Projects All new brakes, worse than before!!

no real difference. No booster fitted. View attachment 3959765
Any brake gurus out there??

 

Are the shoes arced to the drums? Shoes adjusted correctly?

 

That is a disk/drum master cylinder... Not drum/drum.

Do you still have drum/drum setup?

 

DING ! DING !

 

All you need to do is measure the bore sizes of the new parts and the bore sizes of the old parts and post up those results.
After you do that you'll have an answer in 10 mins or less

 

A double cylinder requires a longer push rod.
Did you change that? The stock F100 is an inch or so too short.
A Galaxie, Fairlane or Mustang rod can be trimmed to fit...... So they say.....

I got into this on my 65. I went so far as to get a double cylinder. Due to pedal throw and all that, I decided to stay with the stock system.

Another thing..... The stock system was not designed for a proportioning valve. Cylinder and shoe size determines that factor.

Do you have the front brakes connected to the rear port? It should be.

To me it sounds like you are getting full use of the cylinder throw.

 

I wish there was a better way to verbalize that.

 

The port closest to the mounting flange is for the front brakes.

 

So, it wasn't stopping without lots of pedal pressure with a single bore master cylinder?
Now the dual cylinder takes more effort...
Do you have other brake component problems like primary secondary shoe position swapped,
over sized brake drums (didn't see new drums on your list) and as mentioned proper brake shoe to drum contact that may require proper brake shoe arcing to match drum radius?

 

Are you hauling 12,000 pound payload in the bed?

 

Convert it to single master with 4 drum brakes...then it will work.

 

There are different friction materials too. Some provide more friction/stopping power with the same pressure applied. There are codes on all DOT legal brake friction material.
http://faculty.ccbcmd.edu/~smacadof/DOTPadCodes.htm

 

I added a dual master and booster to my 60 F100 and learned that I had to drill a hole 3/4" lower on the brake arm for the pushrod. That gave me more leverage

 

Assuming top mounted swing pedals, that will give you less leverage but more movement on the master piston.

 

Get the right dual master cyl.

 

Reduce double MC bore to about 85% of single.. If single was 1.125 go to 1.00 for the double..Linkage to pedal can stay same as single..Throw will stay the same but pedal effort will be reduced by about 15%.

 

Be sure to compare wheel cylinder bore size of new cylinders with original. A smaller diameter wheel cyl will reduce force applied to shoes at a given line pressure.

Ray

 

Would i be able to still use this m/c and just take off the proportioning valve?

 

If wheel cylinders are same size I see no reason to add proportioning valve.

 

NO.
Buy the right one, throw that shit away.

 

If the proportioning valve is opened all the way, is there still restriction in it? D

 

Bri62,
Changing from a single to dual master cylinder will have no effect on pedal effort or brake performance IF the bores are the same size.
You could keep the disc/drum master and remove the prop valve, but you will need residual valves for your vintage drum brakes. The secondary drum port (below the smaller fluid reservoir in your case) may have an internal residual behind the tube seat, or just add inline 10lb valves to each axle.
You have to make sure any dual master you use can full stroke (open circuits) before the pedal bottoms out, or you will not have the safety advantage of a dual master.

Dennis D,
Running an adjustable proportioning valve full open just raises the pressure point the valve starts to operate, but will continue proportioning in percentage above this setting. The only way to bypass a prop valve is to remove it.

 

Thanks Bob, D

 

thanks guys, i will have to start thinking hard, which way to go.
bore on original single pot was 1.0625"
new one 1"
would this be a significant amount to alter brake performance?
not sure of the bore sizes on the wheel cylinders, as i just ordered the ones for my year truck!

 

The new smaller bore will actually produce a little more line pressure for the same amount of pedal pressure. It could also slightly increase pedal travel, but neither of these consequences is a big deal with so small a difference..'in my opinion', of course.....other opinions may vary...

Ray

 

Echo in here

 

V8 Bob got it right in post 23.

The main difference between drum/drum and disk/drum or Disk/disk master cylinders is the built in residual valves in drum brake master cylinders. Disk brakes cylinders don't have them. We used to pull the seat out of the drum brake master cylinder, remove the little valve piece and spring and put the seat back when doing disk conversions on Chevelles and the like in the early and Mid 70's.

 

Yes, I know....but two things.....I already knew that too....and.....your post was so far back by that time, it was obscure...but as you said in another thread about a detail I noticed...."good catch" edit: just realized that 'good catch' was a comment by Gimpy,
not you. this just keep getting worser and worser. My SO often reminds me that 'when you find yourself in a hole, stop digging'...

and another poor excuse....it happens to me...a lot...so I know how you feel about being overlooked when you were first with the scoop.....I feel your pain! ....and I promise I won't do it again....at least to you.

Ray

 

He who posts without reading the whole thread first shall suffer the red face moment on occasion.
If you line up those who have had that moment over here and those that haven't over >>>> there over >>> will be a real short line.

 

I agree with you....the thing is I DO read prior posts...and I read the 31Vickie with a hemi's post.....I knowingly decided not to cite that one sentence buried deeeep inside his post....I am truly sorry..

Ray