Disc brake conversion pictures

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Here are some pics of the progress in converting my Unimog 416 axles to use common and available Ford F-250/350 disc brake components rather than the stock Mercedes drum brakes or the expensive Mercedes disc brakes.

That is a view of the naked reduction box end for the rear axle.. all existing drum brake hardware has been removed, and the stock mounting points can be seen. It is from these mounting points that the new caliper mounting brackets will be hung.

This is a view of the 416 reduction box as seen from the outside. The stock brake hardware mounting holes can be clearly seen. Also visible, is the face of the bull gear, with the 10 bolt holes and center locating recess. The green thing there surrounding it, is the grease seal. The inner surface of the grease seal, seals against the bull gear, and the outer surface of the grease seal, seals against a face on an recess cutout in the brake disc (or a sheet metal ring on the stock wheel adaptor) to keep out dust and most dirt. The center recess of the bull gear, clearly visible, is what actually locates the brake disc and or wheel adaptor in place.. having a good fit is critical.

Another angle view of the same end of the reduction box.

Here is a front side view of the wheel adaptor plate. This plate bolts to the bull gear with the 10 large bolts and is what actually allows mounting the wheel on the axle.

Here is a backside view of that same wheel adaptor plate. Note the center "LIP" that locates the adaptor plate on the bull gear, by fitting into the recess on the face of the bull gear. Also visible is the outer seal surface lip. This lip is stamped out of sheetmetal and just pressed onto the wheel adaptor plate. It provides a cover for the backside of the lug studs as well, to change a lug stud, if one were broken, you would need to remove this sheet metal cover to allow you to press out the lug stud, from the front. On my brake discs, this profile will be machined right into the disc, so no sheet metal cover thingy will be used. :)

Above is a shot of the bare, blank, rough machined brake disc. The only holes in it so far, are the two initial holes that allow me to fasten it to the D1-6 Lathe mounting plate. This allows me to secure the brake disc to the lathe for the first machining operations. Once the accessible side of the disc is machined, these holes are not used again. They have no bearing on the finished disc. (they are just extra holes then, not hurting anything or mounting anything)

Shown above is the D1-6 mounting backplate for my Monarch lathe. It will be bolted to the brake disc, and in turn allows me to secure the brake disc to the lathe spindle for machining.

Shown above is the D1-6 back plate actually bolted to the brake disc. The whole assembly is now ready to be mounted on the lathe spindle.

Here is the tranfer plate shown actually in place on the brake disc. The donut groove has been machined and the tranfer plate is located on that center lip. It is a snug fit so the holes should transfer very accurately. A transfer punch is show inserted into one of the holes.

Here is a picture of the layout fixture I made for transferring the 10 bolt holes onto the brake disc. After machining the layout fixture ring, I used the stock Unimog "wheel adaptor plate" to tranfer the bolt pattern to the layout adaptor plate, shown. That was a mistake!! The bolt pattern in the stock unimog wheel adaptor plate, was NOT concentric with the main locator lip.. in fact it was nearly 16 of an inch off. Ah well, live and learn (to never trust mercedes machining, and always double check) Here it show sitting on the brake disc with the holes having been transferred by transfer punch into the brake disc. the punchmarks can be seen.

Here is the disc, set up on the milling machine, having the pilot holes drilled for the 10 mounting bolts.

Enlarging the pilot hole in the disc to the finished size for the large bolt.

Testing the finished size of the hole, by dropping in one of the actual bolts to be used. a NICE fit. :)

Ah, the bolt holes are finally done! (so I thought, until I discovered that they were out of position and had to be enlarged oversize to compensate, due to mercedes' poor machine work... Yes I am ticked off and ragging on mercedes.. :))

Chamfering the bolt holes with a countersink tool. Makes for a nicer job. :)

Here is the brake disc on the lathe, secured to the mount, from the back, by those two bolts. In the intial machining operation I cut the donut pocket you see. The mounting holes weren't in there yet.. I ended up REMOUNTING the disc to the lathe after I finished drilling the 10 holes, because I had FORGOTTEN to inlet the center of the disc to clear the nut that secures the bull gear into the reduction box. OOPS! :) More to follow:

Here is the caliper I have chosen to use with the disc brake conversion for the 416 axles. It is a 1994 Ford F-250 4X4, Dayton dual piston caliper. They are large, strong and cheap. :)

Same caliper show with 12 scale

Caliper flipped over with scale

Caliper show with pads. These exact same pads fit from 1977 to 1994 F-250 so should be easy to get for a long time.

This view shows a shallow relief milling cut I made to the caliper to insure clearing the large diameter of the brake rotors I made.

Another view showing this shallow milling cut for clearance.

Some of the blank parts I used to make the caliper mounts. The starting material for this is 2 inch by 1/2 inch thick hot rolled steel bar.

Same parts show as they will be aligned for welding.

A nearly completed caliper mount.

Another view.

Still another view.

And yet another angle.

Tired of pics yet? :P

This is a front in shot of the caliper mount bolted into place on the portal box

Here is a shot from the backside of the portal, showing the caliper mount in place. If desired, each portal box can carry two caliper mounts and two calipers for maximum braking power, though I will start with one per wheel as I dont think that two will be needed with these large rotors and powerful dual piston calipers.

This shot shows a closeup of the clevis pin end of the caliper mount, with the holes lined up in place ready for the pin.

Another view of the same.

And with the pin in place.

Here is a shot of one of the caliper brackets and the caliper in place on a portal box. One thing NOT shown in these pictures is an outside strap that ties the ends of the caliper slide rails in place. This is probably not needed, but I tend towards overkill. :)

Another view of the caliper mount and caliper in place on the portal box.

Here is a view from the backside of the portal box.

The caliper mount and the disc in place for a fit up. In this shot you can see that the caliper is not yet installed. The discs are 14 inch in diameter, 1-3/16 inches thick and solid steel. You don't want to drop one on your foot.

That's it for this update, I will post more pics as things progress. :)