Holy stopping power Batman!!! Hydroboost installed!

[tbrumm]

Well, guys, this is why I like Oilburners - There are a lot of very knowledgeable people who are willing to respond with their advice, opinions and most importantly their real world experiences. A little deviation topic but so what - it is still regarding the hydroboost and the fact that we all agree this is a very worthwhile mod regardless of what master you use or what vehicle you put it in To address LCAM's question: my pedal travel is very short and the brakes really start to bite. I have not measured it but it "feels" like not much over an inch. Now, I was used to my old vac booster and the "mushy go half way to the floor" feeling, so the pedal could be travelling further but it just feels like I hardly have to touch the pedal at all and the brakes are right there! And the pedal effort "seems" very easy. Again, remember what I am comparing it too. I am happy with the results and really don't think I will try the big master at this time. I debated whether or not to get the big master, and did a bunch of searching on the internet. It seemed like it was a split decision with some getting good results with vac master, and some getting good results with the big master. In the end, I thought I would give the vac master a try and see how it worked, becuase I could always switch over to the bif master later. I would imagine that the subjective "feel" of either master is heavily influenced by the rest of the components in the braking system. Not to say my system is in brand new condition or anything, but boy does she stop! Now I want to ask a couple of newbie hydroboost questions. Is it normal for the hydro unit to make some noise? Noise isn't really the right word - more like a low hum? It is rpm related and it is not pump whine. It is a definite hum from the hydro unit. Certainly not objectionable and you barely notice it. but it is there. Fluid is up to proper level and is not foamy and the hydro is a brand new Motorcraft unit. I also assume these things can get pretty warm as the PS fluid certainly does even without a hydro unit added. Can't hardly put my hand on it after running the truck for a long while. I don't have an aux. cooler installed (yet) and I am still runinng the OEM tube snake cooler on the front cross member. Thansk for all of your input, guys. I will try and get some pics posted up soon, if the error messages don't crash the thread. Todd

 

[LCAM-01XA]

Well it's good that you're happy with the result and pedal feels just how you like it. If in the future you want it to feel somewhat stiffer you have room for adjustment as well. FWIW, my experience playing with different size masters has been that while the pedal travel does change some I never did notice it, guess the body sorta automatically adjusts to it? What I did notice was the pedal force was different, not by much, but it was noticeable - larger master made the pedal firmer, not to where it's uncomfortable and you need Arnold leg muscles to push on it, but more like a newer car... I like it nice and easy tho, so I'm back down to factory size of 1-1/8" bore. On a go-fast play truck I'd be running 1-1/4" at least.

Onto your questions:
1) yes she will get nice and toasty, IIRC mine can get up to 150F after using the brakes a few times on a short drive. But a lot of that could also simply be heat transfer from the engine thru the pump into the fluid and then the hydro unit. Just idling with no load of any kind ever put on it, that I don't recall if I ever took measurements of, but next time I use the truck as a genset or compressed air source I'll try to remember to hit it with the IR meter.
2) yes she will hum while you're on the brakes, and the harder you're pushing the louder she will whine. While off the brakes she may still hum slightly, but honestly my engine is so loud there's now way I could hear it.

 

[sle2115]

Well it's good that you're happy with the result and pedal feels just how you like it. If in the future you want it to feel somewhat stiffer you have room for adjustment as well. FWIW, my experience playing with different size masters has been that while the pedal travel does change some I never did notice it, guess the body sorta automatically adjusts to it? What I did notice was the pedal force was different, not by much, but it was noticeable - larger master made the pedal firmer, not to where it's uncomfortable and you need Arnold leg muscles to push on it, but more like a newer car... I like it nice and easy tho, so I'm back down to factory size of 1-1/8" bore. On a go-fast play truck I'd be running 1-1/4" at least.

Onto your questions:
1) yes she will get nice and toasty, IIRC mine can get up to 150F after using the brakes a few times on a short drive. But a lot of that could also simply be heat transfer from the engine thru the pump into the fluid and then the hydro unit. Just idling with no load of any kind ever put on it, that I don't recall if I ever took measurements of, but next time I use the truck as a genset or compressed air source I'll try to remember to hit it with the IR meter.
2) yes she will hum while you're on the brakes, and the harder you're pushing the louder she will whine. While off the brakes she may still hum slightly, but honestly my engine is so loud there's now way I could hear it.

What he said!

 

[FORDF250HDXLT]

it takes a while,but you'll forget all about the noise of the hydro eventually.

If the OP is experiencing quick lock times, as I did with the smaller, higher pressure m/cyl

there's an issue im looking forward too right there.

 

[icanfixall]

Many years ago on my chevy truck with the hydrobbost brakes I learned there is a limit to how hard you can press on the brake peddle. What happens is the hydrobbost makes all the pressure it will make. then it goes into a bypass mode. The peddle goes down much closer to the floor and there is a noticable hissing noise coming from the booster. You can let off engough to make the sound go away but the brakes are still at their max pressure the booster will allow. To test this apply the brakes hard enough to hear the sound and feel the peddle become easier to push.

 

[yARIC008]

Well I just read most of the posts and maybe i missed it. But... if you don't change out the master cylinder and just replace the booster what exactly makes your brakes better? The only thing I can see is that the petal will become easier to push down as you're getting more boost. The distance the petal travels and the overall force that the booster outputs should remain the same, and then the master cylinder output will remain the same for the petal distance traveled, correct? Is changing to the different petal what makes the setup really worth something? If you just changed out the petal and not the booster would you still have positive gains?

 

[LCAM-01XA]

Well I just read most of the posts and maybe i missed it. But... if you don't change out the master cylinder and just replace the booster what exactly makes your brakes better?

The hydrobooster is stronger, if you push on it with 100lbs force it will push on the master with 200lbs, whereas under the same conditions the vacuum booster will only push on the master with 150lbs of force. Purely random numbers, but you get the idea, the hydro has a larger force amplification ability than the vacuum one.

The only thing I can see is that the petal will become easier to push down as you're getting more boost.

Isn't that a good thing? The fact that it's easier on you to push on the pedal means that for the same amount of force you're applying at the pedal there is now larger clamping force down at the wheel brakes.

The distance the petal travels and the overall force that the booster outputs should remain the same, and then the master cylinder output will remain the same for the petal distance traveled, correct?

The distance the pedal travels is altered because the hydroboost uses a pin located higher up on the pedal, which results in longer travel at the foot pad to achieve the same travel at the pin. This increased leverage stacks on top of the already stronger hydrobooster, thus the force output of the matched hydrobooster and pedal is much greater than that of a vacuum booster and its pedal. The master cylinder output volume does remain the same.

Is changing to the different petal what makes the setup really worth something? If you just changed out the petal and not the booster would you still have positive gains?

The change of pedal is required because the hydrobooster sits higher on the firewall - if you reuse your vacuum pedal the booster pushrod may bind. You can certainly reuse your vacuum pedal if you move the booster down on the firewall - your brakes will still grab stronger because of the stronger force amplification of the hydro vs. vacuum booster. Alternatively, if you only swapped the pedal but not booster, you'll have to move the vacuum booster higher up on the firewall so it's pushrod don't bind. The input force at the master would then increase, but vacuum boosters make for lousy soft pedal as is, can't imagine how spongy the thing will feel with a higher leverage pedal...

For best results swap both hydro and pedal together. Then play with the master size to get the pedal firmness that is to your liking.

 

[LCAM-01XA]

Many years ago on my chevy truck with the hydrobbost brakes I learned there is a limit to how hard you can press on the brake peddle. What happens is the hydrobbost makes all the pressure it will make. then it goes into a bypass mode. The peddle goes down much closer to the floor and there is a noticable hissing noise coming from the booster. You can let off engough to make the sound go away but the brakes are still at their max pressure the booster will allow. To test this apply the brakes hard enough to hear the sound and feel the peddle become easier to push.

And when that happens it feels almost as if you blew a brake line or hose or something - kinda scary the first time one experiences it

 

[tbrumm]

The hum I am hearing is actually occuring when I am not on the brakes, but rather as I am getting the truck up to speed. And it does change slightly in volume and pitch with rpm. Again, nothing that is loud and objectionable. At idle I really don't hear anything, but as rpm increases, the hum increases. When I reach cruising speed and rpms drop off, I really don't hear much of anything, but by then the tire hum (all-terrains) is a little louder too depending on road surface. I may have not noticed the hum while applying the brakes because I am still overcome with that "warm fuzzy feeling" of good braking! The hum would almost seem like pump whine but it is not loud enough for that and it is definately coming from the hydro unit and not the ps pump. I checked the ps fluid level and that is still good so it would seem like the air is out of the system.

I am glad you guys mentioned what happens during "bypass". I haven't experienced that yet, but certianly would have wondered what the heck ws going on with my new hydro unit. Saved me from checking for the leaking brake line anyway.

 

[FORDF250HDXLT]

Normal Operation Noises
Properly operating hydro-boost units will produce certain noises. These noises occur, for the most part when the brake pedal is manipulated in a manner not associated with everyday driving habits. The general categories of normal operating noises are (1) hissing noises and (2) clunk/clatter noises.

The hydro-boost will emit normal hissing noises when above-normal brake pedal efforts are applied (40 lbs. and up). The hiss sounds particularly noticeable with the vehicle motionless and will increase in intensity as pedal pressure increases above 40 lbs. and system operating temperature increases. Loud hissing sounds at or below normal (20 to 25 lbs.) pedal effort warrants investigation.

Clunk, clatter or clicking noises will be heard when the brake pedal is quickly released from hard (50 to 100 lbs.) pedal efforts.

another good tip:

Power Steering Flush
In addition to requiring the correct pressure, it is also critical that the fluid be clean. The tolerances in the moving parts inside the hydro-boost are such that only a small amount of contaminates can cause a malfunction. This is especially true of the spool valve. The tolerances necessary to form a metal-to-metal seal are quite small and any contaminates or tarnish buildup can prevent smooth operation of the spool valve. Since the spool valve controls the flow of fluid into and out of the power chamber, it is critical it functions properly.

source;
http://www.brakeandfrontend.com/Art...epair_of_hydroboost_power_assist_systems.aspx

along with a cooler in the return line,i also have an inline filter.

 

[tbrumm]

Well, Guys, it has been a while since I installed the hydroboost and I am still lovin' it. I took pictures dirung the install and am finally getting around to posting them. Been a busy summer!
new Motorcraft booster installed with original MC
new Motorcraft PS pump reservoir installed with second return inlet
Superduty brake pedal assembly installed
Magnafine filter installed in return line from booster - thanks for the idea, Al!
"Real" PS cooler installed in front of trans cooler
Hoses to PS cooler connected to factory "tube snake" cooler with brass fittings

 

[riotwarrior]

Looks good nice install good pics, thanks for sharing!

 

[icanfixall]

Nice installation. Clean too., Nothing I like more than working on a clean engine. A note about running the stock master cylinders compared to the factory hydroboost masters. Running the larger 1 5/16 master cylinder gives you more brake fluid available to be pushed into the closed brake hydraulic system. Usuall we have found the reason for the sinking brake peddle is because the rear shoes will not self adjust so they get way out of touch with the drums. Thus it reqiures more fluid to be pushed back there and the stock master cylinder can't do that. You end up with the fronts doing most all the brakeing and that overheats the rotors and pads wearing them out much quicker. No figure a heavy load going down a 6% grade and the fronts doing all the brakinging.. I did several times and cracked two rotors. I went to a brake shop and the guy told me what was going on. I felt he was full of it till I saw my peddle down several months later and adjusted the rear shoes. What a differance to actually feel the rear shoes working too. So try this. Apply the parking brake. If it sets within the last 1/4 of travel or very near the floor then the rears are way out of adjustment. Now set the parking brake about 1/4 down and go do a slow test run on the streets but do it carefully. See if the brake peddle stops the truck quicker and the peddle is higher up when this happens. Again, You have proven the rears need adjustments. With the large bore superduty master cylinders there is more fluid being pushed per foor stroke of the brake peddle. So more is able to reach the rear out of adjustment shoes. So you stop better. I have been running my hydroboost since just before the 2009 rally. I still need to adjust the rears every so often. Very seldom do I feel the rolling into the car in front of me feeling after a complete stop.

 

[LCAM-01XA]

I like running the e-brake so tight it can barely even click in the 1st notch and that's good for holding truck down a steep embankment. Every oil change rear wheels come off for drums cleanup and shoes inspection. Very rarely do I have to actually adjust them between oil changes. But yeah, self adjusters kinda suck, I tossed mine completely long time ago, adjusting manually now and brakes work good. Loose rears are hell on the fronts, like Icanfixall said, dangerous too in the mountains. Wish they had discs that are an easy swap on a DRW axle, but noo, just single wheels get those... I got spoiled with air discs long time ago, been hating drums in all sizes shapes and forms ever since

 

[fsmyth]

Another thing that has not been mentioned (probably because no one uses them anymore),
is that the larger master cylinder is very much needed when using a hydraulic brake controller.
I use 'em because I have a bunch. Much easier to adjust than the electronic jobs (have those, too).
My only ***** is that jumping out of vacuum-boosted trucks into hydros is that it tends to throw you
into the windshield
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