Something doesn't seem quite right (rear brake cylinders)

[slixtyfive]

This just doesn't seem right - the amount of interference between the bracket on the backing plate and the rubber 'sleeves' on the brake cylinders. I'm using '71 backing plates and brakes (eventually) to get the wider rear drum brakes. I asked for '71 cylinders but quite honestly, relative to this particular aspect i don't see any difference compared to the '65 backing plates. If i put these cylinders on the '65 backing plates, I think i would have the same conflict......

[URL=http://s1021.photobucket.com/user/slump69/media/100_6679_zps6e0467c8.jpg.html][/URL

Is the 'conflict' normal? Thoughts/comments? it looks pretty much the same on both sides.

[banjopicker66]

I realize this does not answer your question, but are you aware that you cannot use the '66 half axles (axle shafts) with the '68 - '79 backing plates?

[banjopicker66]

If I may volunteer my experience, I put '78 brakes on my (original) '66 axle housing. Well worth the trouble, too. The difference was really significant!

By the way, all my information applies only to a Ford 9" axle. I have no experience with the Danas that were available.

I used '78 backing plates, wheel cylinders, brake shoes. springs, adjusters and everything else affixed to the backing plate.
'73-'79 half axles are too long for the '56-'72 axle housings.

I used '78 drums, but had to waller out the stud holes. The reason - the '72 and earlier drums have a larger stud hole made to fit over a shoulder on the stud that protrudes out of the face of the half-axle. See the shoulders sticking out in your photograph? The '73-'79 studs do not have a protruding shoulder, so the stud holes punched in the face of the later drums are too small to fit over the '72 and earlier studs and their shoulders. If I had purchased '68-'72 drums, there would have been no problem.

The axle shafts almost threw me. Although the '56-'72 rear axles all both right up into the truck as a complete unit, the internal half-shafts are different.
In '68, Ford widened the rear brake shoes, which means the drums stick out more from the backing plate, which further means the half-shafts must extend further from the backing plate.
If you use '66 axle shafts, they will not extend out from the backing plate enough, and will bind the drum against the backing plate.

One more thing - the '68 and later wheel cylinders have a larger bore. It requires more brake fluid to activate them and more brake fluid to get sufficient pressure on the fronts - discs or drums. The original master cylinder does not have a large enough bore to supply enough fluid under pressure and safely use the later brakes. You will be double pumping the brakes much of the time. I wouldn't recommend installing the newer brakes until a later dual reservoir master cylinder is installed and working.

To summarize.
In my opinion, using the '66 axle housing and installing the later brakes is the best way to go, but only after or in conjunction with a dual reservoir master cylinder upgrade.
Use '68 - '79 backing plates and hardware.
Use '68-'72 half axles and drums.

Hope this helps.

[Blackwaterforge]

Could you have installed front cylinders on the back by mistake?

[therealjoeshmoe]

mine have been like that ever since i can remember i think thats just the ay they are

[slixtyfive]

Banjopicker
I've heard both ways on the axles. Based on the measurements I took, it looks like the originals ('65) will work. The '65 backing plates are basically flat while the '71 backing plates I used are 'cupped' more so the extra width for the drums/shoes goes toward the middle of the truck (around the housing tube). But I do have a later rear with axles if it doesn't work out. I am also upgrading to disks on the front and thus a dual res MC.

Blackwaterforge
I'll have to check that. I asked for rears but I can't say for sure that is what they sold me......

[longcabjohn]

That looks right, that is to keep the piston from blowing out in case off failure.


Johnny

[slixtyfive]

I checked the part numbers and they are correct for the rear.

Here is a picture of the '65 backing plates to better show the offset i was talking about compared to the '71 backing plates in the picture in the original post above.