Hydro-Boost Astro Van Drop In

[Evaddave 87gn]

Okay, Okay, I know this kind of thread has been done to death a hundred times. But I can guarantee it has not been done like I am about to. This thread will give solutions to all the parts that everyone else just butchers together. This is a true drop in. It you ever have a problem with the booster you can simply walk into any part store purchase a new unit and bolt it in. Now when I make mine it will be made with the benefit of a multi-million dollar machine shop at my disposal, but you won’t need one.
Now I got a unit out of a late 80’s early 90’s astro van. This unit had a straight four bolt plate that attached directly to the firewall. When I got the unit home I took some basic measurements. I first saw the rod looked longer with a larger diameter attachment hole.

 

[Evaddave 87gn]

Solutions

First I do not want to cut the rod, or remove the brake pedal. I want to just drop in the unit. So here are my solutions.
1) A bushing be inserted into the astro unit make up the space between the pedal and rod
2) A spacer to slide over the GN firewall bracket to keep the correct angle and attach the booster
3) An additional spacer to make up the difference in rod length.

 

[Evaddave 87gn]

The Build

First off it’s important to note that once all the parts have been fabricated and all adjustments made, I will post up the technical drawings for the above PDFs. The only part that you may want to pay to make would be the pedal spacer. The bracket that holds the hydro-booster can be cut from the four bolt plate, just like I did for my mock-up. The spacer plate can be a simple square with four blot holes and a square cut out of the center. (I’ll be using aluminum plate for mine, but you can just about any material even plastic with spacers to prevent compression of the material.)
To start off I had to remove the four studs from the bracket that holds the power master, since they at welded on I cut off the heads and the threaded section fell to the ground. I then took a bur bit and enlarged the hole that the booster slides through.
I cut the bracket that came with the unit and drilled a couple holes to use for mock-up, (see the first post.)

 

[Evaddave 87gn]

Pedal Spacer

Big thanks to Hugh, ( you know who you are!) Hugh turned the spacer from a 1” 4140 round bar. It slides right into the booster and right on the pedal. Therefore I am either an engineering god or Hugh is one hell of a machinist. I’m running with the second choice myself….
This spacer will also take the place of the washer on the brake arm.

 

[NorEaster]

More Pics, I like this. What about cost of these parts? Are you just tying into the power steering lines? Good work so far.

 

[TurboTnZ06]

Looks good, but a true "drop in" from parts stores is: the 84/85 GN hydrobooster, the 2 premade 84/85 GN hydrobooster power steering lines and an '81 Caddy Eldorado Fenco master cylinder. No fabbing, just bolt them on.

 

[Evaddave 87gn]

Redundant Systems

@TurboTnZ06

Yes, I agree that your statement is correct.

However, you are overlooking the major reason why I would not use the 84-85 system. In the event of pressure loss in the hydraulic system, whether a blown hose, engine stalling etc… I want to be able to stop my car. That will require an accumulator which the 84-85 system does not have.

Therefore, for me, the 84-85 system is not an option.

Safety first

 

[Evaddave 87gn]

More Pics, I like this. What about cost of these parts? Are you just tying into the power steering lines? Good work so far.

Lots of pics to come.

Could be costly if you make it exactly like mine, but you don't need to. As I said before the only piece you would need to have made is the pedal spacer. Find a local machine shop, I bet you could have it made for under 30 bucks.

I will be useing the 84-85 lines, but I may alter them, this will depend on how they fit.

 

[TurboTnZ06]

@TurboTnZ06

Yes, I agree that your statement is correct.

However, you are overlooking the major reason why I would not use the 84-85 system. In the event of pressure loss in the hydraulic system, whether a blown hose, engine stalling etc… I want to be able to stop my car. That will require an accumulator which the 84-85 system does not have.

Therefore, for me, the 84-85 system is not an option.

Safety first

I've had that happen where the maf blew off (at 120+ mph in the 1/4) and the engine died, I had to crank the engine and had plenty of pressure to stop then. Also if the belt slips off, although I've never had a serpentine belt break or slip off since I started driving in 1993. I wonder if I could retrofit an accumulator before it gets to the hydroboost...

 

[1quick6]

I agree that's the downfall of fitting an 84/85 HB in the PM equipped cars. The astro conversion is a nice option if you have the resources to fit it correctly. The 84/85 is a true drop in with a few hours of work.

Nice job on your work!

 

[Evaddave 87gn]

In process

Update: The bracket and spacer are in process. They should be done tonight. I will be posting new pictures Wendnesday night!

Just a thought, would anyone be interested in a kit like this?

Dave

 

[Ken Adams]

Evaddave 87gn- maybe, depends on the cost

 

[turb0buick57]

x2 if you build it(at the right price) they will come

 

[jlat]

hello; I might be interested. I have a 94 Astro and I like the brakes better than my TB. To me it has a better feel and not like am I going to stop quick enough. It does have ABS and that might help abit.
IBBY

 

[bsdlinux]

You bet. Price but fit and finish also. Let us know what you think. I'd be willing to go from Vacuum to Hydroboost.

 

[Evaddave 87gn]

The prototypes have been made!

Everything came out pretty well. There are a few small adjustments I need to make to the bracket. The bolt holes are a little close together, but the plate still fits great. The spacer plate lines up fine but the outside dimension is not exact. I plan on using a small hand grinder to shave some material off the factory bracket to make both plates the same shape.

The spacer plate is 1.250” thick. I should only need 1.000” spacer, but I left the .250” on it in case the measurement is not exact. This way I can face off the plate to the correct dimension. Tomorrow I will pick up some hardware and mock the unit up. Then either Friday or Saturday I will face the plate off.

I quick word about my hose selection, after seeing different hose set-ups on other conversions it was a no brainer to go to the stock 84-85 set up. I see no reason to pay for braided hoses and different adaptors to make them work. GM had the right idea to have both the lines on the same side of the unit away from the header.
My hoses have come in from Auto Zone since Advanced said they are no longer available. Big thanks to ‘1quick6’ for the part numbers since I swiped them from his website.:biggrin:

 

[Evaddave 87gn]

The Mock-up!

Well I took all the parts and installed them into the car to check the fit. I had expected to have to mill down the spacer plate, but to my surprise I didn’t need to. Everything lined right up. The Astro van’s master cylinder is quite long so I decided I needed to change it out. Besides I wanted to install a new unit anyway.

 

[Evaddave 87gn]

Completing the install

I purchased a master cylinder from a 1990 Chevy C1500 2-wheel drive truck. The heavy duty brake system uses a master with a 1.25 bore, basically the same as the Astro’s unit. I bolted it up and man did it look good! Until I tried to shut the hood. The reservoir was simply too tall. I placed some playdoh on the cover and I can see only the front section was touching the hood. So I came to the decision that I either needed a different master cylinder or a new reservoir. I found a very nicely polished aluminum unit from Summit for $160.00. But before I bought it I wanted to try a new reservoir. I headed to the scrap yard and found one on a wrecked 88 Monte Carlo. This was nice and wide with a gentle slope. I took some measurements and the ports are the same size and height. I took it home and snapped it right on.

 

[TURBOPOWERED68]

love the work dude

 

[Evaddave 87gn]

Any intrest?

Well I kind of dropped the ball on this project, I wanted to put up my drawings for my fellow Turbo Buick owners but I never got around to finishing the drawings.

If anyone is intrested in the finished drawings, let me know and I'll put them in this thread.

Dave