Hey Larry, just wanted to know if the info on hydroboost in this thread was what you posted on page 6? As far as I can read from your info you just need the hydroboost master cylinder and the high pressure line that goes down to the power steering pump. Can you elaborate on this and give any more pics or info? Cheers, Chilli...
Hey Chili,
Well, the easiest method of doing a hydroboost swap is to find a 73-91 square body donor truck at the salvage yard and scavenge as many bits and pieces as you can get. There are two pieces to the hydroboost system that are nonexistent other than salvage yards and that is the bracket that goes between the booster and firewall as well as the pushrod between the master cylinder and hydrobooster. The firewall bracket is unique to square body trucks and is not included if you buy a reman booster. There is also a round keeper in the bore of the booster that you would need as well as the nice little standoff brackets at the booster you would want to grab. The master cylinder is also different from vacuum to hydroboost but I've seen people reuse vacuum master cylinders on hydroboost. I wouldn't personally do that myself, but some people do.
The main thing to keep in mind is GM changed the hydraulic line fittings from standard to metric threads in 1980 so finding a 1979 or older truck in the salvage yard with a standard thread hydroboost unit to swap onto your truck will be near impossible. That said, you would either need to also replace the steering gear box to a later unit with metric fittings or have the hoses custom made with standard threads at the steering gear and pump and metric threads at the hydrobooster. This also means the pressure valve in the older ps pump would also need to be removed and replaced with one with metric threads if you chose to replace the steering gear with a metric piece…or just install a metric power steering pump. Against my better judgement I chose to have a custom hose made which I am sure I will regret someday if I blow a hose out on trip where I won’t be able to just walk into Napa and buy one off the shelf. I’ll have to have another made. If I ever replace the steering gear again I will go to a metric one and get off the shelf line.
I’ve also read where the brake pedal itself is different due to the pivot pin location between vacuum and hydroboost systems so keep that in mind. I did not have to worry about the brake pedal differences at the time of the hydroboost swap as I swapped in a new clutch/brake pedal box at the same time to gain hydraulic clutch for the NV4500. It just so happened the truck I robbed the pedals from was also the same truck I got the hydroboost pieces. I wish I would have studied the pedal differences when I had them next to each other so I would know exactly what is different because I would love to do hydroboost on the Polar Bear while it is down for the engine swap.
There are lots of good write ups on hydroboost swaps on coloradok5. You would be surprised the difference in braking power hydroboost makes. Hydroboost is a much more worthwhile swap over rear disks ANYDAY! Don’t let anyone tell you otherwise.
