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Rear disc brakes

A

andyf

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Getting ready to install the new S60 rear end complete with disc brakes into my '65 Coronet. This rear end has 3.23 gears, the S-trac differential, 35 spline axles and the Doctor Diff rear disc kit. Should have it in the Coronet and running in a few days.
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Nice, identical to what I put in mine with the exception of wilwood brakes and 4.10 gears.

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Sure wish Dr. Diff would get more of those 3.23’s made for the Dana 60 cause I could use a set.
 
Last time I talked to him, he was looking at December for the 3.23 gear sets.
 
andyf said:
Yes. Those are Ford Cobra calipers so they use the factory style e brake setup.
Click to expand...
Agree because i also got them from Diff. I asked him about replacing pads in the future and he said 98 to 2004 cobra pads.
 
Pulled the old Dana out the other day and put the new S60 under the car. Still working on hooking up the new e brake setup plus a little bit of plumbing. Decided to build new shock mounts too while I was under there.
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That is a transmission jack with a rear end adapter bolted on. That tranny jack used to just sit under the bench until I figured out one day that I could use it for a lot of stuff. I just had to build the correct adapters for it and now I use it all the time. It is the perfect tool for moving a heavy Dana 60 rear end around with since you can move it sideways. A floor jack is a lot more difficult to use and doesn't hold the rear end very securely.
DSC_2297 (Large).JPG
 
I've been driving the car for a few weeks and so far it is working just fine. The new 3.23 gears seem like a good match for the 5 speed transmission. The rear disc brakes require more pedal pressure so I'll probably swap in a master cylinder with a smaller bore size.
 
^^^this seems counter intuitive...i would say if you need more pressure, get a larger bore master cylinder
 
Pressure versus volume....The ongoing conundrum.
I made the mistake of doubting Andy's statements a few years ago. Lucky for me, he is humble and did not gloat about being right.
 
Kern Dog said:
Pressure versus volume....The ongoing conundrum.
I made the mistake of doubting Andy's statements a few years ago. Lucky for me, he is humble and did not gloat about being right.
Click to expand...

My wife says everything I do is wrong so it is nice to hear that I was correct about something once!
 
mentor70 said:
^^^this seems counter intuitive...i would say if you need more pressure, get a larger bore master cylinder
Click to expand...

Well it appears that your intuition isn't very good when it comes to hydraulic systems since that isn't how they work! Not to worry though, everyone used to think the sun revolved around the earth which is a much bigger error than how a hydraulic cylinder works.

It turns out that intuition is a bad way to make decisions in many areas, especially economics and finance. Even trained mechanics tend to bad intuition about stuff they aren't familiar with. There are common internet myths about slowing down the water flow so the radiator can work better and stuff like that.

Even experienced magazine guys get stuff wrong. I've seen some big errors in various hot rod magazines over the years that were due to people assuming they knew how stuff worked. Last one I saw like that was from a well known writer who said that four piston calipers would deliver twice the braking force of a two piston sliding caliper. His intuition on the subject was wrong and evidently he didn't bother to spend a few minutes to google the topic.

Don't get the wrong idea, I make a ton of bad assumptions myself. I'm constantly out in the shop redesigning stuff that I thought would work but didn't. That is just the way it goes. We constantly assume that we know what is going on but the laws of physics don't care about our assumptions.
 
well, id say that if the total displacement of the 4 piston calipers is larger than the displacment of 2 piston calipers, the writer was correct in his logic.

a 1 inch bore master cylinder pushing a 1 inch brake caliper is a 1 to 1 ratio

if that same 1 inch bore master cylinder is pushing a 2 inch bore caliper you have hydraulic multiplication...more stopping power.
so really you need larger rear calipers.

i dont see how shrinking you master cylinder is going to fix your problem
 
Look at it this way:
If you try to push 50 ccs of fluid through a 1 inch pipe THEN try to push the same amount through a 1/2 inch pipe, which one would have higher pressure?
 
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