I have been thinking of converting to manual brakes. Skinnykid race cars has some nice kits with lines and everything included.

How would manual brakes be on the street with 4 wheel disks and 13" up front? Car is probably 3200+lbs.

 

If you don't need to do it, and if it isn't a race car, don't do it. It ain't fun AT ALL.

 

dsman is right. manual brakes are a lot of work on the street. hell, they're a lot of work at the track. my aerospace are very hard to get the car to stop at the track. i have to basically stand on the pedal and hope i slow down enough for the last turn.

 

If the brake system is sized properly the manual brakes should work. Manual brakes are more critical in regards to bore size and pedal lever ratio. I have used manual and power assist on my Chevelle. Both have worked..of course we're not talking road course quality in either form.
I put a manual GM master cylinder on my sbc BMW project. I had to change the pedal ratio to 7 or 8:1 to get enuf pressure out. Talking about standing on the brakes..it was an understatement at 6:1 with that MC.
$.02
Walt

 

hey walt,

when i installed my master cylinder (1 1/16" wilwood), i had to redrill the pedal according to the directions. i forget what ratio it was, but i know i did it the way they called for. i still have to stand on them. according to aerospace, my system is more than adequate. and they do stop the car, just not as fast as i would like. definitely not adequate for street use.

 

I DID IT AND REGRETTED IT. I WOULD NOT DO IT ON A STREET CAR. THE WIEGHT SAVINGS IS NOT WORTH IT. AND THERE ARE WAYS AROUND VACUUM PROBLEMS FOR POWER BRAKES.

 

Huh.

Thats funny I have manual brakes on my big block powered car and I can stop it with one foot (Don't really have a choice as I still have the three pedal assembly in there.)

I'll hold my final verdict until I try some stops from high mph.

Greg

 

http://www.wilwood.com/Products/005-PedalAssemblies/Pages/techtip/pedaltech.asp

Take a look down the page. It shows 6:1 as optimal in the example. I ended up with more than that in the BMW install. Of course MC bore diameter comes into play as well other braking components. Can you easily adjust the ratio to add a little more pressure? Do you have access to guages that will show you the pressure? My guess is inadequate pressure at the calipers. That is what was going on with mine.

Walt

 

To add to the stand on it and NO STOP. That is how the bmw project started out. The first drive was short drive W/O brakes(from outbuilding to attached garage) The second drive with brakes didn't seem much different..car just slowed down no way would it lock up the brakes...added a few : to the ratio.
Walt

 

How do you change the pedal ratio? I'd like to try that, otherwise I'm buying another booster and electric vacuum pump and going back to power brakes.

 

i don't have a gauge right now, maybe i should buy one. driving around normally it works great. just stopping at high speeds is the problem.

 

to change the pedal ratio you have to drill a new hole and mount the rod either lower or higher, depending on what ratio you are looking for. there's a formula for it, i don't have it with me. maybe blownshovel has it.

 

Take a look at this page:
http://www.wilwood.com/Products/005...p/pedaltech.asp
Down toward the bottom there are a few diagrams showing the basic mechanical principles of lever/ratio. You will need to move pivot point toward the MC rod or you can extend the brake pedal(making it longer). Basically let's say you push 100lbs with your foot. A 5:1 ratio would provide @ 500lbs of internal brake line pressure. A 6:1 would provide @ 600 etc. The calipers may require different(higher) pressure.

If you are not Big $$$ into the manual setup the factory boosted systems work very well. If you purchased all new aftermarket Manual brakes I would be giving someone a call.
Walt

 

yeah, basic physics right. i could make the pedal longer and get more torque out of it. that would create more pressure on the cylinder. just might have to try that. i have had the system on the car for about 2 years now, but i just got the car running recently. i started the project and finished the chassis long before it ran. also, it runs a lot faster than i had orginally intened.
thanks for the help.

 

I had no issues at all stopping in my car, infact it was downright uneventfull. The shutdown area at PIR is known for being very short as well for a 1/4 mile track.

I'm running the Strange master cylinder and manual conversion from Skinny Kid with the rod moved up 1" from stock. Pedal effort is fine, and it stops hard.

 

i think i just need to check my pedal ratio again. it stops, just not like i want it to.

 

should i be looking for a pedal out of an automatic '94+ mustang?? I am looking at skinny kid's site, their Strange master cylinder is the same Chrysler master cylinder that I have STRANGE: B-3359 MASTER CYL. (MOPAR TYPE 1.125" BORE). The only thing I see listed is this, but nothing in the picture looks like it would change the way the rod bolts up.
DEVELOPED WITH CORRECT PEDAL RATIOS

 

dan, your mc will be fine, as will your pedal. getting one out of an auto won't matter, i think. either way, you will still have to drill it to make it right. you just have to measure to get the right ratio. apparently, mine is a little off, so i need to go home and remeasure.

 

Generally, do you think I will be drilling a hole HIGHER on the pedal so the rod from the mc bolts up higher?? or lower?

 

ummm, i think it will be lower. its been a while since i have done this. i am not sure. if i remember correctly, it was lower.