Power Booster question

[prayers1 153]

I have a 1969 with an AOD trans. I'm converting from Manual brakes to Power (disc/drum).

I'm concerned about Vacuum for the Pwr Brakes. I'm looking for the best Booster with the most vacuum.

 

My new Cleveland stroked 408 Cam has 235/241 @ 50 duration, 602/574 lift.

 

Question:

Do you have more vacuum reserve with an 8" vs. a 9" booster???

 

 

CJ's has a (Master Power: BM15214-2) Pancake type Booster 9", 1-1/8" bore 7/16" stroke master cylinder .

 

Master Power Brakes also sells smaller Bendix type *' that has a 1" bore.

 

Master Power Brakes also makes another Pancake style w/ a 1" bore.

 

Question:

What benefit is the 1" vs. 1 1/8 bore???

 

IIRC- the 1970 Mach 1's had a 8" booster auto trans, not the pancake type

 

What Booster do you think is best for my App???

[Raven R code 281]

I would consult Mustang Steve

[1969_Mach1 333]

I would stick with a stock power brake booster, Bendix or Midland depending on year.  I think early 1969 and older used a Midland, late 1969 and newer used a Bendix.  I don't know the exact changeover date.  West Coast Classic Cougars has the best video I've seen discussing differences between the original boosters and pedals.  What years used what type, Bendix, or Midland, and what pedal goes with each.  They sell Mustang parts including rebuilt boosters.

 

I tried the replacement booster Scott Drake offers.  Looks close to original but isn't.  Actually all internal parts are metric.  And it doesn't fit correctly.  Some issues I had: 1) Where the rod attaches to the pedal and brake light switch, the rod is not shaped correctly so the brake lights are stuck on all the time.  2)  The studs used to attach it to the firewall are not straight and it was extremely difficult to install.  3)  There are some strange tabs under the boot where it passes through the firewall that need to be cut off for it to fit.  4)  The master cylinder studs are too long and the master cylinder could not be installed or removed after the booster was installed.  I tried three of those Scott Drake boosters, returned all three of them for a refund.  Fixed my original Bendix booster and reinstalled it.

 

You need more cam specs to get an idea if that motor will create 12"-14" vacuum at idle to have reasonable power assist.  Lobe separation angle, advertised duration, is advertised duration at 0.004" or 0.006" tappet lift, intake centerline.  Valve overlap and intake closing location have a major affect on engine vacuum.  I.E.  as duration increases the lobe separation angle must also increase to minimize an increase in valve overlap and maintain decent engine vacuum.  I hope you discussed using power brakes with your engine builder.  Otherwise, they might be building a motor that will not reasonably operate power brakes.  I've seen it happen many many times.

 

[det0326 179]

John

 

I have read that the 9" pancake type interferes with the outer steering column tube on some 69's and mine was one of them. I installed the 9" on mine, while it gives you plenty of room for a M/C of choice  it does come very close and in some cases actually touches the column tube .  Just wanted you to be aware of it. If I did it again I would use stock style booster.

 

Dave

[1969_Mach1 333]

Just to add, I believe all Mustangs used an 8" Booster regardless of year, except for maybe something like a Boss 429 (not certain about that).  And the 8" Boosters, either Bendix or Midland are dual diaphragm which is supposed to provide more assist than a single diaphragm of the same size.

[LoneWolf2U 136]

Just adding this, You may need to add a vac canister to have enough vac to operate the booster at lower rpm.

I had to add one on mine when I went to the Strip dom intake or keep the idle rpm at 1k.

[Brian Conway 264]

How much vacuum so you have available at the manifold port ?  That's what you really need to know.  Brian

[prayers1 153]

All very good information.

I did catch that WCCC vid a long time ago. At that time they had a stock pile of OEM Boosters, MC's & Pedal, but it was not until yesterday I just found out that they are sold out.

 

Yes, the cam was suppose to be design with Power Brakes in mine.

 

Here's what Master Power Brakes said today-

" I do have a Booster/Master kit with Pedal (Pn# BM15214-1) and will Retail at $425.00  Any of your boosters will require 18" of vacuum the only difference is some of the larger diameter ones will band-aid it slightly if your close to 18".  I would say your probably going to be under 10" of vacuum so you will most likely need a vacuum pump in order to go with a power brake setup".  So yeah, I think I'd eventually need a vacuum canister.

 

If the 9" pancake style hits the steering tube then how did they do it on the Boss 429's?

 

I did check out Mustang Steves (Bendix Booster PB-6770 AT, MC PB-6.1 & Port valve PB100), but his Dist Valve looks aftermarket and I want the factory look. I don't know if his Boosters will work w/ oem stuff.

 

Too bad about Scott Drake, at one point in time they were bragging on how their stuff was the perfect OEM replacement. I read on various websites many complaints about incorrect true fitment and most stuff made overseas, too bad for them they started good.

 

My major concern is valve cover clearance and vacuum...........

As of now, I still don't know what booster will give me more vacuum or more stopping power. It seems CJ's and MPB's are selling the Automatic set up with the Pancake type.

[1969_Mach1 333]

15 or so years ago Scott Drake's stuff was some of the best for aftermarket reproductions.  Not any more.  Alot of it is made overseas like you mentioned.

 

Try Perogie Enterprises in New Jersey for your power brake conversion parts.  They deal almost exclusively with used and rebuilt original parts.  They are sometimes higher priced than others.  They have always treated me well.  If you tell them you are making a power brake conversion I'm sure they will know all the OEM parts you will need.  Their website is not the best so it's best to call them.

[det0326 179]

The 9" pancake type will go on, but at the time that I put mine on I was in the process of assembling the steering column etc. so I could shift things around slightly and make it clear. Why I said some 69's is because it depends on exact   position the plate is in when it was assembled at the factory. This clearance is very tight and u have to loosing every thing up including the brake petal support to gain enough. Again it can be done because I did it to mine and it may fit right on yours with no problem but just letting u know in advance.

 

Dave 

[RPM 1,190]

I'm pretty sure Booster Dewey sells boosters w/o a core, but they'll add for a core charge.

[newstang 388]

Or,,,,,,,,, Hydroboost :-)

[1969_Mach1 333]

I'm pretty sure Booster Dewey sells boosters w/o a core, but they'll add for a core charge.

That's one route I would take and get an original rebuilt booster.  Use a parts store for a rebuilt booster as a very last resort.  Then at worse, the pedal, combination valve, and lines are being reproduced.  I would stick with original parts and original reproduction parts (if needed) as much as possible for a power brake conversion.  Put it together, bleed the system and be done.

[Rsanter 152]

I have the booster on my 69 from TUFF-STUFF and love it.

It is basically the same booster used for the boss429 cars but not concourse correct.

If you have a car that will tend toward limited vacume then you for sure should run a vacume reservoir.

Depending on your engine the bugger the rest our the better. You can also run an electric vacume booster if needed. A friend has one on his street rod that has limited vacume.

Someone mentioned a hydroboost. That is an option but may require some modifications to the car and pedals

 

Bob