SJTD wrote: ↑Sun Jan 16, 2022 11:43 pm Some rules of thumb:
You probably know this stuff but I'll post it anyhoo:
Smaller MC pistons mean more power but require more travel and vice versa.
Bigger wheel pistons mean more power but require more MC piston travel and vice versa.
Increasing the ratio of the pedal pivot to pedal length vs the pivot to master length increases power but with greater pedal travel.
Thanks guys!Yeller wrote: ↑Sun Jan 16, 2022 7:01 pm I just went back and looked through your thread. With the massive K30 front calipers you need a 1-1/4” bore master cylinder. My go to for that is for an 85 K30. There are 2 models, hydro boost and vacuum booster. They are the same specs exempt for the depth of the piston. The hydro unit is flush and the vac unit is recessed at the piston.
I’ve run those calipers with 1” and 1-1/8” bore cylinders. Both will work but will make you feel like you need a change of underwear when the pedal slaps the floor when you really need brakes, good news is they are usually locked up, but still squishy and scary. More volume is the only fix.
As a note about bore size some K10 and all K20 use 1-1/8” bore. I’ve only found 1-1/4” on 78-91 disc brake K30’s. I’ve played with this extensively, those calipers need 1-1/4” bore minimum to have a good pedal feel.
I’m running k30 hydro boost on my M715 (k30 drivetrain) and I’ve been using that as a reference for what I’m doing for the FC. The M stops on a dime with the hydro boost set up, so my braking expectations are stupid high for the FC.
I’m stewing on those numbers, diameters and facts you provided. I appreciate the info. And I have a sinking feeling major MC mods will be required, or I’ll have to swap in an 8 lug Dana 44 to replace the Dana 60 front (I don’t want to swap out the front axle! Lol).
I do have the new inline valves coming sometime this week and then I’ll dig further into the squishy brake syndrome.
Meanwhile I am pouring over the details and researching build threads on the Dana 60 front axle swap in all kinds of trucks to see what solutions others have come up with to get their rides to stop properly.
I appreciate the info!