Ive been reading up on the 46 ford brakes swap for the model a. They say for the rear swap that you need to have the 46 backing plates and drums turned down for clearance. I think it said an 1/8 inch off of each. The backing plate is straight forward, just take 1/8inch off of the lip. Now the drum has 2 lips an inner and the outside lip. Which one do I turn down 1/8inch? Or do I do both? Now could I just take a 1/4inch off of either the backing plate or the drum so that I dont have to mess with both of them?
I dont remember doing my backing plates. The brake drum its the inner lip as it will hit the inside to the backing plate. Youll also need to grind down the outer edge of the shoes. I brake drum surfacing machine can be used on the drum lip.
I was aware of grinding down the shoes, thanks. do you remember how much material you took off? 1/8 inch or 1/4 inch?
It should be a simple job on any brake drum lathe to cut the lip down to clear. Probably the best thing on the shoes is to lay the outside edge of the shoes on a belt sander and dress them down to fit.
Those shims can be bought from Macs. Cheap. Captain J.... if you do a search on posts from a Hamber called Koz, a while back he went into explicit detail and pics of this very same conversion. It might be of help to you.
Put the shims on the axles and you won't have any problems, they are available in most Model A catalogs and Vintage Ford dealers.
thanks, I found them on the brattons site. there $1.80 for a pair so I'll prob pick up to sets just in case I need to use 2 shims on each side. If I use the shims instead of turning down the drums does that mean I wont have to grind the edge of the shoes because the drum should be spaced close to the original distance away from the backing plate?
just wanted to share a couple pics of my ride. 1931 deluxe, 12 volts with alternator, all rewired, centrifugal advance electronic distributor, holly 94 with downdraft intake manifold. plans are to do juice brakes and s10 t5 trans swap.
I used 1940 drums on my A. 46s didnt fit. I have put Wilson Weldings 39 Lincoln backing plates on the front of my Model A. This is done the usual way with the two spacers per spindle. I am using 1971 to 76 Chevy (only!) Station wagon (only!) rear brakes on the rear axle of my Model A. These brakes are 12" X 2" and come on the big wagons ONLY. The big wagons were Caprice, Impala, Kingswood and Bel Air. I am using the complete brake assembly on the rear. This gives you self energizing self adjusting Bendix brakes and a working parking brake on the rear. Simply cut out the center with the chevy bolt pattern and make a Ford pattern center, then make up a spacer on the lathe, everything bolts up on the rear. Back to the front, you can ask for front wheel cylinders for 1948 to 66 Ford pickup. I am also using the 12" X 2" shoes, holddown springs and the self adjusting star wheel from the 71-76 Chevy wagon. You can get all this at the auto parts store. I havent been able to get the self adjusting arm from the parts store but I see that the self adjusting arm (its 2 piece) on the rear of my 57 Chevy is the same design wth one piece being too short for the 12" brakes. Tomorrow I'm going to the u-pull-it to get the same ones I used on the 57. They came off a mid 70s El Camino. I will cut and weld, using the 12" part as a pattern. The 40 Ford brake drums work front and rear. There you have it--self adjusting, self energizing brakes that bolt onto your stock Model A and accept the Model A wheels and all other 5 on 5.5 Ford wheels. Someone is bound to notice that the Ford brake drums used a 12" X 1 3/4" shoe. Yeah and you remember every time you tried to get the drum off and it wouldnt come off because of the 1/4" wide ridge? Turn the Ford drum fresh and you will find a good 2 3/16" usable surface for the 12" X 2" shoes. The pictures show one complete front brake and one rear brake sitting on the rear axle housing before the spacer is fitted One more thing--the cost after buying Wilson Weldings backing plate----$13.88 for shoes per axle, $11.88 per wheel cylinder, $4.44 for the holddown springs, about $7 for the star wheels. These are Advance Auto prices <fieldset class="fieldset"> <legend>Attached Thumbnails</legend> </fieldset>
This self energizing setup looks like id have a hell of a time hunting down the parts. I already have the front and rear out of a 46 with all brand new rebuilt brakes. Ill give that a try first. This is good info though thanks. Maybe someone else reading this thread may use that setup before trying the 40's braked.
hi there Capt J, I did the juice brake conversion and some one has a book out step bt step on this conversion. I believe it's like the 39 thru 40 something backing plates and drums you need. Anyway the book gave the diamensions you needed to do to modify the backing plates and drums. They say that you can grind the lips on the drums and backing plaes yourself. I did it and I don't recommend doing it your self. let a machine shop do it. The cone shime will help space out the drum on the tapered shaft.. I believe the max number of shims is four per side. I was also advised by one of my fellow Model a buddies to mount the rear backing plates upside down. It makes plumbing the rear wheel cylinders a lot easier by getting around the rear spring and assorted hardeware in that area. I said that goes against everything I everheard of about mounting the wheel cylinders up hi to aid bleeding and geting the air out but he said he hadn't had any problems in that area. I did the same and no problems. Also did the chevy s-10 bw t-5 5 speed/It's awe sum but screwed up my mechanical brakes. t hats how I found out about juice brakes.
Check out model a brakes in tech section BTW i took off 1/8 inch from the axle housing where the backing plate bolts to....which is a lot simpler IMHO
I have read up on doing these brakes but somethings just are not clear. From everones responses there seems to be about 20 different ways of doing this. Some really good ideas too! I have seen about flipping the backing plares upside down so that the wheel cylinders are upside down. Not sure if I want to do that I may just rotate them just far enough (about 20degrees or so) to clear the radius arm stuff. Like I was saying there are many different ways of going about it.
No, you install the backing plates upside down and swap sides. Then you install the wheel cylinder right side up, but on the bottom of the plate so you can bleed the air out of the system. Then, the emergency brake cable comes out on top and points forward. Yes, there are many ways to install hydraulic brakes on a Model A...
Yep... Then you gave them to me for this conversion on "endlessearth's" '29... Still can get them at So-Cal Phoenix, though.
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