Disc brake without a power booster

Looking for ideas – I want to put a Muncie in my 34 – was going to use the Pete and Jake bracket for a hyd clutch and brake set-up – problem I may have is (power booster)the car has Mustang 2 with disc in front and drum in back – Question is has any one run a disc brake set-up with no power booster (this would be for front only)-

 

I have ran mustang 2 front discs ( stock diameter) with stock 68 mustang drums on back . No booster. 68 mustang master cylinder. 27 t. No problems whatsoever

 

You just have to push a little harder and keep little girls out from behind the wheel.

 

Sure, all the time. No even hard to push the pedal.

 

Got Granada rotors on a Must II frontend with no booster and it's fine, they will lock up if you need to. Also have a non power setup on a '41 ford truck and that one will lock the fronts easily.

 

Early Corvettes had 4 wheel disks without power.

 

Match the master cylinder bore to your application. You can adjust pedal pressure by increasing or decreasing bore diameter. Master cylinders for stock manual applications tend to have a deeper pedal rod hole also.

 

I am running disc all the way around with no booster it breaks great just a little firmer peddle then with a booster

 

My 72 Montego GT stops fine with manual disk brakes... and it is a heavy car

 

Sure this was built 30 years ago using everything from a non-power disc brake equipped 71 Camaro. I rebuilt the calipers. The M/cyl is a stock replacement for the 71 Camaro. AFAIK it's sill running the streets. I used the P&J pedal kit back then. It worked just fine. I used the brake distribution block and everything from the Camaro

 

i have a el camino with non power disk front and drum back , and my 34 has 4 wheel disk non power , you will just have to devolope your leg mustlea little more , they work great , just a firmer pedal

 

Most every racecar has manual brakes. A properly designed manual brake system will take 60lbs of leg pressure for an aggressive stop with 1200psi at the brake drum or caliper.
So, yes a disc/drum combo without power assist will stop just as quick as power assist, give a brake company call with your specs before buying the MC and they will sell you the right size.

 

You gota love the Hamb - you guys are great - ask a question and get the answer <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
Thanks all - made my day - I will keep going with my PJ bracket idea which has the clutch and brake peddle<o></o>

 

just remember to use a M/cyl that was designed for non-power brakes.

 

Thanks - any ideas on who has them

 

And if the M/C is under the floor you need residual pressure valves. (no big deal, but you have to run them)

 

Thanks for the tip it will be under the floor

 

Its all about leverage &#8230;. If its to hard to push? Increase the leverage.

 

Why?

 

When I did the deisk conversion on my 64 I found that a 68 Camaro used the same bolt pattern on the master cylinder which was used for disk both power and non power. I've driven it that way for about 15 years now, and recently noticed that I don't have the stopping power of all the new compact cars with 4 wheel disks. After researching it some I found that I went from a 1" bore on the master to a 1.125, which made me work harder, not easier. I'll be swapping it out for a 7/8 bore master soon and expxecting a big improvement.

Devin

 

we have been running disk brakes front and rear with no boster for years,just make sure you have the rite combo.

 

Um, so it works. Seriously, every day there is another thread about brakes made of non-matching parts, randomly picked from a catalog and guess what? they don't work.

 

Drivers in the U.S. have come to believe that every car needs power steering and power brakes. As has been pointed out, in the past some heavy cars were available with manual discs. Although there are some variables, with proper design and planning light cars typically don't really need power brakes.

 

2lb for disc and 10 lb drum.

 

Its all in the pedal ratio !
Some applications DO have a different part # master cylinder for manual or power brakes some DO NOT.
85 range of Chevy truck doesn't have any different master or calipers for power vs manual.
What is different is the pedal ratio and on this particular truck, the brake pedal is much higher off the floor with manual brakes because the travel distance needs to be much more.

There are different steering boxes for manual vs power. The internal gearing is different and its more turns of the wheel to go from lock to lock .

Now I suppose I could re engineer the system by altering the master bore size and the caliper bore size and lower the pedal but I ain't.

 

I will be guided by what you is or ain't going to do.

For safety reasons the pedal should have enough travel to at least nearly bottom the master cylinder. That needs to be taken into consideration when establishing pedal ratio and pedal height.

 

To make things easy, A Manual disc/drum '68 Mustang master cylinder will do the deal for you quite nicely. This has a 15/16" bore and nicely balances pressure with volume for most hot rod brake needs. It will have the residual built into the rear brake chamber, so you will probably have to do a seperate 2lb residual for the front circut. By the way, one of the many reasons for using a manual master is that MOST manual cylinders have a deeper input for the brake pushrod. A very nice thing in an under floor type set up.

 

"Randomly picked" is the key phrase here. There are plenty of resources available to figure out what size master cylinder will be required based on what calipers and drum cylinders are used. Sure it's easy to just use every component from a factory engineered system, but sometimes that just isn't possible.

A combo consisting of components where your master cylinder bore is too small (not enough fluid volume to effectively apply the brakes) is about the only scenario where a change in pedal ratio cannot cure the problem.

 

15/16" came with the disc brake conversion kit for my Dart project. Easy to push but spongy pedal. The company swears up and down that's the right size manual MS disc/drum. I had them send me the 1-1/32" bore they have for power brakes. Have not tried it yet but hopefully it firms up the brakes without too much pedal pressre.

 

It could, but I honestly would have gone with a 1" before a 1 1/32". As the diameter increases, the volume rises but the pressure falls, as the bore gets smaller, the opposite is true. My experience with this stuff tells me to start with 15/16" in MOST cases.
I do have to note though that I have had one hell of a time getting systems blead lately for some reason, leaving pedals somewhat spongy feeling. Not sure why, but in my little Falcon after three goes, it's still just a bit softer than I would like. Each time I go through it again it improves though.