ABS HydroMax Braking System - Master Cylinder

Abs Hydromax Braking System Abs Power Brake

We've preached to you about the need to upgrade brakes when lifting a truck on huge tires, and here's an example where we do as we say. This '02 Ford F-250 Super Duty was in issue #11 of 2008 where we gave it a Rubicon Express lift and 37-inch rubber. The stock brakes were able to stop the 37s pretty well, but that's because the truck already had some decent brakes from the factory. The factory brakes are meant to stop the truck when fully loaded, and the larger wheels and tires probably took up a good portion of the safety margin built into the factory system. We didn't get a chance to really test the factory brakes while towing or while fully loaded, but we do know that they didn't have enough force to lock the tires up and cause the ABS to kick in. When we heard about ABS Power Brake Inc.'s new Hydro Max brake system, we were interested to see if this was the answer we were looking for. Once we pulled into ABS's shop in Orange, California, Junior took the wheel and had our Super Duty stopping like it never had before.

The factory booster looked like any other vacuum-assisted brake setup. It worked fine when the truck was stock, but the large tires and trailer towing taxed it to its limit.
The factory booster looked like any other vacuum-assisted brake setup. It worked fine when
The first thing Junior did was measure the pressure at the caliper. With the engine off and the pedal depressed, the pressure measured 200 psi. With the engine started and the factory booster working, the pressure went to 900 psi. We were looking for much more than that when we finished.
The first thing Junior did was measure the pressure at the caliper. With the engine off an
To remove the factory booster and master cylinder, Junior unplugged the two wiring harnesses and removed the vacuum line. He then plugged the vacuum port on the throttle body.
To remove the factory booster and master cylinder, Junior unplugged the two wiring harness

With the air cleaner out of the way, a flare nut wrench was used to remove the front and rear brake lines from the master cylinder.
With the air cleaner out of the way, a flare nut wrench was used to remove the front and r
Two bolts held the master cylinder to the booster, a socket and long extension were used to remove them.
Two bolts held the master cylinder to the booster, a socket and long extension were used t
Inside the truck, under the dash, Junior removed a pin that connected the pedal to the brake pushrod. Then he removed the brake light switch.
Inside the truck, under the dash, Junior removed a pin that connected the pedal to the bra

The booster is mounted through the firewall with four bolts. Junior had no problem getting a socket and extension on them.
The booster is mounted through the firewall with four bolts. Junior had no problem getting
The Hydro Max unit used the same master cylinder, but the billet aluminum booster is much more compact than the vacuum unit.
The Hydro Max unit used the same master cylinder, but the billet aluminum booster is much
Looking at the bottom of the booster, the high-pressure feed line is on the left, near the firewall. The larger port on the right is the low-pressure return line.
Looking at the bottom of the booster, the high-pressure feed line is on the left, near the

The guys at ABS fabricated a firewall mounting plate out of 3/16-inch steel and bolted the booster/master cylinder assembly to the firewall.
The guys at ABS fabricated a firewall mounting plate out of 3/16-inch steel and bolted the
Back under the dash, Junior reconnected the brake pedal and brake light switch.
One fitting was removed from the power steering box. Here's a shot looking straight down from the driver side fender.
One fitting was removed from the power steering box. Here's a shot looking straight down f

A high-pressure hydraulic fitting was tightened into the port on the steering box and routed to the port on the booster closest to the firewall. The barbed fitting that's pointing down is the return line.
A high-pressure hydraulic fitting was tightened into the port on the steering box and rout
The flare was cut off of the factory power steering return line to accept the return line from the booster.
The flare was cut off of the factory power steering return line to accept the return line
Next Junior topped off the new master cylinder and bled the brakes.

After topping off the power steering reservoir with new ATF, Junior bled the booster. That's a geyser of ATF coming from the valve.
After topping off the power steering reservoir with new ATF, Junior bled the booster. That
The final check of the brake pressure gave us 200 psi with the engine off, and 1,800 psi when boosted. That's twice the clamping force!
The final check of the brake pressure gave us 200 psi with the engine off, and 1,800 psi w

From The Driver Seat
The truck now has enough braking power to cause the anti-lock system to kick in, but it's not a harsh application of braking. At half pedal pressure you've got the same brakes you had before, but when you really need it, the extra power is there. There are only two drawbacks to the system. First, the sound: It's not loud, but you can definitely hear the master cylinder, it's sort of a rushing sound. We bled the system, but maybe there's still some air in there. Second, at full steering lock, on either side, there's no brake power. We'll have to work on getting stops at either the spindle or the steering box, but since it's only the last 10-15 degrees of steering wheel travel, we won't lose any of our turning radius. When driving the truck in a parking lot we had to really crank the wheel to get it to full lock, but ABS is going to correct the steering of the Super Duty so that it’s not an issue.

Your Questions Answered

Time Spent Working: 8 hours
(most of the time was spent fabricating a mounting plate)
Degree of Difficulty: Moderate
(aside from crimping the proper length hydraulic hose and fabricating the mounting plate, the job was simple)

Tools Used:
Sockets and extensions, tubing cutter, flare nut wrench, pressure gauge.

Parts Used:
ABS Hydro Max booster $950.00
DOT3 brake fluid (one quart)
AFT fluid (two quarts)

Total $950.00
(labor not included)