Hydraulic Conversion

[popcorn-guy]

OK, here's what I know. I went to look at a 1930 w/29 tin on it and it had "hyd" brakes. The job was accomplished by using a hole saw on the backing plate and drilling two holes to mount the hyd. cyl's. The brake shoes were modified to accept the brake shoe rods that the cyl. pushes the shoes with. The man who did the modification used a Ford F-250 master (single system) and wheel cylinders.

Now one has to think about this for a moment. You now have hyd's pushing on the stock shoes and linings which work against the pressed steel drums. Do you really have any more efficient use of the linings? Imho, no. The easy method, which was used in the 20's through and up to the 50's was to add a vacuum assist to the mechanical brakes. Commonly used on every truck from the AA size on up to what was then the class 8 trucks. Premium cars which were the heavy and expensive models which had mechanical brakes also used this system. These old boys weren't dummies, but actually very smart and practical. One has to remember that hyd's were not a proven system at that point in time and were bleeding edge technology. Plus it was very easy and inexpensive to use vacuum. Then, they had the vacuum canister and a seperate controler, which could make it intimidating for us now, but now they make the controller part of the canister and it simplifies the system. One must attach the vacuum can/controller to a mount someplace and use a rod between it and the brake pedal and then have vacuum assisted brakes. That's the simplified version.

One small tip. Use a small canister as the bigger you go the more power and then you will subject your brake rods to bending. A 7" canister should be quite adequate. It's something that has to be trialed. One will get all the benefits of power and will not have to modify their original equipment, other than to mount the rod with, most likely, a clevis. One must still remember what kind of linings they are using and their efficiency. I am always thinking about the pressed steel drums and where would I get replacements if I put too aggresive of linings on the shoes. Remember, there aren't after market replacements available and Ford sure as hell isn't making them today. There are a couple of fellows in Hemmings that may be able to supply a better lining w/o grinding the steel and ruining the drum and I'll sure let the forum know if I go down that road and its' results.

I searched for months attempting to convert to a more modern system and have yet to find the elusive answer. I have some other ideas, yet to be researched and proven, but I'm a masochist and will keep trying. In the mean time I'm going to use the vacuum type when I can get back to my trucks. I've a shop to finish and projects related that the war dept. requires to be finished as well.

Hope this helps.

[Bob C]

Here is a vacuum booster setup.

[scl009]

So I have been having some discussions with some guys over on FTE, this is what they said with respect to a 47 1 tonner

"The rear drums were 14" on the tonner so the backing plates would be too. The only other thing you should check is the hub diameter and center hole size on the tonner wheels. I found a reference that says the hub is 4.5", but would suggest you check that to be sure. I went out to my shop and checked a rear from a 48-50 that also has 14" drums and found the hub is 4.75" wide on this later axle. So I'd say check it on the tonner. The center hole on your '31 AA wheel is 4 5/8" so you're in business as long as these wheels will clear the later hub."

The 47 has 6 7/8inch bolt pattern for sure, and I think the 48-50 so too.

So I think this is the way I'm going, gonna get the assemblies from a 47-50 one tonner and see what I can do.

Scott

[spectria]

Thanks for the info Scott, Please keep us informed!

[Drew Mashburn]

Bob C:

Years ago, I had an AA "parts" truck that was rigged pretty much in the same manner as the photo you posted. I should have saved the set up. Kick myself in the tail now!

-- Drew

[rollingsculpture]

Ok I have to put this out there , with the possibility of looking as dumb as a box of rocks. We already have a braking system in place that is fully mechanical . if youve worked on your brakes and made sure your linings and drums are in good shape and have adjusted the shoes so they activate within a minimal amount of freeplay movement of the brake pedal , before they activate the wedges that than force open the shoe which than rubs on the drum and stops the truck , than unless you are removing your foot from the pedal the pressure will be constant on the rod that forces the wedge to move and open the shoe against the drum . in my experience with my truck i have found that i can stop very quickly and apply any degree of stopping power from light slowing to full lock up of the wheel , which of course grinds rubber from the wheel . my point being if i have vacuum assist or hydraulic assist it isnt going to apply any better or constant pressure than the system that is currently in place mechanically especially since the original system is being used with the addl hydraulic/vacuum system .my truck did not stop quickly or powerfully until i went through and made adjustments to my brake pedal play and the wedge adjuster on the backing plates than i was able to get the stopping power that does the job. all right thats it...... what am i missing in this formula that would make me want to change .

[spectria]

I think for some of us it's a matter of wanting to put our own stamp on something or experiment a little, or for others the reliability of Hydraulic brakes can't be argued with, otherwise we would still be using the type of brakes that came with the Model A and AA.

I personally like the idea of cleverly adapting hydraulic brakes in a way that is almost invisible to the casual eye. I plan to do that on one of my more sad specimens, but fully intend to make my better flatbed all stock, and I have the parts to do that.

I am gathering info here, and learning from others, I don't think anyone is trying to foist their personal plans on anyone else, but I like that this forum really teaches allot about what's "Possible".

JMHO

[spectria]

OK, here's what I know. I went to look at a 1930 w/29 tin on it and it had "hyd" brakes. The job was accomplished by using a hole saw on the backing plate and drilling two holes to mount the hyd. cyl's. The brake shoes were modified to accept the brake shoe rods that the cyl. pushes the shoes with. The man who did the modification used a Ford F-250 master (single system) and wheel cylinders.

Now one has to think about this for a moment. You now have hyd's pushing on the stock shoes and linings which work against the pressed steel drums. Do you really have any more efficient use of the linings? Imho, no. The easy method, which was used in the 20's through and up to the 50's was to add a vacuum assist to the mechanical brakes. Commonly used on every truck from the AA size on up to what was then the class 8 trucks. Premium cars which were the heavy and expensive models which had mechanical brakes also used this system. These old boys weren't dummies, but actually very smart and practical. One has to remember that hyd's were not a proven system at that point in time and were bleeding edge technology. Plus it was very easy and inexpensive to use vacuum. Then, they had the vacuum canister and a seperate controler, which could make it intimidating for us now, but now they make the controller part of the canister and it simplifies the system. One must attach the vacuum can/controller to a mount someplace and use a rod between it and the brake pedal and then have vacuum assisted brakes. That's the simplified version.

One small tip. Use a small canister as the bigger you go the more power and then you will subject your brake rods to bending. A 7" canister should be quite adequate. It's something that has to be trialed. One will get all the benefits of power and will not have to modify their original equipment, other than to mount the rod with, most likely, a clevis. One must still remember what kind of linings they are using and their efficiency. I am always thinking about the pressed steel drums and where would I get replacements if I put too aggresive of linings on the shoes. Remember, there aren't after market replacements available and Ford sure as hell isn't making them today. There are a couple of fellows in Hemmings that may be able to supply a better lining w/o grinding the steel and ruining the drum and I'll sure let the forum know if I go down that road and its' results.
I searched for months attempting to convert to a more modern system and have yet to find the elusive answer. I have some other ideas, yet to be researched and proven, but I'm a masochist and will keep trying. In the mean time I'm going to use the vacuum type when I can get back to my trucks. I've a shop to finish and projects related that the war dept. requires to be finished as well. Hope this helps.

Thanks Allan, I appreciate the research, there is still more to learn.

[rollingsculpture]

im not trying to say its a bad idea or get on a rant about originality etc or put anyone down for doing research and the hard work of actually making the change over .and by all means keep it up and the sharing of your result thats why i look at this site 5 times a day .. im just not seeing the reason to change it out when it seems to be working fine as is. thanks all and keep on trucking

[spectria]

Actually RS, I would like to replace the shoes and drums with something that does the job without all the hassle of matching one type of drum with a certain type of shoe.

I would love to put late type linings in Cast drums, which would make for long life and even braking.

More research needs to be done.

[njcar757]

I'm restoring a 29 AA. I haven't started on the brakes yet but I've thought about them alot. I think I'll go with brake floaters on all four wheels. I've thought alot about converting the front wheels to cast iron drums. Does anyone think it's possible to take a model A automobile cast iron drum, them drill a new bolt hole pattern 6 7/8" diameter? I have a mill with a digital read out and it has a circular bolt hole program,. So what I would do is find the center of the drum then put the new holes between the existing holes with a pattern of 6 7/8 dia.
Later model Ford half ton pickups used 11" drums and they had a 5 hole pattern.
Drums a expensive, about $100. each.
I really need you input.
thanks nick

[spectria]

I would say going with smaller brakes on a 1 ton truck wouldn't be a good idea, and I haven't measured my brakes, but I think the drums are 14".

Anyone, is that the size, 14"?

[scl009]

yep, my drums are 14 inchers

[njcar757]

According to the Jim Schild AA book, the 28AA came out with a front axle similar to the automobile axle with 11" drums, they continued the 11" drums till October 1929 when the heavier axle with 14" drums were introduced. According to the frame serial number it was made in october 29 but it has 11" drums.
nick

[spectria]

According to the Jim Schild AA book, the 28AA came out with a front axle similar to the automobile axle with 11" drums, they continued the 11" drums till October 1929 when the heavier axle with 14" drums were introduced. According to the frame serial number it was made in october 29 but it has 11" drums.
nick

I guess we are talking two different animals!