65TerrorCuda
Well-Known Member
I thought the 76 was smaller? I could go measure but... still drinking my coffee
Factory disc question for those with stock disc brakes. NOT aftermarkets
- Thread starter 63Tigerlily
- Start date
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2.75 v 2.6x
though the larger piston caliper was standard on a whole mess of other stuff-- B's, F,M,J & R's
65TerrorCuda
Well-Known Member
You're right. I had it backwards.
i only knew because i had already done the coffee (and a few cookies) and my notes were sitting within arms reach.
65TerrorCuda
Well-Known Member
A smart man right there. Running into battle half cocked is my style
Hyper_pak
Old School Chrysler Fan
Good to know.
Jeremiah (jd)
Well-Known Member
I deceased ordering parts from RockAuto a couple of years ago because we kept getting faulty brake ignition and suspension parts. You must inspect things very carefully. With respect to this thread I was burned on two different Masters cylinders and at that point I decided it wasn't worth saving eight bucks
63Tigerlily
Well-Known Member
Yup
63Tigerlily
Well-Known Member
New definitely doesn’t mean good. From working my caliper under the dash I’m getting about .950” bore, which is about a 15/16. I canibalized the old single pot and cut the piston off the integral pushrod and I probably have too much freeplay. I’ll snap a pic of the combo valve plumbing today
jos51700
Green Bearing thread connoisseur
You're a better man than me, I always get my stuff all plumbed up, brakes don't work, get pissed, throw stuff, THEN remember lol. Good job!
can you expound on this bolded part a bit?
Dave999
Well-Known Member
Sounds to me like the safety piston has switched off the front or rear brakes..
get it hooked up correctly on the distribution block the thing with the warning light wire going to it
get the brakes working nice
then fit the proportioning valve these usually go only in the line that goes to the rear
you can get a distribution block with a proportioning valve in it.... if you have that. then replace the distribution block you have with the new one.
keep in mind that any loss of pressure in front or rear circuit will be measured across the distribution block safety piston and it will shuttle one way to cut off the circuit with the low pressure. For example an air bubble in one circuit or the other and this imbalance will switch off the circuit with the perceived pressure loss
if your distribution block is standard US, all will be fine you just need to rectify the situation and the piston shuttles back when the pressure equalises on both sides
if your master cylinder incorporates the safety piston and you have no distribution block it is actually a safety switch in there ....
your safety piston is then in my mind a danger switch because it leaves the circuit switched off forever, until you undo the collar around the indicator wire housing and move the thing the wire plugs into out 1/8 of an inch till you hear a click, that lets the switch unlatch from the piston and let it go back to a setting where both circuits work again
This was a thing on 1970 -73 australian cars with the cast iron disk brake kelsey master cylinders
No idea if they got this idea from the USA. but i think its down right daft... if the idiot light in the dahs fails you have no idea that you are driving around with either no front or no rear brakes
master cylinder with DANGER switch pictured see where the wire goes...
if your doesn't look like this you have a sensible USA version
get it hooked up correctly on the distribution block the thing with the warning light wire going to it
get the brakes working nice
then fit the proportioning valve these usually go only in the line that goes to the rear
you can get a distribution block with a proportioning valve in it.... if you have that. then replace the distribution block you have with the new one.
keep in mind that any loss of pressure in front or rear circuit will be measured across the distribution block safety piston and it will shuttle one way to cut off the circuit with the low pressure. For example an air bubble in one circuit or the other and this imbalance will switch off the circuit with the perceived pressure loss
if your distribution block is standard US, all will be fine you just need to rectify the situation and the piston shuttles back when the pressure equalises on both sides
if your master cylinder incorporates the safety piston and you have no distribution block it is actually a safety switch in there ....
your safety piston is then in my mind a danger switch because it leaves the circuit switched off forever, until you undo the collar around the indicator wire housing and move the thing the wire plugs into out 1/8 of an inch till you hear a click, that lets the switch unlatch from the piston and let it go back to a setting where both circuits work again
This was a thing on 1970 -73 australian cars with the cast iron disk brake kelsey master cylinders
No idea if they got this idea from the USA. but i think its down right daft... if the idiot light in the dahs fails you have no idea that you are driving around with either no front or no rear brakes
master cylinder with DANGER switch pictured see where the wire goes...
if your doesn't look like this you have a sensible USA version
Icetech
Well-Known Member
Mine are the same way... and it makes me nuts.. i have replaced every single part in the brakes including 3 master cyls. The one on it now is a 15/16 drdiff one. Mine basically will slow me.. but no chance of a quick stop at all. I finally got a pressure gauge and am only getting 400psi at the calipers no matter how hard you stand on it.. should be 800-1000psi.
The gauge is worth it to diagnose.. still can't figure why the pressure is low though (Brake arm is 6:1 ratio)
P.S. i need to remove and measure my caliper pistons... betting i have the smaller ones, not sure how you would order new ones and be sure to get the larger.
At this point i wish i had stayed with drums, i fell for everyone saying how great discs are.. never had drums let me down in normal driving
MoparLeo
NRA BENEFACTOR LEVEL LIFE MEMBER
I am going to assume that the brake system on a 1963 vehicle uses an single line m/c .
And being a 62 year old car, all of the brake lines hard and soft need to be replaced.
This when you get all of the brake lines plumbed properly.
Using vintage parts on a brake system is asking for it.
And being a 62 year old car, all of the brake lines hard and soft need to be replaced.
This when you get all of the brake lines plumbed properly.
Using vintage parts on a brake system is asking for it.
Speedy Pedi
Well-Known Member
I have just started early road tests on my 67 Barracuda, driven 7 miles total, top speed driven 45 mph, so far and brakes under normal stopping gave good results. I'm using the 15/16 master cylinder, if I was to switch to the 1 1/32 master cylinder should there be an appreciable difference? My setup currently K/H front and 10 x 1 3/4 rear drum, using 4 drum distribution block and an adjustable proportioning valve to rear brakes.
Dave999
Well-Known Member
harder peddle
shorter peddle travel
less progressive application
go too big on the master cylinder bore and it feels like your brake pads are made of varnished wood
i.e %^$$$^%!!!!! stop
dave
shorter peddle travel
less progressive application
go too big on the master cylinder bore and it feels like your brake pads are made of varnished wood
i.e %^$$$^%!!!!! stop
dave
63Tigerlily
Well-Known Member
That doesn’t make a ton of hydraulic sense to me.
The hoses are all new. The hardlines were working fine with the drums and are the same size as disc systems. The fluid runs clear when bleeding.
63Tigerlily
Well-Known Member
63Tigerlily
Well-Known Member
So here you can see the valve from doctor dif. The only difference from his diagram is that I use one front circuit to feed the original block that splits into two front circuits.
This was only to get it going temporarily. One of the original nuts of the front circuit rounded off.
I still don’t see, once bled, why this would cause a soft pedal.
This was only to get it going temporarily. One of the original nuts of the front circuit rounded off.
I still don’t see, once bled, why this would cause a soft pedal.
63Tigerlily
Well-Known Member
Measured my pedal ratio and it’s roughly 7:1
your fine, we all did not understand what you had hooked up now it is clear
63Tigerlily
Well-Known Member
Tonight I’ll recheck the rear brake adjustment, re-bench bleed the master, and see where I’m at.
At that pedal ratio, with all stock ‘76 equipment, it should be applying hard.
At that pedal ratio, with all stock ‘76 equipment, it should be applying hard.
The later sliding caliper front disk brakes should be high and firm. I totally agree with those that say that this is by far the best braking system for A-Bodies. I run the Mopar Action Liberty disk brake conversion on the rear of my '68 FS FB and really like this setup. I have a summit proportioning valve to make sure I get front lockup before rear, but I can hardly lock the fronts as they grip so well. This setup simply works great with the only drawback being the wider track of the front wheels compared to the K-H original disk brakes.
63Tigerlily
Well-Known Member
Nobody’s driving a 76ish with factory manual discs around out there?
My wife drove it and said the brakes feel fine to her.
They feel like the old 9inch drums
My wife drove it and said the brakes feel fine to her.
They feel like the old 9inch drums
Make sure the rears are adjusted properly. Kim
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