APEX Steering Boost Kit for Jeep JL and JT - without cooler

On bigger tyres and with a heavier front end, the electric steering in the JL gives up exactly when it is needed most: in the rocks, and manoeuvring in a car park on a hot day.

The Boost Kit does not replace the pump — it retunes the factory blow-off valve, raising working pressure and, the manufacturer states, steering force by 40%.

Key benefits

The effects the manufacturer lists:

• no stiff steering in frost and smooth parking manoeuvres in the heat
• better feel in sand and fewer bumps fed back to the wheel
• easier steering at reduced tyre pressure
• beyond the assistance itself it does not change how the vehicle drives compared with the factory system

Technical data

• Manufacturer part number: X02-04-001
• Version: without a power steering cooler
• Stated effect: a 40% increase in steering assistance
• Pressure: 2000 PSI recommended, 2300 PSI maximum allowable
• High pressure line bolt (pump): M8x1.25x22 mm
• Vehicles: Jeep JL and JT
• Engines: 2.0L, 3.6L, 392 and diesel
• Tyres: up to 39" fully covered in most cases; at 40" some resistance may appear at reduced pressure on high traction surfaces
• What it does not fix: steering play caused by problems with the aluminium steering box
• Requirement: the kit must run with a cooler — in this version you buy one separately
• Version with cooler: part X02-04-002

Who it is for

For Jeep JL and JT owners who already run a power steering cooler, or are sourcing one separately, and want more force at the wheel without replacing the pump. If you do not have a cooler, the version with one included is the simpler buy.

The manufacturer's warnings — read before buying

The install instructions open with five warnings, and each of them is about either money or a working vehicle.

1. The pressure limit. The factory setting is about 1300 PSI. The recommended 2000 PSI is described as the best compromise between output and reliability, and 2300 PSI is the maximum allowable, not to be exceeded: going past it leads to pump or steering gear failure. The green zone on the supplied gauge is safe, the yellow one can shorten pump life.

2. The cooler is mandatory. Without one the system overheats, and that means a failed pump or steering gear. Only the APEX cooler has been tested with the boost valve — other types may not cool enough.

3. Temperature checks. After hard use, check the oil temperature periodically. Do not exceed 300 °F (about 150 °C).

4. Systems already overheated. A system previously overheated or run in extreme conditions will most likely fail at the raised pressure. APEX accepts no liability for the factory power assist system — hoses, pump or steering gear.

5. The oil. The system must run a high-grade pure synthetic fluid. ATF is prohibited. The named oils: MOPAR 68088485AB, PENTOSIN CHF 11S, REDLINE 30404.

Installation: the pump comes out of the vehicle

This is not a job done in place. The pump MUST be removed from the vehicle, and the valve port must face up throughout removal and installation — otherwise the spool valve falls out, most likely gets lost, and a new pump is needed. The instructions are based on the 3.6 and 2.0 turbo engines, where the steering system is identical; on the diesel and the 392 the strip-down may differ, and APEX then refers to the MOPAR pump removal procedure.

Before fitting, back the pressure set screw all the way out against the snap ring. Left screwed in, it can create a high-pressure condition before the pressure is even set and damage the pump. The boost valve itself goes in with a 15 mm hex at 6 ft-lbs — take care not to drop anything into the pump.

Setting the pressure is a two-person job: one turns the steering lock to lock, the other watches the gauge and adjusts. The rule is never more than a quarter turn at a time. Once it is set, the gauge and the sandwich plate come off and the factory high pressure line goes back directly to the pump.

Frequently asked questions

Will the kit remove steering play?

No — play caused by problems with the aluminium steering box is not something this kit fixes.

Will it work on 40" tyres?

Up to 39" — yes, in most cases. At 40" expect some resistance at reduced tyre pressure — the condition is in the technical data.

Does it fit the diesel and the 392?

Yes, both are on the engine list. The pump strip-down can differ on them and the manufacturer then refers to the MOPAR procedure — the rest is in the installation section.

Is the cooler essential?

Yes, the manufacturer makes it a condition: without a cooler the system overheats, and that ends in pump or steering gear failure. With any cooler other than the APEX one, the choice is on you. No cooler yet? Get in touch and we will put the set together or point you to the version that includes one.