In a previous thread I inquired about how to convert a G body to manual brakes. See here: http://www.hotrodders.com/t66458.html
Well, mission accomplished, my car officially has brakes again. I thought I'd share how I did it.
Here's the basics:
I bought an S10 manual master cylinder from a wrecker. With the master cylinder I also took the factory block off plate, pushrod, and pushrod retainer cup. The pushrod fits really nicely into the back of the master cylinder. The metal cup holds the pushrod against the back of the piston so that it is impossible for the pushrod to fall out of place. This is very important for a power to manual conversion because with power brakes the pushrod is locked into the booster. If you switch to manual it's necessary to make sure the pushrod cannot fall out.
The S10 pushrod is about two times longer than it needs to be for a G body. Pictured is the rod end I used to shorten the pushrod.
I measured the length required and cut the pushrod. I threaded it and attached a 3/8 rod end. The rod end is a high quality piece. With the fine threads this pushrod is very sturdy and I won't have to worry about it at all.
These are all the pieces layed out. With the booster removed there is a large hole in the firewall. The stock S10 blocking plate fills it nicely. It is also required to hold the retaining cup against the master cylinder. I'm using the stock G body pedals. The pedals came with two holes drilled. The lower hole is used for power brakes. The top hole is used for manual brakes. I welded a bolt through the upper hole for the new pushrod attachment. I also welded four bolts to the pedal bracket to make the studs which will go through the firewall.
This is the pedal, pushrod, and master cylinder assembled pretty much as it will be in the car.
This is another view with the pushrod more visible. A nice thing about the threaded end is that it's possible to make adjustments in pushrod length. For final assembly I used some loctite and locked the rod end with the nut. Even if the rod end loosens (which it won't), it's impossible for it to fall apart. The longer the rod is, the higher the brake pedal. It can only move so far, so it's impossible for the rod to come apart. As with the factory setup, the rod end is spaced with washers and a held in place with a cotter pin.
This is the master cylinder installed on the firewall. It's nice having that big ugly booster out of there. Of course, now I have to clean up all the wires that were hiding behind the booster. The S10 resevoir doesn't fit too well. I cut a little notch out of the hood bracing so that I have about an inch clearance. On my next trip to the wrecker I'm going to look for a smaller resevoir with more of an angle. This one does work fine however.
Total cost: master cylinder $15, rod end $15.50 = total $31.50 Canadian.
As a concurrent upgrade, I also put 7/8" wheel cylinders from a manual braked S10 in my rear drums. These should help increase the power of the rear drums. The factory G body wheel cylinders are 3/4".
Results:
I am very happy with this conversion. My engine doesn't make enough vacuum to run power brakes well enough. Now I have consistent braking with a simple system. I've only tested the new brakes for one day, but so far they seem to work quite well. The pedal isn't too heavy. You have to push a bit harder, but it's no big deal. The pedal travels a bit further than power brakes; but I don't mind that either. The braking power seems fine; its comparable to normally working power brakes. In the future I plan on swaping the front discs to 12" from a caprice station wagon. That's it.
dh
Well, mission accomplished, my car officially has brakes again. I thought I'd share how I did it.
Here's the basics:
I bought an S10 manual master cylinder from a wrecker. With the master cylinder I also took the factory block off plate, pushrod, and pushrod retainer cup. The pushrod fits really nicely into the back of the master cylinder. The metal cup holds the pushrod against the back of the piston so that it is impossible for the pushrod to fall out of place. This is very important for a power to manual conversion because with power brakes the pushrod is locked into the booster. If you switch to manual it's necessary to make sure the pushrod cannot fall out.
The S10 pushrod is about two times longer than it needs to be for a G body. Pictured is the rod end I used to shorten the pushrod.
I measured the length required and cut the pushrod. I threaded it and attached a 3/8 rod end. The rod end is a high quality piece. With the fine threads this pushrod is very sturdy and I won't have to worry about it at all.
These are all the pieces layed out. With the booster removed there is a large hole in the firewall. The stock S10 blocking plate fills it nicely. It is also required to hold the retaining cup against the master cylinder. I'm using the stock G body pedals. The pedals came with two holes drilled. The lower hole is used for power brakes. The top hole is used for manual brakes. I welded a bolt through the upper hole for the new pushrod attachment. I also welded four bolts to the pedal bracket to make the studs which will go through the firewall.
This is the pedal, pushrod, and master cylinder assembled pretty much as it will be in the car.
This is another view with the pushrod more visible. A nice thing about the threaded end is that it's possible to make adjustments in pushrod length. For final assembly I used some loctite and locked the rod end with the nut. Even if the rod end loosens (which it won't), it's impossible for it to fall apart. The longer the rod is, the higher the brake pedal. It can only move so far, so it's impossible for the rod to come apart. As with the factory setup, the rod end is spaced with washers and a held in place with a cotter pin.
This is the master cylinder installed on the firewall. It's nice having that big ugly booster out of there. Of course, now I have to clean up all the wires that were hiding behind the booster. The S10 resevoir doesn't fit too well. I cut a little notch out of the hood bracing so that I have about an inch clearance. On my next trip to the wrecker I'm going to look for a smaller resevoir with more of an angle. This one does work fine however.
Total cost: master cylinder $15, rod end $15.50 = total $31.50 Canadian.
As a concurrent upgrade, I also put 7/8" wheel cylinders from a manual braked S10 in my rear drums. These should help increase the power of the rear drums. The factory G body wheel cylinders are 3/4".
Results:
I am very happy with this conversion. My engine doesn't make enough vacuum to run power brakes well enough. Now I have consistent braking with a simple system. I've only tested the new brakes for one day, but so far they seem to work quite well. The pedal isn't too heavy. You have to push a bit harder, but it's no big deal. The pedal travels a bit further than power brakes; but I don't mind that either. The braking power seems fine; its comparable to normally working power brakes. In the future I plan on swaping the front discs to 12" from a caprice station wagon. That's it.
dh