Rear Drum Brakes...assembling backing plate

[mattt]

I'm putting back together a set of 10 x 2.5 "medium duty" rear drum brakes. I spaced it and didn't take any pics before taking everything apart. I can figure it out by trial and error, but have a few questions about what I have here.

It looks like this thread has a good write up for how it goes together. That was the best I found when searching. Thank you ILikeBond!
http://classicbroncos.com/forums/showthread.php?t=214838

What I'm questioning is if all Bronco rear drum brakes had spreader bars? There were none in this brake set I picked up from another member. I suspect these brakes had been messed with in the past because only one side had the small adjusting cable in there too. Both sides should have the cable that goes from bottom adjust bracket up to the top post, correct?

What is the purpose of the spreader bar...is it for normal braking or just for E-brake? I think I have some spreaders around so I plan to add them back in.

I looked inside the drum of my original 69 small bearing rear axle and the assembly is different. There are no adjusting cables going from bottom up to top. I thought I could use the small bearing 10 x 2.5 as a guide but they're different. Is the difference because of year differences, 69 vs. 74-75 or is it big bearing vs. small bearing differences?

I'm cleaning up all the parts before putting the brake backing plates back together. Some parts have no....or no more paint and have surface rust. Is it typical for brake parts inside the drum to be painted or raw?

If there are other write up's for how all this crap goes together, besides the one I linked above, it would be much appreciated when posted. Thanks.

 

[Viperwolf1]

All rear drums had the bar. That is what actuates the shoes with the park brake. All had the cable also except maybe the very early ones without auto adjusters. The setup is the same regardless of size.

Springs were painted to prevent rust. You can buy them new and I recommend replacing them if they are questionable. You could do the old drop test on them. Drop them on concrete. If they land with a dull thud sound they're ok. If they have a springy sound they're stretched out and bad.

 

[mattt]

Thanks Viper...always great info! The "drop test" huh...ha ha. They pass the drop test....no springy sound and some of the paint remains on the springs, 1 red and 2 blue per side.

Is there any good reason the previous owner might remove the spreader bars? I'm thinking no mechanical reason, just didn't put them back in when brakes were done or something like that. What I probably don't have after looking at the exploded diagram is the spring for the spreader bar. Are those available separate or with a "spring kit?"

I'm guessing the rear axle in my 69 is not original because it doesn't have the same style self adjuster. There is something going on at the bottom with a smaller diameter spring bridging from one shoe to the other. This rear axle also has a back fill plug on the housing which I think was pre 69...maybe the whole axle was swapped in the past.

 

[thegreatjustino]

I just did this a couple of weeks ago. As was said, the rears all had the spreader bars for the parking brakes. If you look at a set of front drums, there's no spreader. Knowing what a pain it is to assemble everything correctly when you haven't done it before, I'd suspect that a previous owner put everything together without the spreaders, then realized he'd have to take most everything back apart to put them in, and decided to just leave them out.

 

[Golfball]

I just did the rears on my 75 last night and it has the 10" brakes. You could get either 10" or 11" brakes for several years.
And, yes, you should have the adjuster cable and spreader bar.

 

[smokinjoe]

I though the only difference between the different years/sizes was the surface area of the shoes and the width of the drum. Is this correct?

Isn't the hardware, wheel cylinder, etc the same?

 

[75junebug]

Differnce in Hardware?........I dont think so. The cylinders are different(choice of three) depending on yr/size

 

[Viperwolf1]

Those spreader bars would be different lengths for the different size breaks. Adjustment cable probably is different also. Springs and other hardware maybe the same.

 

[thegreatjustino]

I though the only difference between the different years/sizes was the surface area of the shoes and the width of the drum. Is this correct?

Isn't the hardware, wheel cylinder, etc the same?

Nope, 10" diameter or 11" diameter and three different widths.

 

[707Bronk]

I'm kind of in the same boat. Sorry to hyjack, but this info should helpful to the OP as well.

I'm building a 76/77 rear axle to replace the stock 71 sm bearing axle. I have a new 76/77 housing and the right axle shafts, and a set of 76/77 drum backing plates. But, I need new drums, shoes and everything else.

I was planning on buying a new spring kit and new wheel cylinders, but not sure if the spreader bars and auto-adjusters from the 71 sm bearing will work on the 76/77 brake setup.

It sounds like my 71 spreader bars won't work on the 76/77 brake setup. Can anyone confirm this?

Are the spreader bars available at auto part stores?

 

[broncojo]

I believe as long as the diameter is the same then the springs, adjust cable, adjuster, and spreader will work. The brake pins holding the shoe may be different if your width is different.

 

[thegreatjustino]

71 small bearing would be 10" brakes, and the spreader bars will be too short for the 11" brakes on the 77 setup.

 

[mattt]

I started putting these brakes together today and I may have the incorrect spreader bar. The spreader bars that were sent with the drum brakes I bought here have Bendix # 316274 stamped on them. Anyone know by the #, is this the correct spreader bar for 10" brakes? It appears too long....by you guessed it, about an inch.

Anyone have some 10" brake spreader bars for sale or want to trade for what are probably 11" brake spreader bars?


On a hunch, I pulled the drum off my old small bearing rear axle which I believe has the same 10"x 2.5" drum brakes. The spreader bar is shorter and the front forks on it are angled down. On the spreader bar I have with the brakes I'm working on, both forked ends are straight. I would assume both(small bearing & big bearing) 10x2.5 drum brakes use the same spreader bar? Worse case scenario, I guess I could rob the ones out of the small bearing rear axle.

Anyone know of another application besides Bronco that uses 10" brakes? I'm hoping to find something tomorrow either at parts store or junkyard.

Spreader bars I have look like this with straight fork... http://www.tomsbroncoparts.com/images/products/1430/2536.jpg

 

[thegreatjustino]

When I assembled the set I mentioned above last month, I cannibalized a couple of sets of used 11" brakes I had in the garage from non Bronco applications. All four of the 11" spreaders I had looked the same (like the one you posted the link to) regardless of application or width of the brake shoes.

It seems like using the 10" small bearing spreaders on the big bearing 10" brakes would be the easiest solution. Of course, you'd need to track down another set of 10" spreaders if you ever wanted to use the small bearing brakes again.

 

[mattt]

I found some 10" spreader bars at the jy the other day. First generation Explorers have 10" rear drums. Every truck I looked at had 11" brakes, so no luck with the trucks. I searched here prior to heading to the jy and saw some reference to 10" brakes on some Rangers or Bronco II's. Every Ranger I saw had 9" brakes and didn't see any B-II's. Once I got these 10" spreaders home, I saw an obvious difference that may or may not be an issue. The relief, or step back on the inside edge of the bar is less on these Explorer spreaders vs. truck spreaders. I have installed the 10" spreaders on my backing plates and the inside edge does not touch the backing plate, but it is close. I could clearance them a little bit too. Anyone have an opinion if these will work? I know it's pure speculation at this point.

One additional question....quite a few of the brakes I looked at had this washer(pictured next to spring) in front of the spreader bar spring. It looks like Broncos didn't use it originally. Is it best to use the washer in conjunction with the spring, or leave it out and let the spring contact the shoe directly? I have 2 pair of spreader bar springs, one with tighter wound spring, and one with fewer wraps per inch on the spring. Since I don't know which spring the Bronco used, it's another guess.

 

[Golfball]

That washer is the retaining washer and you need that to keep the spring from bending around the shoe basically, you can go without but use it if you got it. The spreader bar on top looks more like the one on my 75 but mine had a slight hump in the middle. I will see if I have a picture when I get home and post it. Mine were Wagner though, not Bendix.

 

[thegreatjustino]

All the drums I've taken apart had the washer with the spring and spreader. I'd use it.

 

[dave67fd]

Here's a few pics that may help.

 

[mattt]

Thanks for the pics. Here is a pic of the odd spreader bars in my small bearing rear axle. Notice the bent down fork ends and no washer at the spreader bar spring.

Golfball....thanks for the offer on the pics of what they should look like. I'm interested to see if they look like the ones in my small bearing axle. I was thinking....it might be best to take the spreaders out of the small bearing axle and lay them over the 10" Explorer spreader bars I have for a pattern of where to trim the Explorer spreaders. Like I mentioned, the Explorer spreaders don't contact the brake backing plate when assembled, but they are very close to it.

Thanks again guys.

 

[bronco t]

I have always put the washer on towards the shoe as it keeps the spring centered.