When I set out to improve the braking on my daily driven 64 F250 I converted it to disc/drum and purchased a booster to go with it. I decided to install it without the booster as I looked at the clearance to the YBlock valve covers. I used the Wilwood 1" bore Compact MC. Very happy with the results and the pedal feel is great. I have a rebuilt D60 with a disc brake conversion to put in this Summer. We will see how it feels after that and see if I need the booster then. I think the quality of the Wilwood MC has an affect on the feel but that's more of a feeling and not proven science.

 

What is the pedal ratio on your truck? Manual brakes are usually around 6:1 but I've never measured the actual pedal length and pivot to pushrod length of an F series.

My '66 C10 also has a 1" bore MC, the same D52 calipers as yours, 12" rotors, rear drums that have a 1" wheel cylinder bore, and the pedal feel is perfect. The pedal ratio is 6.25:1 on the C10.

I just did the hydraulics math on a '58 Impala in our shop for brake work that has 11" rotors, slightly smaller bore metric GM calipers, and the same 6.25 pedal ratio as my C10. For the same pedal input force/pedal effort, it needs a 7/8" bore MC to have right around the same effective braking force at the wheel compared to the setup my C10 has.


When adding a booster you typically modify the pedal ratio to be close to 4:1, and use a larger 1 1/8" master cylinder to avoid the pedal being too easy or touchy, and so the pedal doesn't travel too far. To me it doesn't make sense to add a booster then do two other things that take away line pressure when you could just pick the correct size master cylinder bore for your pedal ratio and caliper/wheel cylinder diameter and not need a booster. This is why I said that if you just add a booster you'll have too easy of a pedal with too much pedal travel and the brakes will be hard to modulate.

 

Good Info. Honestly I cannot remember. When figuring out which bore to purchase I had a conversation with Wilwood tech. Base on the numbers I gave them this is what they suggested. I had originally planned this MC for my 62 Unibody getting discs all the way around. I ended up stealing from that build for my 64 F250 with just disc/drum for now. I will check my notes from that conversation and see if I wrote it down. I am so far, very happy with the setup.

 

Ok, checked notes... 6:1 with stock pedal setup. I purchased the Wilwood 7:1 pedals for the 62 build. The 1" bore with disc/disc is what Wilwood suggested with their pedals. Getting those setup is still off in the future.

 

Thank you. I will look it up for sure

 

Asatronaut: You've done a comprehensive analysis/discussion of the conversion of '66 single chamber to dual chamber brake M/C.
I have mounted a '67 F250 M/C in my '66 F250 and now need to replace the brake pedal to M/C push rod.
In the course of your analysis/experience, did you come across the correct length of push rod for the dual chamber M/C?
Thanks. Jeff