Newer ford dual mastercylinder on 40 ford brakes

[sabre62]

I replaced the single master cylinder with a newer 2 chamber type from 79 mustang..can not get any pedal to speak of bled out ok but no full pedal, is this a volume problem ? 1/4 in lines as opposed to 3/16 that the lter mustang used.

[paul2748]

Originally Posted by sabre62

I replaced the single master cylinder with a newer 2 chamber type from 79 mustang..can not get any pedal to speak of bled out ok but no full pedal, is this a volume problem ? 1/4 in lines as opposed to 3/16 that the lter mustang used.

Did you bench bleed the cylinder before installing. Very important with the dual chamber models.

[40cpe]

Richard will probably jump in here on this one, but I think you are on the right track with volume. A small piston master will take a longer stroke to fill the wheel cylinders but require less pedal effort, and vice-versa. I think I got that right. Brake adjustment will also affect stroke.

[41ford1]

I had a similar problem using a 69 Mustang dual circuit M/C on a 40 pickup. I ended up using a dual M/C from a 68- 70 Chev GMC C20. That unit is 1 1/8" cylinder diameter. Currently running it with a speedway disk kit for the front. Works well.

[richard crow]

you have to use a master cyl that has drum brakes front & rear as they have a check valve. i asume your runing orignal drum front & rear on the 40

[Flathead Fever]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by sabre62

I replaced the single master cylinder with a newer 2 chamber type from 79 mustang..can not get any pedal to speak of bled out ok but no full pedal, is this a volume problem ? 1/4 in lines as opposed to 3/16 that the lter mustang used.

Brake tubing size will make no difference. Since the fluid does not compress, what ever amount you pump into one end of the tubing will come out the other side regardless of the size of the tubing. Ford was probably worried about the size of the line restricting the fluid flow so they over engineered it.
　
I dug out my Eis and Bendix Brake catalogs. They list the '40 Ford with 1"X 1 ¼" front wheel cylinders and 1"X1 1/8” rear cylinders. The master cylinder has a 1 1/16" bore.

The 1979 Mustang is equipped with disc brakes. The master cylinder has a 7/8" bore, the rear cylinders are 13/16". The smaller bore in the master cylinder is probably too small to displace enough fluid to expand the larger '40 wheel cylinders. Since it is designed for disk brakes it will not have a residual pressure check valve built into the disc brake half of the cylinder. A slight pressure is required in a drum brake system at all times. This keeps the rubbers cups expanded against the walls of the wheel cylinders so they do not leak. In a disc brake system there are no return springs to pull the pads away from the brake rotor. A residual brake valve would cause a slight pressure causing the disc brakes pads to drag all the time.

You need to find a master cylinder designed for front and rear drum brakes. Most of the Late 60s early 70s Fords had dual reservoirs with an 1-inch bore and 1 1/8” wheel cylinders. Something like this might be a better choice. I’m sure the guys on the HAMB site could recommend something.

There is absolutely nothing wrong with a well maintained single system. Ford used them on heavy duty F600 trucks all the way up into the late 70s. I have to admit it scared me so I always made sure they were in perfect condition. The slightest leak or complaint and it got a new master cylinder and wheel cylinders. Obviously a dual system is safer but it is really rare that you have a catastrophic brake failure on a single system We had a few instances where snow chain cross links broke and sheered off the steel brakes lines but your probably not going to have that problem on your ’40 Ford. In 30 years I only ever saw one brake hose fail and it was because the metal sleeve that crimped the rubber hose on had corroded, it was below the battery box and got acid on it. Most of the time total brake loss is caused by the master cylinder running out of fluid because of a slight leak in the system. Seepage usually takes weeks to empty a master cylinder. If your checking fluid levels you should notice that the master cylinder is low and then find where the fluid is going long before it becomes an emergency situation. You should also flush the fluid out every two years or install silicone fluid. Some people complain that the silicone fluid causes a slightly spongy pedal. I have it in my ‘66 Shelby and it feels the same to me.

A well maintained single system is safe if your inspecting it regularly.

[1oldtimer]

you need to either get a master for 4 wheel drum or use residual valves (also SOME drum masters don't have res valves inside). also you need to get real close to the bore size of the stock master if your using stock wheel cylinders. i made a mount and used a late 60's chrysler master for my '47 ford with lincoln brakes.

http://www.jalopyjournal.com/forum/s...d.php?t=367059

[quickchange34]

The one you should have used is the 67 Mustang master cyl. for drum drum front and rear.

[sabre62]

OK.. Here is what (I know).. I am running the same reservoir on my duece 3/16" lines only difference is 56 ford truck brakes on front mustang 10" on back ..no residual valves no difference works great The 40 brakes are adjusted up rears to back of res (small end) fronts to the large section. The brakes are all new linings turned and so forth. Now the old master was 1" and the new is 7/8 as one of the gentleman pointed out fluid does not compress the only change would be less volume and probably pedal pressure. Have tried two new masters and have no leaks ' I converted because the brakes while having pedal (with the old single cylinder)were not that great anyway. Thinking more truck brakes...

[Richard (EV8G)]

Originally Posted by sabre62

I replaced the single master cylinder with a newer 2 chamber type from 79 mustang..can not get any pedal to speak of bled out ok but no full pedal, is this a volume problem ? 1/4 in lines as opposed to 3/16 that the lter mustang used.

In addition to everything posted by others, it is helpful to understand how the so-called "dual" MC's work. Because the two systems are not totally independent, but are co-dependent on pressure in each other, bleeding them using the typical "pump and hold" method will not purge all of the air out, with resulting low or no pedal, and/or very spongy pedal, due to air in the system. IF the MC you have is in fact a 7/8", it will not move enough fluid in the pedal travel/piston stroke available. Should replace with a 1", as the original MC for the brakes you have was 1-1/16" - I do not think a "dual" with 1-1/16" is available??? Also, it was mentioned that the front forward piston diameter on a 40 was 1-1/4" - Ford increased that to 1-3/8" in 1942 (in an attempt to increase front braking and reduce pedal effort...) and all new front WC's are the larger size. With a 7/8" MC, that makes the problem worse...

The method to bleed these dual MC's is to bench-bleed them so both chambers are filled with fluid and no air is present, then plug off the outlets and install on the vehicle. Connect ONE END of the system, probably the front, but leave the other plugged so it will stay full of fluid and provide a "wall" so the rear piston cannot move when the pedal is pumped, and therefore all fluid will be directed to the front brakes only. Then bleed the front brakes, checking and adding fluid as necessary so it does not run dry and you have to start over. When the fronts have been bled and the pedal is rock-hard, connect the rears and bleed them. The front system will have pressure, so fluid will now be directed to the rear brakes, allowing the air to be purged. When the pedal is again rock-hard, redo the fronts and then the rears to be sure that ALL air has been removed.

The dual MC design requires pressure in both ends in order to function under normal conditions. If a failure in either end occurs, the "back-pressure" is lost and the inner workings of the MC must resort to mechanical operation between the front-rear in order to recover any braking in the surviving end. This unfortunately takes ALOT of pedal travel, which is largely not available on the old Fords (look at pedal stem length - available travel is measurement from
bottom of pedal to top of floor/carpeting/mat etc.) If there is not enough, a dual MC may not be able to recover ANY braking... this does not mean that dual MC's are a bad thing, but when retrofit to an old Ford, one should be aware of the limitations... Most people do not understand how the duals work, so cannot visualize what is going on or what to expect in case of a failure - they are not all that they are "cracked up" (what does that mean???) to be...

I run singles on my own cars... but this is one of those on-going controversial subjects... (DOT 3 vs. DOT 5, mechanical vs. hydraulic, etc.) I can furnish my 1932 and 33-34 conversions with either type, but 35-36's and 37-38's are limited by space constraints... which is also an issue when a 39-later is converted to a
dual MC.

[sabre62]

All the info is well taken,I am mixing apples and oranges... I will investigate an alternate master cylinder . As usual this forum provides a wealth of knowledge learned the hard way and is most appreciated. G Man aka Gordon

[345 DeSoto]

RICHARD (EV8G) - Of all the discussions, arguments, and BS I've seen written over the years on dual master cylinder conversions, this is probably the most informative I've read. NOW I know what the theory is, behind the practical. I've come across an NOS '67 Corvette, 1" bore, manual disc/disc master cylinder (free). I will be using it to replace the what-the -hell-EVER-it-is dual master I now have on the 32 in my Avatar. Your Post has helped me immensely with what to do, as far as bleeding the Master and installing it on the system. I've included a representative picture of the MC. BTW, what is the procedure to bleed a MC which has bleeder screws on it?...

[Richard (EV8G)]

Glad to be of help... The bleeders on the MC can be opened to bench bleed both ends, maybe instead of the usual procedure of running lines from the ports back into the reservoirs, which can be messy. After installation and during the bleeding operation, open them again just to be sure that no air is trapped.

BTW, the operation of dual/tandem mc's is explained in Motor's and other shop manuals. The basic design was created in response to the Fed's National Highway Safety Act, or whatever it was actually called, of around 1966? which mandated two separate braking systems and a warning light. The people who wrote the bill probably had a truly independent setup in mind, but this is what the people in charge of enforcing the new law apparently signed off on... They are not what people think they are... and not much has changed...

[V8 Bob]

" Most people do not understand how the duals work, so cannot visualize what is going on or what to expect in case of a failure - they are not all that they are "cracked up" (what does that mean???) to be..."

I find it hard to believe so many "car" people still do not understand hydraulic brake operation , especially the safety advantages of the dual system found on all US cars/light trucks since 1966.

"I run singles on my own cars... but this is one of those on-going controversial subjects... (DOT 3 vs. DOT 5, mechanical vs. hydraulic, etc.) "

There should be NO controversy. Hydraulic brakes ARE safer than mechanical, and dual systems, when set up properly, ARE safer than single, period! These are facts, not opinions.

One mistake often made is not picking a dual master with the proper bore size, as has been stated. Too small a bore can lead to inadequate fluid volumn and excessive pedal travel.
The biggest issue with any master cylinder is making sure the master cylinder piston(s) can be bottomed out BEFORE the pedal hits the floor. A single piston master will not have its full displacement potential, and a dual will loose most/all its safety advantage, along with never attaining a full bleed.
When working with brakes and unsure about something, consult with someone who does know...or grab a book, shop manual, etc, and take the time to try and learn. Hydraulic brakes have been around for over 70 years, and dual systems for over 45. Its not rocket science...
Some masters have bleeders located above the ports because the port passages, through design, orientation, etc, can have air pockets that normal bleeding will not dislodge. Bleed these first before any others.

[FRANK PKNY]

I can tell you from expierence that a single master cylinder set up should never be used. I lost my brakes years ago in a dump truck and went straight through a intersection off the road and into a building. Luck had me and I survived and no one got hurt. Ever since then I have always converted my brakes to a dual system. Better to be on the safe side. Frankpkny

[Richard (EV8G)]

[QUOTE=V8 Bob;103056]"

"There should be NO controversy. Hydraulic brakes ARE safer than mechanical, and dual systems, when set up properly, ARE safer than single, period! These are facts, not opinions."

There are still differing "opinions" on what is "fact" ... You may be hearing from the "properly set up and adjusted mechanicals are just as good as hydraulics" group?

[37fatfender]

" ARE safer than single".......... I don't know why? From my first hand expeience, I don't believe it. I lost all my brake fluid in the rear resivor due to a small gradual leak in a street rod that I had owned. I always ASSUMED that if you lost fluid in one you would have brakes to back you up. NOT in my experience. I was traveling from Kalamzaoo, Mi to north of Chicago on interstate 294 at 70 mph and nearly killed my self and almost totaled my car. If I lost the rear fluld I should have front brakes....right NOT so. I darted around cars like a bumble bee in slowing traffic.....using only the emergency brake.......virtually no use for stopping at any substantial speed. I got the car to the next exit called the wrecker. I did not know why any of this happened at the time. Upon tear down when I got home the leak at a residual valve fitting was discovered. I fixed the leak and decided a new master cylinder was in order also. Thinking ahead of my self I decided that I would install the new master, bleed the system and then recreate the problem and open the rear bleeder......guess what NO brakes........pedal to the floor. I have never gotten any satisfactory explanation as to why. I do know that my master cylinder and brake lines are checked VERY regularly.

[V8 Bob]

Originally Posted by 37fatfender

" ARE safer than single".......... I don't know why? From my first hand expeience, I don't believe it. I lost all my brake fluid in the rear resivor due to a small gradual leak in a street rod that I had owned. I always ASSUMED that if you lost fluid in one you would have brakes to back you up. NOT in my experience. I was traveling from Kalamzaoo, Mi to north of Chicago on interstate 294 at 70 mph and nearly killed my self and almost totaled my car. If I lost the rear fluld I should have front brakes....right NOT so. I darted around cars like a bumble bee in slowing traffic.....using only the emergency brake.......virtually no use for stopping at any substantial speed. I got the car to the next exit called the wrecker. I did not know why any of this happened at the time. Upon tear down when I got home the leak at a residual valve fitting was discovered. I fixed the leak and decided a new master cylinder was in order also. Thinking ahead of my self I decided that I would install the new master, bleed the system and then recreate the problem and open the rear bleeder......guess what NO brakes........pedal to the floor. I have never gotten any satisfactory explanation as to why. I do know that my master cylinder and brake lines are checked VERY regularly.

IF the master can be FULL stroked BEFORE the pedal bottoms out, and IF the bore size is adequate for the calipers (system), you will have FULL FRONT BRAKING from the master in the event of a rear failure, and FULL rear braking in the event of a front failure, PERIOD, on a typical front/rear system. You WILL have increased pedal travel, BUT FULL FRONT or REAR BRAKING.

Sorry you don't believe dual systems are safer, but its something you are doing/did wrong that caused your brake failure. Do you know DOT brake testing requires the primary AND secondary systems to stop vehicles from 60 MPH and/or 100 KPH in a certain measured distance, loaded and empty? Do you really think DOT has mandated the dual system since 1967 because it sounds like a good idea?

The dual systems work, and work damm well, but you have to use some logic, common sense, and knowledge to put together a custom brake system that performs like it should, not just "throwing" a dual master on a vehicle and expecting it to work correctly.

Not saying that's what you did, but you have to find out what you are or are not doing, and correct the problem, not give up on the dual master.

[Pat B]

I use a Monte Carlo / Chevelle master cylinder with 40 brakes on the roadster.....Works great!

Pat

[345 DeSoto]

I have seen, on at least 2 vehicles (plus my own) that "stopped great" either the front only, or the back only brakes were working...giving the appearence of "great brakes". However, they wouldn't lock up all four brakes, but would stop the car fine. Unless all four brakes can be locked up, something's not right...including mine...which is why I'm replacing the MC...

[19Fordy]

Originally Posted by Pat B

I use a Monte Carlo / Chevelle master cylinder with 40 brakes on the roadster.....Works great!

Pat

Pat, What years would that be?

[Richard (EV8G)]

Originally Posted by 37fatfender

" ARE safer than single".......... Thinking ahead of my self I decided that I would install the new master, bleed the system and then recreate the problem and open the rear bleeder...guess what NO brakes........pedal to the floor. I have never gotten any satisfactory explanation as to why. I do know that my master cylinder and brake lines are checked VERY regularly.

I will try:

As V-8 Bob has posted, there must be full travel of the MC piston at or before full pedal travel. Early Ford pedal ratios are such that it takes more pedal travel for a given MC piston travel, and using a 1" MC instead of the original 1-1/16" with 40 Ford brakes requires even more MC piston travel. (It may be that the later cars that originally came with the dual/tandem MC's had a lower pedal ratio, maybe
also had power brakes, and maybe less fluid was required with the Bendix brakes -smaller wheel cylinders in front and maybe rear, like 1-1/8" and 1" or even 7/8" rears. Using the 1" dual/tandem MC with old Ford brakes will require more pedal travel than with the original 1-1/16" MC and might not be getting full MC piston travel for full pedal travel... this is easy to check and would be the place to start.
Note that excessive clearance between the push rod and the MC piston will waste pedal travel. It only needs to be about 1/16", or enough to allow the MC piston to fully return when the brake pedal is released.

Beyond that, the dual/tandem MC works kind of like this: When both ends have fluid/pressure and no air, when the brake pedal is pushed, the front piston pushes fluid to the front brakes, but also that same pressure is applied against the rear piston, which in turn pushes fluid to the rear brakes. If as in your case, there is a failure in the rear brakes, there will be a pressure drop in the fronts while the rear piston moves rearward pushing nothing, because fluid in the rear is no longer present. The rear piston has a "prong" and when the rear piston has moved all the way to the rear in the MC bore, the prong bottoms out, and after that happens, the front system can again direct fluid to the front brakes. This happens in a very short time period, BUT there is a (hopefully momentary) loss of pressure to the front brakes AND alot of pedal travel while all this takes place. Obviously, if this retro-fit setup does not provide full MC piston stroke, the rear piston will not bottom out, and therefore no front brakes will be recovered - but under normal conditions with pressure in both ends, it will work just fine... right up until there is a failure.

In the case of front failure, the front piston must travel rearward alot until a big spring is compressed and the rear piston is physically pushed to the rear, at which time the rear braking will be recovered. Again, without full stroke, there will not be enough pedal travel available to recover the rear brakes before the pedal hits the floor.

The above, pertains to a typical GM dual/tandem MC, but Ford and others I believe function about the same. As can be seen, the two systems are NOT independent at all, but are co-dependent. That is why all the pedal travel, which a typical person who has not had a previous failure with a dual/tandem MC will be surprised by and may become disoriented and panic, especially if what they were stopping for is REAL CLOSE in front of them...

The workings of a dual/tandem MC is fully explained in a Motor's Manual for the late 60's.

[CA Victoria]

I am experiencing a weak brake on my (originalish) 35 with a 39 brake setup using a new 67 ford for dual MC. Bled the MC as suggested (plugging method) and bled the rears first with the front plugged and then the rears. The pedal is firm after bleeding the rears are then soft after bleeding the fronts. (I haven't tried doing the fronts first?) I'm using a pressure bleeder. The cylinders are not new but have had kits and are not leaking. Brakes have been adjusted. When I depress the pedal after bleeding all four, the first half of the stroke is soft and then firms up after depressing about 1/2 to 2/3 of its stroke. The last time I bleed the brakes I used a qt of fluid, pretty sure the air is out......not sure what to try next? The flex lines are older but do not appear to be damaged. One comment on the MC bleeding. With both ports plugged and slowly pumping the pedal I get fluid pumping into the resivour from the chamber furtherest from the rod, the other I do not see the fluid pumping into the MC. Don't know it this is common? Maybe try a single MC?

[George G]

A mc for a 4 wheel disc brake car with no brake booster?

Originally Posted by 345 DeSoto

RICHARD (EV8G) - Of all the discussions, arguments, and BS I've seen written over the years on dual master cylinder conversions, this is probably the most informative I've read. NOW I know what the theory is, behind the practical. I've come across an NOS '67 Corvette, 1" bore, manual disc/disc master cylinder (free). I will be using it to replace the what-the -hell-EVER-it-is dual master I now have on the 32 in my Avatar. Your Post has helped me immensely with what to do, as far as bleeding the Master and installing it on the system. I've included a representative picture of the MC. BTW, what is the procedure to bleed a MC which has bleeder screws on it?...

[NYfatboy]

Originally Posted by George G

A mc for a 4 wheel disc brake car with no brake booster?

Why not, I did this to my 67 mustang back in 1980- it takes a little more pressure, but works well.

[Mart]

Sponsored Links (Register now to hide all advertisements)

Is there a commonly available drum/drum dual cylinder with a 1-1/16" bore?
I remember trying to find one some time ago, and it was difficult.
Make, model, part number would be good.

Mart.

[George G]

Originally Posted by NYfatboy

Why not, I did this to my 67 mustang back in 1980- it takes a little more pressure, but works well.

No I have no problem with it. I didn't know there was such a beast. Got a part number??

[NYfatboy]

I worked at a parts jobber, and lead parts man got me a master from a big ford truck,I think maybe an inch and an eight bore, and we took out the residual check valve. Then I put a dial down proportioning valve in line to rear, and tested and adjusted until brakes worked correctly. Sorry I dont remember the part #, but look into late 70's big ford trucks. Master bolted into mustang.Hope this helps

Originally Posted by George G

No I have no problem with it. I didn't know there was such a beast. Got a part number??

[CA Victoria]

I have re read the earlier post describing the dual MC operation. In my application with the 39 brake setup the 1970s ford MC, it would be reversed. On mine the front brakes line is plumbed to the rear most chamber (closest to the plunger). If I understand ed's post the front chamber is furtherst from the plunger, this would not let the MC function as it should???????
Also pinched off the front flex lines just above the wheel cylinders and the softness goes away...
I bought the 35 plumbed this way and don't know if it ever worked properly......
Suggestions?

[coolcoupe]

I have 47 ford and wondered if a person could hookup two orginal master cyinders side by side and hook one up for the front brakes and the other for the back brakes.You could join the the two together so they would both work off the same brake pedal. Is this possible ??

[John R]

The two master cylinder approach is feasible but tricky to set up properly. Many old sports racing cars were set up this way. Part the reason was to allow the front-rear brake balance to be changed by adjusting the linkage.

[HemiDeuce]

I have just installed a 260-4893 Wilwood 1 1/16" bore Dual Master Cylinder, with two 260-3279 Residual Check Valves in my 32 Roadster with 41 Lincoln front brakes and 2 1/4" X 11" rear Ford brakes. The pedal is nice and high and I am expecting a slightly heavier pedal that I had with the 1" Fruit Jar master cylinder that I have been running. I expect to drive it this weekend, so I'll let you know how it works out.
HemiDeuce.

[coolcoupe]

Hi John,could you tell me more about the setting up part.Might be worth a try.

[HemiDeuce]

Originally Posted by HemiDeuce

I have just installed a 260-4893 Wilwood 1 1/16" bore Dual Master Cylinder, with two 260-3279 Residual Check Valves in my 32 Roadster with 41 Lincoln front brakes and 2 1/4" X 11" rear Ford brakes. The pedal is nice and high and I am expecting a slightly heavier pedal that I had with the 1" Fruit Jar master cylinder that I have been running. I expect to drive it this weekend, so I'll let you know how it works out.
HemiDeuce.

I drove my Roadster with the new Master Cylinder today and I worked great.
The pedal was nice and high and the extra 1/16" on the bore of the Master Cylinder made a nice difference in the stopping power.
I very happy how it worked out.
HemiDeuce.

[Mart]

Can anyone help with this query?

Is there a commonly available drum/drum dual cylinder with a 1-1/16" bore?
I remember trying to find one some time ago, and it was difficult.
Make, model, part number would be good.

Mart.

[V8 Bob]

Originally Posted by Mart

Is there a commonly available drum/drum dual cylinder with a 1-1/16" bore?
I remember trying to find one some time ago, and it was difficult.
Make, model, part number would be good.

Mart.

You don't need to limit your search to drum/drum masters, as disc/drum and disc/disc masters can also be used in drum/drum setups. Residual valves (10 lb) will have to be added for the fronts, and also to the rears if not present internally inside any drum outlet ports on disc/drum masters.

I recommend using a master from a power (vacuum) application, as the push rod bores are usually deeper and are safer/easier to adapt on a custom build.

One last thing--the larger chamber, as with most disc/drum masters, is ALWAYS plumbed to the fronts.

[Richard (EV8G)]

I recommend using a master from a power (vacuum) application, as the push rod bores are usually deeper and are safer/easier to adapt on a custom build.

There is a MC that we use (7/8" bore, dual/tandem) that does not have a pushrod bore, but just a "cone-shaped" dimple. I always figured it was originally intended for use with a power booster??? When we use them, we also install a pushrod guide to keep the pushrod centered in the "cone" and prevent it from falling out, worst case...

[V8 Bob]

Originally Posted by Richard (EV8G)

I recommend using a master from a power (vacuum) application, as the push rod bores are usually deeper and are safer/easier to adapt on a custom build.

There is a MC that we use (7/8" bore, dual/tandem) that does not have a pushrod bore, but just a "cone-shaped" dimple. I always figured it was originally intended for use with a power booster??? When we use them, we also install a pushrod guide to keep the pushrod centered in the "cone" and prevent it from falling out, worst case...

Richard,
Generally, non-power masters have shallow bores because the push rods are usually fixed or restrained by special clips in the bore. Power masters have a deeper bore because the push rod cannot be restrained in the bore, or separating the master from the booster would not be possible.
As long as you have some sort of guide to prevent the push rod from falling out, using masters with shallow bores is OK, but the deeper bores on power masters just makes the job easier.

[1oldtimer]

Originally Posted by coolcoupe

I have 47 ford and wondered if a person could hookup two orginal master cyinders side by side and hook one up for the front brakes and the other for the back brakes.You could join the the two together so they would both work off the same brake pedal. Is this possible ??

they've been doing that on the HAMB with chevy truck masters and a balance bar. so i would think you could use 2 stock masters if room permitted.

[HemiDeuce]

Originally Posted by Mart

Can anyone help with this query?

Is there a commonly available drum/drum dual cylinder with a 1-1/16" bore?
I remember trying to find one some time ago, and it was difficult.
Make, model, part number would be good.

Mart.

Part Number 1050 Wagner, Eis, Raybestos etc fits 40 to 48 Fords with drum brakes and has a 1 1/16 bore.
It is not a dual master cylinder though.

[HemiDeuce]

Originally Posted by HemiDeuce

I drove my Roadster with the new Master Cylinder today and I worked great.
The pedal was nice and high and the extra 1/16" on the bore of the Master Cylinder made a nice difference in the stopping power.
I very happy how it worked out.
HemiDeuce.

Just a quick update on the Wilwood Master Cylinder that I reported on in the previous post.
After driving my 32 Roadster to the LA Roadster Show I discovered that the rear brakes were not receiving very much pressure from this new master cylinder. Whether it is designed this way, or the master cylinder defective I'm not sure. I replaced this master cylinder with a 1" bore 1967 Mustang dual bore cylinder and the brakes work much better.
The search continues for a 1 1/16" bore dual master that we can use with our early Ford and Lincoln brakes.
HemiDeuce.

[Gary in Mozarks]

Originally Posted by FRANK PKNY

I can tell you from expierence that a single master cylinder set up should never be used. I lost my brakes years ago in a dump truck and went straight through a intersection off the road and into a building. Luck had me and I survived and no one got hurt. Ever since then I have always converted my brakes to a dual system. Better to be on the safe side. Frankpkny

Frank,

I had a simular situation many years ago. A friend of mine was showing off, (burning rubber big time) in a 500 hp 55 chevy with a single master cylinder. I watched in horror as he proceeded to plow into the back of a UPS truck because a brake line ruptured over his rear differential. I ALWAYS convert.

[Gary in Mozarks]

Here is a picture of my 39 ford dual master cylinder installed using a ECI adapter kit. I ran the brake light switch off the rear line.

[19ED30]

Bump ,,, this is a interesting thread , I am looking at a 1 1/4 bore for my 32 ford with 40 brakes , anyone use a Dual master cylinder this big ???

[JSeery]

Originally Posted by 19ED30

Bump ,,, this is a interesting thread , I am looking at a 1 1/4 bore for my 32 ford with 40 brakes , anyone use a Dual master cylinder this big ???

Is there any reason you are wanting to use a large bore master cylinder? It reduces the brake stroke required, but it also reduces the brake pressure to the wheel cylinders. The larger the diameter of the mater cylinder bore the lower the braking pressure.

As an example of line pressure:

line pressure = leg pressure on pedal x pedal ratio divided by cross-section area of master cylinder.

Just for an example, us 150 lbs of leg pressure and a 7:1 pedal ratio.

for a 1 inch bore cylinder - (150 x 7) / .7854 = 1337 psi line pressure

for a 1 1/8 in bore cylinder - (150 x 7) / .9940 = 1056 psi line pressure

for a 1 1.4 in bore cylinder - (150 x 7 ) / 1.2272 = 856 psi line pressure

[42merc]

Sponsored Links (Register now to hide all advertisements)

Most of the theory has been thrashed before.
The reason we're going to the larger bore M/C is because of the limitations associated with the existing '39-'48 Ford limited pedal ratios & travel.
Small bore = more pedal travel, you don't have enough travel with stock old Ford pedal setups.

[JSeery]

Everything with brakes is a balancing act, pedal travel, pedal ratio, bore size, etc. It all works as a system and each component needs to be correct for the combination to work correctly. Still 1 1/4 is a large master cylinder bore size, I would think that through before typing it.

[V8COOPMAN]

In other words, it may take pushin' with both feet to get things slowed-down. DD

[deuce lover]

Originally Posted by 42merc

Most of the theory has been thrashed before.
The reason we're going to the larger bore M/C is because of the limitations associated with the existing '39-'48 Ford limited pedal ratios & travel.
Small bore = more pedal travel, you don't have enough travel with stock old Ford pedal setups.

Last sentence IMO is not true.Last 4 cars I built I used a 7/8" bore dual MC and worked perfectly.That MC work fine with disc/disc,disc/drum and drum/drum.In each case I used the 39 Ford pedal assy w/adapter to the dual MC.

[40cpe]

Originally Posted by deuce lover

Last 4 cars I built I used a 7/8" bore dual MC and worked perfectly.That MC work fine with disc/disc,disc/drum and drum/drum.In each case I used the 39 Ford pedal assy w/adapter to the dual MC.

Would you please share the application or part number for that master cylinder? Thanks, Gene

[19ED30]

The way I was reading this thread was, on early Ford's had a 1 1/16 bore mc, ( single reservoir ) Front w/c 1 1/4 , rear w/c 1 1/8 . If you where to convert to a dual Mc & if you use a Biger bore ,would be less peddle movement & more brake pressure to wheel cylinder ( a little help like a power brakes )
I check my car out every 2,000 miles change oil ,service every thing , on lift,
When I was 16 I was street Racing my X race car ,late @ night ,quite fast at the time & lost brake , It had a single M/c reservoir , If I would have been @ the drag strip , I would have not been able to stop ,with out a crash , I did use the old under dash hand brake to stop ,
Even to this day ,I even run dual hand brakes in my Blown Altered,(no front brakes ) 4 calipers on the rear,
1 hand brake for each set , parachute's just slows you down .
My 32 has its Original steel , I drive daily 300-500 miles a week , Pepole always pulling out in front of you , Off topic, but does any one remember rule of thumb,
For every 10 mph ,you put 1 Second between you and the car you're following ,So if you're running 70 it should be seven seconds !!! Does this rule apply anymore ,,
because everybody is up my A$$!!
I do not like to driving aggressive, I'm not saying I'm the best driver but I'm sure there's not too many around me that can drive like I can !!
Not quite 50 yet

[V8COOPMAN]

The "TWO SECOND" rule applies and works well, no matter the speed. SOME folks may need to think this out to finally realize that it works. "THREE second" rule applies in rainy conditions. DD

[42merc]

Originally Posted by deuce lover

Last sentence IMO is not true.Last 4 cars I built I used a 7/8" bore dual MC and worked perfectly.That MC work fine with disc/disc,disc/drum and drum/drum.In each case I used the 39 Ford pedal assy w/adapter to the dual MC.

In my applcation it is true.

Had F100 drum all around on my '40, yes all around, 15/16" M/C worked well.
Went to a front disc kit on the front, could get only 1/3 pedal with the 15/16" M/C. Changed to a 1" M/C, now have a good 2/3 pedal.

I do not want to go to a larger bore because of the effort required.

This is what works for me.

[19ED30]

42 Merc, yr quote

I do not want to go to a larger bore because of the effort required.

You are using Disc & drum ?
On my 32 , 40 drums on all four , & you are saying the Biger bore Mc will required More effort from my leg (pushing power )
I would think Less because of more Volume,
Is this not correct?

[FlatheadTed]

Something to be aware of is some 40 wheel cylinders are not drilled correctly at the inlet port and bleed hole ,they have a 1/4 " hole instead of a 1/16 and the cup straddles it specially when fully adjusted backed of , As I understand it the GM two reservoir master cylinder is the one to use 1 n1/16 or 1-1/8,don't know the part number .I worked on a 32 Roadster the car could not be pushed around due to the disc brakes being on slightly heating the brakes up .This had the residual valve that could be moved from port to port so we moved it to the back problem solved , Another part that's not well under stood is what type of lining should be used on a given brake system rods verses hydraulics ,a 40 brake system often power boosted linings are used and result in poor braking .If you have rods try and get them working if they are driven under 60MPH .The rust in cylinders on cars that are not driven frequently is a problem .Ted


Qaute I run singles on my own cars... but this is one of those on-going controversial subjects... (DOT 3 vs. DOT 5, mechanical vs. hydraulic, etc.) I can furnish my 1932 and 33-34 conversions with either type, but 35-36's and 37-38's are limited by space constraints... which is also an issue when a 39-later is converted to a
dual MC.

[JSeery]

Originally Posted by 19ED30

42 Merc, yr quote

I do not want to go to a larger bore because of the effort required.

You are using Disc & drum ?
On my 32 , 40 drums on all four , & you are saying the Biger bore Mc will required More effort from my leg (pushing power )
I would think Less because of more Volume,
Is this not correct?

Did you read my post #45? No, Bigger bore means more leg pressure, smaller bore less leg pressure. Not sure why so many seem to have this backward. The larger the bore in the master cylinder the lower the line pressure and the more leg force that is required. The only reason to go to a larger master cylinder diameter is if you are having brake pedal stroke problems. The larger cylinder diameter will move more volume of fluid (at a lower line pressure) and require less pedal travel. You really need to understand how all of this works together, the system has to be matched, you can't put just any master cylinder with any pedal ratio, they work together.

This is not one of the subjects that is just an opinion, it is the facts of physics. It doesn't matter if it's an engine hoist, floor jack and car brakes, this is how fluid physics works. A floor jack with a smaller piston and cylinder will lift a weight easier, but it takes more strokes. A larger piston will lift the weight much faster, but requires more effort for each stroke.

[42merc]

Originally Posted by 19ED30

42 Merc, yr quote

I do not want to go to a larger bore because of the effort required.

You are using Disc & drum ?
On my 32 , 40 drums on all four , & you are saying the Biger bore Mc will required More effort from my leg (pushing power )
I would think Less because of more Volume,
Is this not correct?

I'm using a '72ish Mustang disc-drum M/C with a 1" bore. Disc on the front, F-100 fronts on the rear, 11"x2" drum with a 1-1/6" wheel cylinder.

Refer back to J Seery & his info about bore size & pedal effort.

Larger M/C bore needs more foot pressure & granted there is more volume.

[deuce lover]

Originally Posted by 40cpe

Would you please share the application or part number for that master cylinder? Thanks, Gene

Raybestos 39037. Napa's number is the same also.I only use DOT 4 fluid also.What's nice with this MC is that the ports face the frame side rails if your MC is pointing to the rear.Makes a nice clean brake line run.

[Bassman/NZ]

I use a 67 Mustang dual, the one intended for drum brakes, not discs. I spent forever trying to get pedal, same as you. Then one day I had a lightbulb moment and reversed the lines into the dual. Voila! There it was... instant brakes. Turns out the rears need to come in first when the pedal is depressed, I had assumed it was the fronts that needed to come in first. My brakes have been great ever since. My brakes are '39 fronts, '47 pickup rears.

[al pa.]

47 merc,front disc,rear stock drum,corvette style dual m.c.,with proportion valve,and residual pressure valves.bench bled m.c.,and hooked up both front and rear lines.did NOT bleed rear,then hook up front lines as described earlier.bled right,rear,left rear,right front,left front.Only getting half pedal.Any ideas what to do now? thx.

[19ED30]

JSeery , I missread post 45 !!

So it seem that a 67 mustang Mc is the choice for four wheel drum with 40 pedal's ,
I am just a little nervous about the single reservoir Mc , its been many years since I drove a car with 4 wheel drum , I just feel like a am applying heavy leg pressure, But maybe I am not , just spoiled from Disc brake set up's !

Allso on 40 brakes , wants the shoe has been centered , when You ajust yr brakes @each service you now just ajust the top on each shoe correct?

[JSeery]

Originally Posted by 19ED30

JSeery , I missread post 45 !!

So it seem that a 67 mustang Mc is the choice for four wheel drum with 40 pedal's ,
I am just a little nervous about the single reservoir Mc , its been many years since I drove a car with 4 wheel drum , I just feel like a am applying heavy leg pressure, But maybe I am not , just spoiled from Disc brake set up's !

Allso on 40 brakes , wants the shoe has been centered , when You ajust yr brakes @each service you now just ajust the top on each shoe correct?

I use the 67 mustang drum-drum master cylinder is my cars. You can get the 67 mustang MC in disc-drum and drum-drum configurations.

[JSeery]

Originally Posted by Bassman/NZ

I use a 67 Mustang dual, the one intended for drum brakes, not discs. I spent forever trying to get pedal, same as you. Then one day I had a lightbulb moment and reversed the lines into the dual. Voila! There it was... instant brakes. Turns out the rears need to come in first when the pedal is depressed, I had assumed it was the fronts that needed to come in first. My brakes have been great ever since. My brakes are '39 fronts, '47 pickup rears.

The front brakes do the majority of the stopping, but you don't want the rear end coming around on you.

[Kahuna]

Like Hemideuce, I have Lincoln 12 x1.75 fronts and Late Ford 11 x 2.25 rears on a banjo axle.
I use a single Mustang Master due to space considerations for the Master, The brakes are great.
As has been posted many times, I'm a firm believer that if the system is in good order and well adjusted/maintained, there is really no reason to use a dual MS setup.
Maybe I'm wrong. JMO
Jim

[Kahuna]

For 19ED30
This is perhaps the best tutorial for brake adjusting
http://www.btc-bci.com/~billben/brakeadj.html
Hope it helps
Jim

[JSeery]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by Kahuna

Like Hemideuce, I have Lincoln 12 x1.75 fronts and Late Ford 11 x 2.25 rears on a banjo axle.
I use a single Mustang Master due to space considerations for the Master, The brakes are great.
As has been posted many times, I'm a firm believer that if the system is in good order and well adjusted/maintained, there is really no reason to use a dual MS setup.
Maybe I'm wrong. JMO
Jim

Well, that would explain why ALL modern cars use double systems! The newer Fords even go a little further, Left Front coupled with Right Rear and Right Front coupled with Left Rear. Them silly engineers think they are accomplishing something!!!

[Kahuna]

Yeah, J
What do they know?
Ha ha

[JSeery]

I'm a period Hot Rodder, so I get it. Just couldn't resist.

[fordor41]

I'll throw my $.02 in here. I installed a Torino M/C (1" bore) in my '41 with front disc and 29/32" wheel cylinders in the rear. Only problem I had was brake pedal were VERY low but solid.. I adjusted the rod between the M/C and the pedal longer until the compensating port in the bottom of the M/C was open with the pedal up. After that I had about 1"-1.5" of free travel before the brakes took. I heard all about keeping a loose rod between the pedal and the M/C but that causes a lot of free play. Now I have a Corvette M/C with power , same disc and rear cylinders. Have about 1.5" free play. If your pedal is low but a good pedal I'd check the pedal free play and try to eliminate as much as possible.

[Newc]

Wow, large Post; I found an early '60's Cadillac drum/drum/ dual master cyl in my '34 PU with '40 brakes, it even used the large Ford hyd lines and fittings.... Still available new! Newc

[fcompoccio]

Does anyone have information on mounting a master cylinder to the firewall on a 40 Ford? Any help or info would be appreciated.

Thanks
Frank

[JSeery]

Originally Posted by fcompoccio

Does anyone have information on mounting a master cylinder to the firewall on a 40 Ford? Any help or info would be appreciated. Thanks Frank

That would require a hanging pedal setup. If that is what you are wanting to do, need to look for a hanging pedal bracket, a street rod vender would carry them.

[TJ]

Originally Posted by fcompoccio

Does anyone have information on mounting a master cylinder to the firewall on a 40 Ford? Any help or info would be appreciated.

Thanks
Frank

Why would you want to do that? The firewall was not designed to take on the pressure you would exert on the brake pedal and the firewall will flex and later crack. Unless you put some extra bracing into the firewall it's not a good idea. In addition if the cylinder ever leaks or you spill brake fluid while filling, it will eat up the paint on the firewall.

[fcompoccio]

Ive seen many 40s with this mod and that's what I want to do. they are all reinforced. All 6 of my other classics are mounted on the firewall whats the problem?

[JSeery]

Not a problem if you want it that way. It requires the bracket and reinforcing. But it is not the type of modification that most stock flathead Ford guys or even period hot rod guys would do. Might get a response from folks with more experience on a street rod site.

[38bill]

Originally Posted by fcompoccio

Does anyone have information on mounting a master cylinder to the firewall on a 40 Ford? Any help or info would be appreciated.

Thanks
Frank

Check out Speedway Motors. They have several different kits to mount brakes. I guessing that you are thinking about something like an under dash pedal assembly.

[47Merc]

A lot of really good info in this discussion and interesting to see the different master cylinders that have been used but no one mentioned whether they were using a booster or not and if so what type / size. Particularly with the ones with disc front brakes.


Many years ago I had a 40 coupe with 4 wheel discs and a Mico master cylinder on it. No booster and brilliant brakes but only 1 circuit. They have twin pistons inside them and it was the first time I came across a M/C that had to be bench bled.

[37 Cab]

I have this master cylinder but have not installed it yet. Winter project. It is for a 75 AMC gremlin with manual front disc brakes and has a 1 1/16 bore. Outlets point towards frame. I plan to add a 10 lb residual valve if I need it since my fronts are drum. (disc brakes require a 2 lb valve and drum brakes a 10lb.

[JSeery]

Originally Posted by 37 Cab

I have this master cylinder but have not installed it yet. Winter project. It is for a 75 AMC gremlin with manual front disc brakes and has a 1 1/16 bore. Outlets point towards frame. I plan to add a 10 lb residual valve if I need it since my fronts are drum. (disc brakes require a 2 lb valve and drum brakes a 10lb.

Be interesting to see how it works, keep us updated.

[37 Cab]

Forgot to add Raybestos part number is MC 36456

[TomT/Williamsburg]

This has been a very informative and interesting thread, one of the best here on the board on this subject. Thanks to all who have responded ...

Right or wrong, I am using a 70-72 Mustang drum-drum mc having F100 front brakes and 46-48 style Ford rear brakes on my avatar. It has worked well with me for 7+ years and many, many hard miles but I am constantly having to adjust them, add small amounts of fluid, and the pedal was never really hard. Up to a while ago I thought that was normal until I drove my buddies 29 pickup with 40 brakes front and rear and a Corvette mc sold by Speedway with outlets on either side. It locked up all 4 wheels, stopped very well, and had a great pedal feel, like "right there". My present 32 project with F100 front brakes converted to self adjusters and a 9" drum brake rear will have this mc also. Not quite the same but still drum-drum. I am close to completing this one and will let you know how she does ....

This mc btw can be for drum-drum or disc-drum and I am using 3/16" lines throughout. Both reservoirs on this mc are the same size. Once the present project and my wife's 40 pickup are done, my avatar will be due for some updates and I will swap to the Speedway Corvette style mc with it.

[40 Deluxe]

Originally Posted by TomT/Williamsburg

This has been a very informative and interesting thread, one of the best here on the board on this subject. Thanks to all who have responded ...

Right or wrong, I am using a 70-72 Mustang drum-drum mc having F100 front brakes and 46-48 style Ford rear brakes on my avatar. It has worked well with me for 7+ years and many, many hard miles but I am constantly having to adjust them, add small amounts of fluid, and the pedal was never really hard. Up to a while ago I thought that was normal until I drove my buddies 29 pickup with 40 brakes front and rear and a Corvette mc sold by Speedway with outlets on either side. It locked up all 4 wheels, stopped very well, and had a great pedal feel, like "right there". My present 32 project with F100 front brakes converted to self adjusters and a 9" drum brake rear will have this mc also. Not quite the same but still drum-drum. I am close to completing this one and will let you know how she does ....

This mc btw can be for drum-drum or disc-drum and I am using 3/16" lines throughout. Both reservoirs on this mc are the same size. Once the present project and my wife's 40 pickup are done, my avatar will be due for some updates and I will swap to the Speedway Corvette style mc with it.

Have you tested your system to verify that it will still stop when a hose blows? In other words, you need to open a bleeder screw (either front or rear) and then do a panic stop. Then do the same on the other end of the car. If the pedal goes completely to the floor without even slowing you down your dual setup is totally worthless! The pedal goes almost to the floor even in OEM applications, so if a conversion to an early Ford is not engineered properly, the safety factor is lost because the pedal hits the floor before the master cylinder can build any pressure.

[TomT/Williamsburg]

Gotcha - I will check this out ......

[fcompoccio]

Yes Ive seen the under dash kits, but would like to talk to someone that's done it.