What is the gear ratio of the 91 LS400?
The 1991 Lexus LS400 uses a four‑speed automatic transmission with a final‑drive ratio commonly cited around 4.10:1. This configuration shapes highway RPM and overall efficiency. Below is a detailed look at what those ratios are and how they affect the car’s performance.
Understanding the LS400 drivetrain
Gear ratios map engine speed to wheel speed. In a luxury sedan like the LS400, a higher final-drive ratio (a larger number) means more engine RPM at a given road speed, which can improve acceleration but reduce fuel economy at highway speeds. The LS400’s setup prioritizes a smooth, quiet ride with ample torque for confident daily driving.
Transmission specifics
The LS400 from this era uses a four‑speed automatic transmission (the A340E family) paired with a dedicated final drive. The combined effect of the transmission gear sets and the differential determines how the engine’s power translates into road speed across gears.
Key ratios at a glance
Below is a concise breakdown of the main ratios for the 1991 LS400. Note that exact numbers can vary by market, production batch, and VIN.
- Final drive (differential): about 4.10:1 (commonly cited for US‑market LS400).
- Transmission type: 4‑speed automatic (A340E family).
- First gear ratio: approximately 3.61:1.
- Second gear ratio: approximately 2.03:1.
- Third gear ratio: approximately 1.37:1.
- Fourth gear ratio (overdrive): 1.00:1.
These figures illustrate how the engine’s torque is multiplied and then delivered to the wheels, with the first gear providing strong initial response and the overdrive fourth gear supporting relaxed highway cruising.
Real‑world implications
With a final drive around 4.10:1 and a four‑speed automatic, the LS400 tends to run at moderate engine speeds during highway travel, contributing to its characteristic smoothness and relatively quiet cabin. The gearing favors comfortable long‑distance driving and confident mid‑range acceleration rather than sporty, high‑revs performance.
How to verify the exact ratios on your car
Because there were regional variations and production revisions, the authoritative source for your specific vehicle is the build sheet or service manual tied to your VIN. You can verify the ratios by checking:
- VIN‑specific build information from Lexus or the dealer.
- Under‑hood or differential data plates showing the final drive ratio.
- Official shop manuals for the UCF10 LS400 with the A340E transmission.
For best results, refer to your car’s exact manual or build sheet to confirm the precise numbers for your VIN and market.
Summary
The 1991 LS400 commonly employs a final‑drive ratio near 4.10:1 with a four‑speed automatic transmission. This pairing yields smooth acceleration, comfortable highway cruising, and a refined overall driving experience typical of early Lexus luxury sedans. Always check the vehicle’s specific documentation to confirm the exact gearing for your particular car.
How much horsepower does a 1991 Lexus LS400 have?
250 horsepower
At the heart of the LS400 was its 4.0-liter V8 engine, known for its smoothness and performance. The engine produced 250 horsepower, allowing the car to accelerate smoothly and confidently.
What makes the LS400 so special?
LS400. So what made it. Great. It all starts with the original petrol V8 dual overhead cam. And just smooth as butter to drive it was made to a four-speed automatic transmission.
What is the top speed of the 91 LS400?
The chassis used an independent, high-mount upper arm double-wishbone suspension setup with twin tube shock absorbers, and a passive air suspension system was optional. The LS 400's 0–100 kilometres per hour (62 mph) time was 8.5 seconds, and its top speed was 250 km/h (155 mph).
What is the rear end ratio of the LS400?
3.62 ratio
LEXUS LS400 97 thru 6/97 (3.62 ratio).
