Near "bolt-on" Hydra-Boost brakes

[cornfed]

Re: Near "bolt-on" Hydra-Boost brakes

I'm about to convert my 1210 over the hydra-boost and have all the parts except for the spacer. My 1210 came without a vac boost so my master bolted straight to the firewall. Does anyone know offhand if I will still need a spacer to make the push rod length correct for my pedal? I was going to mill it 1.5" thick, then take some off the top if I need to thin 'er down a bit to get my pedal right. Just trying to get everything ready before I tear it all apart. Thanks

['71 800B]

Re: Near "bolt-on" Hydra-Boost brakes

Grab a tape measure and check things out. I installed hydro boost in my scout and needed to modify the mount and the push rod on the hydro unit.
I would venture to say that you will need to mount the hydro unit to the fire wall and see how much you need to adjust the push rod length. Adjust the length Then mount up the master, connect the brake lines and figure out what power steering lines will work. Bleed the snot out of it and bounce your face off of the windshield.

[BigMookieD]

Re: Near "bolt-on" Hydra-Boost brakes

Just did the initil install on my '69 1200D and it bolted directly into the stock bracket. I may modify it a little down the road to tilt down so I can use the S-10 reservoir. Right now the S-10 res contacts the hood.

I only needed to frankenstein the push rod to match the 13 7/8" length my original unit had.

Now for the plumbing!

[Tres]

Re: Near "bolt-on" Hydra-Boost brakes

Hey Bill,

I know this is an old thread but I wanted to update it a little. Lee Manufacturing is now out of business. So finding the flare adapter is proving very hard to do.

I ran across this today because I am doing another system on one of my Scouts. This seems to be a replacement for the lee adapter. I just ordered two sets and will be installing them this weekend.

http://www.summitracing.com/parts/brg-925122

[ByronRACE]

MS 1510 HB Upgrade

Inspired by this post, and motivated by the expense behind replacing the master cylinder and booster in my MS 1510 step van, I decided to go the HB route.

My truck has 2 wheel cylinders per drum, and the rears are 1 3/8" bore and dual acting. The master cylinder is a midland dual circuit 1" bore very long stroke odd-duck. I was concerned about volume (bore and stroke) of the master cylinder as well as the reserve capacity of the reserve cylinder on the booster in the event of engine or power steering pump failure. I did the math, confirmed it with some Bosch engineers for accuracy, and found that the AstroVan booster in my application did not have sufficient reserve to activate the brakes reliably in engine failure mode and the combination of bore and stroke was marginal to activate the large rear wheel cylinders. Because of this, I was pushed in the direction of a HydroMAX system until an engineer at Bosch mentioned one particular unusual hydroboost system found in the 2004-2007 Chevy Express vans. Long story short, I ended up using it because it has a very large reserve, has boost pressures strong enough to push a large bore master cylinder, and comes with a 1.47" bore (37mm) master cylinder stock that has a 1.7" stroke.

Here's a cut-n-paste of the summary info I posted on another forum.

The HB unit and master came from a 2004 Chevy Express van in the boneyard; $40 is the Pick-n-Pull price. I got extra stuff and paid $30 more, and ended up using part of it. If I do it again, I'll cut the power steering hoses off and leave the hose ends attached to the HB unit; they are fine with that and won't charge for them...but if you're nice to the parts and bring complete hose assemblies to the counter, they will.

I used 2 of these 10psi residual valves for the front/rear drum brake circuits. Don't be tempted by the half-price ebay china stuff; the fittings will not be adaptable.

WIL-260-13784
Residual Pressure Valve, Red Anodized, 10 psi, Drum Brakes, 1/8 in. NPT Female Inlet/Outlet, Each
(Mfr. #: 260-13784)

I used 4 of these fittings to adapt the 1/8NPT Wilwood 10psi residual valves to the 7/16" brake line (for 1/4" line) brake fittings on the truck.
EDD-124420
Fitting, Brass, Straight, 7/16 in.-24 in. Inverted Flare Female Threads, 1/8 in NPT Male Threads, Each
(Mfr. #: 124420)

I used these 2 fittings to adapt the brakes lines to the master cylinder.
EDD-258450
Brake Fitting, Adapter, Hydraulic, Straight, Brass, Each
(Mfr. #: 258450)

The parts above came from Summit Racing.

4 short pre-terminated hard lines were sourced from O'reilleys. The 7/16-24 stuff is stocked. I bent to fit and did not have to flare a single junction.

The power steering hoses were custom made at a hydraulic shop. Make sure you grab the ends of the hoses nearest the hydroboost from the donor truck; they can be flared and adapted to new hydraulic hose assemblies and will save you some heartburn if the hydraulic shop doesn't deal with metric o-ring fittings (mine did not stock them). Total cost of the hoses was about $50. If you buy a new HB unit, you won't get the fittings. Summit Racing has metric o-ring to AN fittings so you could go that route but it's not cheap.

When you get this all together and crack your bleeder to bleed the system, be forewarned...it will no longer gravity bleed due to the residual valve. You also can not use a handy-vac to bleed it due to the residual valve. You need a helper and will have to force bleed it the old fashioned way...down, open, squirt, close, up...repeat.

When you fill the PS reservoir and turn the system on for the first time, it will consume a lot of fluid and generate a lot of foam. Keep topping it off, cycling the steering lock to lock, and pushing the brake pedal until you get it primed and bubble free. If it foams badly, shut it off and let the foam settle for a while, then try again. Mine settled out within a few minutes after getting enough fluid. A pulsing pedal means air in the lines. After you do all that and get the air out, shut it off and press the brake pedal hard about 20 times to use up everything in the reserve cylinder, then start it back up and let it refill. You want to do this, because you probably filled the reserve with foam the first time.

Here are some pictures that may be helpful to the next guy that comes along:

http://www.racesystems.com/beast/hb/adapter.jpg
http://www.racesystems.com/beast/hb/installed.jpg
http://www.racesystems.com/beast/hb/adapter.pdf (print to scale for template)
http://www.racesystems.com/beast/hb/hydroboostdone.jpg

Please note; the FRONT circuit is the one closest to the booster on the donor express van. The cylinder is the same bore front/rear, but when I plumbed it, I used the same (closest to booster) circuit for the front brakes.

And lastly, I discovered a high-flow readily-available compact tee solution for tying in the hydroboost return line to the power steering reservoir.

http://www.homedepot.com/p/SharkBite...2LFA/202270638

This fitting is a tight fit into 3/8" power steering hose even though it is labeled half inch. Try it. It has a very high internal flow; higher than other style 3/8" fittings.

I have hundreds of miles of mountain driving on this conversion now. It's a terrific upgrade; highly recommended. The pedal effort is greatly reduced and it stops like a modern car. 6-wheel lockup is completely doable if you stand on the brakes; which was not possible before. During panic braking, the fronts lock before the rears; the front/rear bias is just perfect without a prop valve. I've also tested the key-off, engine-stopped, downhill in neutral, braking capability. I can press and hold the brake pedal hard 5 times with full assist from the reserve before the assist diminishes. The 7th press is full manual...and god help you at that point if you're on a grade. I'm satisfied that I could stop the truck at full GVWR before I ran out of reserve cylinder braking capacity during a complete engine/pump/line failure scenario.

Hope this helps someone down the road.

Byron

[EvilMrClean]

Re: Near "bolt-on" Hydra-Boost brakes

In response to the above message about Lee being out of business, they are still there. I called them on the number listed in this thread and they have the inserts in stock and shipped me a set. The price is now $10 each, and they insist on selling an installation tool at $10 as well.

[EvilMrClean]

Re: Near "bolt-on" Hydra-Boost brakes

In response to the above message about Lee being out of business, they are still there. I called them on the number listed in this thread and they have the inserts in stock and shipped me a set. The price is now $10 each, and they insist on selling an installation tool at $10 as well.

the correct phone number for Lee is 661-568-9170. if you tell them you already have the installation tool, you can get just the inserts.