Rear axle flanges and rear disc brakes

So, I've got my rear axle all apart for a rebuild and figured that I should replace all of the brake parts while I'm at it. After researching and adding all of the various parts in my shopping carts on the rockauto and amazon websites I didn't end up buying.  I started revisiting the idea of a complete brake upgrade.  I know that there are no bolt on options for disc brakes but it has been done by the adventurous.

It appears that there is an option that would fit inside my stock rear wheels.  Wilwood makes a series of kits that use an 11 inch disc that would fit comfortably and they make a series that use a 12.19 inch disc that probably would fit and be tight.  Both of these kit types come with an integrated brake drum for parking.  Both offer several flange to hub offset options which would make it possible to keep the wheel in the original location. I'm considering the smaller disc kit for wheel removal and installation clearance.

It seems like the ideal solution except none are machined for the wagon's uncommon axle flange.  It looks like it would be easy to drill holes in the brake backing plate to match the axle holes as long as I order a kit with the right size axle hole in it.  Assuming that the kits for a 3.150 hole are close enough to my axle which I measured at 3.190 (but not super accurately since the brake plate is still on).

My options would be for Big Ford, Big Ford (new style), or 8.8 Ford Special as these all have the desired offset options, desired 5x5 wheel bolt spacing and the large axle hole (3.150").



Does anyone know which would be the better option? My main concerns is how close the bolt holes are to where the new drilled ones would be.  Ideally they would either be exactly where I need them or far enough away to not create a large oblong hole.  I can't find any accurate scale drawings of these to compare.  The axle pictures like the ones I posted are not to scale enough to be useful when enlarged.

Did you check with Navylifer on ISSF? he makes a kit for the B body.

I did not. I had been going through old posts on the ISSF forum and had only seen a big brake kit done by Navylifer. There also were a few other members big brake conversions. I like the stock look to the car so a wheel change is out. Somebody had even modified the sedan rear disk setup to fit the wagon but that looked like more trouble than it's worth and it isn't the right offset so the wheel can rub the outer wheel well. Somehow I think this small disc low profile kit from Wilwood would be the easiest and most stock like way to do it.

i think you have some incorrect info,.
disc or drum goes over the studs and wheel stays in the same spot,.
Bill has a kit that is simple,. it lets you bolt on a modified sedan backing plate and use a stock sedan rear disc,.with a parking brake.
Choosing to delete the parking brake opens up more options,.

Are you sure? I wish that it was that simple and inexpensive. Ideally there would be a disk/drum casting available like the sedan's but with the wagon's narrower offset. Since the sedan's original rear disks and drums have a larger offset something has to be moved. Unless the modified backing plate also has been significantly altered to move the entire useful backing plate area 1/4" closer to the axle, things won't line up.  You more likely need to add about a 1/4" spacer between the hub and the disk/drum to keep it from hitting the backing plate and align the drum portion with the shoes. I recently learned the hard way to appreciate the concept of disk offset differences. I just did the Astro brake upgrade on the front and unsuccessfully tried it without spacers.  The discs bound up and wouldn't rotate when the wheels were bolted on.

Also everything that Navylifer posts in his product thread says you need 17" wheels minimum.  Another one of his replies to a member asking about 15" wheels states

"The wagon axle design has less flange-to-flange offset than the sedan axle--so, basically, the sedan rotors will only work by spacing them out (specifically machined spacer and longer wheel studs) OR longer axle shafts--both methods which result in a wider track and reduced clearance with the wheel opening....or looking at it another way....more limited options for wheel and/or tire choice.

I'll respond with more specifics in the PM, but the WRDC (rear) brake kit will not allow use of 15" wheels, under any circumstance.

Then later he says that maybe it could work with 15" wheels but you'd still have to space the wheel out further at a minimum.

I can't really space my wheels further out without issues. I have 235/75 R15 tires on it and they take a lot of wiggling to get on and off as it is. With the one on the tighter side I have to pull out on the sheet metal a bit to keep the chrome trim from getting ruined.

Thanks for the replies. I'm probably going to just put the mostly worn drum stuff back on when I finish rebuilding the axle just to get the wagon back on the road. I should just be content with how much better the brakes are from doing the sherlock9c1/JaySS Astro brake upgrade in the front. By the time I absolutely have to replace the drums and shoes I'll be more certain with what to do.

Just a little trick that might help,. when you take your rear tires off, tilt the top of the tire towards you rather than the bottom, once it clears the studs let the rim down a little till its almost touching the drum,..so as you are removing it, the bottom of the tire actually goes towards the underneath of the car,..the tire needs to clear the ground by 6" or so before removing,.
It works for me,.

Chevy C10 pattern may be close, or even spot on. Those have an 8.5 rear axle with 5x5 lug pattern. I was actually going to use 9C1/SS rear brakes on my C10 in similar fashion to the "Wagon rear disc" swap, were you drill the mounting holes into the stock backing plates to mount them up. I believe the wagons have the truck pattern on the axle ends, but obviously I will confirm before making holes