TECH WEEK:Bendix brake conversion for Ford backing plates

I found a real good pair of -39/-41 front backing plates and i decided to use them for bendix brake conversion. There was many earlier posts but nowhere was good photos or explanation how it was done.

Here is what i started with:


Closer look of cylinder mounting place:


First i marked cutting lines and cut of a piece:


Then i made a patch of 1/8" (3mm) plate and tacked it with tig:


Then i welded it :


Grinded the welds:


Then i marked the place for top post, it`s from GM 10-bolt rear brakes:


Drilled a 5/8" (16mm) hole for top pin:


Marked a place for brake cylinder:


The i used my hand drill and 1.5" (38mm)holesaw:

 

ok so far so good....

 

Drilled:


Then i drilled smaller holes for cylinder mounting bolts:


Then i had to make some room for brakecylinder, i drilled two 3/8" (10mm) holes:


Then i cutted the piece off:


The brakecylinder was too close to backing plate, shoes wouldn`t be in line with cylinder, so i made a 1/4"(6mm) plate under cylinder:


Next i drilled same holes to 1/4"plate as i did for backing plate:




Back side:


Top pin wasn`t in line with shoes, so i had to make there another plate of 3/16" (4mm) steel:

 

Plate under top pin:




Spindle in place:


Next to the lower section, there is not enough room for star adjuster. So i marked cutting lines:


Cut off the piece:


I sectioned it 5/16" (8mm) to make room for star adjuster:



Pieces welded together:

 

Lower section welded back in place:





Then i made 6 little pads(1/4")(6mm) under the brakeshoes, i checked the places from -46/-48 backing plates. -46/-48 backing plates have little higher pads (5/16", 8mm) but i didn`t have that material at home, so i used what i had:



Round spindle fits:


Tight fit:


Square spindle fits better:



Star adjuster fits too:

 

Great tech post. What wheel cylinder are you using?

 

Shoes are in right hight for top pin:




I haven`t got all parts for final test fit, missing all springs at the moment.
Brake parts are from -71 to -76 GM big wagon rear brakes except brake cylinders, they come from some Ford. I will post later the list of parts and i can take some measures for drilling backing plates.
I`m going to use buick drums (45 fins) with original buick hubs, and my friend is going to make me some adapters next week for that conversation. I`ll post some pictures when i have all parts at home.
Sorry for my bad english, it has been so long time since school.

 

Are you using self adjusting hardware? Also seems the center retaining pin positions are going to need to be refined a bit.

 

Yes, im using self adjusting hardware. I managed to found those new parts here in Finland, i`ve heard that 12" self adjuster arms are difficult to find even in USA.
-39/-41 backing plates don`t have holes for center retaining pins, i`ll have to drill them when i get my pins.

 

The reason I asked about the adjusters is that there is no place to put an adjustment slot. One idea I had was to have the reinforcement plate at the bottom of the backing plate removable with one of the dummy adjuster bolts retaining it and the other attached to the plate to allow for a hidden slot.

 

I found that the self adjusting stuff does not work with the alum drums. I took them off. The drums would get hot and expand and the adjusters would take up the slack and then drag.
I think you might need a bigger wheel cylinder. I would get one from front brakes that has the tab that the anchor pin goes thru. Solves two probs at once. I wrote the original article on converting backing plates.
I like the way you added tabs for the shoes. I did not think of that and used 46-48 plates. What you did is simular to what I did otherwise. Excellent work!!!!!! Much better than mine!

 

I will add this. I took my stuff off and went to F-1 brakes. They are loose on the floor if you would like any pics.

 

Thanks Andy.
Those cylinders are fronts, i think they were 1 1/8".
I have read your post many times before i started mine.
Too bad if those self adjusters dont work with alum drums, didn`t buick use self adjusters at 60`s?, my 60 cadillac has self adjusters.

 

NOw that is what tech week is about, Actually doing something and teaching others too, thanks for sharing

 

Excellent step by step information.

 

Great tech.Thanks for posting.
Mark

 

Great post! Nice and clear, you make it look so easy, even a cave man could do it...

 

Now this is interesting.Going to be watching for updates on this.

 

funny, I was sitting here thinking that you are doing a pretty good job. I work with guys that have worse English and grammar skills than you.

great post!

 

Good photos give more value for this post!
No problem with your English skills, at least I understood it.

 

If you don`t use self adjusters, that would be a great idea to hide a slot. It took me a little time before i understood what you ment

 

Andy, what issues made you decide to switch over to the F1's?
You would think that with a larger diameter and now self-energizing that the older setup would outperform the F1's.
Was it simply the irritation of constant adjustment or is there a performance difference with the smaller, but I think wider, F1/F100 series of brakes?

This conversion looks great! Nice work siipiveikko!!!

 

thanks for that...might even give it a go

 

This is great!! Nice tech article.

Another thing to think about is access to the adjuster, just in case something goes wrong. I've had to go through the cutoff in the backing plate to back off adjusters more than once.

 

Wow ! that is really cool , Thanks

 

Excellent tech article ! Totally bad ***!

 

If this set-up is going on a light weight car, the 1 1/8" bore wheel cylinder will translate hydraulic pressure into plenty enough force to apply the brake shoes to the drum. This is, after all, a Bendix duo-servo brake system - far superior to Ford's dual anchor system you are replacing.