed numerous electrical issues. Anyway, can somebody tell me on the steering control valve, are there any moving parts? I'm guessing there must be, but mine is seized up. Does the shaft that connects to the steering gear box via a tie rod move in and out of the valve body? When I turn the steering wheel the whole control valve unit moves and turns the wheels, but there is absolutely no power assist. I'm sure it's an easy fix, but I thought I'd post here before tearing into it. The 400 is a dog with manual steering!!!
Thanks in advance

 

[tfgaasch]

You are correct. There is a plunger that allows hydraulic fluid pass through to the assist cylinder. That is one thing I have not tore into yet. So I don't know what retainers or Seals (let alone sizes) are required. One of these days I need to invest in a service manual.

 

[jdalchemist]

Paul,
The diagram below is from jdparts.com and shows the steering cylinder, and some of the steering valve components. In this diagram the spool rod is not pulled out of the valve body. The second picture shows components from a valve I have disassembled. The primary cause of poor (or no) power steering response in the JD 400 is corrosion in the spool rod left end, the sleeve, the dowel rod, and the valve body. A broken spring on the spool will also cause problems.

Disassembly of the valve removed from the tractor involves pulling off the retainer wire/spring #11 (Deere calls this a washer), and driving out the dowel pin #10 with a punch. The sleeve #15 should then come out of the valve body. However, it will likely be rusted into the body--I removed this one by putting some vice grips on the sleeve (after soaking with penetrating oil), tapping the vice grips with a mallet, and twisting out the sleeve. (Do not try to drive the sleeve out by pressing on or hitting the spool end). The spool rod assembly can then be gently tapped out of the body. The spring need not be removed from the spool unless it is rusted or worn and needs replacing.

Be careful removing the fiber backing washer #7 from the valve body--replacement involves buying the seal repair kit AM35535 (O-rings and washer). The two O-rings #8 can be removed from deep in the valve body with a pick or bent fish hook. In the best of circumstances, a trip to the hardware store for these #212 O-rings, along with clean-up of all the corrosion and reassembly (grease the sleeve and rod end parts)will have you back in business. However, if in doubt, buy the Deere seal kit, the spring #13, and the washers and clip #12, #14.
Harold

 

[scotian]

Gentlemen,
Thanks so much for the insight, this site and it's members are awesome!