Well, I've finally got my "mad money" stash built up again. I've got my COE on the road. When I bought the truck the hydrovac had been bypassed I just assumed it is toast. I rebuilt or replaced all the wheel cylinders, and brake hoses. After I adjusted the brakes the truck will slide the two front wheels. This only takes moderate pedal pressure when the truck is empty, but when I put an empty dual wheel, tandem axle trailer behind the truck it takes considerable pedal pressure to lock up the wheels. Before putting on anymore load than the empty trailer I want to get some type of power assist. While I’m at it I’d really like to convert over to a dual chamber system. I plan on working this truck when I’m done. The GVW is 19500lbs. I want the truck to be safe up to this weight. The options I’m considering are:
1. Rebuild the existing Hydrovac unit. This would probably be the easiest and perhaps the cheapest, but it doesn’t accomplish the dual system goal.
2. Put in a vacuum assist system from a newer gas powered big GM truck. There is room under the cab floor for the 10 ¾” booster behind the engine. I would have to fab up some mounting brackets and re-route the pedal rod. My uncle own a machine shop so this shouldn’t be too hard to solve.
3. Put in a power steering assist system (hydro boost?) from a newer diesel powered GM truck. This could be easier than the vacuum assist because it is a smaller set up than the vacuum boost canister. I would have to add a power steering pump to the 302. This may not be so easy on COE without pulling the front end sheet metal.
My questions for the masses are:
1. Is there any merit in one type over the others? Safety in the #1 goal.
2. How do you size a donor master cylinder? All I know is that the service manual says that my stock master is a 1 ½” bore. I’ve been looking at a master for a 1997 5500 Chevy. (Alaskabob used this setup on his truck with a through the firewall pedal) There are two part #’s listed, one with either a 1 ¾” or 2” bore. I don’t know if either of these are appropriate or not. These masters appears to be used with either a vacuum or hydro boost.
3. If I decide to go with a hydro boost system where could I find power steering brackets and a pump for the 302 GMC? I am not planning on adding power steering to the truck at this time, but might later. Will a power steering pump live supplying only a hydro boost?
I know this a long post, thanks for sticking in there. Any advice is greatly appreciated.
Scott
