Why? Because after many years of searching for a master cylinder setup that would work on my FJ40 that has disc brakes front and rear, I’ve finally found exactly what I’ve needed.
FJ, 4Runner and Mini truck owners around the globe has searched high and low for a master cylinder to quell their braking woes, to no avail. These people have tried various mini truck master cylinder swaps, they have tried hydroboost systems, and they have tried everything shy of cutting holes in the floor boards for the ol’ Fred Flintstone method of braking. All Pro Off Road has yet again delivered. And if things couldn’t get better, the price was right too and installation took only 30 minutes. Too good to be true? Hardly.
Here’s a little background to clarify… If you have added disc brakes to your pre-disc-brake FJ series, or your ’79-’95 4Runner or Toyota Mini truck, then you know that your stock master cylinder probably doesn’t quite cut it. Even if your rig had discs up front and you converted the rear, there was still likely not enough brakes. There are two primary reasons why your OE master cylinder won’t stop your rig:
Your master cylinder doesn’t have one (or two) residual valves (more on that momentarily).
The master cylinder bore size is too small. Disc brakes require more volume than pressure – vice versa for drum brakes.
All Pro Off Road however has done all of the homework and has even sourced a cost-effective master cylinder that comes with residual valves for the front and rear brake lines, and has a 1″ bore diameter (as compared to a more common 13/16″ bore). A residual valve, the disc pads expand and open up after braking, which causes excessive pedal travel the next time you step on the brakes. The bore diameter of the master cylinder is also critical. Too small of a bore and you’ll generate too much pressure, but not enough volume, which simply doesn’t work well with disc brakes. Too large of a bore and you won’t generate enough pressure, which also doesn’t work. In the end, there is a science, and an art, to dialing in brake systems for any vehicle. However, All Pro Off Road has found a unit that should work darn-near perfectly (and a darn sight better than anything else) for your rig.
Installation of the new master cylinder on our project FJ40 was a snap. A few libations and a bacon sandwich convinced our feature editor, Mike Batchelor, to help me do the swap so I could focus on barking orders and taking pictures.
Start by removing your existing master cylinder. We won’t go into details because it will vary from vehicle to vehicle, but in our case, we drained the cup first. We then removed the front and rear hard brake lines and placed a catch rag underneath. Lastly, we removed the four nuts that retain the master cylinder to the brake booster and pulled the old unit out.
Now it was time to install the new master cylinder, in the reverse order. Simply install the four retaining nuts, attach your hard, brake lines and fill the cup with brake fluid. The last step is to bleed the brakes, and we recommend starting with a brake cylinder furthest away from the master cylinder and working your way closer – we’ve found this to be a most effective way of bleeding brakes.
Installation Pictures, from left to right:
The All Pro Off Road FJ80 master cylinder
A shot of our Toyota mini truck master cylinder in our FJ40
Remove the hose clamp of the cup tube and drain
Remove the 4 master cylinder retaining nuts
Remove the front and rear hard, brake lines
After removing the old master cylinder, install the new one
Install and tighten the 4 master cylinder retaining nuts
Attach the hard, brake lines and bleed the brakes
Braking is markedly improved on our project FJ40. Even with 35″ tires, the truck stops in short order. We can’t completely lock up the tires for a full 4-wheel slide, but we’d prefer not to have that anyhow. Instead, the new master cylinder has enough mojo to stop the truck very similar to that of a vehicle with anti-lock brakes – that is, the tires chirp a bit under an emergency stop, but never actually lock up completely. In our minds – perfect! At $139 (at time of publishing), it won’t break your wallet.
All Pro Off Road’s FJ80 master cylinder was a 20 minute swap (including the time needed to take pictures and bleed the brakes) and it’s one of the best modifications we could have made to our rig.
|All Pro Off Road|
|541 N. Palm Ave.
Hemet, CA 92543