Return To Home Page
AFCO HE Pictures
2004 Cobra Pictures
BAP Installed
Kenne Bell Installed

Mystic Supercharged Cobra
from 381 rwhp to a whopping...

555 RWHP

I've started a compilation of photos that I've been taking while I
convert my '94 GT from the pushrod 5.0L motor to a 4.6L modular motor. I'll update this as I get time...

These are pictures of what it takes to replace the existing vacuum brake booster with a hydroboost brake booster.

1. Remove the master cylinder from the vacuum brake booster. This will require removing the steel brake lines going to the master cylinder. You will end up replacing this master cylinder with an updated one.

2. You'll need to remove the stock vacuum brake booster. To do this you will need to go under the dash and remove the rod that connects the brake pedal to the booster. There's a clip, a white plastic washer, the brake pedal switch, and a black plastic washer that goes in the brake booster rod. There are four bolts that will need to be removed that hold the booster to the firewall - these are 1/2" nuts if I remember correctly. They are a PITA to loosen because of the tight area to work in.

3. Pull the booster from the firewall.

4. You will need to cut 2 1/2" slits about 1" from each of the top bolt holes on the firewall that connect the hydroboost to the firewall. This is because the hydroboost rod assembly that connects to the brake pedal has been located higher on that bracket and it will hit the firewall preventing you from bolting the hydroboost up to the firewall. Below is a picture of what I had to do to make it fit. You will also need to drill a hole for the dowel that sticks out of the hydroboost (as shown in the picture below), or, you could just remove the dowel all together. I had already cut part of the hole and decided not to cut the rest so I simply shortened the dowel so that it would fit through the firewall, but not the second plate that sits 3/4" or so behind the firewall (I believe that part is part of the brake pedal assembly).

5. Now you will need to modify the hydroboost unit. Because the rod in the hydroboost is at the wrong angle compared to that of the vacuum booster, you'll need to cut off the end of the rod on the hydroboost unit. Then, you will need to cut off the end of the rod on the vacuum booster end. With the end from the vacuum boost unit, you will need to have this welded on to the hydroboost unit making sure that it's the same distance from where the mounting studs are (I measured about 5-5/16"). The new welded assembly that I did looks like the picture below. Another option would be to replace the entire pedal assembly with the updated version and then you wouldn't have to do this - but, to me, that seemed like a lot more work. Although, the downside is that I'll have to make this "upgrade" to a new hydroboost unit if/when this one goes out.

This is the vacuum booster rod - you'll notice it's at a different angle than the hydroboost unit.

This is the newer hydroboost rod - notice the angle is different.

Here's a side by side shot...

The rubber boot on mine was torn, so I opted to use the boot from the original vacuum booster.
This is the "upgraded" hydroboost with the vacuum booster rod end.

6. I cut the dowel...

7. Finally, I bolted up the hydroboost to the firewall. I haven't found a bolt yet for the lower left corner of the hydroboost unit. When I get one I'll post the one I used, but I think anything that will secure it would probably be sufficient.


After (I haven't connected the master cylinder yet...)

8. Connecting the master cylinder is next, however, I don't have the correct one. The one I have is at the wrong angle, so I'll need to order a new one. I am also looking into having custom flexible brake lines made to connect the master cylinder to the distribution unit below it. I'll update this when I get those parts...


Contact David at for more information...