Lexus RX300 Big Brake Kit Upgrade / TTSPORT Classic 8657
Lexus builds the RX to be smooth, quiet, and reliable — not necessarily quick to stop. This RX300 owner ran into that exact limitation and swapped the factory twin-piston brakes for a TTSPORT front six-piston / rear four-piston big brake kit, complete with an EPB caliper for the rear parking brake.
The RX is Lexus's best-selling model worldwide, and it's easy to see why: it undercuts its German rivals on price while matching them on cabin quality and reliability. This particular RX runs the 2.0T high-output turbo four — 238 hp, 175 kW, 350 Nm — good for a 7.9-second run to 100 km/h. The brakes, though, never got the same attention as the engine.
The Problem: A Soft Pedal on a Fast SUV
Lexus tunes its brakes for a soft, progressive feel across the lineup, and the RX is no exception. At roughly 2 tons, the stock 100-0 km/h stopping distance runs past 40 meters — weak by current standards. The twin-piston front calipers cope fine around town, but owners report the pedal going soft during hard braking from highway speeds: it bites initially, then fades toward the end of the stop. Owner forums have pointed to the piston not fully clamping the pad under sustained load. Short of a driving-style change, the fix is a caliper and rotor upgrade.
Vehicle & Kit Specs
| Item | Specification |
|---|---|
| Vehicle | Lexus RX300, 2.0T, 20-inch factory wheels |
| Front caliper | TTSPORT TT8657 forged six-piston monobloc caliper (red) |
| Front rotor | 380x34mm high-carbon, heat-treated rotor |
| Rear caliper | TTSPORT TT6411 forged four-piston caliper + TTSPORT single-piston EPB caliper |
| Rear rotor | 380x28mm high-carbon, heat-treated rotor |
| Lines | TTSPORT stainless steel brake lines |
Front axle first: the TT8657 caliper bolts up with a vehicle-specific bracket, and the 380x34mm rotor replaces the factory disc with no spacers needed to clear the 20-inch wheels.
The kit ships with all the mounting hardware needed for a bolt-on install — bracket, pads, and stainless lines included alongside the caliper and rotor.
Why It Works
- Every part of the TT8657, from caliper body to mounting hardware, is forged rather than cast — TTSPORT states that adds roughly 30% more rigidity, so caliper flex under hard braking is reduced and pedal feel stays firm from initiation to full stop.
- Competition-spec pistons in the front caliper respond more consistently to pedal input, giving a more linear feel through the stop instead of the fade the stock calipers exhibited.
- The TT8657 caliper accepts rotors from 355x32mm up to 405x34mm, so this platform runs a 380x34mm front disc — meaningfully larger surface and mass than the factory rotor for better heat capacity.
- The rear four-piston caliper handles service braking while a separate TTSPORT EPB caliper takes over the parking brake — a non-destructive way to upgrade rear braking without losing electronic parking brake function.
The red powder coat on the TT8657 isn't just cosmetic — it makes it easy to confirm the caliper is fully seated and clocked correctly during install, and it's visible behind the RX's 20-inch wheels once the job is done.
Installation Gallery
Frequently Asked Questions
Does this TTSPORT big brake kit fit the RX300's factory 20-inch wheels?
Does the rear kit replace the factory electronic parking brake?
What rotor sizes work with the TT8657 front caliper?
Need fitment confirmation? Choose the closest TTSPORT series or send your vehicle, wheel size, and intended use before ordering.