Has anyone ever used a vacuum canister for power brakes?

[My427stang]

I appreciate all the responses, I didn't put the whole chain of events that got me here

- Truck had incredible stock drum/drum power brakes.  Pedal right at the top little effort, this was with stock 302, stock 351, and later stock 360, and a mild (270H) 390   ..... going back 30 years here, brakes were incredible, even for drums

- Sat for 14 years, 2007 rebuilt stock brakes, all new name brand stock stuff, brakes were OK, but never like they were

- Built the stroker, had lower vacuum, (same 12 in or so) pulled vacuum on the stock booster, it was leaking, 46 years old, no surprises, replaced it with a dual 7.5 inch designed for lower vacuum.  Master sized accordingly during purchase and bought for discs

- Had issues with the stroker, built a "bench motor" mild cam, 390 cid, bench motor only has 12 in of vac at 600 rpm idle.  Also I always wanted discs, built a complete front end with all new brake parts, factory 1979 F150/Bronco parts.

- Off idle brakes are great, idle, brakes have some travel then hard pedal.  Checked booster 1 way valve, wasn't a perfect seal, so replaced it.  No difference in behavior. 

- So, the bench motor is a temp and runs like a sweetheart, nothing significant to gain through timing and carb adjustment and it isn't coming apart until the 462 is ready.  Not because I don't care, but because it's just a temp and runs like a swiss watch. Since brakes are all new, and constant was the low vacuum, figured maybe a band aid with a tank

However, since then, Brent and I were BSing in our normal knitting circle conversations and deduced that maybe I can get a little vacuum by raising the idle.  I'll see today.   The thing sounds so mild that I dropped idle to the dirt to try to get it to sound like something through the 3 inch pipes LOL but there is no reason it needs to idle so low.  I can try raising it a few hundred RPM and see if vacuum comes up

If it is what it is, the discs suck a little compared to the drums because they used to self-energize a bit, but it will be OK until the 462 is done, because I don't really want to mount a tank under there, but if the tank was very effective, it'd be a cheap short term solution

Thanks everyone!

[blykins]

I don’t know, but if you tell anyone else about our knitting circle, I’ll never talk to you again.

[Drew Pojedinec]

I don’t know, but if you tell anyone else about our knitting circle, I’ll never talk to you again.

Fo real....
Anyway, bridge on Wednesday and don’t forget to bring your potato salad for the book club tomorrow.

[My427stang]

I don’t know, but if you tell anyone else about our knitting circle, I’ll never talk to you again.

Fo real....
Anyway, bridge on Wednesday and don’t forget to bring your potato salad for the book club tomorrow.

Brent - First rule of fight club....

Drew - My wife is a librarian, you don't know how true your statement is around my house.  I come in from the garage and wash my hands, jaws drop, and not for my dashing good looks

[Yellow Truck]

I don't knit, but I'm a fair baker, need an XL apron.

About drum to disc - don't disc brakes need more pressure? I've been toying with going to discs up front (on a '69 F100 4WD there are limited options for bolt on but SSBC has a kit I'm eyeing). One of my reservations is that I don't have huge vacuum now, and the drums are just ok (engage well but require a fair bit of leg).

I also would like to go to a smaller diameter booster for valve cover clearance, but I'm afraid that a smaller diameter will be less responsive (smaller surface area for the vacuum to act on).

Been idly wondering about going to a vacuum pump, but haven't really dug in on the subject.

[Barry_R]

A few more RPM wont hurt - but a closed throttle will generally add vacuum.  You could raise idle with a bit more base timing???  Also check to see if all the blades in the barrels are centered and closed up evenly - one that is open more might make closed throttle a bit tougher to nail down.  My '46 has the problem with a really hard pedal and a small diameter booster.  Guys that sold me that kit a decade or two ago say they have gone to a 1/8 smaller diameter master cylinder bore to help the problem, which they were aware of.  Have not tried that yet but I will...

[Thumperbird]

Here's another setup for fyi.
My 65 Thunderbird has lots of vacuum accessories, large discs up front and drums rear.  I put an 8" dual diaphragm booster on for tall valve cover clearance and added a 1" dual master cylinder.

Expecting the stroker to be light on vacuum I installed a vacuum pump to supplement things.
The Tbird has several canisters which do add a little capacity for pumping breaks and the nice part is they retain the higher vacuum from the vacuum pump assist.  The engine is isolated with 1 way valve from the rest of the system and the booster is directly off of 1 canister which is also isolated from the rest.

Breaking with this system is excellent, yes there is a pump but it does not run much at all since the engine is getting me to around 12 (likely higher when I let off the gas) and the pump just needs to take it to 17 or so. 

[Yellow Truck]

Here's another setup for fyi.
My 65 Thunderbird has lots of vacuum accessories, large discs up front and drums rear.  I put an 8" dual diaphragm booster on for tall valve cover clearance and added a 1" dual master cylinder.

Expecting the stroker to be light on vacuum I installed a vacuum pump to supplement things.
The Tbird has several canisters which do add a little capacity for pumping breaks and the nice part is they retain the higher vacuum from the vacuum pump assist.  The engine is isolated with 1 way valve from the rest of the system and the booster is directly off of 1 canister which is also isolated from the rest.

Breaking with this system is excellent, yes there is a pump but it does not run much at all since the engine is getting me to around 12 (likely higher when I let off the gas) and the pump just needs to take it to 17 or so.

So educate me a little about pumps. How is it piped, and what are you running?

[Heo]

Yellow Truck if you run Power stearing you can run
a hydroboost for the brakes and use the P.S pump
for that

[Thumperbird]

Hydroboost is a good way to go as well, I just wanted to make sure I had good vacuum for everything in the car so I went the pump route.

Many pumps out there, bought a CVR for about $300, seems to be working fine although the vacuum sensor was bad on the first unit but got a replacement for free, so far the pump is fine but not that many hours on it yet.  Wired to turn on with ignition.  Kind of a nice safety back up, if engine dies I still have vacuum.

Many ways to skin the cat plumbing wise, I chose run an isolated leg for the brakes with it's own canister and another isolated leg for accessories.  Both legs are fed by engine vacuum but as i stated there is an in-line one way valve right at the manifold to make sure the engine is not depleting system vacuum when it is not making making much.  With no isolation of course the engine wins by volume and the pump would run constantly.

I suspect with a couple canisters, tbirds happen to have 2, you could run with just the pump if your system is tight, would not cycle often at all except maybe when braking a lot in heavy traffic, no real need for any engine vacuum.  Boosters eat a lot of volume though so a good size reservoir is a must.

[Coreyc619]

I have run one since I got my drivers license.  I learned how to use it to my advantage over time. The one I have is the aluminum body canister style from summit. Some notes:
-the comment about it only pulling 12" is inaccurate. Downshift before applying the brakes or coast some beforehand will generate a spike in vacuum that the check valve should maintain. That's part of what I adapted into my driving style to help
-it works fine if you pay attention and plan your slower/casual stops accordingly.  You really only get one good stab of the pedal before you're back to leg-press mode.  So, if you're coasting up to a red light and have a habit of kind of bumping the brakes multiple times rather than judging the distance/braking needs more carefully, you're going to want to change that.  This is especially important for situations where you might be trying to get across oncoming traffic and have a small window to do so.  You only get one good vacuum assisted stab of the pedal. This will put you up on a curb in short order.
-you will learn how to manipulate and best use it in time if you just pay attention to the limitations of it, after the install. After that, it works just fine in my opinion.

[FElony]

I have run one since I got my drivers license. 

Have you actually had enough time since then to buy a second?

Sorry, I can't help it.

[wayne]

Yes i run one it works good i had a ele pump but it was  to noisy.

[Pentroof]

My opinion isn't worth much, but I don't think it's vacuum. I think it's the junk Chinese GM dual booster you bought from Pirate Jack.
I saw your post on Fordification and bought the same setup. Aside from the extremely poor quality of the kit, I'm not all that impressed with the function. New hard lines front to back, new cylinders in the rear, new calipers up front, new soft lines.....bled all 4 corners 3 times. I can't lock up my brakes if I wanted to. And the fronts are 12" disks!

[My427stang]

Jim, certainly not saying you are wrong, because I expected the booster and master cyl swap to make a heck of a difference, but I have very good brakes when vacuum is up. 

I don't think the vacuum can will be right for me, but not sure I am ready to give up on the setup yet.  I'll take it out this weekend and diagnose a bit more.

What was poor quality in your kit?  It used some cheap looking brackets and bell crank, but I didn't even use those, I just bolted the booster in place and swapped to the correct line ends, it was pretty much a bolt on for my 71 4x4

I appreciate the input though, hate to hear you bought something based on my purchase and it didn't work out