Brainstorming and info about late model disc brakes with "drum in hat" parking brakes.
These brakes come on 3/4 and 1 ton approximately 2000->present? GM 2500Hd and 3500HD trucks and I think also on some similar vans. I don't know all the exact models and what variations may exist, I think the list is quite broad, this is a very widely used disc brake setup.
The ones I have and the pictures to follow are from a 2007 model single wheel GM axle. More specifically an American Axle Manufacturing "AAM" 11.5" axle.
They would also come on the AAM 10.5" (new revised version of the old 14 bolt) and I think on some GM Dana axles that may be used in vans.
This is the axle as I found it in the junkyard. PICTURE 1
The whole axle is too wide for my truck, thus I want to only swap the brakes onto an axle that is the width I want. PICTURE 2
I'll use single wheels but just for fun/curiosity sake I test fit with a dual type 19.5" wheel, the dual wheel won't fit over this single wheel brake/axle setup. PICTURE 3
However brakes from a Dually axle (longer/taller rotor) should fit.
Couple pictures of the parking brake cables, they exit the rear and then turn forward. PICTURE 4
and PICTURE 5
The rotors are 13", and uses quite large double piston calipers in a carrier which then bolts to the caliper bracket bolted to the axle tube flange. PICTURE 6
The rotor just slides over the hub. Bore in the rotor is 4.834" (Excuse the grease from a bad hub seal) PICTURE 7
The hubs while very similar to the old 14 bolt will not interchange, the bearings are 1/2" closer together. From what I read if the (later model) axle has slide off rotors or drums it should have the short spindles, 4-3/4". PICTURE 8
The flange on the axle tube is slightly strange shaped, larger and different than the familiar square pattern found on Eaton and 14 bolt axles for years and years. PICTURE 9
The flange also has a pilot about 1/8" long to center the caliper bracket. The diameter is 3.807" this fits in a 3-13/16" bore in the bracket. PICTURE 10
The non symmetrical 4 bolt flanges are welded on the axle tubes in weird orientations because they do use the same caliper bracket on both sides, not mirror images. PICTURE 11
The following shots show those angles.
Start with the spring pads dead level. PICTURE 12
Drivers side flange has the widely spaced holes on top and it is tipped back 22° PICTURE 12
Passenger's side flange has narrow spaced holes on top and tilted forward only 8° PICTURE 13
Next I need to figure out how to adapt these brakes to a 14 bolt axle and maintain about 63" width over the wheel mounting surfaces.
To start with I'll have some flanges burned out and I'll machine the pilot on them. They can be very carefully welded on the axle of choice. (originally the flanges were welded on and then machined true)
For an expensive bolt on bracket solution for some 14 bolt axles look at picture and read the article titled "Affordable 14-Bolt Disc Brake Conversion" part way down the page here: http://www.fourwheeler.com/product-reviews/129-1107-july-2011-parts-rack-new-products/
At one time and perhaps still offered by Right Gear and Axle
though not found on their website. Occasionally found listed by them on eBay
For some discussion and pictures of adapting this disc brake setup to the old Eaton axle check out this in the "Truck Parts for Sale"
Lots of good info in this document on installing the kit from Dave Chapman at The Hollister Road Company Install Doc