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Power Brakes with flathead six engine Vacuum inquiry


40desoto

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is anybody running a power brake booster with a straight six engine?  Does the engine produce enough vacuum to operate the brake booster?

If so where are you grabbing vacuum from?

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Chrysler Corp has made many factory installations of power brake boosters on cars and trucks from the mid 1930' onward.

Most of the Dodge, DeSoto and Chryler long wheel base cars and station wagons used a frame mount vacuum booster.

Plymouth's first booster came out as an option in 1954.

Many of the medium duty Dodge trucks of the  late 40's thru the 50's had brake boosters too.

The vacuum source was a 3/8" to 1/2" pipe fitting at the intake manifold.

Edited by Dodgeb4ya
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There are several single circuit remote brake boosters available on the aftermarket and they are not hard to hook up.

The booster itself stores the vacuum ( kind of like an accumulator ) There's a one way valve on the inlet so the vacuum stays constant, not like the vacuum windshield wipers.

Any location on the intake manifold will work fine as the vacuum source. High vacuum occurs when the throttle is closed ( just when you need it for braking )

The old early 50s DeSotos and Chryslers used the same master cylinder with a remote booster so its not rocket science. 

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3 hours ago, Loren said:

There are several single circuit remote brake boosters available on the aftermarket and they are not hard to hook up.

The booster itself stores the vacuum ( kind of like an accumulator ) There's a one way valve on the inlet so the vacuum stays constant, not like the vacuum windshield wipers.

Any location on the intake manifold will work fine as the vacuum source. High vacuum occurs when the throttle is closed ( just when you need it for braking )

The old early 50s DeSotos and Chryslers used the same master cylinder with a remote booster so its not rocket science. 

I wonder if there's a way to put a similar type accumulator on the wipers? The wipers don't work on my car or truck and its one of the things I plan to work on this year. It seems like there's a lot wrong with wipers of this era, hard to source blades, no pressure on the glass, vacuum motors don't work, run outta vacuum at the worse times etc. 

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Get one of those GM vacuum reservoirs that look like a pizza sauce can.  Make sure it has a check valve.  You can hang it under the dash and plumb it into the wiper vacuum tube.  Should be good for 10 to 12 swipes.  You can improve the  operation by introducing something to lubricate the leather flapper inside.  Some have used pb blaster, others atf, and brake fluid was also mentioned.

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1 hour ago, greg g said:

Get one of those GM vacuum reservoirs that look like a pizza sauce can.  Make sure it has a check valve.  You can hang it under the dash and plumb it into the wiper vacuum tube.  Should be good for 10 to 12 swipes.  You can improve the  operation by introducing something to lubricate the leather flapper inside.  Some have used pb blaster, others atf, and brake fluid was also mentioned.

Or make one to fit the space you want to use.  A short piece of 3 or 4" sched 40PVC and caps to fit.  Make it as long as possible.  Drill and tap for fittings

Edited by kencombs
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3 hours ago, greg g said:

Get one of those GM vacuum reservoirs that look like a pizza sauce can.  Make sure it has a check valve.  You can hang it under the dash and plumb it into the wiper vacuum tube.  Should be good for 10 to 12 swipes.  You can improve the  operation by introducing something to lubricate the leather flapper inside.  Some have used pb blaster, others atf, and brake fluid was also mentioned.

I think I'm going to have to rebuild or replace them, the leather is likely long gone. I wonder if you can take them apart and replace the leather with some kind of durable rubber?

Edited by LeRoy
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You can see my vacuum reservoir right under the heater box.  Came off a early 2000s F250 - 350 and has a built in check valve.  The factory mounts worked perfect on the flat top of the inner fender.  If you find a Diesel version, it has an electric vacuum pump too.

Completely hidden when the heater duct is installed.

 

IMG_2150.PNG.4c330d792a82b825ab5e4469e18cdd18.PNG

 

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Call me old fashion but I get a kick out of using old tech.

The easiest way to help with wide open throttle slow down of the wipers is of course a vacuum tank.

Another way is to get a dual chamber fuel pump. The top chamber only pumps vacuum.

What makes the dual chamber pump so useful is that in the situations of prolonged high rpm wide open throttle ( going up a long grade ) which would drain the vacuum tank, the pump is actually pumping more vacuum than you'd need.

Put them both together for a really workable system.

 

Electric wipers are two speed and aftermarket motors are 12 volt only. I find it fun to live with a good working 6 volt system so the aftermarket is out for me.

However, vacuum wipers have an infinite speed control ( between slow and slower lol ).

Good modern rubber wipers, dual chamber fuel pump and a vacuum tank give you a serviceable system.

Add a momentary vacuum switch foot or dash mounted and you can have manual intermittent wipers!

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i had the booster rebuilt for my 54 windsor. have not installed it yet.i have to assume the vacuum produced by the 265 in my car will be enough. i had this system on a 53 imperial but that car had the hemi engine. i do know that if the diaphragm in the booster fails then the vacuum side in the booster will suck all the brake fluid out of the master cylinder leaving you with no brakes. it will happen fast when it does. not very bright engineering. however, on the plus side they work real nice and take the work out of braking like they should. you also need a master cylinder that has an extra fitting on top of it to connect to the booster to drain any leakage back to the master so you do not run low on brake fluid.    capt den 

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Thank You all for all the information.  I'll be running it with a 265 and triple carb intake.  I was thinking I can tap the intake to use as vacuum for the 7" booster.  Not sure it this will produce enough vacuum (now after reading the responds- too much vacuum). Or pulling vacuum from the intake wil effect carburetor performance.

 

 

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Wipers: I've taken a couple apart (off a Ford, but all those old Tricos are similar.) I tried various lubricants to get them going but nothing worked so hot. Ficker's Wiper Service does a good job with decent turnaround. It's also a good idea to go through and make sure all the linkages are well greased. Now, some models were electric from the factory (my 49 Chrysler is) and I wonder how hard it would be to rig one up, assuming you found one? But I do agree with Loren, I greatly prefer using the old tech. The old Ford I had came with the dual pump. I rebuilt it myself but must not have gotten it right because it never seemed to offer much boost. I added a "soup-can" vacuum tank, a 90's era F-series truck part that includes a check valve. Painted black, it didn't look out of place under the hood. Didn't really work wonders, though.

 

Brakes: my car has the factory power brakes; when I got the car the vacuum line was still connected (fairly large line off the intake) but the brakes lines were unhooked. I couldn't find anyplace to connect a return line to the master cylinder, so I reason that someone replaced it long ago with a non-power model. Probably the only thing they could get? One of these days I guess I need to find the part number for the correct model, and start searching. I'd like to have it all back to original and working. It's certainly workable with manual brakes. The other challenge is getting the stock booster rebuilt. None of the places I've called would touch it. As I recall, Steele Rubber lists the diaphragm in their catalog. I figured I can call them and see who's buying 'em!  My ears do perk up a bit at the idea of an aftermarket add-on booster. There's plenty of room underneath to install one where Chrysler did.

Edited by Bryan G
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Honestly I’ve never seen a return line on a remote booster.

What I have seen is the slave cylinder losing a seal.

In fact any master connected to a vacuum booster can even modern cars.

The tell tale sign is the white cloud following you and stinking badly.

Anti freeze and brake fluid are made of the same stuff and have similar actions when sent through the combustion chamber.


One of the projects I have my list is a remote reservoir for the original master cylinder.

One you could check under the hood. You could even add a cap with float switch if you wanted, for a warning light.

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The 1949-54 MoPar frame mount brake boosters do have a 3/16" bleed off return line. It bleeds off  very small amounts of internal booster brake fluid leakage.

This brake fluid is returned to a 90 degree 1/8" pipe fitting located at the top of the master cylinder reservoir.

The power brake madter cylinders are usually a 1" bore and are exactly the same as the typical 1-1/8"  master cylinders msde for 1946-54 cars.

The top of the PB master cylinder just has a 1/8" tapped hole in the top of the cylinder reservoir for the 90 degree brass return line fitting.

 

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21 hours ago, Dodgeb4ya said:

The 1949-54 MoPar frame mount brake boosters do have a 3/16" bleed off return line. It bleeds off  very small amounts of internal booster brake fluid leakage.

This brake fluid is returned to a 90 degree 1/8" pipe fitting located at the top of the master cylinder reservoir.

The power brake madter cylinders are usually a 1" bore and are exactly the same as the typical 1-1/8"  master cylinders msde for 1946-54 cars.

The top of the PB master cylinder just has a 1/8" tapped hole in the top of the cylinder reservoir for the 90 degree brass return line fitting.

 

Tempting to tap my cylinder. Just have to be super clean about it. Last night I was browsing Andy Bernbaum's and noted they're now offering a rebuild service on these boosters, $600. 

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On 1/6/2023 at 6:45 PM, Loren said:

Call me old fashion but I get a kick out of using old tech.

The easiest way to help with wide open throttle slow down of the wipers is of course a vacuum tank.

Another way is to get a dual chamber fuel pump. The top chamber only pumps vacuum.

What makes the dual chamber pump so useful is that in the situations of prolonged high rpm wide open throttle ( going up a long grade ) which would drain the vacuum tank, the pump is actually pumping more vacuum than you'd need.

Put them both together for a really workable system.

 

Electric wipers are two speed and aftermarket motors are 12 volt only. I find it fun to live with a good working 6 volt system so the aftermarket is out for me.

However, vacuum wipers have an infinite speed control ( between slow and slower lol ).

Good modern rubber wipers, dual chamber fuel pump and a vacuum tank give you a serviceable system.

Add a momentary vacuum switch foot or dash mounted and you can have manual intermittent wipers!

Gosh Loren, you're sure old fashioned. ?

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