L120 master cylinder upgrade

Hello everyone. I'm new here and new to IH trucks so go easy on me! ☺
I have a 51 or so L122, sd220, T9 trans and the 6 on 7-1/4" pattern reversable wheel system. It's a very solid truck for the most part but it has sat for 35 years and needs a lot of rebuilding. I worked on it all winter and it runs nice now.

So it's time to look at the brakes. I'll be staying with the stock components but I'm not happy with the idea of single circuit brakes so my question is this: what might be a good modernish dual-circuit non-boosted master cylinder that would match up with my stock drum-drum system? I'd like to do the 90 degree bracket welded to the original mount thing, so ports exiting engine side are a must.

Thanks in advance!

I can not answer your Question, but I think that someone has done what you are talking about.
My Questions for you are, What do you intend to do with the truck? What type of driving do you anticipate? What type of traffic do you think you might encounter when driving?
The reasons for my questions are: We all love these trucks and the looks of them, however, they were made for a different time and "pace" of life on the roads. The tech, in my opinion is adequate for the truck, but perhaps not the current situations that a person may find themselves in. My opinion: most people will not know that the axle and wheels are not original if you were to change them out to more modern components better suited to the current driving conditions. The outside of the truck can remain the same to most peoples eyes, but you would be better prepared to stop in a panic situation.
If you are going to drive this truck in parades only and trailer it to those parades, "original" parts may just do the trick. I do think that you will find it a challenge to find some of the parts that you might need for the original braking system. Parts are to be found, but not always inexpensive or easy to find. An upgrade to a different rear axle and front discs could give you an easier route in the long run. And if you should decide to "upgrade" the motor,you are already a step ahead when that is done, as your brakes are now able to handle the upgrade. These are my thoughts only.

Welcome to our merry little band of Internationals. I agree with Lloyd. Maybe the running gear from a Scout, Blazer, Explorer, Bronco, Ram, Silverado, F-150 (250) or ??? (pick a brand) would bring all the elements you'd need together from one donor vehicle. Using parts from more common vehicles will bring the ability to get replacement parts. There are millions of guys who have successfully swapped components to get an up-grade. However, there are also millions of guys who have ruined their project, too, because their plan was ill-conceived and trying to "make do" with what they had instead of researching the equipment to get the best alternative. Bottom line. Make a plan, research it to your satisfaction, stick with the plan. I know, making one change causes another change and leads to other changes. But, it is finite and once you're through, you have a safer vehicle to drive, not just for you the driver, but for your precious passengers and your fellow drivers on the road, too. (Putting in seat belts, too, I presume?)

That is one Beefy L-122. looks more like a L-130 or so,,,,but anyway, your best bet is to go to a Brake/Clutch Supply, I go to

http://www.brakeandclutchsupply.com/locations.shtml in Seattle, but there should be someone near you,

find the older counter guy who isn't grumpy, <may be tough to do.

and ask him for options for a drum drum dual master with same diameter as your original, a little larger might be OK.

I did this a few yrs. back for my 47 Ferd 1 ton panel, & they gave me a drum/drum master for a 60s Dodge mid size motorhome,

regular parts house isn't going to be very helpful,

the re-plumb of the lines is a little fussy as it goes from master to front left wheel then splits off to right and rear brakes from a three way union,

Thanks for the comments and advice guys - all very good. This project is well planned and understood on my part. I should have mentioned though that I've done this type of thing before and I believe my expectations for this truck are well in line with what I will get. I know it will be slow and underpowered compared to modern vehicles and I'm just fine with that. As a matter of fact, that's why I bought it. I've already got a modern truck to get me around town, so the model L is more for personal enjoyment. I drove a 65 Land Rover daily for 6 years so I know about beastly vehicles! lol

I want the truck to look and operate just as it did in 1950 - that's the goal. This truck will undoubtedly see some modern improvements but they will be well hidden. The master cylinder is the only non-stock item so far. This winter I have rebuilt the engine and transmission, completely rewired it, and rebuilt the cab. All new glass, seals, and weatherstripping are going in right now. The springs will be done soon along with the front axle. Brakes are the current issue and lastly will be wheels and tires. Oh, and finally a re-covered original seat and yes - seat belts. Hopefully all by June.

As for the difficulty of finding parts, well, I enjoy that type of thing too. I've been a machinist for 25 years so if I have to whittle new drums out of Durabar I will. I would be very dissapointed if I had to lose the original wheels - to the point where I can say that it won't happen.

Many comments have been made that when operating properly the brakes on 50's IH's are actually quite good. I'm counting on that, but I don't get a warm fuzzy feeling from a single circuit master cylinder. That thing's got to go. I can do the legwork and figure it out for myself, but I just thought that for all the brake talk on here that someone else has probably done it already and could save me some time.

Bedrockjon: It does seem rather beefy for a 120 doesn't it? I like it! The box hoist lifts the back about 4" and gives it a real lifted look. The 32" Open Country's don't lower it any either. They're just there to hold it up till I get something more appropriate. I do have an Braden MU3 lined up for it too. That aught to make it look serious!

(A couple of more pics: Parked by the sellers barn, interior "before", and engine now.)

nice, does that have a factory optional hoist bed, do you know? there was a R-130 pickup that looked a lot like yours in Orygun,

it had duallys under factory dually fenders in back,

I really wanted it bad.

The hoist was built by an outfit called Robin-Nodwell Mfg out of Calgary, Alberta. It's a pretty loose assembly and it's bound to make a lot of noise so I may take it off. I would like the truck to be as quiet and tight as I can get it.

Nodwell Manufacturing was a really big deal in Alberta when I lived there. Nodwell made some really big all terrain vehicles, with really big flotation tires, for driving on the tundra. I think Nodwell build lots of heavy-duty Oil Patch trucks. One of the Nodwell heavy duty trucks was shown on the TV series, Highway through Hell. If I remember, the truck had three rear axles and three steering axles, all driven.
I have not looked for anything about Nodwell, on the internet.
I like the hoist, but it is your truck. Is it possible to install bushings to take out the clatter?

I’m glad to see you are keeping the original wheels and drivetrain. I like to see pickups with the “big truck” wheels. I guess you do pay the price in terms of parts availability, but after doing it once you likely won’t ever wear anything out. In the 1990s I had a Studebaker 2R11 with similar wheels and big brakes it stopped surprisingly well. Lots of surface area on those brakes, though they would fade a little on long, curvy downhill runs.

I have been looking for a similar dual cylinder as well. Plans for my L-110 are close to yours – mostly stock with a few safety upgrades. I found some that might work but apparently didn't keep my notes. I’ll see if I can find them again.

One I do remember is something kind of unusual, but it should work. I am 99% going to use this CNC dual cylinder, so I’ll kind of explain the details behind it just to float the idea. Just adding to the list of options…

http://www.cncbrakes.com/mc.asp?grp=mc&subgrp=dcsb&series=717&subseries=

You can find them here:

http://secure.chassisshop.com/partlist/6130/

Basically they are two discrete masters with separate outputs for total separation of the front/rear circuits. Also, they can be side-mounted just like the original cylinder, so no bracket fab other than drilling one hole (looks like one of the existing holes can be used as is).

So the question is, if you went this way, which size would you use?

The original master cylinder on trucks up through the L-150 is 1.125” diameter for a surface area of pi*(1.125”/2)^2 = 0.994 square inches. For equal feel/movement at the brake pedal, each of the two separate cylinders should ideally have a surface area of half 0.994 square inches – so about 0.5 square inches.

So, going the opposite direction, 2*square root of (0.5”/pi) = 0.796” diameter. BTW, a faster way around is to divide the original diameter by the square root of 2, so 1.125”/1.414 = 0.796” diameter.

Either way 0.796” is just a shade over 3/4” or under 7/8”. Units are available in both sizes. Skipping the math, the dual 3/4" units is roughly equivalent to a single bore of 1-1/16” while the dual 7/8” unit is roughly equivalent to a single bore of 1-1/4”)

Another thing to consider is stroke which, along with total piston area, determines the total fluid displacement available to move the wheel cylinders. The dual 3/4” unit has a stroke of 1.4”, very close to 1-7/16” (or 1.4375”) of the stock cylinder. This would be fine for my L-110. However, your L-122 has larger rear wheel cylinders (1.125” vs. 1” on the L-110 – fronts are the same on both models at 1”). Larger wheel cylinders = more fluid required. The dual 7/8” unit has a stroke of 1.6”. That, plus the larger bore, would provide plenty of capacity and safety margin for the L-122.

Sorry for the long post…

Your truck is looking great. Should be a real pleasure to drive.

I rebuilt the stock MC on my 51 L-120 Panel truck and with the stock size brakes on all 4 wheels it will stop just fine. also have 53 chevy wagon and 65 Plymouth 9 passenger fury 111 wagon with factory single MC . I drive the wagons all the time the panel is just for fun running around town. am I worried about the brakes ? no. would I change anything to make it more fun to drive? yes the transmission.