Disc back to drum retrofit?

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smallfoot

He's rockin' the "Nuttin Special"!
Joined
Nov 15, 2013
Messages
7,210
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Flawda Flats
OK guys, I'm going to hit ya'll up for the real deal. I've been researching info on a rearend/brake swap. Unfortunately, most everything I see is upgrading from drums to disc brake. I'm going the other way unless somebody tells me different. The rearend in my build was a 1995 stock 2wd 7.5 s10 rearend with drums. I put all new brake parts in this when I put it in the truck. I found a 2002 s10 blazer 2wd rearend with disc brakes, locking rear, and 3:42 gears. My question is: can I swap my drum stuff onto this newer disc rearend. Like I said, most info is covering going the other way so it's got me somewhat confused. Looks like all mods done on the swap going the other way has to do with the disc rears fitting to the older drum axle setups due to the ebrake differences. That should mean going this way would not require the mods. Axle assembly widths are the same....54.7" wms to wms. The only reason I don't just swap it out completely is the idea that I might not have the hydraulics to operate discs and the question of how that setup would work with drum front and disc rear. I've always heard the front should do most of the work for stability during hard braking. I do have an adjustable proportioning valve where I can control pressure to the rear circuit. I'm just wondering if I can make the total swap and get things right enough for good braking. My other concern is I have all new parts in the drum rear. Drums, wheel cylinders, shoes,...etc placed new when I put this rearend in. The rotors and pads need replacing on this disc rear but that's not really a problem if this setup would work. Anybody have experience going backwards on this...???[S
 
No experience... but, if your measurements from flange to flange (the backing plate flanges) are alike, I'd expect the drum assembly to bolt on. (Assuming the bolt pattern is also alike.)

I would definitely try to fit the drums, especially because your existing system is built for their volume and pressure.
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I'm in agreement with Dr C
If the two axles have the same flange offsets, backing plate face to drum mounting face, then it should work. (BS measurement in the diagram)
If the backing bolt pattern is different then, you should be able to re-drill to make it work.
Another place to check dimension is the centering flange on the end of the axle to the diameter of the hole in the drum. If the drum has a smaller diameter hole then it can be enlarged [P
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Thanks Dr.C and Old Iron! That's what I was hoping too! Along with ya'll I was visualizing it working. I had same measurements everywhere until I got to the axle tube end that protruded past the flange. This issue rights itself with the differences in the backing plate shapes. The only other differences noted were the lengths of the flange bolts(longer on the disc brake rear for the additional thickness of the Ebrake bracket) about 1/2" difference so I just swapped the bolts from the old one to the new. The pinion/u-joint is same. Assemblies are centered. There are differences in some of the brake line fittings which will be negated when I swap everything from the drum rear. The disc brake lines have short rubber sections before entering the cylinder, but there is enough coil armored steel line if you want to take the time to unbend it here and there.
I need to pick up some more seals, cleaner,paint, gear oil, some gasket stuff too tomorrow so I can go on with it. Took a shot of the G80 carrier and the passenger side drum brake in place on the disc style rear. In my studies, i found some differences of opinion on the GOV-LOCK differencial....looks like they are a weak link if hotrodded. OK officer....I'll keep it down...:D

 
I'm glad it worked out for ya! [cl

I wouldn't be concerned with the gov-lock. It'll do fine until you overwhelm it with weight and fat-tire traction... neither of which seem an issue with your build.

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