Well folks, Barney being the gentleman he is, responded to me personally
about rear brake master cylinders message. I knew when I was writing it
that I was a little out of my area of expertise but continued to compose
anyway. Well Barney straightened me out. He would never send this to the
list because he wouldn't want to make me, or anyone else, look like they
didn't know what they were talking about. So I asked him if I could forward
it to the list. I felt it is valuable enough that I can swallow a little
pride.
So what follows is *the* answer to the "up-rated" rear wheel cylinder
question.
Larry "scraping it off the bottom of his shoes" Hoy, Denver, CO USA
1970 Daily Driver ~ 1967 Vintage Racer ~ 1969 Undergoing V8 conversion
http://home.cwix.com/~larryhoy@cwix.com/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----Original Message-----
From: Barney Gaylord [mailto:barneymg@ntsource.com]
Sent: Friday, April 02, 1999 5:21 PM
To: Larry Hoy
Subject: RE: Wet brakes don't work, Part II
Larry,
I think you just stepped in it. Larger rear wheel cylinders do increase
braking force at the rear wheels.
None of the brakes apply any noticable braking force until all of the
linings are in contact with the rotors and/or drums (except when half of a
dual hydraulic braking system fails). Until then the pedal travel is just
moving fluid through the lines to get the pads and shoes to move into
contact with the mating friction surfaces. Larger rear wheel cylinders
will increase the pedal travel (slightly), but not more than 10% of total
travel (taking 18% more fluid for the rear cylinders but no more fluid for
the front). Once the linings are firmly in contact with the disks and/or
drums and some real hydraulic pressure can be applied, then the force at
the wheels is proportional to the square of the cylinder diameter. So,
(.870/.800)^2 = 1.183, or 18% more braking force for the rear wheels. I
trust this was done for the GT because the car weighs more at the rear.
For sure the use of these larger rear cylinders on the roadster would
increase the tendedcy for rear wheel lockup (if in fact that is a problem).
If the reae brakes are underpowered to begin with, then the GT rear
cyliners would indeed be an upgrade.
Barney
---------------
At 10:19 PM 4/2/99 -0700, you wrote:
>......so by installing the cylinder with the .870 bore you get less brake
>shoe travel for the same amount of brake pedal travel. This has the effect
>of putting greater emphasis on the front brakes. Front brakes are
generally
>considered to do the lions share of the braking. This must by why the
>larger rear cylinders are considered "up rated"?
>
>Larry Hoy, Denver, CO USA
>1970 Daily Driver ~ 1967 Vintage Racer ~ 1969 Undergoing V8 conversion
>http://home.cwix.com/~larryhoy@cwix.com/
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> -----Original Message-----
>> From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
>> Behalf Of Florrie & Allen Bachelder
>> Sent: Friday, April 02, 1999 7:13 PM
>> To: mgs@autox.team.net
>> Subject: Re: Wet brakes don't work, Part II
>>
>>
>> Except GT cylinders are larger: .870 vs .800 for the Tourer.
>>
>> Allen
>
>
>
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