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I swapped 1-ton axles and brake calipers under my 2005 F-150. I left the F-150 brake vac booster and master cylinder, but now my brake pedal goes all the way to the floor. I'm thinking I need a larger bore Master Cylinder. Which one is the easiest to swap into this era F-150? I picked up a MC from an 07 SuperDuty with hydroboost, and the flange and outer bore diameter are the same as my F-150, however the part that sticks in the vac booster is about an inch shorter. Will this work, or will it not seal inside the vac booster? They also make a slightly smaller bore (1.31") that was used in the v10 Gas Super Duty, but they didn't have it in stock for me to look and compare.

So to summarize my questions..
1) Which master cylinder will bolt up to my stock vac booster with as little modification as possible?
2) Do I need to get a MC that was used in a Vac Boost application?
3) Should I just ditch the Vac Booster and go full hydroboost, and if so, off of which vehicle should I get the hydroboost/MC system??
 

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Not sure how much I can help, but here's some info I found. Your 2005 F150 came with 2 possible master cylinder bore sizes. 1.06" and 1.13". I suspect those sizes depended on whether the truck had traction control or not. In the same year model the F350 had 1.31" on vacuum assist and 1.50" for hydroboost. The larger brakes on those trucks would need more volume of fluid as you have found. The vacuum booster used with the F350 system is not the same as your F150. In fact there are 2 models for that year, one for rear disc brakes and one for rear drum brakes. The all disc booster is larger. I suspect it is a bit larger for the heavier application. Of course hydroboost is a different animal. All the later model Ford diesels used hydroboost. It's a proven good system that's been around for probably 50 years or more. Whichever you decide to use is your call, but you do need a different master cylinder regardless of which you use. Not sure if an F350 booster would be a direct bolt on to an F150 since they have different bodies. Physically, hydroboost probably takes a lost less room on the firewall.
 
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