Packard Forum Index » Modification Discussion

I have owned a few cars with BTV.My only complaint is that they are often very sensitive and stop the car a little to quickly for my liking.I have one now on my 56 that works great.Stops smoothly with light pressure and on a dime if you slam on it.

The 1977 full size (impala) GM used a nine inch double booster that fits easier than the 10 3/4" used 71' to 76' and 78'79'. With plenty of power for drums as originally on disc application. A-1 cardone rebuilt number 54-71201 . Later boosters may use metric studs that require earlier bracket holes opened by 030".

My friend Chris always complained that BTV caused you to keep all the windows rolled up in the summer.
Otherwise a fly could fly in, land on the brake pedal, and put you through the windshield.

I know this is a little late
You don't need to use a GM brake setup,
Ford, Chrysler all work the same.
Ford has been using Bosh dual action vacuum canister
for a few year, like 15 or so.. they are used on the
big Crown Vic, Merc's and last of the big Lincolns.
They mount directly to the fire wall.
Also the dual master cylinder is much smaller then
what was used in Graig's setup. Nothing wrong with
what he has done, just different options out there.
You don't need to mount a modern M\C to the frame
rail or the fire wall. Do some research and you'll
see Hot Rods mount them in many different places
given the small engine compartment size.
Back in the late 80's after I got my Packard
I was looking for way's to change the TV to more
modern, then other things got in the way...
you know how that goes.

The main problem with using a booster/MC in the stock BTV location is not so much fitment, but pedal leverage. Most modern boosters require about 4:1 (but 3.5:1 to 4.5:1 is OK) pedal leverage. Since the BTV is 1:1 therein lies the problem.

My 55 Pat has reworked pedal leverage and position and that bothers some people. Lance's use of the 1979 Caprice booster/MC and pedal assembly has a pedal position very close stock, but mounts the booster/MC on the firewall and requires eliminating the D-side vent and closing the hole. My Panther project also mounts on the firewall and retains the D-side vent but requires extensive work to the pedal pivot and arm. ALL THESE SOLUTIONS (and some others done by PackardInfo members) work much more reliably than the BTV.

Pick your poison.

Sanddoc, what pedal leverage does the booster you cited require?

Craig

Quote:

I can not agree more,
On my conversion i am currently doing I studied and planed which way I was going for the best solution for sturdyness eliminating flex on the firewall and made my own bracing brakets for my 54' and she is firm.

Them firewalls are like tin cans to the pedal compression that would just tear apart in no time.

There are many different boosters and masters that one could use but there are a lot of mathmatics to it.

The first place to start is to find them mathmatics.
What is your brake caliper bore or total bores on a multi piston caliper. (Add only one caliper)

Then from there you can do the math and figure in your Master piston size and your pedal ratio. and then adding in you your rear brakes is another added mathmatical throw in...

Im not going to throw out a bunch of mathatical solutions up on here as im in relax mode right now.

But in short, to start you need to know your starting point!
#1 what disk conversion are you going to use with what caliper piston/piston's bore and along with the firewall support being firm.

I took my insterment panel out today and took some pictures of the supprot I constructed, I'll post on here. (I do have stencils of my configurations)

Now to say this;
Graig on here seems to have been around the block a few times and I trust what I see of his work, as we also have a common friend Packard Paul and when that man talks I listen...

In all to worry about an extact postion of the pedal closest to the original position!
Remember this; Your installing a booster/master which is not original....
In all yes we all would like it near the same area.

Here is the pic I took today of from under the dash from firewall to a main support area where the steering wheel bracket is bolted too...

Looks as though i'll have to upload it from my phone, hang tight.

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