Drum brakes for ZR2 axle?

[Zenwren]

I've run into a bit of a snag with the axle swap into my 1949 3100. I have an axle from a 2000 ZR2 Blazer and was hoping to swap it over to drum brakes. I don't like the parking brake setup that GM devised for rear disks and my truck is already set up for rear drums. The problem I've run into is that the backing plate mounting tab is about 11/16" inboard of where it would be on a normal housing (see pictures, ZR2 with axle shaft, vs '78 Camaro which is missing the axle but it sits in the same place as the ZR2) I'm thinking I may get by with installing the '78 Camaro backing plates for standard 9.5x2" drums that I already have and mixing and matching hardware to put early 70's GM FRONT 9.5x2.5" shoes and drums with a 3/16" spacer between backing plate and axle housing plate. Does anyone know why this wouldn't work? The inner profile of the front shoes appears to be the same as the Camaro shoes. The hub hole in the drum is the same, the only concern I have is getting the wheel cylinder in the correct place if the inner rib of the 2.5" shoe is centered (bringing it out an extra 1/4"). Am I over thinking this? I'm about to just go buy some parts from my local parts store and see what I can make fit unless someone has a better idea?

[mongocanfly]

I think your overthinking...id just leave the disc brake setup...but that's just me...theres nothing wrong with the zr2 e-brake.. the e-break on mine holds good

[Captainfab]

I would keep the disc brakes too, but that's my personal preference too.

A larger brake offset is typical with most differentials 1988+. Is the backing plate bolt hole pattern the same between the ZR2 and the Camaro differential? You can put a spacer between the backing plate flange and the backing plate, but it should be machined to register on the step in the backing plate flange and also it will need a step machined to locate the backing plate from the center hole.

[b454rat]

The early versions of the ZR2 had drum brakes. Thinking 94 and 95....

[mongocanfly]

disc became standard in 98....according to the net...I didnt know this...I thought all zr2s had discs....

[Zenwren]

Originally Posted by b454rat

The early versions of the ZR2 had drum brakes. Thinking 94 and 95....

Looking at Rockauto it seems like the earlier drum brake offerings were the same as any other S-10 brakes. I suspect the spacing will be different on those axles as they use the standard 2" wide pads. If I had any faith in finding an early ZR2 in a salvage yard to take some measurements I would but from hunting the one I have down I know there isn't one in a salvage yard within 200 miles of me.

I may just be being stubborn here but I really like my drum brakes when it comes to a simple reliable parking brake. That and still having flashbacks of my dealer mechanic days fighting to get those goofy rotors off and having the parking brake shoe come out in rusty chunks. The axle I have didn't come with any of the brake components so I'm also getting a little sticker shock at the cost of new pads, shoes, rotors, calipers, hoses, and proportioning valve. That said, no one said this hobby was cheap. I'm just hoping there is a better solution here.

[geezer#99]

I’m surprised you’re using that zr2 reared considering how wide it is!

[Zenwren]

Originally Posted by geezer#99

I’m surprised you’re using that zr2 reared considering how wide it is!

I know, I went round and round with the tape measure on this one. I have a stock '50 3100 and measured 61" between wheel mounting surfaces. The ZR2 I have measured 62". I got 16x6 rims will 4" back spacing and it ends up being about 1/2" wider overall. That coupled with the disk brake kit up front that supposedly widens the front by 9/16" I'm around 1/4 wider in each wheel well which is pretty minor on those cavernous fenders.