You addressed me directly, so I need to make sure you know I'm not an
expert, just someone who has already performed this conversion. Once.
My understanding is that anytime your master cylinder is lower than your
wheel cylinders or calipers you need a residual valve to prevent brake fluid
from draining back into the master cylinder. If the fluid flows back your
brakes can be slow to respond when you hit the brakes.
So our old trucks with the under-the-floor master cylinders were built with
residual valves. I don't know with certainty about others.
Your drum/drum dual master should work for your disk/drum combination. I
used to think the reason for the larger reservoir was because it took more
fluid displacement to operate the calipers. I've since been told the reason
is that the wear on pads is great enough that over the life of your brake
pads you need to have plenty of fluid to keep the lines full as fluid ends
up in the caliper.
I'd suggest changing to the disk/drum type master because you really don't
want your front brakes to quit on you...
HTH!
----- Original Message -----
From: "Jim (Deacon) and Karen Magill" <dnkmagill@wtxs.net>
To: "Steve Hanberg" <steve@oldsub.com>
Cc: "wayne osborne" <wayne@chevytrucks.org>; <oletrucks@autox.team.net>
Sent: Thursday, December 04, 2003 10:58 AM
Subject: Re: [oletrucks] front disc brakes
Do all master cyl. that are on drum brakes come with the built in 10#
residual
valve? I ask because I switched to the dual master cyl. when I put in the 64
front clip and now I am adding disc brakes on the front from a 72
Chevelle. I
am understanding that I will now have to buy a dual master cyl. for
disc/drum
brakes. Anyone need a slightly used dual/drum master cyl.? Is there no end?
Ha! Deacon / 55 TF STILL in progress!
Steve Hanberg wrote:
> The short answer is no.
>
> The problem is that your current braking system has a built in residual
> valve to maintain about 10 lbs of pressure to hold the brake shoes close
to
> the drums. That much pressure will keep your disk brakes applied and not
> release them.
>
> Its not that you can't make it work with the single cylinder master, its
> that you'd have to deal with that built in residual valve...
>
> Dual cylinder master, with 2 lb and 10 lb residuals (front and back) and a
> proportioning valve would be your best plan.
>
> ----- Original Message -----
> From: "wayne osborne" <wayne@chevytrucks.org>
> To: <IDPHR@aol.com>
> Cc: <oletrucks@autox.team.net>
> Sent: Wednesday, December 03, 2003 10:08 AM
> Subject: Re: [oletrucks] front disc brakes
>
> An even dumber question---would a stock master cylinder be able to push
> enough fluid for a non power front disk brake setup or would a new master
> cylinder have to be installed also. Since redoing my rear end and finally
> getting it under the truck, got different bolt pattern now (front to rear)
> and want to get the same all way around. Gonna have to get new
> wheels--finally be able to rid myself of the polished aluminum ones, kinda
> like a black vehicle-they look good when cleaned but its a job... Just
> wandering if I could use the stock master cylinder, install a
proportioning
> valve, and use the front disc brake kit that are available to match the
> bolt pattern. This way I can buy new wheels--the same all the way
> around..... --wayne
>
> At 12:32 PM 12/3/03 -0500, IDPHR@aol.com wrote:
> >I have non power discs on my 51 3100...(no room for booster)had to change
> >master cylinder (double resevoir mustang master) and install va
> proportioning
> >valve....biggest issue! most of these kits are 5 bolt set-ups and don't
> >match the
> >rear drum bolt pattern. But all in all, since I upgraded power to a '58
235
> >w/ 2 1bbl and dual exhaust, it worked out well.
> >
> >Steve G.
> >oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
> Wayne Osborne
> http://www.chevytrucks.org
> http://www.chevytrucks.org/wayne
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|