Product Description
Upgrade the steering performance of your heavy-duty GM truck with the PSC SG840 Big Bore XD Power Steering Gearbox. Engineered by PSC Steering Components, this high-performance steering box is designed to eliminate steering wander, sloppy steering feel, and sector shaft deflection common in older GM trucks. The SG840 Big Bore XD steering gearbox features an upgraded 45mm sector shaft bearing and larger piston diameter that significantly increases torque output. This allows trucks running oversized tires, locking differentials, and heavy off-road setups to maintain responsive and controlled steering. Unlike rebuilt gearboxes, the PSC SG840 is 100% new construction, providing improved reliability and long service life for both daily driving and extreme off-road use. Whether you're towing, rock crawling, or simply want to restore precise steering feel to your truck, the PSC SG840 Big Bore XD steering box delivers improved steering torque, stability, and durability for demanding driving conditions.
Fitment
- 1988–1999.5 GM Silverado / Sierra 2500 4WD
- 1988–1999.5 GM Silverado / Sierra 3500 4WD
- Compatible with GM C/K 2500 & 3500 heavy-duty trucks
- Direct replacement steering gearbox for factory steering box
Specifications for PSC SG840
| Specification | Details |
|---|---|
| Manufacturer | PSC Steering Components |
| Part Number | SG840 |
| Turning Ratio | 13:1 Ratio / Approx. 3.25 Turns Lock-to-Lock |
| Sector Shaft Bearing | 45mm Heavy-Duty Bearing |
| Input Shaft | GM DD with 3/4-30 Spline Adapter |
| Mounting | Three-Bolt Inside-Frame Mount |
| Port Type | Metric O-Ring |
| Pitman Arm Requirement | Four-Slot Pitman Arm Required |
| UPC | 687927186385 |
| GTIN | 687927186385 |
| Shipping Info | Calculated at checkout |
| Prop 65 | WARNING: Cancer and Reproductive Harm – https://www.P65Warnings.ca.gov |
Frequently Asked Questions
What makes the PSC SG840 better than a stock steering box?
The SG840 features a larger piston and upgraded 45mm sector shaft bearing which greatly increases steering torque and reduces sector shaft deflection commonly found in factory gearboxes.
Is the PSC SG840 a rebuilt steering box?
No. The SG840 is a completely new steering gearbox built by PSC and is not a remanufactured unit.
Will this steering gearbox help with oversized tires?
Yes. The Big Bore design increases hydraulic torque output which helps overcome steering resistance from larger tires and off-road modifications.
Does this steering box support hydraulic steering assist?
No. The SG840 is a non-ported gearbox. If you plan to run hydraulic cylinder assist you would need the SG840R ported version.
Does this steering box reuse the factory pitman arm?
Yes. The SG840 works with a four-slot GM pitman arm commonly used on 1988-1999.5 GM 2500 and 3500 trucks.
