What Master Cylinder

[jeepguy1948]

I am putting '40 Ford Lockheed style brakes on my Model A. I am using a Vacuum type booster. Here's my question: what dual reservoir master cylinder would I want to use? It's my understanding that the original cylinder bore was 1 1/16" bore, Is that correct? The front and rear wheel cylinders are different bore sizes so how would that work with a dual Master? To top it off I am going to need to use a remote reservoir, Would that require a special master or would you just add a remote reservoir to a regular type master. Thanks!

[V8COOPMAN]

Originally Posted by '28 RPU

I am putting '40 Ford Lockheed style brakes on my Model A. I am using a Vacuum type booster. Here's my question: what dual reservoir master cylinder would I want to use? It's my understanding that the original cylinder bore was 1 1/16" bore, Is that correct? The front and rear wheel cylinders are different bore sizes so how would that work with a dual Master? To top it off I am going to need to use a remote reservoir, Would that require a special master or would you just add a remote reservoir to a regular type master. Thanks!

If using a DUAL M/C that has the same bore on BOTH ends of the cylinder, you will effectively be reproducing the results found using the stock, single bore M/C. You noted that the front and rear WHEEL CYLINDERS for the '40 brakes have differing diameters. There are a couple of reasons for this. One reason being that the REAR brakes are responsible for LESS braking than the FRONT brakes are. A couple of factors figure into this, like the front axle of many cars bear more weight than the rear axle, possibly ~60/40 for instance....YOUR RESULTS MAY VARY!

Additionally, when the brakes are applied, especially in taller vehicles like these old Fords tend to be, weight transfer takes place effectively transferring more weight from the rear braking load toward the front brakes' braking load. This amounts to the REAR brakes requiring LESS pressure than the FRONTS, to help refrain from locking-up the REARS with less weight on them. Meanwhile, the FRONTS with a higher percentage of weight on them are working as hard as they possibly can in the attempt to pressurize (slow) the drum BEFORE lock-up.

Remember, a tire that is locked-up and skidding is not producing anything near the stopping power of a tire that is just shy of breaking-loose. For that reason, and taking into account ALL of the above, there is an awful lot of serious engineering that goes into the sizing of wheel cylinder and master cylinder combinations.

Getting back to the rear wheel cylinders being smaller than the fronts. Considering using a M/C with a constant bore for both fronts and rears, an INCREASE in WHEEL cylinder bore to a LARGER DIAMETER will produce MORE pressure at the wheel cylinder/brake shoes. Inversely, DECREASING wheel cylinder bore to a SMALLER DIAMETER will DECREASE pressure at wheel cylinder/brake shoes. Alternatively, changing the M/C bores in relation to wheel cylinder bores will also change effective pressures.

Undoubtedly, most of us mere mortals don't have the credentials nor the facilities to properly engineer a braking system to the fullest. But there are tried & true combinations that guys like us have swapped and used for decades that work efficiently when using quality parts. Lockheed hydraulic brakes on an 'A'-bone is certainly not a new idea. A lot of guys running that combination wanting to employ a dual M/C tend to use a '67-'73-ish Mustang M/C designed for DRUM/DRUM brakes.

One more thing to remember....ALWAYS test that your brake pedal STROKE has enough room for a FULL stroke WHEN ONE SIDE OF YOUR SYSTEM is OPEN. It takes a LONGER STROKE than normal when one side of your system has a leak in it. You can see WHY if you carefully study the system BELOW!

Coop

[51504bat]

I don't know anything about this product but you might contact these guys:


https://www.millworkshotrod.com/prod...=7263515082797
Early Ford Dual Master Cylinder AV8 Adapter Kits 1939-1941 Ford Passenger and Light Truck, 1946-1952 Pick Up
This kit allows you to run a dual master cylinder on both 1939-1941 Ford car and light truck pedal assemblies as well as 1946-1952 Ford pick-up pedal assemblies using the stock push rod and boot. The kit includes a Made in the USA adapter and hardware, upsized brake fittings as well as a brand new dual master cylinder (not remanufactured). Perfect for your AV8 conversion.

[Krylon32]

For over 25 years on all my drum/drum chassis builds I have used a Cardone 1329 which exits toward the frame or a Cardone 1292 which exits toward the trans. I have used these master cylinders with early Ford brakes, Mt Lincoln brakes and a combination of the early style Ford or Lincoln brakes and late Ford 11X2.25 drum brakes. These master cylinders do not require external check valves as they are built into the cylinders.

[glennpm]

Krylon's recommendation for a Cardone 1329 is a good dual bowl cylinder with bore sizes very close to stock Ford's 1 -1/16". It also has good port sizes that can be used and adapted to 1/4" brake lines.


Bore Diameter: 1" (25.4 mm)
Master Cylinder Primary Port Size: 9/16 x 18
Master Cylinder Secondary Port Size: 1/2 x 20 more details on - https://www.carid.com/cardone/brake-...n-13-1329.html


I currently have a stepped bore master in my 32. The stepped bore was designed for moving a large volume of fluid quickly to take up the gap in early Chevy applications that used front disks that were low drag. These are the bore sizes on my CARDONE 101905. Note that there are no residual check valves inside this MS so those shall be added into your system.


Bore Diameter (N) 0.945"

Bore Diameter (N-1) 1.25"


For the front brakes, primary side, the initial lower pressure fluid is pushed with the N-1 large bore of 1.25". This closes the gap between front shoes and brake drum, then the N bore of 0.945" applies high pressure to both the front and rear brake drums. The advantage is that the initial 1/4" stroke takes up the gap and then the smaller N bore takes over. The pedal stay6s high without a lot of pedal travel. I'm very happy with this setup but I also believe that Krylon's MS is a great choice too.

[Ol' Ron]

Sponsored Links (Register now to hide all advertisements)

I've used the 73/74 Ford f100 MS. It's the first year Ford had disk brakes without power assist. I'll admit you have to push alittle harder, but it works pretty good on my 47 KB-1 int. been over 30 years.
GrampPS It's for sale.

[V8COOPMAN]

Originally Posted by glennpm

I currently have a stepped bore master in my 32. The stepped bore was designed for moving a large volume of fluid quickly to take up the gap in early Chevy applications.

The advantage is that the initial 1/4" stroke takes up the gap and then the smaller N bore takes over. The pedal stay6s high without a lot of pedal travel.

Hey Glenn.....This is an interesting piece for me, as I had never heard of this "stepped-bore" cylinder design. If I am fully understanding the concept, one of these type M/Cs sounds like it would preclude the pedal from running out of stroke because of the initial "quick-fill" feature. Then, once the shoes have contacted the drums and initial system pressure begins to increase, the SMALLER DIAMETER than usual M/C bore should ultimately cause higher pressures to develop against the shoes, WITHOUT the increased foot pressure on the pedal. Kind'a like killin' both birds with one rock! Am I understanding this correctly, or am I full of it again? Appreciate you posting this info, Glenn! Coop

[glennpm]

Yes Coop you got the concept down correctly!

I remember years ago a product by Mico that is similar in concept so after extensive net searching a couple of years ago I found this MC. There is also another one that has an even larger diameter but it was designed for power brakes. I have a scan of the magazine article reviewing the Mico that I could dig out if you're interested.

https://www.mico.com/products/brake-...ster-cylinders

[V8COOPMAN]

Originally Posted by glennpm

Yes Coop you got the concept down correctly!

I remember years ago a product by Mico that is similar in concept so after extensive net searching a couple of years ago I found this MC. There is also another one that has an even larger diameter but it was designed for power brakes. I have a scan of the magazine article reviewing the Mico that I could dig out if you're interested.

https://www.mico.com/products/brake-...ster-cylinders

Glenn....I appreciate the offer on the magazine article, but not necessary, as you've already done enough to get my wheels turning.

It seems to me that a lot of folks considering upgrading to a DUAL M/C do not realize that when one circuit in a dual M/C becomes compromised, that the stroke of the internal pistons and springs WILL have to increase beyond normal stroke length to create pressure in the circuit that is not compromised. As such, folks MUST TEST their modified systems to assure that there is enough room available in their car to assure enough pedal stroke available IF either circuit becomes compromised. That is why I like to keep posting the drawing BELOW, as studying it shows clearly WHY the stroke must increase beyond normal to produce AVAILABLE stopping pressure.





I believe wholeheartedly that the virtues of this "stepped-bore" design needs to be passed-along to anyone contemplating a M/C change or upgrade. Thanks again!

Coop

.

[tubman]

I have had personal experience with this. Because of rust issues with the steel lines, I have lost the brakes on my "beater" 1999 Ford F150 twice. The first time, I lost a rear line, but I still had enough brakes to get it to my shop to replace it. Before I even had a chance to get to the rest of the lines, I lost a front line. This time, I had virtually no brakes at all, and crept back to my shop 2 miles at 5 mph on the shoulder of a country road. After replacing the rest of the lines and bleeding the brakes, the brakes were perfect again.

Now this was factory designed dual system; in my opinion, a home-designed system without extensive planning and execution would be even worse.

[jeepguy1948]

CoopMan, I appreciate the input and will take that in to consideration when working out the details of my install. Thanks!

[vincent]

Anybody care to explain:
"Considering using a M/C with a constant bore for both fronts and rears, an INCREASE in WHEEL cylinder bore to a LARGER DIAMETER will produce LESS pressure at the wheel cylinder/brake shoes. Inversely, DECREASING wheel cylinder bore to a SMALLER DIAMETER will INCREASE pressure at wheel cylinder/brake shoes."
All my hydraulic experiences in the last 40 years are the opposite.

[V8COOPMAN]

Originally Posted by '28 RPU

CoopMan, I appreciate the input and will take that in to consideration when working out the details of my install. Thanks!

'28 RPU ....I appreciate your comment!

Ya know, if I were you, I believe I'd be very tempted to go with that "CARDONE 101905" M/C that "glennpm" is using. Go back and study POSTS #5, 7 and 8 above. Glenn is a sharp guy, and has a reputation for posting accurate and trustworthy information. I believe it would be reasonable to assume that the weights of his roadster and your RPU wouldn't be too far apart. This sounds like the best "NEW TECHNOLOGY" that I have heard about in a long time.

Coop

.

[V8COOPMAN]

Originally Posted by vincent

Anybody care to explain:
"Considering using a M/C with a constant bore for both fronts and rears, an INCREASE in WHEEL cylinder bore to a LARGER DIAMETER will produce LESS pressure at the wheel cylinder/brake shoes. Inversely, DECREASING wheel cylinder bore to a SMALLER DIAMETER will INCREASE pressure at wheel cylinder/brake shoes."
All my hydraulic experiences in the last 40 years are the opposite.

vincent....YOU are absolutely CORRECT!!! I worded all of that VERY POORLY, and I had a very uneasy feeling that I had worded it backwards when I was pounding that out. Nevertheless, I BLEW IT, and I really thank you for bringing it to my attention. I'm sorry for any heartache that I may have caused here, and I'm gonna go back and attempt to fix it all. The Coopman

.

[vincent]

Thanks Coop!

[glennpm]

Thanks Coop for the accolades!


Glenn

[vincent]

After all, you are not completely backwards as a more powerful wheel cylinder, which does not travel enough distance to put all his pressure on the brake shoe, is indeed less efficient. So the fine line to balance on is: get the maximum leverage from foot pedal to MC, then a good ratio from MC to WC and finally make sure that your WCs travel far enough to put full pressure on the shoes. You could always add adjustable WCs to the backing plate to keep the brake shoes in close proximity to the drum or manufacture your own adjustable brake shoe stops to achieve the same goal. Thus the pulling springs will not pull the shoes (and the WC) too far away from the drum. This will give you minimal clearance between shoe and drum and thus the WC can put all his pressure on the shoe when the pedal is pushed down.

[jeepguy1948]

I am not familiar with adjustable wheel cylinders and would like to hear about them.

[jeepguy1948]

I will have to call Mico, their product looks very interesting but they have way too many products for me to figure it out on their website. Can it work with a booster? Is it available in a 2 circuit (front brake/ rear brake separate) configuration?

[jeepguy1948]

Glenn, can the Cardone 101905 work with a booster?