|
|
Hydraulic Brake Assist System - Just Stop It!Hydra-Boost System From the June, 2012 issue of Modified Mustangs & Fords By Mark Houlahan Photography by Mark Houlahan
|
|
One of the top upgrades we're asked questions about every month is braking. How to get the car to stop better? What brake kit do I use? Should I go four-wheel-disc or just upgrade the front? And so on. One question, however, we don't get asked much is whether an owner should keep the manual brakes or go to power. It seems the majority of the questions center on what to do at the wheels and not so much under the hood. While it's a given that anything you can do to make your brakes more effective and your classic safer on today's roads is good, more often than not we see a dual reservoir manual brake system when a hood is opened. We applaud the dual-reservoir upgrade in the name of safety, however, we feel a lot is being left on the table by not having some sort of assist system backing that master cylinder up. We've heard from some readers that say they prefer their classic Fords to "feel like a classic when they drive them; with manual steering, manual brakes, roll up windows, and so forth. OK, windows that you have to turn a crank to raise and lower is most likely not going to kill you, but having manual steering and manual brakes can be downright dangerous on the modern high-speed roads many of us travel today. Of course, if you drive your car to a show once a month, that's a big difference than those who are out every weekend hitting cruises, using their classic for errands, or even those that drive their car every day (we love seeing classic Fords/Mustangs on the road as a daily driver!). For those that really use their classics, having power steering and power brakes puts you on par with those driving around you. So bolting up a power brake vacuum booster is the solution, right? Well, not always. While the vacuum-assist-based brake booster has been around for more than half a century, it's not always the easiest part to package in a cramped engine bay, plus for those of you with the big lumpity-lump cams, you know all too well how poorly vacuum-based brakes work (or doesn't) because you have little-to-no vacuum to speak of with a cam like that. So, if you're running a big-block, a modern modular swap, or have a fairly radical engine, what's the solution? The solution lies in your power steering pump, that's what! Your power steering system can put upwards of 2,000 psi of fluid pressure to a steering box, rack-and-pinion, or hydraulic ram. Harnessing that fluid pressure to use as a means of brake assist to give a car the feel of vacuum assist brakes, but without the packaging or vacuum hassles, is the job of a hydraulic brake assist unit, commonly referred to as a hydraboost system. First used on heavy trucks and later in GM and Ford vehicles, we bet at least one of your daily drivers has this style of assist system (own a late-model G.T. 500, Terminator Cobra, or a Lincoln Mark VII?). The hydraulic assist unit, in a nutshell, uses the power steering pump's high-pressure fluid to "boost" your brake pedal feel/pressure. The pressurized fluid is then handed off to the steering system and one doesn't affect the other (heavy braking doesn't reduce steering effort, and so on). Now don't go running out to the salvage yard thinking you'll score one of these assist units on the cheap and have killer power brakes in a weekend. The mounting configuration of these units is tricky at best, and there are many different mounts for all of the manufacturers that use this type of system. Save yourself the headache and do what we did; pick up the phone and discuss your brake system needs with the folks at Hydratech Braking. We were so happy with their system on our Factory Five Cobra replica when we built it that they were our first call when we started figuring out the brake package on project Generation Gap. Hydratech's assist units are all brand-new (no used garbage that gets a seal kit and a splash of paint), and are designed for the application. The beefy billet aluminum mounting adapters means most kits simply bolt in place of your old vacuum booster or manual master cylinder (on our '68, we did have to drill out a few holes common to a vacuum booster mounting setup). Its trick, threaded booster pushrod means an adjustable-height brake pedal, and the company offers several master cylinder options to boot. With our project's 4.6L Three-Valve modular engine in place, we only had to take one look at our firewall to know it was a Hydratech assist unit or manual brakes, and there's no way we're building a car with this kind of driveline technology with manual brakes.  1 If your Mustang had factory...  1 If your Mustang had factory vacuum power assist braking, you will not need to break out the drill. For manual brake cars like ours, the two upper mounting holes and the hole directly beneath the master cylinder opening will need to be drilled out. The brake pedal support bracket will also need its threaded inserts removed.  2 While only originally used...  2 While only originally used on the '69-'70 Mustang, the mounting pattern is the same. Thus, we opted to use this gasket between the assist unit and the firewall from National Parts Depot (NPD).  3 Fitting the assist unit...  3 Fitting the assist unit to the firewall will help in determining what holes need to be drilled out/enlarged and what threaded inserts to remove. Hydratech provides the correct mounting hardware for the upper left retaining point, as some firewalls used a bolt and others had a stud and nut affair. We left our pedal support thread insert in place here and used the supplied chrome Allen head bolt.  4 The remaining four mounting...  4 The remaining four mounting points are secured with serrated flange nuts from the passenger compartment side of the firewall. Start all of the nuts and tighten evenly to prevent cocking the assist unit and creating a bind point. A swivel socket helps here on a car with full wiring/gauges, but on an in-progress car like ours, access was easy with a long extension.  5 Displacement wise, the...  5 Displacement wise, the modular engines are relatively small (the 4.6L is but 281ci), but due to their OHC design, they are "broad shouldered," thus the limited room to fit a power brake solution. As you can see here, the Hydratech assist unit clears with 3/8-inch of room--plenty with our urethane engine mounts.  6 Back under the dash, the...  6 Back under the dash, the Hydratech assist unit's pedal mounting eyelet is made from billet steel, and each one is designed for the application intended and not some universal mount. The assist unit pushrod has a pivot feature to it for slight misalignment correction as well. The new brake light switch, retaining pin, and plastic washer are from NPD.  7 One of the neat features...  7 One of the neat features of the Hydratech pedal mounting eyelet is the threaded adjustment ability. The threaded pushrod allows the pedal eyelet to be moved fore and aft to adjust overall pedal height. Initially, our pedal was higher than we liked when we first connected the pedal. A few turns of the adjuster and our pedal was a good half-inch lower and right where we wanted it.  8 A quick check of the brake...  8 A quick check of the brake light switch with our digital ohm meter confirmed it was working as it should, and only allowing continuity when the pedal was depressed.  9 We ordered the deluxe pedal...  9 We ordered the deluxe pedal trim and "disc brake" pedal pad from NPD to offer a nice upgrade over the basic rubber pad that came pre-mounted on our reproduction pedal arm. We do have the brake pedal pad that matches the accelerator pedal, but it's narrower than the '68 pedal. For now we like the idea of a wider brake pedal to step on, but might trim it down later to fit the matching pad.  10 On direct replacement...  10 On direct replacement Hydratech kits, the two high-pressure PTFE braided hoses are pre-made and just need to be threaded onto the appropriate fittings. For custom setups, Hydratech leaves the hoses a little long, and with one end unfinished, so they can be completed in the field. Here, we've loosely installed the assist unit's inlet and outlet high-pressure hoses for measuring. The top hose will go to the power steering pump and the bottom hose to the rack.  11 Included in the Hydratech...  11 Included in the Hydratech kit is a selection of fittings appropriate to your build (rack-and-pinion, stock or aftermarket pump, and so on). For late-model power steering pumps and rack-and-pinion units, these O-ring–style fittings seal the ports and convert them to standard -6 AN ports.  12 On the modular engine...  12 On the modular engine power steering pump, the outlet port is at the bottom. Thread the fitting in and then tighten with a socket and ratchet.  13 Route the correct braided...  13 Route the correct braided line to the pump and install (loosely) one of the supplied fittings that will allow the hose to clear all moving parts (a 90-degree elbow in our case), and then mark the hose with tape or a marker/paint pen where it needs to be trimmed to length.  14a The Heidts Superide II...  14a The Heidts Superide II front suspension we used on our project features a late-model Mustang power steering rack, and Hydratech's O-ring fittings thread right in to convert the ports.  14b The lower port is the...  14b The lower port is the high-pressure inlet port and the upper port (closer to the steering shaft) is the low-pressure return port. We used a 45-degree elbow fitting for the rack's high-pressure hose.  15 Hose assembly isn't difficult,...  15 Hose assembly isn't difficult, but care must be taken at each step. Begin by applying tape to the area where you will be making your cut. You can use a hacksaw, hose shears, or a high-speed cutoff wheel if you have one. We prefer the cutoff wheel.  16 each fitting is comprised...  16 each fitting is comprised of three components: the socket, the sleeve, and the nipple, shown from left to right. These fittings are reusable and clockable for routing, but it's recommended new sleeves be used if the hose is disassembled for any reason.  17 After the hose is cut...  17 After the hose is cut to its new length, the socket is slid over the braided outer jacket as shown. Think of this step as the same as flaring a brake line and ensuring the tube nut is installed before the line is flared (I know, we've all done it).  18 Insert the sleeve so that...  18 Insert the sleeve so that the PTFE liner is seated inside the sleeve to the lip of the sleeve and the braided covering is over the sleeve body. You can usually start the sleeve by hand, but pressing the assembly against the workbench or a block of wood will fully seat the sleeve.  19 Use a tapered punch to...  19 Use a tapered punch to push the PTFE liner into the barbs of the sleeve, seating the liner into the sleeve.  20 With the hose nipple retained...  20 With the hose nipple retained in a vice, apply a small amount of lubricant to the nipple and push the PTFE hose onto the nipple until it seats/bottoms. Slide the socket back up the hose to the nipple and then tighten it with the appropriate wrench to seal the hose end. You want 1/32-inch or less gap between the nipple and socket (use your thumbnail as a guide). Use compressed air or solvent to flush the line of any cutting/assembly debris.  21 Reinstallation of the...  21 Reinstallation of the hoses may require minor clocking of the end fittings. You can simply use two wrenches to hold the socket while turning the nipple end; just don't exceed the 1/32-inch installed gap doing so. Hydratech offers these simple, yet, elegant, billet hose clamps to retain the two pressure lines, as we've done here.  22 The last hose to connect...  22 The last hose to connect to the assist unit is the low-pressure return hose. Hydratech provides the correct style of hose and the necessary clamps. One end of the hose features a simulated hose nut with integral clamp and this end is attached to the assist unit's return port. The rubber cap on the return port can be used to plug the intake manifold vacuum port if you had factory power brakes.  23 Route the hose as necessary...  23 Route the hose as necessary to your power steering pump's return line where it will be tee'd into via the brass hose tee shown here. The assist unit's return hose is to be connected to the base of the tee, as shown, and then the regular power steering return line will be connected to the remaining ports. This prevents back pressure that can cause issues with the assist unit. You also have the option of running this hose directly to your power steering reservoir by adding an additional hose fitting to the reservoir. Lastly, if you have a power steering cooler installed, be certain the return hose tee is installed after any such device.  24 Hydratech offers several...  24 Hydratech offers several master cylinder options for its systems, but in our case, with the assist unit clocked to clear the engine, a vertical mounting pattern meant we had to use the '96-'99 Mustang master cylinder. Bolting it up is a simple matter of sliding the studs in place and securing with the included lock nuts.  25 However, as nothing is...  25 However, as nothing is ever that easy for us, we ran into our one and only installation issue. The master cylinder's bleeder screws were hitting our engine's cam cover, preventing the master cylinder from fully seating on the assist unit. Not good.  26 We found a solution to...  26 We found a solution to our issue with these port plug fittings from Brakequip. The fitting on the left is designed to block off high-pressure fluid ports. Brakequip sells male and female versions in both metric and standard sizes. You can buy direct at www.brakequip.com or via phone at (865) 251-9193 with a $25 minimum order (these plugs are 99 cents each) or you can find you nearest dealer via the website or phone to purchase locally. Brakequip has hundreds of cool hose and fitting parts for projects like ours, so check them out.  27 Simply remove the bleeder...  27 Simply remove the bleeder screws, thread in the port plugs, and tighten with an Allen wrench. What could be easier! Because of their matching 45-degree seat, there's no need for sealers, as the plug seats just like the bleeder screw does to seal off the port.  28 Back on the assist unit...  28 Back on the assist unit and with the two master cylinder retaining nuts tightened, our problem is solved. Due to the angle of the engine install, the front master cylinder port is still a little close, but we're not going to worry about it until the car is running. If it touches on engine torque we can cut/grind down the port boss a good 1/4-inch additional clearance.  29 We also ordered an adjustable...  29 We also ordered an adjustable proportioning valve from NPD to install in our rear brake line. We often mount these to the inner fender somewhere with long screws and spacers made from 3/8-inch tube, but we found a metric-threaded boss on the side of the master cylinder that made for a perfect mounting location. We used a couple of washers to space the unit away from the master cylinder reservoir. 30 Hydratech includes master cylinder fitting adapters when required. Such is the case with our late-model Mustang master cylinder, which is machined for metric bubble flares. These adapters allow standard 3/16-inch brake line with 3/8-24 tube nuts to simply thread right in, making the new assist unit easy to adapt to existing lines or even allow new lines to be bent up using locally available parts store brake lines.
|
|
|