Do swaps change wheel fitment?

[BirdsThaWord]

On a '68 Firebird, if you change from drum to disc on the rear, would I have to get new wheels? I just bought the wheels and they fit great! Wouldn't want to go down that road if I didn't have to. Can the mounting bracket be built so that the wheels end up where they are now?

[GenPac]

On a '68 Firebird, if you change from drum to disc on the rear, would I have to get new wheels? I just bought the wheels and they fit great! Wouldn't want to go down that road if I didn't have to. Can the mounting bracket be built so that the wheels end up where they are now?

The difference in track width for the rear axle when swapping from OE drum to disc is the difference in thickness of the OE drum vs. swapped rotor at the hub flange. So, generally, less than 1/16" of increase per side, depending on the material of the rotor hat.

Rear brake swaps do not affect the placement of the axles so the only change is what's bolted to the axle flange.

Your biggest concern should be if your new shiny wheels will fit over whatever discs you want to go with and if that brake package will interfere with your suspension at all.

[BirdsThaWord]

The difference in track width for the rear axle when swapping from OE drum to disc is the difference in thickness of the OE drum vs. swapped rotor at the hub flange. So, generally, less than 1/16" of increase per side, depending on the material of the rotor hat.

Rear brake swaps do not affect the placement of the axles so the only change is what's bolted to the axle flange.

Your biggest concern should be if your new shiny wheels will fit over whatever discs you want to go with and if that brake package will interfere with your suspension at all.
If there's only a 1/16" difference then i think I'd be o.k. The new wheels are 18" and I'm not thinking about really big brakes. Just a decent set of discs, something like these: http://www.getdiscbrakes.com/RSeCommerce/ProductDetails.aspx?mName=AFXRD05&source=List Suspension wise, I don't know yet. I may just be simple and go with the Eaton lowering leafs, but may end up going with a Morrison 4 link. Hope that stuff would clear!

[TnBlkC230WZ]

Those calipers should work. The caliper will not stick out past the rotor. I will say those GM calipers are the worst calipers in the world to bleed. Most brakets clock the calipers so the bleeder is not at the highest point. Makes bleeding them a real chore.