Rear drum brakes

[Jdgephar]

I went through the rear brakes on my 72 yesterday. When I put the new drums back on, I thought they would go on a little farther. It makes me wonder if I have the wrong setup on this axle.

Its a big bearing 9". No idea if it is stock to my 72. All of the parts I took off are the big bearing 11" drums and shoes for a 72, and I believe the backing plate is for the same. Bolt pattern for the axle matches the old style big bearing for 72.

Here are the pics. Does this look correct, or do I have some mis-match of parts? I'm used to the drum overlapping the backing plate a little bit more. Now, if it bolt up the drum, its about even.

Sent from my SM-G950U using Tapatalk

 

[SHX669]

Does the center hole on the new Drum have to slip further over the " lip " on the surface of the axle flange -- ?

 

[tpatton75]

Are shoes for 77 they are wider

 

[Timmy390]

Maybe it's just the picture....but that axle looks like it's not all the way in. Did you put new axles bearings on? Maybe it's not all the way in position. I recall my axle being in so deep the back of the wheel studs almost touch the E-brake spreader bar.

Also, there is a left and right axle.......2 inch difference as I recall?

Just thinking outside the box.......

Tim

 

[Justafordguy]

If the drum is all the way up against the end of the axle and still outside the backing plate lip then those are the wrong drums.

 

[Jdgephar]

I was wondering about the axle being all the way in. I did not change the bearings. The axles just came out of the tube when I pulled on them. Likewise, they just pushed back in. I smacked the ends with a mallet just to make sure they were all the way in. I had no issue bolting up the axle retainers. Axles are on the correct sides, they stick out the same.

Sent from my SM-G950U using Tapatalk

 

[Master Chief]

I went through this on mine until I figured out that I have ‘76 axles. Looks like wrong size drums but this may help ...

https://www.wildhorses4x4.com/category/bronco_rear_axle

 

[Jdgephar]

Thats what i have been referencing so far. I'm thinking if I measure from flange to flange, that would tell me if the bearings are all the way on the axles, and all the way in the housing, correct? 58" should be my measurement, right, or is that just the tube flange, and the axle would be longer?

Sent from my SM-G950U using Tapatalk

 

[Master Chief]

If you kept your old drums, just measure the difference between the new and old.

My guess is you have 1.75" drums and need the 2.25" ones. In other words, at some point, I bet someone installed a '76-'77 rear end, like they did to mine. I am fortunate that they did both front and rear from the donor.

 

[jamesroney]

I hope that you are not using the reference in the link above. That article has been goofy for many years. The guy that wrote it knew exactly what he meant. But it can be interpreted horribly wrong.

The confusion comes from the fact that there are 4 pictures labeled 1,2,3,4 and 4 descriptions labeled 1,2,3,4.

Those pictures do NOT correspond to the descriptions.

Sure, there are 4 different back plates, but there are only pictures of three back plates!
Photo #1 is indeed small bearing, and matches description #1.
Photo #2 is 66-75 big bearing, 11x1.75 and matches description #2.
Photo #3 is 76-77 big bearing, 11x2.25 and matches description #4.
Photo #4 is a picture of some axle splines.

There is no picture for description #3 for big bearing, 10 inch drum, 74-75 medium duty.

That being said, it looks to me like you have a 76-77 drum paired with a 66-75 back plate.

 

[Jdgephar]

Just to recap what I know:
1) I have the '72 big bearing axle housing. It matches the "big Ford" (old style) bolt pattern shown here:

2) All of the parts I removed are the 11x1.75" 1972 big bearing drums (this doesn't mean that they are correct, but that's what was on it). Both the shoes and the drums are the 11 x 1.75".

3) The backing plate, to the best of my knowledge, is also the 11x1.75" 1972 style.

When I have some time this weekend, I'll pull the axles back out and see if the bearings are seated all the way on the axle shaft.

Is it possible that the axles were replaced with 76-77" style? Would that push the axle out farther (which allows the 11x2.25" brakes to work)?

I didn't mention this before, but the center section does have an aftermarket limited slip installed. Could that be preventing the axles from installing all the way in? I believe it is a Truetrac.

I'm thinking that to properly fix this, assuming the bearings are installed properly, I need to either replace the axles, or replace everything from the backing plate out. But the backing plate for the 11x2.25 brakes wouldn't fit on my axle housing, since the 76-77 bolt pattern is different? That leaves the only possibility that I have the wrong axles if I'm thinking about this correctly.

 

[EPB72]

if need be I can take measurments of mine its a 72 big bearing/bolt 11 by 1.75 its all apart now but the wheel is on ,but I can do that tomarrow

 

[jamesroney]

What is the distance from the Wheel Mounting Surface (WMS) to the axle housing flange?

The brake offset, or axle offset is either 1.86 (72 BB) or 2.36 (76-77 BB)

Also, What happens when you put your old drums on?

https://www.wildhorses4x4.com/product/Wilwood-Dynapro-Lug-Mount-Rear-Parking-Brake-Kit-66-75-Lg-Bear-Bronco-with-drums-15in-Wheel-Bl/wilwood-brake-kits-rear

 

[Jdgephar]

What is the distance from the Wheel Mounting Surface (WMS) to the axle housing flange?

The brake offset, or axle offset is either 1.86 (72 BB) or 2.36 (76-77 BB)

Also, What happens when you put your old drums on?

https://www.wildhorses4x4.com/produ...h-drums-15in-Wheel-Bl/wilwood-brake-kits-rear

I think it has the wrong axles. Offset is about 2-1/4 from the backing plate to the drum mating surface.

Sent from my SM-G950U using Tapatalk

 

[Jdgephar]

I have two options at this point.

1 - swap the axle shafts to a 72 style.

2 - I have all of the parts from a full width 9" that will fit on the housing. However, that leaves me quite the mix of parts...72 housing, 76 axle shafts, and ?? year 11x2.5" F1?0 drum brakes. I don't know if these are considered 2.25 or 2.5" wide. The larger brake surface might be nice with my 35" tires. This setup also has the missing parts I need for my parking brake...

However, I think I would rather just swap the shafts so I don't have to forever remeber the mix of parts...

Anyone have a set of axle shafts they don't need? I need 28 spline big bearing for a '72. I have other 9" parts I could trade. I also need the parking brake spreader bar if someone has it (otherwise I'll just order them).

Sent from my SM-G950U using Tapatalk

 

[suckerpunched]

I don't believe changing the axles is the answer. I think you probably just need 2.25 drums and shoes. I have swapped out skinny brakes for wider ones. you have to change backing plates, drums, shoes and maybe some other hardware to do it, but not the axles. The backing plates intended for wider brakes have a deeper pocket stamped into them where they fit over the end of the axle housing giving clearance for the wider drums.

also a decent parts house does not need to know the application to match you up with the correct components in the future. they should be able to tell by looking at the shoes that they are Bendix brakes and are 11 x whatever, they are not specific to the make of the vehicle. and the drums are a mater of bolt circle, center hole diameter, brake diameter and brake width.

another thing you might be able to look at is the way the push rods in the wheel cylinders line up to the shoe. It is my belief that if the you have a narrower shoe than what the backing plate was designed for, the center line of the shoe would be closer to the backing plate, throwing off the alignment of the center of the wheel cylinder bore to center line of the shoe.

Or I might be full of shit on all this but I think I am not

 

[Viperwolf1]

I have two options at this point.

1 - swap the axle shafts to a 72 style.

2 - I have all of the parts from a full width 9" that will fit on the housing. However, that leaves me quite the mix of parts...72 housing, 76 axle shafts, and ?? year 11x2.5" F1?0 drum brakes. I don't know if these are considered 2.25 or 2.5" wide. The larger brake surface might be nice with my 35" tires. This setup also has the missing parts I need for my parking brake...

However, I think I would rather just swap the shafts so I don't have to forever remeber the mix of parts...

Anyone have a set of axle shafts they don't need? I need 28 spline big bearing for a '72. I have other 9" parts I could trade. I also need the parking brake spreader bar if someone has it (otherwise I'll just order them).

Sent from my SM-G950U using Tapatalk

I would pick option 2. You will end up with all '76-'77 parts. Easy to remember.

I don't believe changing the axles is the answer. I think you probably just need 2.25 drums and shoes. I have swapped out skinny brakes for wider ones. you have to change backing plates, drums, shoes and maybe some outher harware to do it, but not the axles. The backing plates intended for wider brakes have a deeper pocket stamped into them where they fit over the end of the axle housing giving clearance for the wider drums.

It won't work. The '76-'77 drums and shoes are not compatible with his old style heavy duty backing plates. The brake offset is also different between the old HD axles and the '76-'77 axles.

 

[Jdgephar]

I would pick option 2. You will end up with all '76-'77 parts. Easy to remember.

Thanks Viper! I'll try these parts with a new set of 2.25" shoes.

 

[Jdgephar]

Thanks for everyone's help. Here's what I ended up with...

I swapped the backing plates to another set that I had from an F150 axle. I was also able to get the parking brake pieces that I needed from this axle.

This allowed me to use all of the '77 parts, the shoes, drums, etc. Now everything on the rear is '77 big bearing parts.

Thankfully, it only cost me a new set of shoes and drums.

If anyone needs backing plates, shoes and drums for an early style big bearing, I have no use for these. My '68 has the 10" brakes, so I don't need these parts.

Sent from my SM-G950U using Tapatalk