The hydroboost has a curved pedal rod that will move the pin about 3/4” lower than stock.
That changes the pedal ratio from 6:1 stock to a little over 4:1. 
That is the change that the MustangSteve vacuum power booster retrofit uses. I have been experimenting on 65 Mustang with moving the pedal pivot up as high as possible in the car and adding a section to the pedal to increase the distance between the pedal pivot and the pedal pin. That moves the pin lower and puts the foot contact plate back down to stock position.  It will also help reduce pedal ratio. The 98 pedal is closer to 3:1, so any change you can add will help. Do not go with less than 3:1 brake pedal ratio. 
As you know, the clutch pedal has to be modified similarly. By relocating the bearing kit as high as possible on the pedal support, the clutch pedal can be moved upward with the brake pedal. Around 1/2” higher is max.  Then, shorten the distance between the quadrant and the clutch pivot bearing, then lengthen the clutch pedal length between the foot contact plate and the pivot. This will increase the clutch pedal length, giving a more effective clutch pedal ratio, but less travel for the cable. Luckily, in stock configuration, the clutch pedal pulls the cable far farther than needed, so this mod will help with clutch pedal leg effort and still pull the cable the required 1” to properly operate a diaphragm type pressure plate.

The Falcon has more room under the cowl to work with than a Mustang, so you might be able to get it closer to what you need than in a Mustang.  Just work within two parameters.  At least 3:1 ratio on brakes and clutch cable must be able to pull 1”.  You don’t have to have free travel like a z-bar needs, so every movement of the clutch pedal is translated to movement of the cable.

On a side note, be sure to use a FORD throwout bearing.  Anything else and you will get to replace it in a short time.

MS wrote:

The hydroboost has a curved pedal rod that will move the pin about 3/4” lower than stock.
That changes the pedal ratio from 6:1 stock to a little over 4:1.
That is the change that the MustangSteve vacuum power booster retrofit uses. I have been experimenting on 65 Mustang with moving the pedal pivot up as high as possible in the car and adding a section to the pedal to increase the distance between the pedal pivot and the pedal pin. That moves the pin lower and puts the foot contact plate back down to stock position. It will also help reduce pedal ratio. The 98 pedal is closer to 3:1, so any change you can add will help. Do not go with less than 3:1 brake pedal ratio.
As you know, the clutch pedal has to be modified similarly. By relocating the bearing kit as high as possible on the pedal support, the clutch pedal can be moved upward with the brake pedal. Around 1/2” higher is max. Then, shorten the distance between the quadrant and the clutch pivot bearing, then lengthen the clutch pedal length between the foot contact plate and the pivot. This will increase the clutch pedal length, giving a more effective clutch pedal ratio, but less travel for the cable. Luckily, in stock configuration, the clutch pedal pulls the cable far farther than needed, so this mod will help with clutch pedal leg effort and still pull the cable the required 1” to properly operate a diaphragm type pressure plate.

The Falcon has more room under the cowl to work with than a Mustang, so you might be able to get it closer to what you need than in a Mustang. Just work within two parameters. At least 3:1 ratio on brakes and clutch cable must be able to pull 1”. You don’t have to have free travel like a z-bar needs, so every movement of the clutch pedal is translated to movement of the cable.

On a side note, be sure to use a FORD throwout bearing. Anything else and you will get to replace it in a short time.

The brake pedal rod on the Cobra boosters appears to be straight but the booster mounts at an upward angle which would should lower the pedal pin. Is this what you're referring to? If that moves it to the 4 to 1 ratio by relocating the pin down to match the new angled rod that would probably work great. I'm not an engineer so if I can steal as much of what Ford did on the 03-04 setup I know it should work like OEM.
 

Some of the pictures are not showing up. 

https://fyi.boardhost.com/viewtopic.php?id=10312

RTM wrote:

Some of the pictures are not showing up.

https://fyi.boardhost.com/viewtopic.php?id=10312

Thanks! My only concern is that I have no room to move anything downwards, if I did I would probably go vacuum. You can kind of see the master cylinder hole in the firewall. I could try to go up but that could give me export brace issues, I can't go towards the drivers side or I'll have shock tower issues. I should know more in the next few days once the cobra hydroboost setup shows up. I can't get the image posted but I have a link to the pic of what I'm dealing with.

https://ibb.co/jwvwkCg

Last edited by cj428mach (8/15/2024 2:48 PM)

I'm not sure why but some of my pics on ImgBB are not availble, here are two that I had previuosly posted on the Forum in 2018.  I have some more, maybe PM me with your email address and I'll forward along.
I'll add that I had to use the MDL offset clutch MC, and there wasn't any interference with the shock towers as they had been removed.  And it is a very tight fit, had to modify a few wrenchs in order to tighten several bolts and fittings.

kardad wrote:

BobE:
Do you have any photos of the finished product in your 66? Did you lower the master cylinder or leave it and the stock location?

Did everyone miss the fact that CJ428Mach is putting a 7.3 Godzilla motor and 5-speed in a 64 Falcon for his daughter? I'm extremely jealous, that will be a BEAST. All of my boys got Jeeps with 4.0 6cyl

Last edited by BobE (8/16/2024 7:42 AM)