The Stovebolt Site Forums The Shop Area Engine Shop Hydro Boost Brakes?

Hiya, i have been told about a system in astro vans as well as other gm cars and trucks called hydro boost for power brakes and was wondering if anyone had more info on the install needs and or what all i need to pirate from the donor vehicals
i was told main advantage to it no power brake booster on the fire wall "which for my 39 is a major plus" and the fact it dosn't use engine vacum but runs from the power steering unit but if i am to use this i really need info and have found almost no info on any site about it

I have seen it on Astro vans and also Chevy 1 ton trucks. It was also used in the 80's Chevy trucks that had a diesel engine. Instead of using a vacuum brake booster it uses hydraulic pressure from your power steering pump. It still has an assembly that is mounted to the firewall, just not the big round can you have with a vacuum booster.

I believe all the diesels use it-- my 2003 has it, and my 95 had it. Go rob all the parts from a late model diesel Chevy truck INCLUDING the pump and brackets. Get all the assembly from the firewall and the pushrod from the pedal. That should give you enough parts to get started. It is a really nice setup--

Practically all Chev.- GMC 1 ton trucks used it from 74 on.

I never had a gas motor truck so I wasn't aware what they came with. I have always had 3/4 ton diesels so I am familiar with them. Good to know some of the gassers were equipped with the hydroboost

Mr Stocker is correct that there is no large round vacuum chamber on a hydraboost but he didn't mention that they are very long and protrude into the engine bay quite a distance. To me that would present as many installation problems as dealing with the large round chamber. Something else to consider.

I have a hydrobooster on my truck (under the floor), and really like it. I'll never build another truck with a vacuum booster, they suck

This is not what I did, but the bracket design may give you some ideas, it mounts the booster farther back.
http://www.abspowerbrake.com/4754chevytruck.html
Second picture up from the bottom.
You use your original brake pedal and a longer push-rod back to the booster and MC.

The Hydroboosters are all mostly the same even between makes of vehicles. They are continually improving them, so newer is better. I know ford and GM use a different MC mounting pattern, but the hydrobooster mounts to the bracket the same.

I bought my first kit from these folks http://www.hydratechbraking.com/ and learned a lot. They had great service, and charged a little more for the whole package than what you can put together your self (if you know what your doing and what you need), however the education is well worth the extra money.
They have a great tech section and FAQ, you should browse through them.

Grigg

Ok you are talking about a pertrusion into the compartment not sure if that would work either "and before i get sent to an after market site" i am on an extream budget so aftermarket isn't viable with the prices they charge but anyway main concern is keeping the footprint on the firewall as small as possible, if there is an even smaller option or even a car or truck out there with a remote booster "stock" from factory love to hear about it factory stock is good since we have tons of U-pull-it type salvage yards here in tulsa

I'm getting the feeling that you are thinking of the Hyd0-Vac, rather than the Hydo-Boost. The Hydo-Vac was the original style power brake system that was used on GM trucks starting in the mid '50s, and did mount under the truck or on the frame depending on model. It is a separate booster, but it was still a vacuum operated system. There is still a similar system available in the aftermarket made by Midland. They Hydo-Boost simply replaces the vacuum booster with a hydraulic one, run off the power steering pump. If this is the way you would like to go, I would suggest getting the M/C mount that gooes in the stock location under floor, and use that booster, perhaps run with hard line. One from an Astro Van would be the best bet, as is rather compact compared to the full size truck version. Get the pump as well, as they are different form the std power steering pumps (if you plan to have power steering).

yep power steering is the plan had too many trucks without it lol gets old fast not having any

If it's under the floor it's not on the firewall. A 39 is supposed to have the MC under the floor right??

I would make a bracket like ABS power brakes sells (link above), it's very simple.
I modified my pedal bracket to fit the hydrobooster, would have been simpler to use the separate bracket mounted on the frame.
http://rides.webshots.com/photo/1484168811080251109bfKirL

Even if you don't buy anything from Hydratech do check out the tech section and the FAQ, you can learn all you need to to then pull your own parts from the junk yard.

Brakes are not a place to cut corners, don't be to cheap and end up with an unsafe and unreliable system.

Grigg

the one aftermarket piece i am getting "because there is no other game in town" is a disk brake conversion braket but i have noticed there prices very wildly, anyone know who sells the best priced absolute basic kit "you supply the calipers and rotor
and thanks for all the feed back on the boosters guys been a big help

Not true, the pump is the same, the reservoir is slightly different, but that's not a problem.
So if you already have a PS pump you can still use it with the hydrobooster.

To use a hydrobooster you preferably need two return nipples on your PS reservoir, one for the steering gear box as usual, and one for the hydrobooster. IF you don't have a reservoir with dual return nipples you can add a second one if you have the reservoir off, or you can use a T fitting in the PS return line close to the reservoir.

Grigg

I though they were different, meaning having the 2 exra ports for pressure and return. Or at least one of my manuals (a '73-'80) shows it that way. Never really looked at an Astro to see how it was setup on the pump. Learn somthin' new all the time!

yeah grigg the 39's mc is under the drivers side and has a bellows type system for the brake pedels and rods

One observation- - - - - -since there's no accumulator in the system, you'll lose power boost as soon as the engine quits, without the one power-assisted stop that's available with a vacuum-boost system. Not a problem, as long as you're aware the brake pedal will get hard immediately if the engine dies. The BIG ford rigs (2-ton and up) with that setup had an electric motor driven auxiliary pump to handle brake boost with the engine off.
Jerry

Some of the older hydroboost units have no accumulator (does an Astro van booster have one?)

Most newer ones have an aluminum cylinder that is the accumulator, and you get one or two applications of the brakes.
The blue cylinder in this picture http://rides.webshots.com/photo/1484170241080251109KNOQFn some are gold or silver, the color makes no difference that I know of.
If your engine does die; to stop depress the brake once until you stop, if you don't pump the brakes you'll have an assisted stop.

I've had some of the really big ones with an electric motor backup pump, you don't want one that big, GM and IH also used them, and my still?

Grigg

lol all the vacum based ones i have driven cars and trucks alike once the engine cuts off gets really hard to brake with so thats just par for the course lol

lol wow i really didn't expect to get all this responce lol glad to see the interest

Next time I get an Astro in the shop, I'll take a look.

i am also interested in this discussion as i have a 62 with the hydrauliic clutch...i've been researching the best option for what kind of booster i can use, and get a small master for my clutch in or near the stock position next to the brake master. this hydroboost opens a whole new can of worms.

i installed a hydro boost on my 46, most of the parts came from late seventies early eighties 1 ton gas engine truck, you will need to brace the fire wall also.

lol on a 39 any mounting of brakes on the firewall would need bracing weather hydro or standard that was to be expected

Just for info , I have an '84 Chevy caprice estate (ie wagon) that has a hydro-boost too. One more possible junk yard source!

ty for the source

Is there a double pulley for the 235? i know the later 250 had a place to bolt a power steering pump...did they have these on the 235?

235 was used up into the 70s i beleive in both cars and trucks might be wrong so someone feel free to correct me if not

The 235 was only used to '62, or at least for US use. It did see use in South America (GM do Brasil) well into the '70s, though.