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About leg press of brake pedal. You should be able to press more than your body weight. I'm 160lb with zero gym/workouts and I think last time I did leg press it was over 250lb. Also press strength may be different for how that force is applied to pedal. Typically you never hit 100% brake pedal pressure I thought and on top of that when you hit it your in a thrusting action which will result in higher forces applied to brake pedal than a slow push. Kinda like kicking a door down vs pushing it down. I may be way off, just thinking out loud.
About leg press of brake pedal. You should be able to press more than your body weight. I'm 160lb with zero gym/workouts and I think last time I did leg press it was over 250lb. Also press strength may be different for how that force is applied to pedal. Typically you never hit 100% brake pedal pressure I thought and on top of that when you hit it your in a thrusting action which will result in higher forces applied to brake pedal than a slow push. Kinda like kicking a door down vs pushing it down. I may be way off, just thinking out loud.
Thinking out loud is all I got right now, so I appreciate any thoughts or feedback! Not like this has ever been done before.
As thrust vrs. ankle action goes - its particular as well. My seat positioning is much higher than the normal diver positioning (Like a bus driver rather than knees up). This really limits my leverage to ~90 lbs max.
I've got a new seat and seat riser on COVID backorder from Kirkey. Plan is to lower the steering column and seat riser to help with a better and more orthodox leg position.
Originally Posted by oreo
Link to my thread on the Titan flaring tool, and Amazon copper/nickel brake lines. Titan Flaring tool
Thanks! This confirms my copper/nickle choice. I was able to grab a flair tool from another forum member.
I was worried about pedal stroke length because of your leg length. I thought it would be really uncomfortable to operate at some point as that got longer.
Yes, the smaller bores and extended pedals are probably going to be very long.. but like you said, the circumstances are weird.
Originally Posted by sixshooter
I was worried about pedal stroke length because of your leg length. I thought it would be really uncomfortable to operate at some point as that got longer.
If the travel ends up being too long, maybe you could relatively improve the effort of a larger MC setup with pads that have an extremely high coefficient of friction? Hawk DTC-70s, for example, have very high mu and might cut effort and improve the travel-vs-force tradeoff for you.
Some good and bad news. Good news is I am stronger than I thought. I ran a pull scale on the current set up and estimate around 105 lbs of force at what i can only describe as "comfortable track pressure". I was able to gather around 160-165 lbs when I really put my back into it. (Guess you were right Ian). Not bad for 75lbs and one leg.. but I don't ever want to be in that position willingly.
The bad news is, after briefly speaking with someone who has experience designing brake systems (not sure if he wants to be identified)... his first thought is it cant be done =(
I was learned that you need approximately 210lbs for manual brakes and my whole idea on extending the pedal is flawed. My understanding of where the fulcrum is was incorrect, and I was wrong in thinking adding height to the pedal would show a linear increase in force. In reality the fulcrum is between the pedal face and the plunger inside the master, and not between the pedal, and the master cylinder arm.
I was learned that you need approximately 210lbs for manual brakes and my whole idea on extending the pedal is flawed. My understanding of where the fulcrum is was incorrect, and I was wrong in thinking adding height to the pedal would show a linear increase in force. In reality the fulcrum is between the pedal face and the plunger inside the master, and not between the pedal, and the master cylinder arm.
The fulcrum is actually the pivot at the bottom of the lever. The distance to the plunger inside the master doesn't matter at all as long as the pushrod is roughly perpendicular to the pedal at pad contact.
For floor mount pedals, the mechanical advantage ("pedal ratio") for the system below is just (A+B) / B
Last edited by afm; May 5, 2020 at 10:40 PM.
Reason: Resize image
Ignore the prototyping mess. To my surprise, I was able to comfortably work the brakes pretty well. However, any type of extra element or other non-optimal factor like heal-toe would put me into a unfavorable position. Especially at track speed, fatigue or brake fade.
This means I will scrub this plan and go with plan B - a combination of factory power brake MC with Tilton clutch and throttle pedals.
Ignore the prototyping mess. To my surprise, I was able to comfortably work the brakes pretty well. However, any type of extra element or other non-optimal factor like heal-toe would put me into a unfavorable position. Especially at track speed, fatigue or brake fade.
This means I will scrub this plan and go with plan B - a combination of factory power brake MC with Tilton clutch and throttle pedals.
This blows.. lost $400 on that test.
Closing the loop for all my fans out there (Shooter).
That looks like an excellent solution, especially for the brakes. The brake master would have been terrible to relocate and it looks like your solution maintains the same travel and effort. Good call.
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