What is the ratio of the steering rack on a 2013 Subaru STI?
The steering rack ratio on the 2013 Subaru WRX STI is approximately 15:1. Exact figures can vary by market, trim, and factory options, so check VIN-specific service materials for a precise value.
Understanding what the ratio means
The steering ratio is a measure of how much the steering wheel must turn to produce a corresponding turn of the front wheels. A roughly 15:1 ratio indicates a balanced feel: steering is responsive enough for quick inputs, but not so quick that high-speed stability is compromised. For a performance model like the 2013 STI, this type of ratio aims to combine precise handling with predictable feedback through corners and at speed.
Typical values and variability
Subaru does not routinely publish an exact rack ratio for consumer reference, and figures can differ by region and production run. Commonly cited ranges for the 2013 STI hover around 14.7:1 to 15.0:1, with minor deviations depending on market-specific tuning or any replacement/race-prep components that may be installed by dealers or aftermarket providers.
Several factors can influence how the ratio is perceived in practice, even if the exact mechanical ratio remains unchanged. These include market-specified steering assist calibration, wheel and tire sizes, and any optional performance packages that alter steering feel or response without altering the official rack ratio itself.
- Market and trim differences can lead to small variations in the published ratio or in the steering feel due to different assist tuning.
- Aftermarket or dealer-installed equipment may replace the rack with a different ratio, affecting steering response.
- Wheel and tire sizes influence the effective steering feel, though they do not change the rack ratio itself.
In practical terms, most drivers experience a direct, confident steering feel in the 2013 STI, consistent with a mid-teen to around 15:1 ratio and a steering system tuned for spirited driving on winding roads.
How to verify the exact ratio for your car
If you need the precise ratio for your vehicle, consider these steps:
- Consult the official Subaru Service Information System (SIS) or the factory workshop manual for your VIN to locate the steering gear ratio data.
- Ask a Subaru dealership or certified shop to pull the VIN-specific service bulletin or parts catalog entry, which may list the exact rack ratio and part number.
- As a measurement-based check, you can estimate the ratio by measuring steering wheel input versus front-wheel angle across the steering range and calculating the ratio from the data you collect.
- Record your vehicle’s wheel/tire size, as larger wheels can alter the perceived steering feel even if the physical ratio remains the same.
Note that for routine maintenance or diagnostics, the exact rack ratio is less critical than ensuring the steering system is functioning properly, with appropriate play, alignment, and assist performance.
Summary
The 2013 Subaru WRX STI commonly uses a steering rack with a ratio around 15:1, providing a balance between quick response and high-speed stability. Exact VIN-specific figures may vary by market or option, so consult factory service materials or a Subaru dealer for the precise value. This ratio, combined with tire choice, alignment, and steering assist tuning, shapes the overall steering feel that drivers experience.
