The Ford Barn - Brake drums

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- - Brake drums (https://www.fordbarn.com/forum/showthread.php?t=324779)

I have a model A I’m improving the front brakes using 32 brakes. Can 1940 and later brake drums ( which I know are hydraulic brakes) work with with my 32 mechanical front brakes? Jerry

Original Model A brakes with cast iron drums properly adjusted work great. FWIW

The way the brakes are set up on a Model A are sort of a carry over from the Model T, which only had rear brakes (in the transmission). The thought at the time was to put more braking effort on the rear wheels to keep the car straight. We now know that the car leans forward when hard braking so that more braking should be on the front. One way to fix this is to put the lever arms used on the rear on the front. They are longer so more braking is on the front. A small collar is needed to reduce the size of the hole in the rear lever arms. There are left and right rear arms so that the arms can be placed in the front to move the rods out a touch to miss the shock absorbers. The arms can also be bent cold as they are ductile. Do not put the arms in the front at the usual 15 degrees but more like 10. If I remember correctly the arms need to be drilled for the pins and the pins peened. After installation it also helps to back off the rear brakes one notch or more. The rear wheels should not skid in hard braking like they normally do with the front wheels not skidding, but all wheels should leave marks on the pavement. I am not sure it this applies to 32 brakes.

To answer the question regarding 40 drums on a 32 braking system, just measure the drums. The first measurement would be the diameter. If it is not the same then you can stop there. Also, just try them. I don't have 32 or 40 parts laying around or I would measure them for you.

Most folks use the round back spindles to fit the hubs & drums for hydraulics. Using wire wheels requires the adapter rings on the 40 & later type drums. Lincoln style Bendix brakes are better. There are kits for those available.

Quote:

Originally Posted by Gerald cook (Post 2213467)

I have a model A I’m improving the front brakes using 32 brakes. Can 1940 and later brake drums ( which I know are hydraulic brakes) work with with my 32 mechanical front brakes? Jerry

The 32 drums are cast into the hub. I guess what you are asking is if the later hubs and drums will match up with the 32 backing plates and shoes?

My experience matches what mhsprecher said above. It is not a question of cash, or time to change over with me. I simply would not convert to juice brakes. One of the guys in my local chapter was driving my car so I could show him how to operate his overdrive unit (my car has one). I told him "now be cafeful when you step on the brake not to throw us through the windshield". When we got to the light that was changing he stepped on the brake...you guessed it. He said "you really got good brakes on this car".

I might add, don't waste your time, and money on the reinforcing bands. I had them once...

Just rebush everything, put on cast iron drums, and then adjust them with the jackstands under the axles using "the stick method", and everything will be just fine. Don't believe me?; take a guys car for a spin in your local club chapter that has done this. Nothing like the seeing is believing method.

The limitation of the Model A in braking is NOT the mechanical system. You get the identical system duplicated in hydraulic when you do the conversion.

Rather the limitation on braking for the Model A is found FIRST in the "square inches" of rubber contacting the road. This doesn't usually change without upgrading to later Ford wheels/Tires. SECOND limitation is the original design of the pressed steel brake drums and their tendency to "fade" as the drums wear thin.

By WWII most of the original Model A brake drums were worn out. Ford themselves knew of the "sensitivity" of the pressed steel drums and for a very short time at the end of the Model A production Ford went with a cast iron drum on a pressed steel center, EXACTLY the same system used in the later 32 up Fords. And this includes the transition to hydraulic brakes after 1939. Model A late model "sandwich" drums are still very much in demand for the show circuit.

Aftermarket cast iron drums in the "hole" pattern (give good ventilation) were also available in the late 30s through the 50s. Until Mel Gross, these were the desired find at automotive flea markets.

Many have done the "change over" to hydraulic brakes using the 39 up setup. They don't fit exactly on the Model A axles, but "shim kits" are available. Without compensation somehow, the later brakes/drums are entirely too "strong" for the lighter Model A car. There are some advantages not the least of which is the cast iron drum. The earlier backing plates still require you to manually adjust. Later post WWII hydraulic backing plates have the advantage of "self adjusting." Clings had/has a good system and actually reverse engineered and "fine tuned" the 39-47 brakes. Nkaminar above describes another change aimed at fine tuning the mechanical brakes of the Model A (and describes PERFECTLY the error in design built into the Model A brakes - an error which can be corrected in adjustment or swapping the levers.)

He brings back memory of my working with my Dad to adjust the brakes the first time by driving the car on a gravel driveway and noting from the skid marks which wheel skids first. Dad had limited knowledge of the car "tilting forward" on braking, but the skid on the driveway tells all.

Really, the BEST thing you can do for Model A brakes is to retain the mechanical system. Buy the "widest" tires that fit your model year rims AND do Mel Gross' cast iron drums.

Widest tire - For a while Firestone tires were the widest available for the 28-29 Model year rims with a stated 5.25/5.75 inches. Some users then noted that the wheels were SO wide that when you take a tight curve the wheels rub against the fender supports (and spall off the inner edge of the tire.) These tires/width may not be available now

Good luck however you go with this.

Joe K

Why are Mel Gross cast iron drums better than other cast iron drums?

I don't know how many cast iron drums for model A cars are being produced in this day and age. From most reports, the Gross (Mel & son Randy) drums are made deliberately undersize so that they can be trued back to nominal size. I gather the undersize is around 0.020" and most reports indicate that they seem to be made to very good tolerances. If a person purchases from them, the price is about the best out there. Their services for drum to hub assembly and shoe fitting are also worth mentioning.

F=fN. What this means is that the force, F, is equal to the coefficient of friction, f, times the normal force, N. The normal force is the weight of the car except for "weight transfer" to the forward wheels when hard braking. There is no "area" in the equation. This is high school physics. So wide tires will do nothing to the braking force except if they have a better coefficient of friction. That said, many wider tires have a better coefficient of friction.

I think I ordered my drums from Brattons.

Quote:

So wide tires will do nothing to the braking force except if they have a better coefficient of friction. That said, many wider tires have a better coefficient of friction.

I couldn't have said it any better myself. One of those "unexplained" of auto-dom.

Like dragster rear "slicks." Which my brother explained given the torque, the sidewalls "fold" and allow greater circumferential belt contact with the tarmac.

"Gumming the track" helped too. https://www.eng-tips.com/viewthread.cfm?qid=14638

The only time I've seen a Model A tire sidewall "fold" was a flat tire. Maybe good for stopping, but terrible on the "going."

Joe K

Quote:

Originally Posted by Gerald cook (Post 2213467)

I have a model A I’m improving the front brakes using 32 brakes. Can 1940 and later brake drums ( which I know are hydraulic brakes) work with with my 32 mechanical front brakes? Jerry

Let's all read this again ...

Using 32 brakes
Do later drums work with 32 mechanical front brakes?

Folks on the V8 side or on the HAMB are more in tune with what would work on a set of 1932 spindles. I think the 1933/34 used the same integral hub/drum as the 1932. I don't know what later hub will fit the spindles. The drum diameter is the same but width is more narrow than the later drums with removable hubs. The spindles likely could be modified to fit the later hydraulic drums but a longer dust cap would likely be needed. Drum and mechanical brake backing plate fit is another unknown.

It likely could be done but I'm sure it would take some modification.

Quote:

Originally Posted by Gerald cook (Post 2213467)

I have a model A I’m improving the front brakes using 32 brakes. Can 1940 and later brake drums ( which I know are hydraulic brakes) work with with my 32 mechanical front brakes? Jerry

I would recommend finding 32-34 front drums. Your Model A wheels will bolt right on. Set them up just as you would Model A front brakes and they will work great.

I have them on one of my cars and have helped several other club members install them on their cars.

On my car, I also installed '32 rear brakes but they are not bolt on and require a lot of work to make everything fit. On future cars, I would only use 32 brakes on the front and Model A with cast iron drums on the rear.

My opinion,

Chris W.

Quote:

Originally Posted by rotorwrench (Post 2213543)

I am going to take the liberty of reposting your post since it is VERY IMPORTANT and easily and often overlooked. Here is a link showing the reason: https://www.fordbarn.com/forum/showt...=1#post1286293

Charlie Stephens

I'm new to Model As. How can I tell if my A has the original steel drums or if it has been upgraded to cast iron drums?
Thanks

the lip at the edges of the drum, the cast iron ones are solid, the stamped steel ones are curled

Quote:

Originally Posted by Fhane (Post 2213850)

Why are Mel Gross cast iron drums better than other cast iron drums?

Are they really???? I know he does a good job but cast iron is cast iron. Sure one alloy might be a little different from another but not by much.
IMO, it's worth remembering that the drum is only part of the equation. The linings and condition of the mechanism also play a big part.

Thanks! I'll check it out.