Master Cylinder Selection

After using my upgraded brake setup for over 2 years now, I’ve begu to research again and source farther potential upgrades. As I mentioned previously, this particular setup increased pedal travel and I had recommended using a larger brake master cylinder. This is of course if you don’t like how the brakes feel. I’d like to state its not necessary as the stock master cylinder has been tested to work for more then 2 years…especially if you’re working with a tight budget, which most of us are.If have to ask yourself, that type of pedal feel do you want and how do you want the brakes to response. Now with that said here’s what I’ve gathered so far.

I always like to begin with a reference diagram of the original parts (brake master cylinder circled in red):

sxa10stockmr2toyotadiagram

The stock Rav4 brake master cylinder has a inner bore of 7/8″ inches. NOTE – I circled the front brake line outlet as this became a vital sourcing a direct bolt on upgrade.

sxa10mc3 sxa10mc2 sxa10mc1

There are two master cylinder upgraded there are direct bolts on’s…

Subject A

The ST204 1994-1999 Toyota Celica with a bore size of 15/16″ inches.

OEM Part Number # 47201-2B090

st204mc3st204mc2st204mc1

Subject B:

The MCU10 1999-2000 Lexus RX300 with a bore size of 1″ inch.

OEM Part # 47201-48030

rx300mc3rx300mc2rx300mc1

A little general advice about selecting bore size in your master cylinder may be helpful… Decreasing MC bore size will decrease your pedal effort and increase your pedal travel. Conversely, a larger bore in your car’s master cylinder will, all other components being consistent, increase your pedal effort and decrease your pedal travel. As with some other brake parts purchases, this comes down to your preference for how the brakes “feel” under foot when you are driving.

To complete this master cylinder swap, you’ll simply have to use the Rav4 brake fluid reservoir with new seals, bolt it all up, pour some fresh fluid and bleed the brakes.

Front Brake Theory Part 2 – Stage 2 Brake Upgrade

Welcome to part 2 of my Front Brake Theory! I left off with alot of material from my first post…some of you have messaged me about a follow-up. I have to apologize for a late response. Since, I have selected my setup and have been testing it for over 4 months.

DISCLAIMER/WARNING: This is simply a guide, written to be and is intended as informational tips. This is not a 100% accurate or guaranteed foolproof guide. Work on your own vehicle at your own risk. If after reading through these tips, you do not feel comfortable doing the work yourself, please seek the help of a professional mechanic. I cannot be held accountable for your safety or vehicle. I do not take any responsibility for any damage to personal property or injury to yourself.

Here is the Stage 2 Brake Upgrade:

I’ve selected: Brake Bracket – Celica GT (95-99)

Part Numbers:

RH 47721-20420

LH 47722-20120

 96celicafrontbrakebracket3a 96celicafrontbrakebracket396celicafrontbrakebracket1

Rotors – Lexus LS430 (01 – 06)

Part Number: 43512-50220

Ls430rotorCalipers – Toyota Avalon (95-97)

Part Number:

RH 47730-07020

LH 47750-07020

avalon96frontcaliper avaloncalipers

Pads – Toyota MR2 Turbo (92-95)

Part Number: 04465-17060

Here are some reference shots: Rotor Comparison…Lexus LS430 (01 – 06) on the left and the Rav4 (96-00) on the right. IMG_8925 Test Fitting…the Celica GT (95-99) Brake Bracket. The dust shield was bent slightly to accommodate the larger 315mm diameter rotor. IMG_8924 More Test Fitting…the Celica GT (95-99) Brake Pads (these were too thick to seat properly into the brake pads clips). IMG_8928 Here is the caliper mounted and the complete what I’ll call “prototype” version of this setup.

IMG_8930IMG_8976

Fitment

There are few spots on the Celica Brake Bracket that need to be grinded to support the (1)thicker rotor, (2)the larger diameter as well as (3)the offset of the rotor. The newer setup will not work with the stock 16 inch wheels unless you use a wheel spacer (25mm thick)…I’m using the H&R one on my stock 16 inch wheels and it barely fits. Its probably better to use the Celica GT caliper over the Avalon calipers because the master cylinder will work much better with the single piston setup. I need to install a larger one with my setup, which means more $$ …which is what I was trying to avoid.

Driving Impressions

It’s a tight fit that will create a front brake bias (with the twin piston calipers) but works with no brake fade unlike that stock setup. Since I did not change/upgrade the master cylinder, the pedal travel has increased…while its good for pedal modulation, its in need of a larger bored cylinder due to the larger hydraulic volume in each caliper. Brake fade resistance has definitely improved. I plan on upgrading the rear brakes, changing the master cylinder and adding some stainless steel brake lines. Good luck, drive safely, and have fun!