High-Volume Third-Party Remanufactured Defender Steering Box
Strip-down and component analysis, 2 December 2025
We bought a widely sold third-party remanufactured Defender steering box, tested it on the Adwest rig, then took it apart. It passed every functional test. The strip-down is on this page.
Why this report exists
A steering box that passes a bench test tells you it works today. It does not tell you what is inside it, or how long it will keep working.
The aim was to document what a typical aftermarket steering box actually consists of once it is taken apart, and to assess that against OE expectations.
The unit is not named. The findings are the point, not the badge on the box.
It passed every functional test
The gear was cleaned enough for safe handling, mounted to a test fixture and connected to the hydraulic rig. Testing followed the Adwest Varamatic Test Procedure.
| Test | Method | Result |
|---|---|---|
| Proof pressure | Raised to proof test pressure at both locks | Pass. No seal failures observed |
| External leakage | Raised to external leak test pressure at both locks, observed under UV light with dyed oil | Pass. No leakage observed |
| Internal leakage | Raised to internal leak test pressure at both locks, observed via flow gauge | Pass. Within specification |
| Valve balance | Raised to valve balance test pressure at both locks, input torque observed | Pass. Within specification |
One thing could not be done. Air could not be vented from the bleed screw, because the bleed screw was completely rusted and had to be removed.
On the rig, this unit passed. Everything below was found after it passed.
What the strip-down found
Original seals were refitted, not replaced
Across five separate locations, the seal that came out of the unit had been put back into it:
- • Cam adjuster square section seal, original fitted, not replaced
- • Piston cap square section seal, original fitted, not replaced, and damaged
- • Piston rack Teflon seal, original fitted, not replaced
- • Valve assembly Teflon seals, original fitted, not replaced
- • Rack pad adjuster seal, original fitted, not replaced
Seals are the wear items. A unit sold as remanufactured with its original seals still in place has not had the one thing done to it that most determines how long it lasts.
Seals of unknown origin, and a hardened compound
Where seals had been replaced, we could not establish what they were. The supplier is not known for the sector shaft output pressure seal, the output backup seal, or the output dirt seal.
On the output pressure seal, a hardened unidentified sealing compound had been used. The cover plate seal and the input dirt seal are both not to OE specification.
A sealing compound is not a seal. It can make a unit hold pressure on a bench and still fail to reseal once it is disturbed, which is why a leak returns after a repair that appeared to work.
A sector shaft ground undersize
The long end of the sector shaft had been ground down below size to remove a corroded area. The sealing diameter is now undersize, but the seal fitted to it is close to original dimensions.
Two consequences follow. Seal engagement is reduced, and the contact area for the box needle bearing is reduced. Sealing compound had been used here as well, which we assume was to make up for the lost engagement.
Grinding a shaft to clean up a corroded sealing area is not a repair we would sign off. It removes the corrosion and the specification at the same time.
Corrosion left in the unit
The bleed screw was completely rusted and had to be removed to test the unit at all. The bleed hole was full of rust. Both were inside a box sold as remanufactured.
Fitment and assembly faults
- • The output shaft dirt seal is not seated correctly, which allows dirt ingress
- • A damaged tooth was observed on the sector shaft, consistent with a reassembly issue
- • The input seal was damaged during dismantling, so no judgement can be made on its condition either way
A dirt seal that is not seated is not a cosmetic fault. It is the part that keeps grit away from the sealing surface the shaft runs against.
What was satisfactory
Not everything was wrong, and the report records that too:
- • Box housing, general condition satisfactory
- • Valve assembly, general condition satisfactory
- • Valve bearings, satisfactory
- • Piston rack teeth, satisfactory
- • Follower assembly, no issues identified
Why it matters
None of the findings above stopped this unit passing a functional test. That is the whole difficulty. Reduced seal engagement, reused seals and an undersize shaft do not usually cause immediate failure. They shorten service life, and on a steering box the failure they eventually produce is not a convenient one.
This is why we inspect before we quote, record what we find, and replace seals as a matter of course rather than on judgement. A rebuild should leave a record of what was actually done to your unit.
See how OE-spec reconditioning works, or read the strip-down of a genuine 1988 unit on our own bench.
Tested and stripped down 2 December 2025, to the Adwest Varamatic Test Procedure.