My hydraulic clutch and Hydroboost setup

[Yukon Jack]

Been seeing some posts the last couple days about hydroboost so I thought I would do a detailed post about the install of a hydroboost system and hydraulic clutch from a donor 1989 Chevy 1 ton (old body style) on to my 1969 Chevy K20.

I really like the hydroboost brake system but, of course, I was used to manual brakes so any assist was welcome.

The hydraulic clutch is also nice. I would have had a major problem using the stock z-bar setup with the headers and the swapped in bbc.

When I started contemplating this project, member MikeC mentioned that it might be wise to reinforce the firewall due to the weight of the hydroboost and fact that I was adding the hydraulic clutch. I had a buddy cut me this reinforcement for my firewall with his plasma cutter.



I have a template of this reinforcement that also has the location of the various holes that were needed. Let me know if a copy of this template is needed by anyone. I have to mail it so I would need your mailing address.

Another buddy made me the metal shim you see that positions the hydraulic cylinder correctly so the push rod will attach to the clutch pedal.



The 1989 old body style 1 ton hydraulic clutch master is angled requiring the shim. I later found out that the new body style hydraulic clutch master would not have required that shim. Regarding the shim for the hydraulic clutch cylinder, the way I have it made, it attaches right next to the hydroboost bracket. The template is angled so the bottom is 5/8" thick and the top of the shim angles down to 1/16" thick. The shim is 2 5/8" wide x 2 5/8" tall.

I got the cylinder mounted on the firewall, threaded the push rod and am using a 5/16" threaded clevis rod end to attach the rod to the clutch pedal. Cycles freely and the rod will push in as far as needed. Might have to make a stop to limit the clutch pedal.



I am using the 1989's engine and bellhousing so the slave cylinder was already attached to the bellhousing.

Next I got the hydroboost brake cylinder hung on the firewall. I had to knock the two lower stud bolts off the pedal assembly and drill a couple holes but no biggie. Because of how this is mounted, I have to modify how the steering column attaches to the firewall as the brake booster bracket covers one of the attachment holes.



Mounted the rod to the brake pedal same as with the clutch. The brake booster rod is 3/8" while the hydraulic clutch rod is 5/16". I cut off the end of the brake booster push rod, threaded it and got it connected to the brake pedal using another clevis rod end.



I did have to have the high pressure line modified. I took the 1989 1 ton's high pressure line along with the stock high pressure line and had them combined - this allowed the metric end to be at the hydroboost master cylinder and they flare end to fit the stock steering box.

Here are some finished pics.