DIY Hydroboost on GM Automobiles

Hydroboost is an influence help for the braking system that runs off the ability steering pump hydraulics. This have a number of benefits: greater line stress over a handbook setup or vacuum booster, and if operating a bigger cam which produces much less total vacuum, it merely is a greater choice to get superior braking again.

One other downside is that full kits from corporations vary from from $900-1200! A brand new GM hydroboost unit runs $200-300, so the place is all the additional value coming from? Seems the bracket to mount hydroboost to firewall and pushrod are actually the one customized “gadgets” wanted to efficiently set up one in your automobile. So lets cowl what is required for the swap.

Set up Video

The video on the prime of this web page goes over the mock-up and set up of hydroboost and T56 grasp cylinder set up. I’d watch the complete video after which reference the under on what components the place used.

Hydroboost Unit

The hydroboost unit you wish to use is AC DELCO 178-1036, which is for a 2011 Silverado 2500. It is a model new unit, and comes absolutely “stuffed” with the small pushrod and “star” centering plate. Reman models is not going to include these components and so they alone will value $60 on ebay. This hydrobooster is known as the “late quick MC pushrod” fashion. Principally the mating grasp cylinder must have a divot for the pushod. Extra on that later.

The very first thing it’s good to do is take away the bracket that comes with the unit. I used a cutoff wheel to take away one of many studs on the mounting plate. Then use a 1-7/8″ crowfoot to take away the nut. This crowfoot prices round $16 and is less expensive that the $80-100 particular sockets required to put in these fancy billet mounting brackets.

Subsequent up is to switch the pushrod. Most older GM automobiles require that the pushrod be threaded 3/8″-24. The unit comes with a rod finish kind connection. You possibly can lower this off and thread it with a die, though I’ve not accomplished this and folks say it’s reasonably troublesome. The OD is tremendous shut for thread measurement wanted. I opted to chop up a common booster extension rod w/clevis and weld it on. Seek advice from the set up video on how I set this up.

Mounting Bracket

Now you want a mounting bracket. I designed 2 kinds of brackets that ought to work for a lot of GM purposes. This design is “common”, which lets you mount the booster in any orientation. You possibly can flip it so the accumulator (silver canister) to mount in direction of the driving force or passenger facet. Each designs solely require the $16 crowfoot to put in. No costly particular sockets are wanted.

HTMR Hydroboost Solely Bracket

This bracket mounts the hydroboost at a 6° angle for extra valve cowl clearance. I’ve created a template to test automobile fitment. Print and lower out the template. Place on firewall and if holes line up and it sits flat with the rectangle, then the bracket will work

I used the OEM kind seal utilized in vacuum boosters to seal the hydrobooster to the firewall. Trimming is required and it finally ends up becoming OK.

HTMR Hydroboost T56 Combo Bracket

This bracket mounts hydroboost and a clutch grasp cylinder for the 68-72′ GM A Physique automobiles.

The next components had been used and/or modified to make every part work.

Energy Steering Traces & Adapters

I used the CPP Hose Equipment HAHK-R. These traces are tremendous straightforward to chop to size and assemble. The package comes with “flare” fashion adapters, so pay attention to that. My Chevelle has a Grand Cherokee PS field swap which makes use of the later O-ring fashion kind connection. You should purchase the O-ring to AN adapters from Holley.



I’ll say that a few of these CPP fittings had been onerous to seal up. I went so far as utilizing valve lapping compound and “grinding” the flare a bit to the adapter, which helped. Then I discovered that these cool little copper AN seals.

My energy steering pump got here out of a GM truck that initially had hydroboost, and the reservoir had 2 return fittings. The one above the fluid stage is the hydroboost return. If you happen to solely have one return port, then you must set up a “tee” becoming. The ability steering gearbox return flows straight by means of the tee, whereas the hydroboost return must be hooked as much as the 90° becoming on the tee.

So far as routing, the excessive stress line exits the PS pump and goes to the hydroboost, then the ability steering field.

Grasp Cylinder Choice

With hydroboost, you will have the right grasp cylinder bore measurement. For many purposes, a 1-1/8″ bore measurement will work properly. In case your brakes are too delicate, then a LARGER bore measurement will INCREASE pedal effort.

AC DELCO 18M91 – 77 corvette 1-1/8″ bore quick pushrod, forged iron